2020 Volume 36 Issue 6

pH-Sensitive nanoscale materials as robust drug delivery systems for cancer therapy
Shi Zhaoqing , Li Qianqian , Mei Lin
2020, 31(6): 1345-1356  doi: 10.1016/j.cclet.2020.03.001
[Abstract](148) [FullText HTML] [PDF 5442KB](7)
Abstract:
Cancer is one of the diseases that have the highest mortality, which threatens the human health. Chemotherapy functions as the most widely used strategy in clinic to treat cancer, still exists urgent problems, like lacking selectivity and causing severe side effects. According to detailed researches on the metabolism, functions and histology of cancer tissues, many different features of cancer are uncovered, like lower pH in microenvironment, abnormal redox level in intracellular compartments and elevated expression level of several enzymes and receptors. Recently, the development of smart nanoparticles that response to tumor specific microenvironment has lighted up hope for selective cancer therapy. Herein, this review mainly focuses on pH-sensitive nanoscale materials for anti-cancer drug delivery. We summarized the formation progress of acidic tumor microenvironment, the mechanism of pH-responsive drug delivery system and nanomaterials that responsive to acidic pH in tumor microenvironment.
Advances in aggregatable nanoparticles for tumor-targeted drug delivery
Yu Wenqi , Maxim Shevtsov , Chen Xianchun , Gao Huile
2020, 31(6): 1366-1374  doi: 10.1016/j.cclet.2020.02.036
[Abstract](151) [FullText HTML] [PDF 1460KB](5)
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Recent days, aggregatable nanoparticles, which can specifically respond to certain stimulus, have shown great potential in tumor-targeted drug delivery with prolonged retention and deeper penetration. In this review, we summarize recent advances in design of aggregatable nanoparticles by different stimuli. Internal (pH and enzyme) and external (light, temperature and ROS) stimuli are introduced for a comprehensive description. Moreover, the aggregated nanoparticles usually exhibit photothermal, photoacoustic, PET and enhanced MRI contrast, which is also described. In the end, we discuss about the potential applications and challenges for the future clinical translation.
The blooming intersection of transcatheter hepatic artery chemoembolization and nanomedicine
Chen Hu , Cheng Hongwei , Wu Wenying , Li Dengfeng , Mao Jingsong , Chu Chengchao , Liu Gang
2020, 31(6): 1375-1381  doi: 10.1016/j.cclet.2020.03.024
[Abstract](135) [FullText HTML] [PDF 5049KB](2)
Abstract:
Transcatheter hepatic artery chemoembolization (TACE) is a universal treatment for patients with hepatocellular carcinoma (HCC) that inhibits tumor growth by cutting off the blood supply and provides chemotherapeutics locally to the tumor. The strategy of combining TACE formulation with image-guided ablation holds tremendous potential, but patient tolerance and undesired toxicity/immunosuppression remains a challenge. The application of nanotechnology in TACE opens new doors for the treatment of HCC. Strikingly, nanomaterials or nano-drugs dispersed in the TACE formulation can effectively improve the delivery efficiency of drugs by achieving both controlled and continuous release. In addition, the utilization of multifunctional nanoparticles can provide guidance and monitoring for various advanced imaging methods for TACE treatment, and can realize the combination therapy of thermal ablation, microwave ablation, in situ radiotherapy, and other therapies, greatly expanding the therapeutic strategies available for HCC treatment. Here, the current exploration of nanotechnology in TACE of HCC is briefly summarized and the challenges of TACE with nanoformulations for clinical translation are comprehensively discussed.
Nanocomposite hydrogels based on carbon dots and polymers
Sui Bowen , Li Yunfeng , Yang Bai
2020, 31(6): 1443-1447  doi: 10.1016/j.cclet.2019.08.023
[Abstract](129) [FullText HTML] [PDF 3972KB](4)
Abstract:
Nanocomposite hydrogels based on carbon dots (CDs) and polymers have emerged as new materials with integrated properties of individual components, leading to their important applications in the field of soft nanomaterials. This perspective highlights recent advances in the development of nanocomposite hydrogels from CDs and polymers. We review the preparation methods of nanocomposite hydrogels based on CDs and polymers, and emerging applications of these nanocomposite hydrogels such as environmental remediation, energy storage, sensing, drug delivery and bioimaging. We conclude with the discussion of new research directions in the development of new type of nanocomposite hydrogels based on CDs and polymers.
Continuous flow synthesis of porous materials
Xin Yu , Peng Sheng , Chen Junxing , Yang Zujin , Zhang Jianyong
2020, 31(6): 1448-1461  doi: 10.1016/j.cclet.2019.09.054
[Abstract](141) [FullText HTML] [PDF 1661KB](5)
Abstract:
Porous materials play an important role in chemical catalysis, separation and other industrial applications. High-efficiency preparation of porous materials has become an active research area. Conventional synthesis of porous materials has been dominated by one-pot solution processing conditions carried out by bulk mixing under conventional electric heating via hydrothermal, solvothermal or ionothermal reactions where high temperatures and pressures are the standard. Continuous flow synthesis has many key advantages in terms of efficient mass and heat transfer, precise control of residence times, improved opportunities for automation and feedback control of synthesis, scaling-up reactions and improved safety parameters compared to above mentioned conventional batch scale synthetic methods. In this review, continuous flow synthesis of various crystalline porous materials such as metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), porous organic cages and zeolites is discussed. Combination of microfluidic methods with other techniques are also shown including various heating ways and various methods of substrate adding.
Research progress of graphene-based nanomaterials for the environmental remediation
Pan Xiaoru , Ji Jiahui , Zhang Nana , Xing Mingyang
2020, 31(6): 1462-1473  doi: 10.1016/j.cclet.2019.10.002
[Abstract](139) [FullText HTML] [PDF 7532KB](4)
Abstract:
Graphene is a two-dimensional nanomaterial with huge surface area, high carrier mobility and high mechanical strength. Because of its great potential in nanotechnology and environmental protection, it has attracted much attention in environmental and energy fields since its discovery in 2004. Although graphene is a star material, many reviews have introduced its use in terms of energy, the research progress in the field of environment, especially water pollution control, has been rarely reported. Here, we review exhaustively the research progress of graphene-based materials in environmental pollution remediation in the past ten years. Firstly, the advantages and classification of graphene were introduced. Secondly, the research progress and main achievements of graphene and its composites in the fields of photocatalytic degradation, pollutant adsorption and water treatment were emphatically described, and the mechanism of action in the above fields was summarized. Finally, we discuss the problems existing in the preparation and summarize the application of graphene in the environment.
Electrode materials derived from plastic wastes and other industrial wastes for supercapacitors
Utetiwabo Wellars , Yang Le , Tufail Muhammad Khurram , Zhou Lei , Chen Renjie , Lian Yimeng , Yang Wen
2020, 31(6): 1474-1489  doi: 10.1016/j.cclet.2020.01.003
[Abstract](129) [FullText HTML] [PDF 5479KB](2)
Abstract:
The present review not only devotes on the environmental consequences of plastic bag wastes and other industrial wastes observable in the landfills, in the oceans or elsewhere but also gives a new insight idea on conversion of them into worth material, carbon, for the best electrochemical supercapacitor. Transformation of plastic wastes into high-value materials is the incentive for plastic recycling, end-of-life handling case for plastic bag wastes in practice quite limited. The plastic recycling waste for reuse saves energy compared with manufacturing virgin materials. Herein, we identified several synthetic methods to convert plastic waste and other industrial wastes into carbon material for supercapacitor. Different kinds of carbon materials, including nanofiber, nanotube, graphene, mesoporous carbon, etc., have been derived from plastic waste, and thus give a superior potential for transforming trash into a "gold capacitor". Finally, conclusions and future trends of high-voltage supercapacitors were made as well as the easy and mass production of high-performance electrode materials for supercapacitors. Our work offers a promising sustainable approach to handle plastic bags, waste, and other industrial wastes and provides a new avenue in supercapacitor applications and other areas.
FRET-based polymer materials for detection of cellular microenvironments
Weng Chuang , Fan Nianqing , Xu Taoran , Chen Haodong , Li Zifen , Li Yiwen , Tan Hong , Fu Qiang , Ding Mingming
2020, 31(6): 1490-1498  doi: 10.1016/j.cclet.2019.11.009
[Abstract](134) [FullText HTML] [PDF 8506KB](2)
Abstract:
Effective detection of cellular microenvironments and understanding of physiological activities in living cells remain a considerable challenge. In recent years, fluorescence (or Förster) resonance energy transfer (FRET) technology has emerged as a valuable method for real-time imaging of intracellular environment with high sensitivity, specificity and spatial resolution. Particularly, polymer-based imaging systems show enhanced stability, improved biodistribution, increased dye payloads, and amplified signal/noise ratio compared with small molecular sensors. This review summarizes the recent progress in FRET-based polymeric systems for probing the physiological environments in cells.
A nanocarrier based on poly(D, L-lactic-co-glycolic acid) for transporting Na+ and Cl- to induce apoptosis
Ma Chen , Zhang Yida , Jiao Zhijuan , Ma Chunmeng , Liu Xiaoyan , Zhang Haixia
2020, 31(6): 1635-1639  doi: 10.1016/j.cclet.2019.09.010
[Abstract](135) [FullText HTML] [PDF 4213KB](3)
Abstract:
Transmembrane anion transporters have attracted significant attention as therapeutic agents because of their potential to disrupt cellular ion homeostasis, in which, most of the synthetic anionic transporters are organic small molecules whose synthesis routes are usually complex and tedious, and the related biological research is also only in infancy. Hence, we synthesized a kind of chloride anion (Cl-) and sodium cation (Na+) nanocarrier based on poly(D, L-lactic-co-glycolic acid) (PLGA) which was coated with polydopamine (PDA) to provide target release factor. When the nanocarrier arrives in acidic environment such as lysosomes through endocytosis, Cl- and Na+ will be released fast from the nanocarrier resulting in imbalance of cell homeostasis for inducing apoptosis. Cell experiments show that the nanocarrier promotes apoptosis and leads to an increased concentration of reactive oxygen species. By exploring the concentration of cytochrome c in mitochondria and cytoplasm and the activities of key enzymes caspase-9 and caspase-3 in apoptosis process, it is proved that the apoptotic pathway is caspase-dependent. This novel strategy allows the research of anion transporter no longer limited to artificial synthesis of small molecular and provides a novel and effective direction to investigate ion homeostasis, ion transport and cancer treatment.
Different defect morphologies in polyethylene crystal induced by surface physicochemical properties
Yaqi Hou , Yi Ye , Zhongjie Du , Chen Zhang , Jianguo Mi , Xu Hou
2020, 31(6): 1640-1643  doi: 10.1016/j.cclet.2019.07.054
[Abstract](144) [FullText HTML] [PDF 3223KB](1)
Abstract:
The physicochemical properties of surfaces have a great effect on the micro-morphologies of the crystal structures which are in contact with them. Understanding the interaction mechanism between the internal driving forces of the crystal and external inducing forces of the surfaces is the prerequisite of controlling and obtaining the desirable morphologies. In this work, the dynamic density functional theory was applied to construct the free energy functional expression of polyethylene (PE) lattice, and the micro-dynamic evolution processes of PE lattice morphology near the surfaces with different properties were observed to reveal the interaction mechanism at atomic scale. The results showed that the physical and chemical properties of the external surfaces synergistically affect the morphologies in both the defect shapes and the distribution of the defect regions. In the absence of the contact surfaces, driven by the oriented interactions among different CH2 groups, PE lattices gradually grow and form a defect-free structure. Conversely, the presence of contact surfaces leads to lattice defects in the interfacial regions, and PE lattice shows different self-healing abilities around different surfaces.
Peony pollen derived nitrogen-doped activated carbon for supercapacitor application
Liu Yiming , An Zhongxun , Wu Mingxia , Yuan Anbao , Zhao Hongbin , Zhang Jiujun , Xu Jiaqiang
2020, 31(6): 1644-1647  doi: 10.1016/j.cclet.2019.08.005
[Abstract](128) [FullText HTML] [PDF 2289KB](2)
Abstract:
Peony pollen is a cheap and readily available biomass material with a relatively high protein content. In this work, it was employed as an N-rich precursor to prepare the nitrogen-doped porous carbon for supercapacitor application. The porous carbon microspheres were prepared through a hydrothermal method and subsequent carbonization process. Notably, ammonium borofruoride and potassium hydroxide were employed respectively as an etchant and an activator to modify the porosity of the materials. The as prepared ANPPCs-700 has a super high BET specific surface area of 824.69 m2/g. The microstructure, chemical state and electrochemical properties of the product were investigated in detail. The prepared nitrogen-doped carbon microspheres exhibits excellent specific capacity of 209 F/g at a current density of 1 A/g and remained 92.5% of the initial capacitance after 5000 deep cycles at 5 A/g.
Functional groups to modify g-C3N4 for improved photocatalytic activity of hydrogen evolution from water splitting
Yu Fan , Wang Laichun , Xing Qiuju , Wang Dengke , Jiang Xunheng , Li Guangchao , Zheng Anmin , Ai Fanrong , Zou Jian-Ping
2020, 31(6): 1648-1653  doi: 10.1016/j.cclet.2019.08.020
[Abstract](131) [FullText HTML] [PDF 5470KB](3)
Abstract:
Rational modification by functional groups was regarded as one of efficient methods to improve the photocatalytic performance of graphitic carbon nitride (g-C3N4). Herein, g-C3N4 with yellow (Y-GCN) and brown (C-GCN) were prepared by using the fresh urea and the urea kept for five years, respectively, for the first time. Experimental results show that the H2 production rate of the C-GCN is 39.06 μmol/h, which is about 5 times of the Y-GCN. Meantime, in terms of apparent quantum efficiency (AQE) at 420 nm, C-GCN has a value of 6.3% and nearly 7.3 times higher than that of Y-GCN (0.86%). The results of XRD, IR, DRS, and NMR show, different from Y-GCN, a new kind of functional group of —N=CH— was firstly in-situ introduced into the C-GCN, resulting in good visible light absorption, and then markedly improving the photocatalytic performance. DFT calculation also confirms the effect of the —N=CH— group band structure of g-C3N4. Furthermore, XPS results demonstrate that the existence of —N=CH— groups in C-GCN results in tight interaction between C-GCN and Pt nanoparticles, and then improves the charge separation and photocatalytic performance. The present work demonstrates a good example of "defect engineering" to modify the intrinsic molecular structure of g-C3N4 and provides a new avenue to enhance the photocatalytic activity of g-C3N4 via facile and environmental-friendly method.
Bio-safety assessment of carbon quantum dots, N-doped and folic acid modified carbon quantum dots: A systemic comparison
Zhang Shu , Pei Xibo , Xue Yiyuan , Xiong Jingyuan , Wang Jian
2020, 31(6): 1654-1659  doi: 10.1016/j.cclet.2019.09.018
[Abstract](135) [FullText HTML] [PDF 6145KB](1)
Abstract:
The carbon quantum dots (CQDs) and their functionalized materials are promising in biomedical field because of their unique properties; meanwhile, a growing concern has been raised about the potential toxicity of these modified materials in biosystem. In this study, we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs (NCQDs) and folic acid-modified CQDs (FA-CQDs), and compared the toxicity and biocompatibility with each other in vitro and in vivo. L929, C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro. No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL. Among these materials, the FA-CQDs show a much lower toxicity. Moreover, in vivo toxicity studies were performed on the nude mice for 15 days. The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution (PBS) after 15 days. The results of the multifarious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration. Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.
New antituberculosis drugs targeting the respiratory chain
Li Qian , Lu Xiaoyun
2020, 31(6): 1357-1365  doi: 10.1016/j.cclet.2020.04.007
[Abstract](127) [FullText HTML] [PDF 3882KB](1)
Abstract:
With the emergence of multidrug-resistant tuberculosis and extensive drug-resistant tuberculosis strains, there is an urgent need to develop novel drugs for the treatment of tuberculosis. The respiratory chain is a promising target for the development of new antimycobacterial agents, and a growing number of compounds have been reported and some have entered clinical trials. In this review, we summarize the main features and the electron transfer process of the mycobacterial respiratory chain, and the recent progress in the search for new small molecule inhibitors targeting the three main potential targets in the respiratory chain of Mycrobacterium tuberculosis. Our emphasis is on the optimization strategy of QcrB inhibitors and the challenges of developing QcrB inhibitors as antituberculosis drugs due to the alternate bd-type oxidase oxidative compensation pathway are discussed.
Dynamic dispersion stability of graphene oxide with metal ions
He Yinghui , Liu Yingjun , Guo Fan , Pang Kai , Fang Bo , Wang Ya , Chang Dan , Xu Zhen , Gao Chao
2020, 31(6): 1625-1629  doi: 10.1016/j.cclet.2019.10.010
[Abstract](124) [FullText HTML] [PDF 4083KB](1)
Abstract:
Graphene oxide (GO), an important chemical precursor of graphene, can stably disperse in aqueous surrounding and undergo aggregation as metal cations introduced. The usual instability of GO with ions is caused by the shielding effect of ions and crosslinking between GO and ions. However, the dynamic stability of GO under ions exchange still remains unclear. Here, we investigated the dynamic dispersion stability of GO with metal ions and observed a redispersion behavior in concentrated Fe3+ solution, other than permanent aggregation. The exchange with Fe3+ ions drives the reversion of zeta (ζ) potential and enables the redispersion to individual GO-Fe3+ complex sheets, following a dynamic electric double layer (EDL) mechanism. It is found that the specifically strong electrostatic shielding effect and coordination attraction between Fe3+ and functional oxygen groups allows the selective redispersion of GO in concentrated Fe3+ solution. The revealed dynamic dispersion stability complements our understanding on the dispersive stability of GO and can be utilized to fabricate graphene-metal hybrids for rich applications.
Polymer hydrogel confined palladium nanoparticles as recyclable catalysts for Suzuki and Heck cross-coupling reactions
Zhan Kan , Lu Ping , Dong Jian , Hou Xu
2020, 31(6): 1630-1634  doi: 10.1016/j.cclet.2019.09.006
[Abstract](129) [FullText HTML] [PDF 1529KB](2)
Abstract:
Reusable palladium nanoparticles highly dispersed in porous and hydrophilic interpenetrating polymer networks (IPN), i.e., Pd@IPN hybrid gels, are employed for catalysis of Suzuki and Heck coupling reactions. Good yields are obtained with high turnover frequencies when the reactions are run with very low Pdloadings. The use of IPN gives better recyclability than that of crosslinked polyvinyl alcohol alone. The polymer networks allow the reactants to have easy access to the Pd metals. The catalysts combine high activity with the reusability offered by the heterogeneous system, without the need for strong coordination or chelating ligands.
Tumor-homing peptide-based NIR-II probes for targeted spontaneous breast tumor imaging
Zhou Hui , Li Shanshan , Zeng Xiaodong , Zhang Mengxian , Tang Lin , Li Qianqian , Chen Deliang , Meng Xianli , Hong Xuechuan
2020, 31(6): 1382-1386  doi: 10.1016/j.cclet.2020.04.030
[Abstract](144) [FullText HTML] [PDF 3990KB](2)
Abstract:
Fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) is a promising modality for real-time imaging of cancer and image-guided surgery with superior in vivo optical properties. So far, very few NIR-II fluorophores have been reported for in vivo biomedical imaging of chemically-induced spontaneous breast carcinoma. Herein, a NIR-II fluorescent probe CH1055-F3 with the nucleolin-targeted tumor-homing peptide F3 was demonstrated to preferentially accumulate in 4T1 tumors. More importantly, CH1055-F3 exhibited specific NIR-II signals with high spatial and temporal resolution, strong tumor uptake, and remarkable NIR-II image-guided surgery in dimethylbenzan-thracene (DMBA)-induced spontaneous breast tumor rats. This report presents the first tumor-homing peptide-based NIR-II probe to diagnose transplantable and spontaneous breast tumors by the active targeting.
Design of high stability thin-film transistor biosensor for the diagnosis of bladder cancer
Li Yingxue , Zeng Bo , Yang Yujie , Liang Huageng , Yang Yanbing , Yuan Quan
2020, 31(6): 1387-1391  doi: 10.1016/j.cclet.2020.03.043
[Abstract](155) [FullText HTML] [PDF 6041KB](6)
Abstract:
Bladder cancer is the most common malignant tumor in the urinary system, with high morbidity, mortality and recurrence after surgery. However, current bladder cancer urine diagnosis methods are limited by the low accuracy and specificity due to the low abundance of bladder cancer biomarkers in the urine with complex biological environments. Herein, we present a high stability indium gallium zinc oxide field effect transistor (IGZO-FET) biosensor for efficient identification of bladder cancer biomarkers from human urine samples. The recognition molecular functionalized IGZO-FET biosensor exhibits stable electronic and sensing performance due to the large-area fabrication of IGZO thin-film FET. Owing to the excellent electrical performance of IGZO-FET, the IGZO-FET biosensor exhibits high sensitivity and extremely low detection limit (2.7 amol/L) towards bladder cancer biomarkers. The IGZO-FET biosensor is also able to directly detect bladder tumor biomarker in human urine with high sensitivity and specificity, and could differentiate bladder cancer patients' urine samples from healthy donors effectively. These results indicate that our designed high-performance biosensor shows great potential in the application of portable digital bladder cancer diagnosis devices.
In-situ conversion of Ni2P/rGO from heterogeneous self-assembled NiO/rGO precursor with boosted pseudocapacitive performance
Song Ge , Yi Zonglin , Xie Lijing , Bi Zhihong , Li Qian , Chen Jingpeng , Kong Qingqiang , Chen Chengmeng
2020, 31(6): 1392-1397  doi: 10.1016/j.cclet.2020.03.046
[Abstract](137) [FullText HTML] [PDF 5920KB](3)
Abstract:
Two-dimensional (2D) heterostructural Ni2P/rGO is successfully fabricated by in-situ phosphating selfassembled NiO/rGO composites and shows the enhanced electrochemical performances. In this design, the rGO sheets effectively reduce the lattice strain created during the phase transformation from NiO to Ni2P, thereby maintaining ultrathin nanostructures of Ni2P. The resulting Ni2P/rGO layered heterostructure gives the composite plenty of pores or channels, good electrical conductivity and well-exposed active sites. Density functional theory (DFT) calculation further demonstrates that the Fermi energy level and electron localize of near Ni atoms in Ni2P is higher than that of NiO, which endow Ni2P with faster and more reversible redox reactivity in dynamic. Benefiting from their structural and compositional merits, the as-synthesized Ni2P/rGO exhibits high specific discharge capacity and excellent rate performance. Furthermore, a hybrid supercapacitor built with Ni2P/rGO and activated carbon shows a high specific energy of 38. 6 Wh/kg at specific power of 375 W/kg.
Ferriporphyrin-inspired MOFs as an artificial metalloenzyme for highly sensitive detection of H2O2 and glucose
Chen Jiajia , Gao Huajian , Li Zhihao , Li Yingxue , Yuan Quan
2020, 31(6): 1398-1401  doi: 10.1016/j.cclet.2020.03.052
[Abstract](119) [FullText HTML] [PDF 3174KB](4)
Abstract:
Metalloenzymes which employ metal species and organic ligands as central active sites play significant roles in various biological activities. Development of artificial metalloenzymes can help to understand the related physiological mechanism and promote the applications of metalloenzymes in biosynthesis, energy conversion and biosensing. In this work, inspired by the active sites of ferriporphyrin-based metalloenzymes, Fe-MOFs by using ferric as the metal center and a porphyrin analog as the organic ligand were developed as an artificial metalloenzyme. The Fe-MOFs exhibit high peroxidase-like catalytic activity with excellent long-term stability. Moreover, highly sensitive biosensors were built to detect H2O2 and glucose based on the Fe-MOFs. Such MOFs-based artificial metalloenzyme offers an efficient strategy for the development of highly stable and efficient metalloenzymes, showing great potential in catalysis, energy transfer, biosensing and medical diagnosis.
Insights into bishemicyanines with long emission wavelengths and high sensitivity in viscous environments
Cao Jianfang , Sun Wen , Fan Jiangli
2020, 31(6): 1402-1405  doi: 10.1016/j.cclet.2019.10.006
[Abstract](132) [FullText HTML] [PDF 2063KB](1)
Abstract:
A systematic spectral analysis was presented for bishemicyanine dyes (Hsd and D2) and monohemicyanine dyes (Hs and DSMI). The bishemicyanine dyes displayed long emission wavelengths, large Stokes shifts, low background quantum yields in aqueous solutions and high sensitivity in viscous environments. Better understanding of the structure-property relationships could benefit the design of improved dyes. Computational studies on these dyes revealed the three conjugated forms of bishemicyanines are in equilibrium due to two positive charges and a branched bulk substituent. Bishemicyanines possessed obviously lower rotating energy barrier of C-C bond rotation compared to the monohemicyanine dyes. Moreover, the synergetic effects of the rotation about the ϕ4 bond, ϕ5 bond and ϕ7 bond of the bishemicyanines (Hsd and D2) lead to lower fluorescence quantum yields in a free state and larger fluorescence quantum yield enhancements in viscous environment compared to that of monohemicyanine dyes (Hs and DSMI). The results demonstrate a foundation for interpretation of the behavior of the dyes, thus providing guidelines for future of new bishemicyanine fluorophores with specific applications.
Anti-inflammatory spirobisnaphthalene natural products from a plant-derived endophytic fungus Edenia gomezpompae
Tan Yingzi , Guo Zhikai , Zhu Mengyue , Shi Jing , Li Wei , Jiao Ruihua , Tan Renxiang , Ge Huiming
2020, 31(6): 1406-1409  doi: 10.1016/j.cclet.2020.03.059
[Abstract](138) [FullText HTML] [PDF 1556KB](1)
Abstract:
Spirobisnaphthalenes comprise a relatively rare family of natural products that are normally isolated from fungi and occasionally from plants. Here we reported the discovery of seven new preussomerintype spirobisnaphthalenes, preussomerins YT1-YT7 (1-7), and seven known ones (8-14), from the endophytic fungus Edenia gomezpompae, enriching the structural diversity of this family of natural products. Their structures were established by 1D and 2D NMR spectroscopy, HRESIMS analysis and comparison with previously reported compounds, with the absolute configurations of compounds 1 and 2 being further confirmed by single-crystal X-ray diffraction using Cu Kα radiation. The antiinflammatory activities of all isolates were assessed by measuring the production of NO in LPS-induced RAW264.7 macrophage cells. Among them, compounds 8 and 13 exhibited potent inhibitory activities on the production of NO, with IC50 values of 2.61 and 1.32 μmol/L, respectively.
Unveiling the secondary pollution in the catalytic elimination of chlorinated organics: The formation of dioxins
Liu Jiajia , Dai Xiaoxia , Wu Zhongbiao , Weng Xiaole
2020, 31(6): 1410-1414  doi: 10.1016/j.cclet.2020.03.056
[Abstract](122) [FullText HTML] [PDF 3988KB](1)
Abstract:
Since the discovery of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the process of municipal solid waste incineration (MSWI), a large number of researches have been conducted to reveal their formation mechanisms and emission characteristics. As one of national priority control pollutants, chlorinated organics are inclined to transfer into PCDD/Fs in the heterogeneously catalyzed process, which has been considered to be one of great challenges in environmental catalysis. However, so far direct evidences to support such a conversion process are insufficient, and the reaction mechanisms are lack of exploration. This study investigated the catalytic elimination of chlorobenzene (CBz) over a range of industrially applied active species including Pt, Ru, V, Ce and Mn oxides, and explored their reaction byproducts, chlorine adsorption/desorption behaviors and PCDD/F formations. We found that all of these species could generate the PCDD/Fs, amongst which, Mn species were the most active for PCDD/F formation. Approximately 140 ng I-TEQ g-1 PCDD/Fs were detected on the Mn-CNTsurface after ageing at 250 ℃ for 30 h. Even using the dichloromethane (DCM) as a precursor, significant PCDD/Fs were still detected. The Ru and V species were shown to generate much less polychlorinated byproducts and PCDD/Fs, owning to their sufficiently high abilities in Cl desorption, which were through the semi-Deacon and Brønsted H reactions, respectively.
Bi/Bi2O3 nanoparticles supported on N-doped reduced graphene oxide for highly efficient CO2 electroreduction to formate
Sun Junjie , Zheng Wanzhen , Lyu Siliu , He Feng , Yang Bin , Li Zhongjian , Lei Lecheng , Hou Yang
2020, 31(6): 1415-1421  doi: 10.1016/j.cclet.2020.04.031
[Abstract](136) [FullText HTML] [PDF 8079KB](5)
Abstract:
Electrocatalytic CO2 reduction (CO2ER) into formate is a desirable route to achieve efficient transformation of CO2 to value-added chemicals, however, it still suffers from limited catalytic activity and poor selectivity. Herein, we develop a hybrid electrocatalyst composed of bismuth and bismuth oxide nanoparticles (NPs) supported on nitrogen-doped reduced graphene oxide (Bi/Bi2O3/NrGO) nanosheets prepared by a combined hydrothermal with calcination treatment. Thanks to the combination of undercoordinated sites and strong synergistic effect between Bi and Bi2O3, Bi/Bi2O3/NrGO-700 hybrid displays a promoted CO2ER catalytic performance and selectivity for formate production, as featured by a small onset potential of -0.5 V, a high current density of -18 mA/cm2, the maximum Faradaic efficiency of 85% at -0.9 V, and a low Tafel slope of 166 mV/dec. Experimental results reveal that the higher CO2ER performance of Bi/Bi2O3/NrGO-700 than that of Bi NPs supported on NrGO (Bi/NrGO) can be due to the partial reduction of Bi2O3 NPs into Bi, which significantly increases undercoordinated active sites on Bi NPs surface, thus boosting its CO2ER performance. Furthermore, a two-electrode device with Ir/C anode and Bi/Bi2O3/NrGO-700 cathode could be integrated with two alkaline batteries or a planar solar cell to achieve highly active water splitting and CO2ER.
Discovery of a novel sodium taurocholate cotransporting polypeptide (NTCP) inhibitor: Design, synthesis, and anti-proliferative activities
Xiang Honggang , Chen Yanmei , Zhang Jifa , Zhang Jin , Pan Dabo , Liu Bo , Ouyang Liang
2020, 31(6): 1422-1426  doi: 10.1016/j.cclet.2020.03.017
[Abstract](131) [FullText HTML] [PDF 4994KB](2)
Abstract:
Sodium taurocholate cotransporting polypeptide (NTCP) is identified as the functional receptor for HBV entry, which is responsible for upregulated HBV transcription in the HBV life cycle. Besides, NTCP is also implicated in the progression of HBV-induced hepatocellular carcinoma (HCC). Thereby, NTCP-targeting entry inhibitors are proposed to suppress HBV infection and replication in HBV-induced hepatoma therapy. Herein, we integrated in silico screening and chemical synthesis to obtain a small-molecule NTCP inhibitor B7, which exhibited moderate anti-proliferative activities against HepG2 cells and anti-HBV activity in vitro. Additionally, CETSA assay, molecular docking, and MD simulation validated that B7 could bind to NTCP. Furthermore, western blot analysis demonstrated that B7 induced apoptosis with an increased expression of Bax and caspase 3 cleaving as well as a decreasing expression of Bcl-2 in HepG2 cells. Taken together, our study identified B7 as a novel NTCP inhibitor with anti-proliferation activities which might provide a new opportunity for HCC therapy.
Preparation of poly(glutamic acid) shielding micelles self-assembled from polylysine-b-polyphenylalanine for gene and drug codelivery
Ma Jing , Zhang Jingpeng , Chi Lin , Liu Chong , Li Yanhui , Tian Huayu
2020, 31(6): 1427-1431  doi: 10.1016/j.cclet.2020.02.034
[Abstract](128) [FullText HTML] [PDF 4517KB](2)
Abstract:
A novel amphiphilic cationic block copolymer polylysine-b-polyphenylalanine (PLL-b-PPhe) was synthesized and self-assembled into micelles in aqueous solution, then shielded with poly(glutamic acid) (marked as PG/PLL-b-PPhe) to codeliver gene and drug for combination cancer therapy. Here, doxorubicin (DOX) was selected to be loaded into PLL-b-PPhe micelles and the drug loading efficiency was 8.0%. The drug release studies revealed that the PLL-b-PPhe micelles were pH sensitive and the released DOX could reach to 53.0%, 65.0%, 72.0% at pH 7.4, 6.8 and 5.0, respectively. In order to reduce positive charge and cytotoxicity of PLL-b-PPhe micelles, PG was used as shelding, simultaneously condensed with Bcl2 siRNA to form gene carrier system. Compared with PEI, PG/PLL-b-PPhe had excellent gene transfection efficiency, especially when the molar ratio of PLL to PPhe was 30:60 and the mixed mass ratio of PLL-b-PPhe to gene was 5:1. More importantly, DOX and Bcl2 siRNA gene codelivery system displayed remarkable cytotoxicity against B16F10 cells. Confocal laser scanning microscopy (CLSM) and flow cytometry were used to characterize endocytosis of the codelivery system, and confirmed that both DOX and Bcl2 siRNA had been endocytosed into B16F10 cells. The above results indicated that gene and drug codelivery was a promising strategy in future cancer therapy.
Comparative study on ciprofloxacin removal in sulfur-mediated biological systems
Zhang Huiqun , Song Shiliu , Sun Lianpeng , Zhao Qing , Lu Hui
2020, 31(6): 1432-1437  doi: 10.1016/j.cclet.2020.04.048
[Abstract](118) [FullText HTML] [PDF 7037KB](2)
Abstract:
The removal of ciprofloxacin (CIP) in sulfur-mediated bioprocesses, e.g., sulfate-reducing bacteria (SRB)-mediated process and sulfur-oxidizing bacteria (SOB)-mediated process, was examined for the first time. The results showed that the SRB-mediated process had more efficient CIP removal than that in SOB-mediated process. Adsorption was the primary removal pathway of CIP in SRB-mediated process and SOB-mediated process with the specific adsorption removal rate of 131.4±1.1 μg/g-SS/d and 30.1±1.4 μg/g-SS/d, respectively, at influent CIP concentration of 500 μg/L. In addition, extracellular polymeric substances (EPS) also played an important role on CIP migration and removal in both types of sludge. Further study was conducted to specify the different adsorption of CIP in these two sludge systems from the perspective of sludge properties. The results indicated that there are more potential adsorption sites exist on the SRB-mediated sludge for CIP adsorption than SOB-mediated sludge since the higher protein (PN) content and more kinds of aromatic amino acid substances in EPS, more negative zeta-potential and stronger and more numbers of functional groups in SRB-mediated sludge compared to SOB-mediated sludge. The findings of this study provide insights into the sludge properties affecting CIP removal in sulfur-mediated bioprocesses, and are of guiding significance to employ sulfur-mediated biological systems for treating CIP-containing wastewaters.
Nitrogen-doped carbon nanotube-encapsulated nickel nanoparticles assembled on graphene for efficient CO2 electroreduction
Wang Tingting , Yang Jian , Chen Jiayi , He Qinggang , Li Zhongjian , Lei Lecheng , Lu Jianguo , Leung Michael K. H. , Yang Bin , Hou Yang
2020, 31(6): 1438-1442  doi: 10.1016/j.cclet.2020.04.056
[Abstract](122) [FullText HTML] [PDF 4650KB](1)
Abstract:
Exploring 3D hybrid nanocarbons encapsulated with metal nanoparticles (NPs) are recently considered as emerging catalysts for boosting CO2 electroreduction reaction (CRR) under practical and economic limits. Herein, we report a one-step pyrolysis strategy for fabricating N-doped carbon nanotube (CNT)-encapsulated Ni NPs assembled on the surface of graphene (N/NiNPs@CNT/G) to efficiently convert CO2 into CO. In such 3D hybrid, the particle size of Ni NPs that coated by five graphitic carbon layers is less than 100 nm, and the amount of N dopants introduced into graphene with countable CNTs is determined to 7.27 at%. Thanks to unique CNT-encapsulated Ni NPs structure and N dopants, the achieved N/NiNPs@CNT/G hybrid displays an exceptional CRR activity with a high Faradaic efficiency of 97.7% and large CO partial current density of 7.9 mA/cm2 at -0.7 V, which outperforms those reported metallic NPs loaded carbon based CRR electrocatalysts. Further, a low Tafel slope of 134 mV/dec, a turnover frequency of 387.3 CO/h at -0.9 V, and tiny performance losses during long-term CRR operation are observed on N/NiNPs@CNT/G. Experimental observations illustrate that the Ni NPs encapsulated by carbon layers along with N dopants are of great importance in the conversion of CO2 into CO with high current density.
Facile scalable one-step wet-spinning of surgical sutures with shape memory function and antibacterial activity for wound healing
Chen Xinghan , Tan Pengfei , Wen Ya , Zhou Wencheng , Cen Ying , You Chao , Tan Lin , Tian Meng
2020, 31(6): 1499-1503  doi: 10.1016/j.cclet.2019.11.006
[Abstract](123) [FullText HTML] [PDF 9640KB](2)
Abstract:
Surgical suture is commonly used in clinic due to its action in accelerating the process of wound healing. However, difficultly handling in minimally invasive surgery and bacteria-induced infection usually limit its use in a wide range of applications. Here, we report a facile scalable strategy to fabricate surgical sutures with shape memory function and antibacterial activity for wound healing. Specifically, a shape memory polyurethane (SMPU) with a transition temperature (Ttrans) at 41.3 ℃ was synthesized by adjusting the mole ratio of the hard/soft segment, and then the shape memory surgical sutures containing polyhexamethylene biguanide hydrochloride (PHMB) as a model drug for antibacterial activity were fabricated by a facile scalable one-step wet-spinning approach, in which PHMB was directly dissolved in the coagulation bath that enable its loading into the sutures through the dual diffusion during the phase separation. The prepared sutures were characterized by their morphology, mechanical properties, shape memory, antibacterial activity, as well as biocompatibility before the wound healing capability was tested in a mouse skin suture-wound model. It was demonstrated that the optimized suture is capable of both shape memory function and antibacterial activity, and promote wound healing, suggesting that the facile scalable one-step wet-spinning strategy provides a promising tool to fabricate surgical sutures for wound healing.
Fluorescence detection of Escherichia coli on mannose modified ZnTe quantum dots
Wu Dudu , Wang Dongming , Ye Xiaomei , Yuan Kangrui , Xie Yuling , Li Baohong , Huang Chaobo , Kuang Tairong , Yu Zhiqiang , Chen Zhi
2020, 31(6): 1504-1507  doi: 10.1016/j.cclet.2019.11.029
[Abstract](117) [FullText HTML] [PDF 1119KB](3)
Abstract:
Rapid detection and identification of Escherichia coli (E. coli) is essential to prevent its quickly spread. In this study, a novel fluorescence probe based on ZnTe quantum dots (QDs) modified by mannose (MAN) had been prepared for the determination of E. coli. The results showed that the obtained QDs showed excellent selectivity toward E. coli, and presented a good linearity in range of 1.0×105~1.0×108 CFU/mL. The optimum fluorescence intensity for detecting E. coli was found to be at pH 7.0 with a temperature of 25 ℃ and incubation time of 20 min. Under these optimum conditions, the detection limit of E. coli was 4.6×104 CFU/mL. The quenching was discussed to be a static quenching procedure, which was proved by the quenching efficiency of QDs decreased with the temperature increasing.
A ratiometric merocyanine-based fluorescent probe for detecting hydrazine in living cells and zebra fish
Han Jinliang , Yue Xiuxiu , Wang Jingpei , Zhang Yun , Wang Benhua , Song Xiangzhi
2020, 31(6): 1508-1510  doi: 10.1016/j.cclet.2020.01.029
[Abstract](121) [FullText HTML] [PDF 4829KB](1)
Abstract:
We developed a merocyanine-based fluorescent probe, NEPB, for tracing hydrazine (N2H4) in a ratiometric manner with large Stokes shifts and long emission wavelength. The fluorescence color of probe NEPB changed from green to yellow upon addition of hydrazine. Probe NEPB displayed high selectivity and sensitivity to hydrazine in solution, and could ratiometrically monitor N2H4 in living cells and zebrafish with low cytotoxicity.
Efficient antimicrobial properties of layered double hydroxide assembled with transition metals via a facile preparation method
Li Mengxue , Li Li , Lin Sijie
2020, 31(6): 1511-1515  doi: 10.1016/j.cclet.2019.09.047
[Abstract](147) [FullText HTML] [PDF 3138KB](1)
Abstract:
Mg2+ in MgAl-layered double hydroxides nanoparticles was substituted with different divalent transition metal ions (MAl-LDHs, M:Mg2+, Cu2+, Ni2+, Co2+, and Mn2+) via a facile method to be used as antibacterial agents. The phase structural and morphological characterizations of MAl-LDHs were investigated by XRD, FTIR spectroscopy and TEM. The results have shown that all of MAl-LDHs had typical layered structures except MnAl-LDH which contained Mn3O4 phases. Particular morphology of MnAl-LDH with ellipsoids, spherical and rod-like structure and CuAl-LDH with rod-like shape existed. IC50 (the concentrations providing 50% antibacterial activity) values of CuAl-LDH, NiAl-LDH, CoAl-LDH, and MnAl-LDH in broth dilution tests were ~800-1500 μg/mL. Dosages of CuAl-LDH, CoAl-LDH, and MnAl-LDH with >10 mm inhibition zone in disk diffusion tests were ~150-300 μg/disk. Antibacterial mechanism of MAl-LDHs may be attributed to the synergistic factors including effected surroundings, surface interactions, morphology of particles, ROS and metal ions. The results indicate a facile method to synthesis LDHs based effective antibacterial agents with the potential application in the area of water treatment and antibacterial coating.
Cascaded electron transition in CuWO4/CdS/CDs heterostructure accelerating charge separation towards enhanced photocatalytic activity
Chen Yibo , Li Jing-Feng , Liao Pei-Yu , Zeng Ying-Shan , Wang Zhu , Liu Zhao-Qing
2020, 31(6): 1516-1519  doi: 10.1016/j.cclet.2019.12.013
[Abstract](122) [FullText HTML] [PDF 5212KB](2)
Abstract:
CuWO4, as an n-type oxide semiconductor with a bandgap of 2.2 eV, has stimulated enormous interest as a potential broad-spectrum-active photocatalyst for environmental pollution remediations. However, rapid charge recombination greatly hinders its practical applications. Herein, we present a cascaded electron transition pathway in a ternary heterostructure consisting of CdS quantum dots, carbon dots (CDs) and CuWO4 hollow spheres, which proves to greatly facilitate the photogenerated electron-hole separation, and eventually boosts the degradation efficiency of phenol and congo red by 100% and 46% compared to bare CuWO4. The enhanced performance of the CuWO4/CdS/CDs heterostructure mainly originates from the unidirectional electron migration from CdS to CuWO4 and then to the organics through CDs. This work elucidates the electron transfer kinetics in multi-phase system and provides a new design paradigm for optimizing the properties of CuWO4 based photocatalysts.
TEMPO visible light photocatalysis: The selective aerobic oxidation of thiols to disulfides
Xu Hui , Zhang Yu-Fei , Lang Xianjun
2020, 31(6): 1520-1524  doi: 10.1016/j.cclet.2019.10.024
[Abstract](125) [FullText HTML] [PDF 1924KB](3)
Abstract:
TEMPO (2, 2, 6, 6-tetramethylpiperidine-1-oxyl) is well-established in orangocatalysis that usually work in synergy with transition-metal catalysis or semiconductor photocatalysis. Here, TEMPO was turned into a visible light photocatalyst to conduct the selective aerobic oxidation of thiols into disulfides. With O2 as an oxidant, a mild and efficient protocol for the selective oxidation of thiols into disulfides including symmetrical and unsymmetrical ones with 5 mol% of TEPMO as a photocatalyst was developed at room temperature under the irradiation of 460 nm blue LEDs. It was found that a complex formed between TEMPO and thiols underpinned the visible light activity and disulfides were obtained in very high isolated yields. This work suggests that TEMPO takes diverse roles in for photocatalytic selective oxidative transformations with O2 as the oxidant.
New strategy for production of primary alcohols from aliphatic olefins by tandem cross-metathesis/hydrogenation
Jia Ruilong , Zuo Zhijun , Li Xu , Liu Lei , Dong Jinxiang
2020, 31(6): 1525-1529  doi: 10.1016/j.cclet.2019.10.001
[Abstract](124) [FullText HTML] [PDF 3150KB](3)
Abstract:
Primary alcohols are widely used in industry as solvents and precursors of detergents. The classic methods for hydration of terminal alkenes always produce the Markovnikov products. Herein, we reported a reliable approach to produce primary alcohols from terminal alkenes combining with biomass-derived allyl alcohol by tandem cross-metathesis/hydrogenation. A series of primary alcohol with different chain lengths was successfully produced in high yields (ca. 90%). Computational studies revealed that self-metathesis and hydrogenation of substrates are accessible but much slower than crossmetathesis. This new methodology represents a unique alternative to primary alcohols from terminal alkenes.
Promotion of photocatalytic steam reforming of methane over Ag0/Ag+-SrTiO3
Tan Bingqing , Ye Yinghao , Huang Zeai , Ye Liqun , Ma Minzhi , Zhou Ying
2020, 31(6): 1530-1534  doi: 10.1016/j.cclet.2019.11.007
[Abstract](136) [FullText HTML] [PDF 2461KB](1)
Abstract:
Methane (CH4) is not only used as a fuel but also as a promising clean energy source for hydrogen generation. The steam reforming of CH4 (SRM) using photocatalysts can realize the production of syngas (CO + H2) with low energy consumption. In this work, Ag0/Ag+-loaded SrTiO3 nanocomposites were successfully prepared through a photodeposition method. When the loading amount of Ag is 0.5 mol%, the atom ratio of Ag+ to Ag0 was found to be 51:49. In this case, a synergistic effect of Ag0 and Ag+ was observed, in which Ag0 was proposed to improve the adsorption of H2O to produce hydroxyl radicals and enhance the utilization of light energy as well as the separation of charge carriers. Meanwhile, Ag0 was regarded as the reduction reaction site with the function of an electron trapping agent. In addition, Ag+ adsorbed the CH4 molecules and acted as the oxidation reaction sites in the process of photocatalytic SRM to further promote electron-hole separation. As a result, 0.5 mol% Ag-SrTiO3 exhibited enhancement of photocatalytic activity for SRM with the highest CO production rate of 4.3 μmol g-1 h-1, which is ca. 5 times higher than that of pure SrTiO3. This work provides a facile route to fabricate nanocomposite with cocatalyst featuring different functions in promoting photocatalytic activity for SRM.
Effective removal of chlorinated organic pollutants by bimetallic iron-nickel sulfide activation of peroxydisulfate
Yan Xuan , Yue Dongting , Guo Chao , Wang Songling , Qian Xufang , Zhao Yixin
2020, 31(6): 1535-1539  doi: 10.1016/j.cclet.2019.11.003
[Abstract](129) [FullText HTML] [PDF 4222KB](1)
Abstract:
Chlorinated organic pollutants (COPs) have caused serious contaminants in soil and groundwater, hence developing methods to remove these pollutants is necessary and urgent. By a simple hydrothermal method, we synthesized the bimetallic iron-nickel sulfide (FeNiS) particles which exhibited excellent catalytic property of COPs removal. FeNiS was chosen as the peroxydisulfate (PDS) activator to removal COPs including 4-chlorophenol (4-CP), 1, 4-dichlorophenol (1, 4-DCP) and 2, 4, 6-trichlorophenol (2, 4, 6-TCP). The results show that FeNiS can efficiently activate PDS to produce sulfate radical (SO4·-) which plays major role in the oxidative dechlorination and degradation due to its strong oxidizing property and the ability of producing hydroxyl radicals (·OH) in the alkaline condition. Meanwhile, the Cl- abscised from COPs during the dechlorination can turn into the chlorine radicals and enhance the degradation and cause further mineralization of intermediate products. This bimetallic FeNiS catalyst is a promising PDS activator for removal of chlorinated organics.
One-step synthesis of monodispersed Pt nanoparticles anchored on 3D graphene foams and its application for electrocatalytic hydrogen evolution
Zhou Dan , Jiang Bei , Yang Rui , Hou Xiandeng , Zheng Chengbin
2020, 31(6): 1540-1544  doi: 10.1016/j.cclet.2019.11.014
[Abstract](124) [FullText HTML] [PDF 5044KB](2)
Abstract:
Although platinum-based materials are regarded as the state-of-the-art electro-catalysts for hydrogen evolution reaction (HER), high cost and quantity scarcity hamper their scale-up utilization in industrial deployment. Herein, a one-step strategy was developed to synthesize multi-walled carbon nanotubes and reduced graphene oxide supported Pt nanoparticle hydrogel (PtNP/rGO-MWCNT), in which only ascorbic acid was used as the reductant for one-pot reduction of both GO and chloroplatinic acid. The hydrogel can be directly used as a flexible binder-free catalytic electrode to achieve high performance of HER. Compared to conventional strategies, the current strategy not only significantly reduces the Pt loading to 3.48 wt%, simplifies the synthesis process, but also eliminates the use of any polymer binders, thus decreasing the series resistance and improving catalytic activity. An overpotential of only 11 mV was achieved on as-prepared PtNP/rGO-MWCNT to drive a geometrical current density of 10 mA/cm2 in 0.5 mol/L H2SO4, with its catalytic activity being kept over 15 h. In acidic medium, the HER activity of the PtNP/rGO-MWCNT catalyst exceeds most of the reported Pt-based electro-catalysts and is 3-fold higher than that obtained on commercial Pt/C electrode.
The effectiveness of bisulfite-activated permanganate technology to enhance the coagulation efficiency of Microcystis aeruginosa
Zhu Yating , Ling Jinfeng , Li Lei , Guan Xiaohong
2020, 31(6): 1545-1549  doi: 10.1016/j.cclet.2019.12.036
[Abstract](127) [FullText HTML] [PDF 2204KB](1)
Abstract:
The effects of bisulfite-activated permanganate technology (PM/BS) as a pre-oxidation process on enhancing Microcystis aeruginosa (M. aeruginosa) removal by post coagulation were investigated. The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness. Compared to the sole coagulation, PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively, decrease the algal cell size, and lead to the formation of more compact flocs due to the in-situ generated MnO2. The effect of oxidant dosages on algal organic matter (AOM) was also studied and no obvious release of macromolecular substances was observed with the dosage of KMnO4 increasing from 3.0 mg/L to 7.0 mg/L, suggesting the integrity of algal cells at a high KMnO4 dosage. Moreover, PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products (DBPs) at a Al2(SO4)3 dosage of 40.0 mg/L. The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water. This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.
Pillar[5]arene-based[3]rotaxanes: Convenient construction via multicomponent reaction and pH responsive self-assembly in water
Ye Junmei , Zhang Runmiao , Yang Wenjuan , Han Ying , Guo Hao , Xie Ju , Yan Chaoguo , Yao Yong
2020, 31(6): 1550-1553  doi: 10.1016/j.cclet.2019.11.041
[Abstract](135) [FullText HTML] [PDF 3805KB](1)
Abstract:
Four pillar[5]arene based [3]rotaxanes (1-4) involving two 1,4-diethoxypillar[5]arene (DEP5) rings and a dumbbell-shaped component were successfully synthesized. The dumbbell-shape molecules contain one longer bridge, two triazole sites and two multicomponent stoppers. After threading DEP5 rings with linear guests (G1-G4) which contain two benzaldehyde units, the base catalyzed three-component reaction of dimedone, malononitrile and benzaldehyde was performed to construct the stoppers and connected the pseudorotaxanes with stoppers to generate 1–4. The structures of [3]rotaxanes and their self-assembly behaviors were characterized by 1H NMR, 13C NMR, NOESY, HR-ESI-MS, DLS and TEM technologies. We hope that pillar[5]arene based [3]rotaxanes may have potential applications in drug delivery systems and molecular devices.
1, 3-Dipolar cycloaddition for selective synthesis of functionalized spiro[indoline-3, 3'-pyrrolizines]
Zhu Meijun , Han Ying , Liu Changzhou , Ma Weiqing , Yan Chao-Guo
2020, 31(6): 1554-1557  doi: 10.1016/j.cclet.2019.12.028
[Abstract](118) [FullText HTML] [PDF 1735KB](1)
Abstract:
The 1, 3-dipolar cycloaddition reaction of dimethyl hex-2-en-4-ynedioate with azomethine ylides derived from reaction of L-proline with various isatins in methanol selectively resulted in the formation of functionalized spiro[indoline-3, 3'-pyrrolizine]acrylates as main products and spiro[indoline-3, 3'-pyrrolizine]propiolates as minor products. This result indicated that the electron-deficient alkyne has higher reactivity than that of electron-deficient alkene in 1, 3-dipolar cycloaddition reaction.
1D Fe3O4@CuSiO3 composites catalyzed decarboxylative A3-coupling for propargylamine synthesis
Wang Fang , Feng Huangdi , Li Huiqiong , Miao Teng , Cao Tiantian , Zhang Min
2020, 31(6): 1558-1563  doi: 10.1016/j.cclet.2019.11.004
[Abstract](138) [FullText HTML] [PDF 3912KB](3)
Abstract:
Highly active and stable magnetic copper catalysts were successfully achieved by magnetic induced Stöber method and subsequent hydrothermal reaction with copper ions in alkaline condition. The high content of Cu2+ as well as the unique structures of hierarchical copper silicate in the as-prepared catalysts endowed their outstanding catalytic performance. Efficient decarboxylative A3-coupling of α-keto acid, amine and alkyne was realized with the low Fe3O4@CuSiO3 loading. A range of propargylamines were produced in good to excellent yields under solvent-free condition. Moreover, the catalyst can be easily separated from the final organic product with an external magnet. Also, this kind of catalyst could be recycled up to six times while maintaining its activity.
Et2Zn-promoted β-trans-selective hydroboration of ynamide
Wang Kefeng , Zhuang Zixi , Ti Huihui , Wu Peishan , Zhao Xin , Wang Honggen
2020, 31(6): 1564-1567  doi: 10.1016/j.cclet.2019.11.008
[Abstract](113) [FullText HTML] [PDF 2194KB](1)
Abstract:
The trans-hydroboration of alkyne represents a challenging task in organic synthesis. Reported herein is an Et2Zn promoted β-trans hydroboration of ynamides by using N-heterocyclic carbene (NHC)-ligated borane as boryl source. The reaction leads to a stereoselective construction of enamides bearing a valuable boryl substituent. Both aromatic and aliphatic ynamides were applicable to the reaction. Synthetic transformation of the C—B bond in the product via Suzuki-Miyaura coupling provides a simple and stereospecific route to multi-substituted enamides. Mechanistic studies were conducted and the possible mechanism was discussed
Lewis base catalyzed ring-expansion of isatin with 2, 2, 2-trifluorodiazoethane (CF3CHN2): An efficient route to 3-hydroxy-4-(trifluoromethyl)quinolinones
Lv Shuaipeng , Sun Yunfang , Xu Yue , Yang Shihai , Wang Lei
2020, 31(6): 1568-1571  doi: 10.1016/j.cclet.2019.11.027
[Abstract](136) [FullText HTML] [PDF 2809KB](1)
Abstract:
A Lewis base catalyzed ring expansion of isatin with 2, 2, 2-trifluorodiazoethane (CF3CHN2) is developed. It is characterized that the merge of tetramethylethylenediamine and CF3CHN2 generates reactive triazene intermediates, which construct substituted 3-hydroxy-4-(trifluoromethyl)quinolinones with high efficiency. Synthetic application of the procedure is broadened by 3-trifluormethylpyrazole fused 3-hydroxy-4-(trifluoromethyl)quinolinone synthesis.
Rh(III)-catalyzed C8 arylation of quinoline N-oxides with arylboronic acids
Huang Yuanqiong , Lv Xueli , Song Hongjian , Liu Yuxiu , Wang Qingmin
2020, 31(6): 1572-1575  doi: 10.1016/j.cclet.2019.11.028
[Abstract](127) [FullText HTML] [PDF 3199KB](2)
Abstract:
Herein, we report the first RhIII-catalyzed regioselective C8 arylation of quinoline N-oxides with commercially available arylboronic acids as coupling partners. This procedure is simple, and the reaction shows perfect regioselectivity, a broad substrate scope, and isolated yields of up to 92%. We demonstrate the utility of the reaction by using it for late-stage functionalization of a fungicide.
Electrochemical synthesis of selenocyanated imidazo[1, 5-a]quinolines under metal catalyst- and chemical oxidant-free conditions
Zhang Jinjin , Wang Huiqiao , Chen Yaru , Xie Haiquan , Ding Chenghua , Tan Jiajing , Xu Kun
2020, 31(6): 1576-1579  doi: 10.1016/j.cclet.2019.11.037
[Abstract](129) [FullText HTML] [PDF 3541KB](2)
Abstract:
Reported herein is the first example of electrochemical selenocyanation of imidazo[1, 5-a]quinolines with KSeCN under metal catalyst- and chemical oxidant-free conditions. This sustainable strategy shows a broad scope and great compatibility with functional groups, and affords synthetically and biologically important selenocyanated imidazo[1, 5-a]quinolines in good to excellent yields with cheap graphite and Ni plates as the electrodes. The gram-scale synthesis was also successfully conducted, which might demonstrate the potential value of this electrochemical protocol.
Dimethyl sulfoxide-aided copper(0)-catalyzed intramolecular decarbonylative rearrangement of N-aryl isatins leading to acridones
Wu Hao , Ma Nana , Song Mengxiao , Zhang Guisheng
2020, 31(6): 1580-1583  doi: 10.1016/j.cclet.2019.10.043
[Abstract](147) [FullText HTML] [PDF 4055KB](1)
Abstract:
Described here is the first example of Cu(0)-catalyzed intramolecular decarbonylative rearrangements of readily available N-aryl isatins assisted by solvent dimethyl sulfoxide (DMSO) under air atmosphere and additive-free conditions leading to various biologically important acridones in good to excellent yields. This novel transformation is proposed to go through a sequential DMSO-aided Cu insertion into the amide C—N bond, CO extrusion, Cu migration, reductive elimination and DMSO-aided proton migration processes, involving multiple types of bond cleavage and formation in a single chemical step.
Basic deep eutectic solvents as reactant, template and solvents for ultra-fast preparation of transition metal oxide nanomaterials
Chen Jia , Chand Ali Mohammad , Liu Ruirui , Claude Munyemana Jean , Li Zhan , Zhai Honglin , Qiu Hongdeng
2020, 31(6): 1584-1587  doi: 10.1016/j.cclet.2019.09.055
[Abstract](125) [FullText HTML] [PDF 2683KB](1)
Abstract:
Developing a new type of deep eutectic solvents (DESs) is indispensable for expanding their application in various fields. Here, we report a series of new highly basic DESs. FT-IR, quantitative 1H NMR, MD simulation and physical properties show that these basic liquids are made up of hydroxide acceptor of alkali metal hydroxides in which the hydrogen bonding interactions coordinate the donor. These DESs can be played three roles as new solvents, template and reactant for facile and ultra-fast preparation of transition metal oxide nanomaterials such as NiCo2O4, MnCo2O4, NiMn2O4, CoCu2O4 and Co3O4 under mild condition. This work shows one of the low energy-intensive methods for nanomaterial preparation. These initial findings of basic deep eutectic solvents provide a potential applicability around the systematic development of transition metal oxide nanosheets.
Atomic Fe-N4 sites on electrospun hierarchical porous carbon nanofibers as an efficient electrocatalyst for oxygen reduction reaction
Zhong Ruiqin , Zhi Chenxu , Wu Yingxiao , Liang Zibin , Tabassum Hassina , Zhang Hao , Qiu Tianjie , Gao Song , Shi Jinming , Zou Ruqiang
2020, 31(6): 1588-1592  doi: 10.1016/j.cclet.2019.12.004
[Abstract](118) [FullText HTML] [PDF 6742KB](1)
Abstract:
Porous carbon materials doped with atomically dispersed metal sites (ADMSs) are promising electrocatalysts for oxygen reduction reaction (ORR) electrocatalysis. In this work, we fabricated hierarchical porous nitrogen-doped carbon nanofibers with atomically dispersed Fe-N4 sites by carbonization of electrospinning iron-based metal-organic frameworks (MOFs)/polyacrylonitrile nanofibers for ORR electrocatalysis. Remarkably, the resultant carbon nanofibers with atomically dispersed Fe-N4 sites exhibit extraordinary electrochemical performance with an onset potential of 0.994 V and a halfwave potential of 0.876 V in alkaline electrolyte, comparable to the benchmark commercial Pt/C catalyst. The high catalytic performance is originated from the unique hierarchically porous 1D carbon structure and abundant highly active atomically dispersed Fe-N4 sites.
Aqueous-processed insulating polymer/nanocrystal solar cells with effective suppression of the leakage current and carrier recombination
Sun Henan , Chen Nannan , Wang Yaohua , Gan Jin , Yuan Wei , Sun Haizhu , Yang Bai
2020, 31(6): 1593-1597  doi: 10.1016/j.cclet.2019.08.024
[Abstract](117) [FullText HTML] [PDF 6376KB](1)
Abstract:
As one of the most environmentally friendly photovoltaic (PV) conversion equipments, aqueousprocessed CdTe nanocrystal solar cells (NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption. However, two issues including interfacial recombination and leakage current seriously restrict their performance. In this paper, insulating polymer poly(vinyl pyrrolidone) (PVP) is introduced into CdTe NC SCs to solve the problems. The experimental results of transmission electron microscopy (TEM), atomic force microscopy (AFM) and dark current measurements, etc., demonstrate the leakage current is effectively suppressed by introducing PVP. Through further designing device structure, the reduction of interfacial recombination after introducing PVP is confirmed. By strategically taking the advantages of PVP properties (e.g., water solubility and thermostability), the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices. This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route. Moreover, it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.
Stepwise construction of Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and magnetic separability for efficient visible-light photocatalysis
Li Zhijian , Wang Yao , A. Elzatahry Ahmed , Yang Xuanyu , Pu Shouzhi , Luo Wei , Cheng Xiaowei , Deng Yonghui
2020, 31(6): 1598-1602  doi: 10.1016/j.cclet.2019.10.016
[Abstract](130) [FullText HTML] [PDF 2603KB](1)
Abstract:
Solid photocatalysts with high specific surface area, superior photoactivity and ease of recycling are highly desired in chemical process, water treatment and so on. In this study, a facile stepwise sol-gel coating approach was utilized to synthesize Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and convenient magnetic separability (denoted as Fe3O4@SiO2@Pt/mTiO2-x). These photocatalysts consist of magnetic Fe3O4 cores, nonporous insulating SiO2 middle layer and mesoporous anatase TiO2-x shell decorated by Pt nanoparticles (~3.5 nm) through wet impregnation and H2 reduction. As a result of high activity of oxygen-deficiency of black TiO2-x by H2 reduction and efficient inhibition of electron-hole recombination by Pt nanoparticles, the rationally designed core-shell Fe3O4@SiO2@Pt/mTiO2-x photocatalysts exhibit superior photocatalytic performance in rhodamine B (RhB) degradation under visible light irradiation, with more than 98% of RhB degraded within 50 min. These core-shell structured photocatalysts show excellent recyclability under the assistance of magnetic separation with well-retained photocatalytic performance even after running five cycles. This stepwise synthesis method paves the way for the rational design of a high-efficiency recyclable heterogeneous catalyst, including photocatalysts, for various applications.
Regulating ambient pressure approach to graphitic carbon nitride towards dispersive layers and rich pyridinic nitrogen
Sun Guangchao , Zhang Fangzhou , Xie Qiusheng , Luo Wei , Yang Jianping
2020, 31(6): 1603-1607  doi: 10.1016/j.cclet.2019.10.018
[Abstract](125) [FullText HTML] [PDF 10673KB](1)
Abstract:
An ambient pressure-induced calcination process was proposed to prepare g-C3N4 with different structures. The porcelain boat with designed porosity is used to control the ambient pressure to change the diffusion behavior of the reaction molecules, thereby controlling the layer structure and rich pyridinic N content of g-C3N4, thus renders superior lithium storage performance.
Multifunctional semitransparent organic solar cells with excellent infrared photon rejection
Li Xue , Xia Ruoxi , Yan Kangrong , Yip Hin-Lap , Chen Hongzheng , Li Chang-Zhi
2020, 31(6): 1608-1611  doi: 10.1016/j.cclet.2019.08.046
[Abstract](130) [FullText HTML] [PDF 4567KB](1)
Abstract:
Semitransparent organic solar cells (ST-OSCs) have the potentials to open promising applications that differ from those of conventional inorganic ones, such as see-through power windows with both energy generation and heat insulation functions. However, to achieve so, there remain significant challenges, especially for balancing critical parameters, such as power conversion efficiency (PCE), average visible transparency (AVT) and low energy infrared photon radiation rejection (IRR) to realize the full potentials of ST-OSCs. Herein, we demonstrate the new design of ST-OSCs through the rational integration of organic materials, transparent electrode and infrared photon reflector in one device. With the assistance of optical simulation, new ST-OSCs with precise layout exhibit state-of-art performance, with near 30% AVT and PCE of 7.3%, as well as an excellent IRR of over 93% (780-2500 nm), representing one of best multifunctional ST-OSCs with promising perspective for window application.
Whole wheat flour coating with antioxidant property accelerates tissue remodeling for enhanced wound healing
Xian Caihong , Gu Zhipeng , Liu Guiting , Wu Jun
2020, 31(6): 1612-1615  doi: 10.1016/j.cclet.2019.09.011
[Abstract](125) [FullText HTML] [PDF 4754KB](3)
Abstract:
As a daily food for billions of people for thousands of years, whole grain is rich in phenolic compounds and may have huge potentials to provide natural antioxidants. Herein, owing to the significant biomedical potential, the effect of whole wheat flour solution as antioxidant wound coating for enhanced wound healing has been studied. The results show that the low concentration of whole wheat flour solutions have good biocompatibility and can scavenge radical and intracellular ROS in vitro, accelerating tissue remodeling in vivo to promote wound healing. This kind of whole wheat flour solution has great potential application for cutaneous wound repair.
Near infrared molybdenum oxide quantum dots with high photoluminescence and photothermal performance
Dong Xiaoxiao , Zhao Hong , Mi Yuanyuan , Liu Yao , Zhang Yida , Liu Ya , Chen Yusheng , Xu Quan
2020, 31(6): 1616-1619  doi: 10.1016/j.cclet.2019.11.010
[Abstract](117) [FullText HTML] [PDF 4797KB](1)
Abstract:
The synthesized near infrared molybdenum oxide quantum dots perform excellent red fluorescence imaging performance and photothermal performance, which have 600, 650 and 700 nm three unique peaks excited at 540 nm, with a high quantum yield around 20%. Meanwhile, with 808 nm NIR laser excitation, 10 mg/mL modified Molybdenum oxide quantum dots can increase temperature up to 72.2 ℃ within 150 s and 77.7 ℃ within 270 s, respectively.
Activated carbon clothes for wide-voltage high-energy-density aqueous symmetric supercapacitors
Asare Owusu Kwadwo , Wang Zhaoyang , Qu Longbing , Liu Zi'ang , Abdul-Aziz Mehrez Jaafar , Wei Qiulong , Zhou Liang , Mai Liqiang
2020, 31(6): 1620-1624  doi: 10.1016/j.cclet.2019.09.045
[Abstract](127) [FullText HTML] [PDF 4809KB](1)
Abstract:
Commercial carbon clothes have the potential to be utilized as supercapacitor electrodes due to their low cost and high conductivity. However, the negligible surface area of the carbon clothes serves as a serious impediment to their utilization. Herein, we report a facile calcination activation method for carbon cloths to realize remarkable comprehensive electrochemical performance. The activated carbon cloths deliver a high areal capacitance (1700 mF/cm2), good rate capability, and stable cycling performance up to 20, 000 cycles. Owing to the stability in the wide potential window, a designed symmetric capacitor can function in a cell voltage of 2.0 V and delivers high volumetric and gravimetric energy densities of 7.62 mWh/cm3 and 18.2 Wh/kg, respectively. The remarkable electrochemical performance is attributed to rich microporosity with high surface area, superior electrolyte wettability, and stability in wide potential window.
Preparation of ABA triblock copolymer assemblies through "one-pot" RAFT PISA
Cao Cao , Shi Yan , Wu Xiaohui , Zhang Liqun
2020, 31(6): 1660-1664  doi: 10.1016/j.cclet.2019.10.026
[Abstract](125) [FullText HTML] [PDF 2453KB](1)
Abstract:
Poly(N, N-dimethyl acrylamide)-block-poly(styrene)-block-poly(N, N-dimethyl acrylamide) (PDMAc-b-PSt-b-PDMAc) amphiphilic triblock copolymer micro/nano-objects were synthesized through reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of St mediated with poly(N, N-dimethyl acrylamide) trithiocarbonate (PDMAc-TTC-PDMAc) bi-functional macromolecular RAFT agent. It is found that the morphology of the PDMAc-b-PSt-b-PDMAc copolymer micro/nano-objects like spheres, vesicles and vesicle with hexagonally packed hollow hoops (HHHs) wall can be tuned by changing the solvent composition. In addition, vesicles with two sizes (600 nm, 264 nm) and vesicles with HHHs features were also synthesized in high solid content systems (30 wt% and 40 wt%, respectively). Besides, as compared with typical AB diblock copolymers (A is the solvophilic, stabilizer block, and B is the solvophobic block), ABA triblock copolymers tend to form higher order morphologies, such as vesicles, under similar conditions. The finding of this study provides a new and robust approach to prepare block copolymer vesicles and other higher order micelles with special structure via PISA.
Water permeability in MXene membranes: Process matters
Zhou Hang , Wang Yuwei , Wang Fuqiang , Deng Hao , Song Yongchen , Li Changping , Ling Zheng
2020, 31(6): 1665-1669  doi: 10.1016/j.cclet.2019.10.037
[Abstract](117) [FullText HTML] [PDF 2794KB](1)
Abstract:
Recent studies have shown impressive transport behaviors of water and ions within lamellar MXene membranes, which endows great promise in developing advanced separation application based high performance MXene membranes. However, most of the researches focused on modification of MXene nanoflakes and optimizing interlayer distance, leaving the impact of membrane fabrication process marginal. In this work, we studied the water flux of membranes made by vacuum filtration using delaminated MXene nanoflakes as the building-blocks. Our results show that the water permeability is extremely sensitive to the process, especially at the drying process, loading and deposit rate of nanoflakes (the feeding concentration). We find that the voids from less ordered stack rather than in-plane defects and interlayer galleries contribute to the large water permeability. The voids can be effectively avoided via deposition of MXene nanoflakes at a slow rate. Manipulating the stack of MXene nanoflakes during vacuum filtration and drying are critical for development of MXene membranes with desired performance for water permeation.
Solid-state template-free fabrication of uniform Mo2C microflowers with lithium storage towards Li-ion batteries
Sun Jinfeng , Guo Lingzhi , Gao Miaomiao , Sun Xuan , Zhang Jinyang , Liang Longwei , Liu Yang , Hou Linrui , Yuan Changzhou
2020, 31(6): 1670-1673  doi: 10.1016/j.cclet.2019.09.049
[Abstract](125) [FullText HTML] [PDF 4339KB](1)
Abstract:
Herein, we first report one-step synthesis of uniform Mo2C microflowers (MCMFs) from low-cost precursors via industrialized solid-state strategy. With fine optimization in precursor ratio and pyrolysis temperatures, the as-fabricated MCMFs are assembled well with interconnected single-crystalline nanosheet subunits. More encouragingly, the resultant MCMFs are further highlighted as a competitive anode with robust and long-duration lithium-storage behaviors towards high-performance Li-ion batteries
A DFT study of the CO adsorption and oxidation at ZnO surfaces and its implication for CO detection
Ni Zibin , Bao Shenyuan , Gong Xue-Qing
2020, 31(6): 1674-1679  doi: 10.1016/j.cclet.2019.10.027
[Abstract](130) [FullText HTML] [PDF 3803KB](4)
Abstract:
Recently, ZnO-based gas sensors have been successfully fabricated and widely studied for their excellent sensitivity and selectivity, especially in CO detection. However, detailed explorations of their mechanisms are rather limited. Herein, aiming at clarifying the sensing mechanism, we carried out density functional theory (DFT) calculations to track down the CO adsorption and oxidation on the ZnO (1010) and (1120) surfaces. The calculated results show that the lattice O of ZnO(1010) is more reactive than that of ZnO(1120) for CO oxidation. From the calculated energetics and structures, the main reaction product on both surfaces can be determined to be CO2 rather than carbonate. Moreover, the surface conductivity changes during the adsorption and reaction processes of CO were also studied. For both ZnO (1010) and (1120), the conductivity would increase upon CO adsorption and decrease following CO oxidation, in consistence with the reported experimental results. This work can help understand the origins of ZnO-based sensors' performances and the development of novel gas sensors with higher sensitivity and selectivity.
Solution-phase synthesis of ordered mesoporous carbon as resonant-gravimetric sensing material for room-temperature H2S detection
Ni Jiawei , Zhao Tao , Tang Lei , Qiu Pengpeng , Jiang Wan , Wang Lianjun , Xu Pengcheng , Luo Wei
2020, 31(6): 1680-1685  doi: 10.1016/j.cclet.2019.11.025
[Abstract](126) [FullText HTML] [PDF 4874KB](2)
Abstract:
H2S can cause multiple diseases and poses a great threat to human health. However, the precise detection of extremely toxic H2S at room temperature is still a great challenge. Here, a facile solvent evaporation induced aggregating assembly (EIAA) method has been applied for the production of ordered mesoporous carbon (OMCs) in an acidic THF/H2O solution with high-molecular-weight poly(ethylene oxide)-b-polystyrene (PEO-b-PS) copolymers as the structure-directing agent, formaldehyde and resorcinol as carbon precursors. Along with the continuous evaporation of THF from the mixed solution, cylindrical micelles are formed in the solution and further assemble into highly ordered mesostructure. The obtained OMCs possesses a two-dimensional (2D) hexagonal mesostructure with uniform and large pore diameter (~19.2 nm), high surface area (599 m2/g), and large pore volume (0.92 cm3/g). When being used as the resonant cantilever gas sensor for room-temperature H2S detection, the OMCs has delivered not only a superior gas sensing performance with ultrafast response (14 s) and recovery (21 s) even at low concentration (2 ppm) but also an excellent selectivity toward H2S among various common interfering gases. Moreover, the limit of detection is better than 0.2 ppm, indicating its potential application in environmental monitoring and health protection.
A novel ferroelectric based on quinuclidine derivatives
Deng Siyu , Li Junyi , Chen Xiang , Hou Yunlong , Chen Lizhuang
2020, 31(6): 1686-1689  doi: 10.1016/j.cclet.2019.11.011
[Abstract](115) [FullText HTML] [PDF 1677KB](2)
Abstract:
The compound[(CH3)2CH-C3H17N] [CoBr4] (1) based on quinuclidine derivatives was achieved by the solution synthetic method and characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structural analysis and dielectric measurement, respectively. Variable-temperature single-crystal X-ray diffraction suggested that the compound underwent the phase transition from the space group C2/c to Cc. The polarization curve was measured using the Sawyer-Tower circuit. The structural phase transitions of 1 was ascribed to the distortion of a[(CH3)2CH-C3H17N]2+ cation from this inorganic-organic hybrid material[(CH3)2CH-C3H17N] [CoBr4]. The strong change in dielectric anomalies makes compound 1 a suitable candidate for promising switchable dielectric materials. This work represents a feasible strategy thought for the targeted harvesting of low temperature ferroelectrics.
A symmetric aqueous redox flow battery based on viologen derivative
Liu Shuang , Zhou Meng , Ma Ting , Liu Jian , Zhang Qiu , Tao Zhanliang , Liang Jing
2020, 31(6): 1690-1693  doi: 10.1016/j.cclet.2019.11.033
[Abstract](133) [FullText HTML] [PDF 1833KB](1)
Abstract:
Due to the diversity and feasibility of structural modification for organic molecules, organic-based redox flow batteries (ORFBs) have been widely investigated, especially in aqueous solution under neutral circumstance. In this work, a symmetric aqueous redox flow battery (SARFB) was rationally designed by employing a bipolar redox active molecule (N, N'-dimethyl-4, 4-bipyridinium diiodide, MVI2) as both cathode and anode materials and combining with an anion exchange membrane. For one MVI2 flow battery, MV2+/MV·+ and I-/I3- serve as the redox couples of anode and cathode, respectively. The MVI2 battery with a working voltage of 1.02 V exhibited a high voltage efficiency of 90.30% and energy efficiency of 89.44% after 450 cycles, and crossover problem was prohibited. The comparable conductivity of MVI2 water solution enabled to construct a battery even without using supporting electrolyte. Besides, the bipolar character of MVI2 battery with/without supporting electrolyte was investigated in the voltage range between -1.2 V and 1.2 V, showing excellent stable cycling stability during the polarity-reversal test.
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