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2018 Volume Issue 7
2018, (7):
Abstract:
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2018, 0(7): 773-775
doi: 10.11777/j.issn1000-3304.2018.18139
Abstract:
Sulfur-containing polymers are important functional materials and can be used as optical, anti-corrosion and antifouling materials. Using C1 monomers (i.e. carbonyl sulfide (COS), carbon disulfide (CS2)) to copolymerize with epoxides have been rapidly developed in very recent years. Recently, Xing-Hong Zhang et al. reported a metal-free living copolymerization of COS with epoxides via the cooperative catalysis of organic Lewis pairs including organic bases and thioureas as hydrogen-bond donors, afforded poly(monothiocarbonate)s with 100% alternating degree, > 99% tail-to-head content, high molecular weight (up to 9.84 × 10 5) and narrow molecular weight distributions (1.13 – 1.23). The turnover frequencies (TOFs) of the catalyst are as high as 112 h −1 at 25 °C. Kinetic and mechanistic results suggest that the supramolecular specific recognition of thiourea to epoxide and base to COS promoted the copolymerization cooperatively. The synthesis of sulfur-containing polymer developed by Xing-Hong Zhang and co-workers is very promising to the utilization of C1 monomers derived from the use of oil and coal.
Sulfur-containing polymers are important functional materials and can be used as optical, anti-corrosion and antifouling materials. Using C1 monomers (i.e. carbonyl sulfide (COS), carbon disulfide (CS2)) to copolymerize with epoxides have been rapidly developed in very recent years. Recently, Xing-Hong Zhang et al. reported a metal-free living copolymerization of COS with epoxides via the cooperative catalysis of organic Lewis pairs including organic bases and thioureas as hydrogen-bond donors, afforded poly(monothiocarbonate)s with 100% alternating degree, > 99% tail-to-head content, high molecular weight (up to 9.84 × 10 5) and narrow molecular weight distributions (1.13 – 1.23). The turnover frequencies (TOFs) of the catalyst are as high as 112 h −1 at 25 °C. Kinetic and mechanistic results suggest that the supramolecular specific recognition of thiourea to epoxide and base to COS promoted the copolymerization cooperatively. The synthesis of sulfur-containing polymer developed by Xing-Hong Zhang and co-workers is very promising to the utilization of C1 monomers derived from the use of oil and coal.
2018, 0(7): 776-785
doi: 10.11777/j.issn1000-3304.2018.18025
Abstract:
Alzheimer’s disease (AD) is a neurodegenerative disorder associated with the loss of memory, cognitive decline, and behavioral disability, leading to dementia and death ultimately. The pathogenesis of AD is still unclear, but it is generally accepted that the occurrence of AD is related to the accumulation of amyloid β (Aβ) in the brain and the oxidative stress effect caused by the enrichment of metal ions. In our previous work, we expanded the targeting site from Aβ16-22 to Aβ11-23 (EVHHQKLVFFAED), which could offer multiple weak interaction sites, such as the electrostatic, hydrophobic interactions and hydrogen bonding. We designed and screened a novel Aβ aggregation inhibitory peptide (RR) by computer simulation. The tripeptide chelator GGH, selected by ITC experiment with selectively Cu ion chelating ability, was introduced into RR to get the bifunctional peptide inhibitor GR, which have the ability to inhibit Aβ aggregation and produce the oxygen species (ROS) production at the same time. The results of ThT fluorescence, turbidity analysis, MTT methods showed that GR can inhibit the aggregation of Aβ and Aβ-Cu complex (Aβ:Cu = 1:0.25) to form amorphous aggregates, and the cell survival of GR group can reach 88%, significantly higher than chelator GGH (49%) and single functional inhibitor RR (68%). Moreover, it is proposed for the first time that the endocytosis of Aβ aggregates in the brain could be promoted by the disaggregation of Aβ or Aβ-Cu complex fibrils to achieve the effect of treating AD. The results showed that RR and GR can disaggregate Aβ and Aβ-Cu complex fibrils to nanorod-like structure with a length of 200 − 250 nm (rA β), and β-sheet structure content in the system was reduced by 45%. rAβ more easily to PC12 cell endocytosis, and it can enter the cells and further into the cell lysosomes. The in vitro lysosomal cathepsin B (CatB) degradation experimental results showed that, compared to fAβ, rAβ is more susceptible to CatB degradation, and its degradation products have no longer full hydrophobic core region, thereby greatly reducing their chances of re-aggregation. Finally the feasibility of GR and RR has been verified in Morris water maze test.
Alzheimer’s disease (AD) is a neurodegenerative disorder associated with the loss of memory, cognitive decline, and behavioral disability, leading to dementia and death ultimately. The pathogenesis of AD is still unclear, but it is generally accepted that the occurrence of AD is related to the accumulation of amyloid β (Aβ) in the brain and the oxidative stress effect caused by the enrichment of metal ions. In our previous work, we expanded the targeting site from Aβ16-22 to Aβ11-23 (EVHHQKLVFFAED), which could offer multiple weak interaction sites, such as the electrostatic, hydrophobic interactions and hydrogen bonding. We designed and screened a novel Aβ aggregation inhibitory peptide (RR) by computer simulation. The tripeptide chelator GGH, selected by ITC experiment with selectively Cu ion chelating ability, was introduced into RR to get the bifunctional peptide inhibitor GR, which have the ability to inhibit Aβ aggregation and produce the oxygen species (ROS) production at the same time. The results of ThT fluorescence, turbidity analysis, MTT methods showed that GR can inhibit the aggregation of Aβ and Aβ-Cu complex (Aβ:Cu = 1:0.25) to form amorphous aggregates, and the cell survival of GR group can reach 88%, significantly higher than chelator GGH (49%) and single functional inhibitor RR (68%). Moreover, it is proposed for the first time that the endocytosis of Aβ aggregates in the brain could be promoted by the disaggregation of Aβ or Aβ-Cu complex fibrils to achieve the effect of treating AD. The results showed that RR and GR can disaggregate Aβ and Aβ-Cu complex fibrils to nanorod-like structure with a length of 200 − 250 nm (rA β), and β-sheet structure content in the system was reduced by 45%. rAβ more easily to PC12 cell endocytosis, and it can enter the cells and further into the cell lysosomes. The in vitro lysosomal cathepsin B (CatB) degradation experimental results showed that, compared to fAβ, rAβ is more susceptible to CatB degradation, and its degradation products have no longer full hydrophobic core region, thereby greatly reducing their chances of re-aggregation. Finally the feasibility of GR and RR has been verified in Morris water maze test.
2018, 0(7): 786-796
doi: 10.11777/j.issn1000-3304.2018.18036
Abstract:
Controlled polymerization is of great significance for the tailoring of macromolecular structure and synthesis of polymers with excellent properties. Several non-toxic organic guanidinines were prepared/selected in our laboratory in recent years and used as the catalysts/initiators to realize controlled melt polycondensation (MP), ring-opening polymerization (ROP), and depolymerization (DEP). Isotactic melt polycondensation (Iso-MP) of L-lactic acid/D-lactic acid (LLa/DLa) was carried out for the first time with biogenic creatinine (CR) catalyst and poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA) with high isotacticity (Iso. > 98%) was obtained; Combined MP with solid-state polycondensation (MP-SSP) of the medium molecular weight PLLA/PDLA ( Mw = 2.2 × 104, Iso. = 98.2%), prepared by the Iso-MP with CR, was carried out, and high molecular weight PLLA/PDLA (Mw > 1.0 × 10 5) with high isotacticity (Iso. > 98%) was obtained. The initial decomposition temperature ( Td,i) of the synthesized PLLA reached up to 324.5 °C, which was 120 °C higher than that of PLLA synthesized by SnCl2·2H2O catalyst; Optical pure (e.e. 100%) L-lactide/D-lactide (OP-LLA/OP-DLA) were synthesized via Iso-MP and the subsequent depolymerization (DEP) of LMW-PLLA/LMW-PDLA (Mw = 8.0 × 102 – 9.0 × 10 2) with CR catalyst. The polymer residues (r-PLLA/r-PDLA), produced accompanying with the lactides formation, were reused as the raw material for LLA/DLA synthesis after being hydrolyzed. The total yield of OP-LLA/OP-DLA reached up to 98%; Several sterically hindered guanidine carboxylates (HBG·OAc, CRA, CRG, CRL, TBDA) were synthesized and used to realize living ROP of LLA. An optical pure morpholine-2,5-dione (3S,6S-BMMD), derived from LLa and L-serine, was synthesized. Living ROP of 3S,6S-BMMD was carried out with CRA catalyst for the first time. After debenzylation of the synthesized P(3S,6S-BMMD), an amphiphillic copolymer P(LLa-co-Ser) was obtained, which is a useful support material in biomedical areas. The fine molecular structures and isotacticities of growing polymeric species were characterized by in situ monitoring with 1H-NMR, 13C-NMR. And the mechanisms of the above mentioned controlled polymerizations were proposed.
Controlled polymerization is of great significance for the tailoring of macromolecular structure and synthesis of polymers with excellent properties. Several non-toxic organic guanidinines were prepared/selected in our laboratory in recent years and used as the catalysts/initiators to realize controlled melt polycondensation (MP), ring-opening polymerization (ROP), and depolymerization (DEP). Isotactic melt polycondensation (Iso-MP) of L-lactic acid/D-lactic acid (LLa/DLa) was carried out for the first time with biogenic creatinine (CR) catalyst and poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA) with high isotacticity (Iso. > 98%) was obtained; Combined MP with solid-state polycondensation (MP-SSP) of the medium molecular weight PLLA/PDLA ( Mw = 2.2 × 104, Iso. = 98.2%), prepared by the Iso-MP with CR, was carried out, and high molecular weight PLLA/PDLA (Mw > 1.0 × 10 5) with high isotacticity (Iso. > 98%) was obtained. The initial decomposition temperature ( Td,i) of the synthesized PLLA reached up to 324.5 °C, which was 120 °C higher than that of PLLA synthesized by SnCl2·2H2O catalyst; Optical pure (e.e. 100%) L-lactide/D-lactide (OP-LLA/OP-DLA) were synthesized via Iso-MP and the subsequent depolymerization (DEP) of LMW-PLLA/LMW-PDLA (Mw = 8.0 × 102 – 9.0 × 10 2) with CR catalyst. The polymer residues (r-PLLA/r-PDLA), produced accompanying with the lactides formation, were reused as the raw material for LLA/DLA synthesis after being hydrolyzed. The total yield of OP-LLA/OP-DLA reached up to 98%; Several sterically hindered guanidine carboxylates (HBG·OAc, CRA, CRG, CRL, TBDA) were synthesized and used to realize living ROP of LLA. An optical pure morpholine-2,5-dione (3S,6S-BMMD), derived from LLa and L-serine, was synthesized. Living ROP of 3S,6S-BMMD was carried out with CRA catalyst for the first time. After debenzylation of the synthesized P(3S,6S-BMMD), an amphiphillic copolymer P(LLa-co-Ser) was obtained, which is a useful support material in biomedical areas. The fine molecular structures and isotacticities of growing polymeric species were characterized by in situ monitoring with 1H-NMR, 13C-NMR. And the mechanisms of the above mentioned controlled polymerizations were proposed.
2018, 0(7): 797-813
doi: 10.11777/j.issn1000-3304.2018.18055
Abstract:
Due to the unique ion transfer characteristics of ion exchange membranes (IEMs), they can be used in the separation and classification of ionic systems. Hence, IEMs have a wide application prospect in clean production, energy conservation, emission reduction and energy conversion. Because of gradually depleted fossil fuel, the ever-increasing power demand of our modern lifestyle and the awareness of environment protection, the conversion and storage of energy from renewable sources (hydrogen, wind and solar energy, for instances) have attracted worldwide attention. For both fuel cells and aqueous organic redox flow batteries operated in neutral pH, ion exchange membranes are crucial in determining the internal resistance (conversion efficiency), working life span of the former and the coulombic efficiency, cycle life of the latter. IEMs have great potential in diverse applications and play prominent roles in addressing energy and environment related issues. Over the past decade, the development of IEMs has attracted much research attention in terms of materials, preparation and applications, due to their academic and industrial values. In this review, we summarized the advanced research on polyphenylene oxide (PPO) polymer based ion exchange membranes. We introduced the membranes synthetic methods, polymer structures, key performances and application processes separately. Besides, we also discussed about the problems of the PPO based ion exchange membranes that should be solved and prospected the development direction in the future. As to the PPO based ion exchange membranes synthetic methods, we divided them into two parts, anion exchange membranes and cation exchange membranes, with a variety of methods enumerated, including introduction of side chains, polymers crosslinking, optimization of functional groups and doping to improve the performances, such as ion conductivity, swelling ratio, mechanical strength and other important performances of the PPO based exchange membranes. We also realized the diversification of the function of ion exchange membranes and application in fuel cells, etc.
Due to the unique ion transfer characteristics of ion exchange membranes (IEMs), they can be used in the separation and classification of ionic systems. Hence, IEMs have a wide application prospect in clean production, energy conservation, emission reduction and energy conversion. Because of gradually depleted fossil fuel, the ever-increasing power demand of our modern lifestyle and the awareness of environment protection, the conversion and storage of energy from renewable sources (hydrogen, wind and solar energy, for instances) have attracted worldwide attention. For both fuel cells and aqueous organic redox flow batteries operated in neutral pH, ion exchange membranes are crucial in determining the internal resistance (conversion efficiency), working life span of the former and the coulombic efficiency, cycle life of the latter. IEMs have great potential in diverse applications and play prominent roles in addressing energy and environment related issues. Over the past decade, the development of IEMs has attracted much research attention in terms of materials, preparation and applications, due to their academic and industrial values. In this review, we summarized the advanced research on polyphenylene oxide (PPO) polymer based ion exchange membranes. We introduced the membranes synthetic methods, polymer structures, key performances and application processes separately. Besides, we also discussed about the problems of the PPO based ion exchange membranes that should be solved and prospected the development direction in the future. As to the PPO based ion exchange membranes synthetic methods, we divided them into two parts, anion exchange membranes and cation exchange membranes, with a variety of methods enumerated, including introduction of side chains, polymers crosslinking, optimization of functional groups and doping to improve the performances, such as ion conductivity, swelling ratio, mechanical strength and other important performances of the PPO based exchange membranes. We also realized the diversification of the function of ion exchange membranes and application in fuel cells, etc.
2018, 0(7): 814-828
doi: 10.11777/j.issn1000-3304.2018.17317
Abstract:
Since 1949, China has been witnessing a rapid development in ion exchange and adsorption technology. Up to date, at least five generations of polymeric resins have been developed, including gel-type resin, macroporous resin, hyper-cross-linked resin, bifunctional resin and resin-based composite adsorbent. These resin-based materials have been widely utilized in various industries, including military defense, medical and health, fine chemicals, hydrometallurgy, environmental protection, making considerable contributions to the modernization of China. In brief, gel-type resin, characterized by non-porous nature, was first developed for uranium extraction and later expanded to other fields such as water softening. Due to abundant porous structure, macroporous resin exhibited faster ion exchange rate and higher mechanical strength over the gel-type one. A variety of macroporous adsorption resins were developed and widely utilized in separation and/or purification in the industries of food, chemicals, rare elements, drugs, toxins, and environmental remediation. Hyper-cross-linked resin was mainly prepared via Friedel-Crafts reaction, possessing ultra-high specific surface area (usually high than 800 m2/g) and abundant microporous structure. Hyper-cross-linked resins have been successfully applied for hemoperfusion purpose, representing one of the most promising adsorbents for organic pollutants in chemical industry effluents. Bifunctional resins were designed for adsorptive removal of highly water-soluble organic pollutants from industrial effluents, because they could offer multiple interactions with target pollutants such as π-π interaction, electrostatic attraction, hydrophobic interaction and hydrogen bonds. In the past decade, resin-based composite adsorbents, including resin-supported nanocomposite and magnetic resin, were obtained by integrating resin hosts with inorganic (nano) particles for advanced (waste) water treatment. The present review summarizes the development of ion exchange and adsorption resins in China since its foundation, particularly focusing on the historic contributions of Prof. Binglin He, the father of China’s ion exchange resins, to the progress of ion exchange and adsorption technology in China. Also, it provides an outlook of the perspective of ion exchange and adsorption resins in emerging applications.
Since 1949, China has been witnessing a rapid development in ion exchange and adsorption technology. Up to date, at least five generations of polymeric resins have been developed, including gel-type resin, macroporous resin, hyper-cross-linked resin, bifunctional resin and resin-based composite adsorbent. These resin-based materials have been widely utilized in various industries, including military defense, medical and health, fine chemicals, hydrometallurgy, environmental protection, making considerable contributions to the modernization of China. In brief, gel-type resin, characterized by non-porous nature, was first developed for uranium extraction and later expanded to other fields such as water softening. Due to abundant porous structure, macroporous resin exhibited faster ion exchange rate and higher mechanical strength over the gel-type one. A variety of macroporous adsorption resins were developed and widely utilized in separation and/or purification in the industries of food, chemicals, rare elements, drugs, toxins, and environmental remediation. Hyper-cross-linked resin was mainly prepared via Friedel-Crafts reaction, possessing ultra-high specific surface area (usually high than 800 m2/g) and abundant microporous structure. Hyper-cross-linked resins have been successfully applied for hemoperfusion purpose, representing one of the most promising adsorbents for organic pollutants in chemical industry effluents. Bifunctional resins were designed for adsorptive removal of highly water-soluble organic pollutants from industrial effluents, because they could offer multiple interactions with target pollutants such as π-π interaction, electrostatic attraction, hydrophobic interaction and hydrogen bonds. In the past decade, resin-based composite adsorbents, including resin-supported nanocomposite and magnetic resin, were obtained by integrating resin hosts with inorganic (nano) particles for advanced (waste) water treatment. The present review summarizes the development of ion exchange and adsorption resins in China since its foundation, particularly focusing on the historic contributions of Prof. Binglin He, the father of China’s ion exchange resins, to the progress of ion exchange and adsorption technology in China. Also, it provides an outlook of the perspective of ion exchange and adsorption resins in emerging applications.
2018, 0(7): 829-852
doi: 10.11777/j.issn1000-3304.2018.18060
Abstract:
Reversible covalent polymers are able to reorganize their topological structures via reversible reactions triggered by external stimuli (including heating, light and pH), while retaining the stability of irreversible covalent polymers in the absence of the stimuli. Because the transformation only deals with polymerized materials and can be conducted mostly in solid state in the absence of solvents, environmentally friendly and energy saving measures, like self-healing that autonomously repairs damages created during fabrication or usage, have been proposed. In the meantime, many researchers are also devoted to using this feature for solving processing problems of crosslinked polymers. It not only breaks through the strict limits of traditional thermoplastic and thermosetting polymers, but also brings in new methods and new functionalities. As a result, material diversification with extended life cycles becomes available. A series of novel prototype techniques specified for the crosslinked polymers containing reversible covalent bonds are developed accordingly, which include mechanical properties regulation, plastic deformation, welding, dispersion of nano-fillers and their reinforcement effect, compression molding, injection molding, extrusion molding, 3D printing, controllable degradation and reprocessing of carbon fibre reinforced composites. Quite a few engineering processes that cannot be realized by means of existing industrial methods come true. Clearly, the research achievements in this area represent possible advancement of classic polymer engineering. In this review, basis of reversible covalent chemistry and rheology of reversible covalent polymer are comprehensively elucidated and analysed, followed by summarizing the applications of above prototype techniques on the basis of the types of the reversible reactions involved (i.e. general reversible reactions and dynamic reversible reactions). Moreover, the challenges and development trend of this emerging field are also outlined. On the whole, the innovative knowledge paths are managed to be introduced in a systematic way. It is hoped that more and more scientists will be attracted and join in this promising research.
Reversible covalent polymers are able to reorganize their topological structures via reversible reactions triggered by external stimuli (including heating, light and pH), while retaining the stability of irreversible covalent polymers in the absence of the stimuli. Because the transformation only deals with polymerized materials and can be conducted mostly in solid state in the absence of solvents, environmentally friendly and energy saving measures, like self-healing that autonomously repairs damages created during fabrication or usage, have been proposed. In the meantime, many researchers are also devoted to using this feature for solving processing problems of crosslinked polymers. It not only breaks through the strict limits of traditional thermoplastic and thermosetting polymers, but also brings in new methods and new functionalities. As a result, material diversification with extended life cycles becomes available. A series of novel prototype techniques specified for the crosslinked polymers containing reversible covalent bonds are developed accordingly, which include mechanical properties regulation, plastic deformation, welding, dispersion of nano-fillers and their reinforcement effect, compression molding, injection molding, extrusion molding, 3D printing, controllable degradation and reprocessing of carbon fibre reinforced composites. Quite a few engineering processes that cannot be realized by means of existing industrial methods come true. Clearly, the research achievements in this area represent possible advancement of classic polymer engineering. In this review, basis of reversible covalent chemistry and rheology of reversible covalent polymer are comprehensively elucidated and analysed, followed by summarizing the applications of above prototype techniques on the basis of the types of the reversible reactions involved (i.e. general reversible reactions and dynamic reversible reactions). Moreover, the challenges and development trend of this emerging field are also outlined. On the whole, the innovative knowledge paths are managed to be introduced in a systematic way. It is hoped that more and more scientists will be attracted and join in this promising research.
2018, 0(7): 853-863
doi: 10.11777/j.issn1000-3304.2018.17313
Abstract:
Gene therapy is a remarkable technique which regulates specific gene expression in targeted cells to treat acquired and inherited diseases via exogenous nucleic acids. However, naked genes could hardly be utilized directly due to their large size, low stability in circulation and poor cellular uptake. Therefore, suitable gene vector plays a crucial role in gene therapy. Though a mass of gene delivery systems have been developed and shown extraordinary potential to treat gene-related diseases, the clinical applications of gene therapy are still limited by various biological barriers. These barriers include DNA packaging, bloodstream clearing, non-specific cellular uptake, cytomembrane obstructing, endosomal escape, DNA release and potential toxicity to normal tissues, etc. In order to overcome these barriers, the gene vectors should satisfy numerous requirements, including effective gene packaging, prolonging the circulation time in bloodstream, excellent targeting ability, the endosomal escape capability, reduced vector-induced toxicity and the capacity of stimuli-responsive gene unpacking, etc. Intelligent responsive polymers have attracted increasing research attentions in gene delivery applications due to their excellent responsiveness, superadditive versatility, prominent biodegradability and superb biocompatibility, etc. Thus, utilizing the intelligent responsive polymers with special functions could overcome a series of barriers in gene delivery. In addition, most intelligent responsive polymers can creatively combine multiple treatments for tumor therapy to achieve more effective therapeutic effects. This review highlights the designs, characteristics as well as biomedical applications of intelligent responsive polymers in gene delivery field in recent years. The types of response in intelligent responsive polymers include pH response, reduction response, enzyme response, light response and multiple response, etc. The research trends and prospects of these polymers are also discussed. In order to push forward the studies of intelligent responsive polymers in gene delivery field and to develop novel gene vectors, more research attention should be paid to responsive polymers with proper chemical properties, suitable physical properties, desired architectures and appropriate functions.
Gene therapy is a remarkable technique which regulates specific gene expression in targeted cells to treat acquired and inherited diseases via exogenous nucleic acids. However, naked genes could hardly be utilized directly due to their large size, low stability in circulation and poor cellular uptake. Therefore, suitable gene vector plays a crucial role in gene therapy. Though a mass of gene delivery systems have been developed and shown extraordinary potential to treat gene-related diseases, the clinical applications of gene therapy are still limited by various biological barriers. These barriers include DNA packaging, bloodstream clearing, non-specific cellular uptake, cytomembrane obstructing, endosomal escape, DNA release and potential toxicity to normal tissues, etc. In order to overcome these barriers, the gene vectors should satisfy numerous requirements, including effective gene packaging, prolonging the circulation time in bloodstream, excellent targeting ability, the endosomal escape capability, reduced vector-induced toxicity and the capacity of stimuli-responsive gene unpacking, etc. Intelligent responsive polymers have attracted increasing research attentions in gene delivery applications due to their excellent responsiveness, superadditive versatility, prominent biodegradability and superb biocompatibility, etc. Thus, utilizing the intelligent responsive polymers with special functions could overcome a series of barriers in gene delivery. In addition, most intelligent responsive polymers can creatively combine multiple treatments for tumor therapy to achieve more effective therapeutic effects. This review highlights the designs, characteristics as well as biomedical applications of intelligent responsive polymers in gene delivery field in recent years. The types of response in intelligent responsive polymers include pH response, reduction response, enzyme response, light response and multiple response, etc. The research trends and prospects of these polymers are also discussed. In order to push forward the studies of intelligent responsive polymers in gene delivery field and to develop novel gene vectors, more research attention should be paid to responsive polymers with proper chemical properties, suitable physical properties, desired architectures and appropriate functions.
2018, 0(7): 864-877
doi: 10.11777/j.issn1000-3304.2018.18023
Abstract:
Porphyrins are naturally occurring macrocyclic compounds containing four pyrroles connected through four methine carbons at their α-positions. Porphyrins and their derivatives are widely found in biological systems and they engage in many essential processes that sustain living systems, such as enzyme catalysis, oxygen transportation and photosynthesis. The unique biological functions and physiochemical properties of porphyrin and its derivatives have made them interesting candidates in the preparation of functional materials for various applications. The recent progress on the synthesis and application of porphyrin derivatives and particularly the related macromolecular and supramolecular structures, is summarized in this review. Following a brief introduction on porphyrin and its derivatives in nature and on the binding and adsorption studies on porphyrin-related bile pigments such as bilirubin, the strategies for the preparation of porphyrin-based polymers are reviewed, including the covalent polymerization and supramolecular self-assembly of linear polymers based on porphyrin, as well as two- and three-dimensional porphyrin assemblies and frameworks. The applications of porphyrin-based polymers and supramolecular-structures are also covered, which include: artificial enzymes, photo-dynamic therapy, chemical sensors, light-energy harvesting and medical imaging. These versatile functions are a synergetic result of porphyrin and its conjunct polymers: the porphyrin has unique photo-physical properties, and the polymers manifested porphyrin moieties stable and switchable chemical environment. Despite the progress having been made, the great potential as functional materials of porphyrin and its derivatives has not been fully exploited. In the future, tailoring the molecular topology of porphyrins-based polymer is believed to be an effective strategy of obtaining functional materials with controlled self-assembly structure. Constructing higher-ordered structure with supramolecular self-assembled porphyrin derivatives is a promising field, because the hierarchical structure would bring more interesting functions that cannot be realized with single molecules. Combination of porphyrin with other biomolecules is worthwhile to pay attention to. With covalent or supramolecular conjunction of porphyrin and biomolecules, functional materials with novel properties that even do not exist in nature might be created.
Porphyrins are naturally occurring macrocyclic compounds containing four pyrroles connected through four methine carbons at their α-positions. Porphyrins and their derivatives are widely found in biological systems and they engage in many essential processes that sustain living systems, such as enzyme catalysis, oxygen transportation and photosynthesis. The unique biological functions and physiochemical properties of porphyrin and its derivatives have made them interesting candidates in the preparation of functional materials for various applications. The recent progress on the synthesis and application of porphyrin derivatives and particularly the related macromolecular and supramolecular structures, is summarized in this review. Following a brief introduction on porphyrin and its derivatives in nature and on the binding and adsorption studies on porphyrin-related bile pigments such as bilirubin, the strategies for the preparation of porphyrin-based polymers are reviewed, including the covalent polymerization and supramolecular self-assembly of linear polymers based on porphyrin, as well as two- and three-dimensional porphyrin assemblies and frameworks. The applications of porphyrin-based polymers and supramolecular-structures are also covered, which include: artificial enzymes, photo-dynamic therapy, chemical sensors, light-energy harvesting and medical imaging. These versatile functions are a synergetic result of porphyrin and its conjunct polymers: the porphyrin has unique photo-physical properties, and the polymers manifested porphyrin moieties stable and switchable chemical environment. Despite the progress having been made, the great potential as functional materials of porphyrin and its derivatives has not been fully exploited. In the future, tailoring the molecular topology of porphyrins-based polymer is believed to be an effective strategy of obtaining functional materials with controlled self-assembly structure. Constructing higher-ordered structure with supramolecular self-assembled porphyrin derivatives is a promising field, because the hierarchical structure would bring more interesting functions that cannot be realized with single molecules. Combination of porphyrin with other biomolecules is worthwhile to pay attention to. With covalent or supramolecular conjunction of porphyrin and biomolecules, functional materials with novel properties that even do not exist in nature might be created.
2018, 0(7): 878-885
doi: 10.11777/j.issn1000-3304.2018.17327
Abstract:
Carbon nanotubes have excellent mechanical properties. However, their application in polymer composites is limited due to their easy aggregation and inert surface. In order to improve their dispersion and surface performance, multiwalled carbon nanotubes (MWCNTs), chemically modified using oligo(para-phenylene terephthanlamide) and denoted as PPTA-MWCNTs-x, were prepared, and used to investigate the reinforcement of the mechanical properties of poly(vinyl chloride) (PVC) composite films. PPTA-MWCNTs-x was obtained by the reaction of carboxymethyl multiwalled carbon nanotubes (MWCNTs-COOH) with amino-terminal para-phenylene terephthanlamide oligomers (PPTA). A typical procedure is as follows: firstly, a desired amount of MWCNTs-COOH was suspended in N-methyl methyl pyrrolidone (NMP), and the suspension was sonicated to form a homogenous dark-brown solution. In a separated experiment, amino-terminal PPTA oligomer was prepared by reacting PDA with TPC at a ratio of 1.5 to 1 in NMP. The above MWCNTs-COOH dispersion was poured into the PPTA solution just prepared, and the mixture was stirred at desired temperature for a given time in the presence of catalyst of N,N-dicyclohexylcarbodiimde under nitrogen atmosphere. The solid substance obtained was filtered and the product PPTA-MWCNTs-x was obtained. Transmission electron microscopy (TEM), scanning electron microscope (SEM), and Fourier transform infrared spectrometer (FTIR) were used to characterize the structure and the morphology of PPTA-MWCNTs-x. The results of FTIR analysis demonstrated that PPTA oligomers were successfully grafted on the surface of PPTA-MWCNTs-x. The dispersion stability of PPTA-MWCNTs-x in some solvents, such as NMP, dimethyl formamide (DMF), dimethyl sulfoxide (DMSO) and ethanol, was investigated. The results showed that the stability of PPTA-MWCNTs-x in DMF and DMSO was higher than that in NMP and ethanol, and the time, that the dispersion remained stable without phase separation, could reach 216 and 240 h, respectively. PVC was chosen as model polymer to investigate the reinforcement effect of PPTA-MWCNTs-x. PVC composite films were prepared by solvent casting using DMF as solvent. Optical microscope images showed that PPTA-MWCNTs-x was more homogeneously dispersed than MWCNTs-COOH in the composite films. The reinforcement results demonstrated that the maximum Young’s modulus, strength and strain of PPTA-MWCNTs-x/PVC composite films increased by 44.4%, 79.4%, and 203.6%, respectively, in comparison to those values from pure PVC films, while those of MWCNTs-COOH/PVC composite films increased by 29.7%, 41.6%, and 104.2%, respectively. Obviously, the MWCNTs modified by oligo-PPTA can significantly improve the mechanical properties of PVC composite films. Based on the observations, PPTA-MWCNTs-x has great potential to be used as reinforcing polymer filler in the future.
Carbon nanotubes have excellent mechanical properties. However, their application in polymer composites is limited due to their easy aggregation and inert surface. In order to improve their dispersion and surface performance, multiwalled carbon nanotubes (MWCNTs), chemically modified using oligo(para-phenylene terephthanlamide) and denoted as PPTA-MWCNTs-x, were prepared, and used to investigate the reinforcement of the mechanical properties of poly(vinyl chloride) (PVC) composite films. PPTA-MWCNTs-x was obtained by the reaction of carboxymethyl multiwalled carbon nanotubes (MWCNTs-COOH) with amino-terminal para-phenylene terephthanlamide oligomers (PPTA). A typical procedure is as follows: firstly, a desired amount of MWCNTs-COOH was suspended in N-methyl methyl pyrrolidone (NMP), and the suspension was sonicated to form a homogenous dark-brown solution. In a separated experiment, amino-terminal PPTA oligomer was prepared by reacting PDA with TPC at a ratio of 1.5 to 1 in NMP. The above MWCNTs-COOH dispersion was poured into the PPTA solution just prepared, and the mixture was stirred at desired temperature for a given time in the presence of catalyst of N,N-dicyclohexylcarbodiimde under nitrogen atmosphere. The solid substance obtained was filtered and the product PPTA-MWCNTs-x was obtained. Transmission electron microscopy (TEM), scanning electron microscope (SEM), and Fourier transform infrared spectrometer (FTIR) were used to characterize the structure and the morphology of PPTA-MWCNTs-x. The results of FTIR analysis demonstrated that PPTA oligomers were successfully grafted on the surface of PPTA-MWCNTs-x. The dispersion stability of PPTA-MWCNTs-x in some solvents, such as NMP, dimethyl formamide (DMF), dimethyl sulfoxide (DMSO) and ethanol, was investigated. The results showed that the stability of PPTA-MWCNTs-x in DMF and DMSO was higher than that in NMP and ethanol, and the time, that the dispersion remained stable without phase separation, could reach 216 and 240 h, respectively. PVC was chosen as model polymer to investigate the reinforcement effect of PPTA-MWCNTs-x. PVC composite films were prepared by solvent casting using DMF as solvent. Optical microscope images showed that PPTA-MWCNTs-x was more homogeneously dispersed than MWCNTs-COOH in the composite films. The reinforcement results demonstrated that the maximum Young’s modulus, strength and strain of PPTA-MWCNTs-x/PVC composite films increased by 44.4%, 79.4%, and 203.6%, respectively, in comparison to those values from pure PVC films, while those of MWCNTs-COOH/PVC composite films increased by 29.7%, 41.6%, and 104.2%, respectively. Obviously, the MWCNTs modified by oligo-PPTA can significantly improve the mechanical properties of PVC composite films. Based on the observations, PPTA-MWCNTs-x has great potential to be used as reinforcing polymer filler in the future.
2018, 0(7): 886-892
doi: 10.11777/j.issn1000-3304.2018.17332
Abstract:
The objective of this study was to develop a novel solid amine adsorbent using porous polyacrylonitrile resin instead of mesoporous silica as support for CO2 adsorption from flue gas. This solid amine adsorbent was prepared by a suspension polymerization of divinylbenzene (DVB) with acrylonitrile (AN), followed by aminating with tetraethylenepentamine (TEPA). Scanning electronic microscope, nitrogen adsorption-desorption isotherms at 77 K, and thermogravimetry (TG) were employed to characterize the surface structure, porosity, and thermal stability of the solid amine adsorbent. Factors that could determine the CO2 adsorption performance of the solid amine adsorbent, such as amine species, adsorption temperature and moisture, were investigated. The experimental results showed that the maximum adsorption capacity of CO2 (1.87 mmol/g) wasachieved at 25 °C with CO2 concentration of 10 vol%, the flow rate of 30 mL/min and TEPA as the organic amine. The solid amine adsorbent modified with TEPA (PAN-TEPA), a longer chain amine among all amines used, showed superior amine efficiency and CO2 adsorption capacity to the other two amine species with shorter chains. CO2 adsorption capacity decreased obviously as the adsorption temperature increased, because the reaction between CO2 and amine groups was an exothermic reaction. The presence of water could significantly improve CO2 amount adsorbed on the adsorbent by promoting the chemical adsorption of CO2 on PAN-TEPA. A higher equilibrium adsorption capacity (2.97 mmol/g) was achieved in the presence of moisture. Meanwhile, the kinetics study found that Avrami kinetic model was more fitted to accurately describe CO2 adsorption than the Pseudo-first and Pseudo-second order models, indicating that both physical adsorption and chemical adsorption were involved in CO2 adsorption. Moreover, this solid amine adsorbent could be regenerated with nitrogen stream at 75 °C, and it kept stable CO2 adsorption capacity after ten cycles of adsorption-desorption. All these features indicated that the amine-functionalized porous polyacrylonitrile resin has a high potential for CO2 capture and separation from flue gas.
The objective of this study was to develop a novel solid amine adsorbent using porous polyacrylonitrile resin instead of mesoporous silica as support for CO2 adsorption from flue gas. This solid amine adsorbent was prepared by a suspension polymerization of divinylbenzene (DVB) with acrylonitrile (AN), followed by aminating with tetraethylenepentamine (TEPA). Scanning electronic microscope, nitrogen adsorption-desorption isotherms at 77 K, and thermogravimetry (TG) were employed to characterize the surface structure, porosity, and thermal stability of the solid amine adsorbent. Factors that could determine the CO2 adsorption performance of the solid amine adsorbent, such as amine species, adsorption temperature and moisture, were investigated. The experimental results showed that the maximum adsorption capacity of CO2 (1.87 mmol/g) wasachieved at 25 °C with CO2 concentration of 10 vol%, the flow rate of 30 mL/min and TEPA as the organic amine. The solid amine adsorbent modified with TEPA (PAN-TEPA), a longer chain amine among all amines used, showed superior amine efficiency and CO2 adsorption capacity to the other two amine species with shorter chains. CO2 adsorption capacity decreased obviously as the adsorption temperature increased, because the reaction between CO2 and amine groups was an exothermic reaction. The presence of water could significantly improve CO2 amount adsorbed on the adsorbent by promoting the chemical adsorption of CO2 on PAN-TEPA. A higher equilibrium adsorption capacity (2.97 mmol/g) was achieved in the presence of moisture. Meanwhile, the kinetics study found that Avrami kinetic model was more fitted to accurately describe CO2 adsorption than the Pseudo-first and Pseudo-second order models, indicating that both physical adsorption and chemical adsorption were involved in CO2 adsorption. Moreover, this solid amine adsorbent could be regenerated with nitrogen stream at 75 °C, and it kept stable CO2 adsorption capacity after ten cycles of adsorption-desorption. All these features indicated that the amine-functionalized porous polyacrylonitrile resin has a high potential for CO2 capture and separation from flue gas.
2018, 0(7): 893-899
doi: 10.11777/j.issn1000-3304.2018.18007
Abstract:
The application of charged nanoparticles in drug delivery and imaging has been extensively investigated. The surface charge density of charged nanoparticles, which is usually characterized by ζ potentials, has a drastic effect on the interaction between the nanoparticles and the biological systems, and this interaction is critical for the in vivo biofate of the nanoparticles. However, the effect of different types of buffer systems and their concentrations on the ζ potentials is often ignored in literature. Various buffer systems, such as phosphate, Tris, Hepes and Mops, and different buffer concentrations from 1 mmol/L to 200 mmol/L, were used for measuring ζ potentials of nanoparticles. Herein the effect of buffer types and their concentrations on the ζ potentials for three different types of amine group-containing nanoparticles, i.e. poly(amido amine) (PAMAM) dendrimer, polystyrene-block-poly((N,N-diethylamino)ethyl methacrylate) (PS-b-PDMAEMA) micelles and chitosan nanoparticles, was studied. The ζ potentials of all the three types of nanoparticles decreased in the order of Tris, Hepes, Mops, and phosphates for buffer systems at the same concentration and pH. The ζ potentials were much lower in phosphate buffer than that in the others. The ζ potentials of amino group-containing chitosan nanoparticles showed even negative values in phosphate buffer with the concentration below ~ 10 mmol/L at pH = 7.4. The ζ potentials of all the three types of nanoparticles drastically decreased with the increase in buffer concentration (from 2 mmol/L to 100 mmol/L) for all the buffer systems investigated. The ζ potentials of chitosan nanoparticles in phosphate buffer (pH = 7.4) were reversed from positive to negative with the increase in phosphate concentration, with the crossover concentration of around 10 mmol/L. This charge reversal was contributed to the low protonation degree of chitosan amino groups (pKa = 6.3) at pH = 7.4, and the presence of trivalent phosphate anions, which should be strongly adsorbed onto the positively charged particle surfaces and subsequently shielded the positive charges. When NaCl was added in the buffers, the ζ potentials of all the three types of nanoparticles decreased with increasing concentrations of the salt.
The application of charged nanoparticles in drug delivery and imaging has been extensively investigated. The surface charge density of charged nanoparticles, which is usually characterized by ζ potentials, has a drastic effect on the interaction between the nanoparticles and the biological systems, and this interaction is critical for the in vivo biofate of the nanoparticles. However, the effect of different types of buffer systems and their concentrations on the ζ potentials is often ignored in literature. Various buffer systems, such as phosphate, Tris, Hepes and Mops, and different buffer concentrations from 1 mmol/L to 200 mmol/L, were used for measuring ζ potentials of nanoparticles. Herein the effect of buffer types and their concentrations on the ζ potentials for three different types of amine group-containing nanoparticles, i.e. poly(amido amine) (PAMAM) dendrimer, polystyrene-block-poly((N,N-diethylamino)ethyl methacrylate) (PS-b-PDMAEMA) micelles and chitosan nanoparticles, was studied. The ζ potentials of all the three types of nanoparticles decreased in the order of Tris, Hepes, Mops, and phosphates for buffer systems at the same concentration and pH. The ζ potentials were much lower in phosphate buffer than that in the others. The ζ potentials of amino group-containing chitosan nanoparticles showed even negative values in phosphate buffer with the concentration below ~ 10 mmol/L at pH = 7.4. The ζ potentials of all the three types of nanoparticles drastically decreased with the increase in buffer concentration (from 2 mmol/L to 100 mmol/L) for all the buffer systems investigated. The ζ potentials of chitosan nanoparticles in phosphate buffer (pH = 7.4) were reversed from positive to negative with the increase in phosphate concentration, with the crossover concentration of around 10 mmol/L. This charge reversal was contributed to the low protonation degree of chitosan amino groups (pKa = 6.3) at pH = 7.4, and the presence of trivalent phosphate anions, which should be strongly adsorbed onto the positively charged particle surfaces and subsequently shielded the positive charges. When NaCl was added in the buffers, the ζ potentials of all the three types of nanoparticles decreased with increasing concentrations of the salt.
2018, 0(7): 900-908
doi: 10.11777/j.issn1000-3304.2018.18028
Abstract:
Monodisperse tetra-layer hybrid microspheres, the types of SiO2/anionic polymer/SiO2/anionic polymer and SiO2/anionic polymer/SiO2/cationic polymer, were prepared by a four-step synthetic procedure. The hollow double-shelled electrolyte microspheres, with either anionic species (−41.43 ~ −54.65 mV) on both shells or zwitterionic structures on the inner and outer shells, were prepared via combination of distillation precipitation polymerization and sol-gel method for the preparation of the tetra-layer inorganic/polymer hybrid microspheres together with the subsequently selective removal of silica core and sandwiched layer. In such a process, the modified Stöber sol-gel technique was utilized for synthesis of silica inner core and the sandwiched third layer for these tetra-layer inorganic/polymer hybrid microspheres. The P(EGDMA-co-MAA) and P(DVB-co-St) polymeric layers were synthesized via the radical capture of EGDMA/MAA and DVB/St comonomers as well as their co-oligomers from the vinyl groups as the reactive sites with presence of the 3-(methacryloxy)propyl trimethoxysilane (MPS) silica nanoparticles as the seeds during the distillation precipitation polymerization. The outer P(DVB-co-StMPPy+Cl−) shell was further developed by a surface pyridinium reaction between the chloromethyl group on the surface of polymer network and the pyridine via suspension of SiO2/P(EGDMA-co-MAA)/SiO2/P(DVB-co-St) tetra-layer microspheres with various DVB crosslinking degrees (30 vol%, 50 vol% and 60 vol%) in pyridine. Transmission electron microscopy (TEM), Fourier transfer infrared spectra (FTIR) and zeta potential were systematically used for characterization of the morphology, chemical components and surface charges of these hollow double-layer polyelectrolyte microspheres. The resultant multi-layer inorganic silica/polymer multi-layer hybrid microspheres had smooth surface with regular shape with efficient interaction between the polymer layer and the inorganic species. The shape of the polymeric shells were deformed in the hollow polyelectrolyte microspheres due to shrinkage and collapse of the shells when they were slightly crosslinked. The thicknesses (12 − 59 nm) and zeta-potentials (8.82 − 39.82 mV) of the polymeric shell-layer can be facilely adjusted by changing the amount of DVB crosslinker in the comonomers (0.30 − 0.60) in the synthesis. The hollow double polymer electrolyte microspheres have great potential for applications as the active components in the field of methanol fuel cell for water reservoirs with high proton conductivity due to its huge cavities and zwitter-ionic channels for electron conductivity.
Monodisperse tetra-layer hybrid microspheres, the types of SiO2/anionic polymer/SiO2/anionic polymer and SiO2/anionic polymer/SiO2/cationic polymer, were prepared by a four-step synthetic procedure. The hollow double-shelled electrolyte microspheres, with either anionic species (−41.43 ~ −54.65 mV) on both shells or zwitterionic structures on the inner and outer shells, were prepared via combination of distillation precipitation polymerization and sol-gel method for the preparation of the tetra-layer inorganic/polymer hybrid microspheres together with the subsequently selective removal of silica core and sandwiched layer. In such a process, the modified Stöber sol-gel technique was utilized for synthesis of silica inner core and the sandwiched third layer for these tetra-layer inorganic/polymer hybrid microspheres. The P(EGDMA-co-MAA) and P(DVB-co-St) polymeric layers were synthesized via the radical capture of EGDMA/MAA and DVB/St comonomers as well as their co-oligomers from the vinyl groups as the reactive sites with presence of the 3-(methacryloxy)propyl trimethoxysilane (MPS) silica nanoparticles as the seeds during the distillation precipitation polymerization. The outer P(DVB-co-StMPPy+Cl−) shell was further developed by a surface pyridinium reaction between the chloromethyl group on the surface of polymer network and the pyridine via suspension of SiO2/P(EGDMA-co-MAA)/SiO2/P(DVB-co-St) tetra-layer microspheres with various DVB crosslinking degrees (30 vol%, 50 vol% and 60 vol%) in pyridine. Transmission electron microscopy (TEM), Fourier transfer infrared spectra (FTIR) and zeta potential were systematically used for characterization of the morphology, chemical components and surface charges of these hollow double-layer polyelectrolyte microspheres. The resultant multi-layer inorganic silica/polymer multi-layer hybrid microspheres had smooth surface with regular shape with efficient interaction between the polymer layer and the inorganic species. The shape of the polymeric shells were deformed in the hollow polyelectrolyte microspheres due to shrinkage and collapse of the shells when they were slightly crosslinked. The thicknesses (12 − 59 nm) and zeta-potentials (8.82 − 39.82 mV) of the polymeric shell-layer can be facilely adjusted by changing the amount of DVB crosslinker in the comonomers (0.30 − 0.60) in the synthesis. The hollow double polymer electrolyte microspheres have great potential for applications as the active components in the field of methanol fuel cell for water reservoirs with high proton conductivity due to its huge cavities and zwitter-ionic channels for electron conductivity.
2018, 0(7): 909-916
doi: 10.11777/j.issn1000-3304.2018.18039
Abstract:
Nanoparticles have been extensively explored as an effective means to deliver photosensitizers for photodynamic therapy (PDT) against cancer. In this work, Pheophorbide A (PheoA), a hydrophobic photosensitizer, was conjugated to natural polysaccharide alginate (PheoA-ALG) via a redox-sensitive disulfide linkage. The critical aggregation concentration (CAC) of PheoA-ALG in aqueous solution was 73.51 μg/mL, detected by pyrene monomer fluorescence probe technology. The resulting amphiphilic PheoA-ALG could form self-assembled nanoparticles (PheoA-ALG NPs) in an aqueous medium as prodrug nanoparticles for tumor photodynamic therapy. The physical and chemical properties of PheoA-ALG NPs were studied. TEM and DLS revealed that PheoA-ALG NPs were monodisperse spherical structures with a hydrodynamic diameter about 198 nm. PheoA release profiles in vitro indicated that PheoA release from PheoA-ALG NPs was redox-sensitive. Whereafter, the cellular uptake and cytotoxicity of PheoA-ALG NPs were investigated in vitro. Cellular uptake results showed that PheoA-ALG NPs were readily taken up by B16 tumor cells and enhanced PheoA uptake was detectable in PheoA-ALG NPs-treated B16 cells in comparison to carrier free drugs. Under light irradiation, PheoA-ALG NPs also elicited intracellular ROS generation, which led to an enhanced toxicity in B16 cells both in vitro and in vivo. The CCK-8 assay showed that PheoA-ALG NPs had good cellular compatibility without cytotoxic in vitro without light irradiation, and PheoA-ALG NPs exhibited light dependent cytotoxic response to B16 cells. After light irradiation, IC50 of PheoA-ALG NPs decreased to 0.16 μg mL−1, which was about 0.67-fold lower than those of the free PheoA groups with light irradiation. In vivo anti-tumor efficacy of PheoA-ALG NPs was assessed using B16 tumor-bearing mice. Notably, mice treated with PheoA-ALG NPs under light irradiation displayed the highest inhibition ratio of 72.8%, among those treated with free PheoA (45.8%). These results suggest that PheoA-ALG NPs have good potential for tumor photodynamic therapy.
Nanoparticles have been extensively explored as an effective means to deliver photosensitizers for photodynamic therapy (PDT) against cancer. In this work, Pheophorbide A (PheoA), a hydrophobic photosensitizer, was conjugated to natural polysaccharide alginate (PheoA-ALG) via a redox-sensitive disulfide linkage. The critical aggregation concentration (CAC) of PheoA-ALG in aqueous solution was 73.51 μg/mL, detected by pyrene monomer fluorescence probe technology. The resulting amphiphilic PheoA-ALG could form self-assembled nanoparticles (PheoA-ALG NPs) in an aqueous medium as prodrug nanoparticles for tumor photodynamic therapy. The physical and chemical properties of PheoA-ALG NPs were studied. TEM and DLS revealed that PheoA-ALG NPs were monodisperse spherical structures with a hydrodynamic diameter about 198 nm. PheoA release profiles in vitro indicated that PheoA release from PheoA-ALG NPs was redox-sensitive. Whereafter, the cellular uptake and cytotoxicity of PheoA-ALG NPs were investigated in vitro. Cellular uptake results showed that PheoA-ALG NPs were readily taken up by B16 tumor cells and enhanced PheoA uptake was detectable in PheoA-ALG NPs-treated B16 cells in comparison to carrier free drugs. Under light irradiation, PheoA-ALG NPs also elicited intracellular ROS generation, which led to an enhanced toxicity in B16 cells both in vitro and in vivo. The CCK-8 assay showed that PheoA-ALG NPs had good cellular compatibility without cytotoxic in vitro without light irradiation, and PheoA-ALG NPs exhibited light dependent cytotoxic response to B16 cells. After light irradiation, IC50 of PheoA-ALG NPs decreased to 0.16 μg mL−1, which was about 0.67-fold lower than those of the free PheoA groups with light irradiation. In vivo anti-tumor efficacy of PheoA-ALG NPs was assessed using B16 tumor-bearing mice. Notably, mice treated with PheoA-ALG NPs under light irradiation displayed the highest inhibition ratio of 72.8%, among those treated with free PheoA (45.8%). These results suggest that PheoA-ALG NPs have good potential for tumor photodynamic therapy.
2018, 0(7): 917-929
doi: 10.11777/j.issn1000-3304.2018.18043
Abstract:
A triblock bottlebrush copolymer, poly(N,N-dimethyl acrylamide)-block-(polyacrylate-graft- (polystyrene-alternate-poly(L-lactide)))-block-poly(N,N-dimethyl acrylamide) (PDMA-b-(PA-g-(PS-alt-PLLA))-b-PDMA), was prepared with an amphiphilic coil-rod-coil macromolecular structure based on the combination of reversible addition-fragmentation chain transfer polymerization (RAFT), copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC), and ring-opening polymerization (ROP). For the formation of the triblock bottlebrush copolymer, RAFT was used to prepare the well-defined triblock copolymer main chain of PDMA-b-PA-b-PDMA. CuAAC was then employed to graft the PS side chains onto the reactive PA block to form the triblock bottlebrush copolymer PDMA-b-(PA-g-PS)-b-PDMA with PS side chains. The in situ ROP of L-lactide to graft PLLA from PA block finally produced the triblock bottlebrush copolymer of PDMA-b-(PA-g-(PS-alt-PLLA))-b-PDMA with V-shaped side chains of PS and PLLA. In this macromolecule, PDMA formed the hydrophilic coil blocks while the bottlebrush polymer of PA-g-(PS-alt-PLLA) formed the hydrophobic rod block. Self-assembly of the amphiphilic PDMA-b-(PA-g-(PS-alt-PLLA))-b-PDMA was subsequently investigated in selective solvents. Due to the unique coil-rod-coil molecular structure, this triblock bottlebrush copolymer self-assembled into sheet-like micelles or vesicles in the selective solvents of THF/methanol or THF/ethanol, respectively. In these self-assemblies, the coil hydrophilic PDMA block formed the dispersing shell to keep their dispersion while the rigid hydrophobic bottlebrush block aggregated into the sheet-like cores to maintain stability of the self-assemblies. The PS and PLLA side chains with V-shaped structure along the middle blocks microphase-separated inside the aggregated micellar sheet or vesicle wall, in which the isolated PLLA microdomain was surrounded by the continuous PS microdomain. Furthermore, the selective hydrolysis of PLLA microdomain left the nanopores inside the cores of micelles and vesicles. It has been demonstrated the hydrolysis rate was heavily depended on the morphology of the self-assemblies, where the hydrolysis of PLLA microdomains of sheet-like micelles was much faster than that of the corresponding vesicles.
A triblock bottlebrush copolymer, poly(N,N-dimethyl acrylamide)-block-(polyacrylate-graft- (polystyrene-alternate-poly(L-lactide)))-block-poly(N,N-dimethyl acrylamide) (PDMA-b-(PA-g-(PS-alt-PLLA))-b-PDMA), was prepared with an amphiphilic coil-rod-coil macromolecular structure based on the combination of reversible addition-fragmentation chain transfer polymerization (RAFT), copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC), and ring-opening polymerization (ROP). For the formation of the triblock bottlebrush copolymer, RAFT was used to prepare the well-defined triblock copolymer main chain of PDMA-b-PA-b-PDMA. CuAAC was then employed to graft the PS side chains onto the reactive PA block to form the triblock bottlebrush copolymer PDMA-b-(PA-g-PS)-b-PDMA with PS side chains. The in situ ROP of L-lactide to graft PLLA from PA block finally produced the triblock bottlebrush copolymer of PDMA-b-(PA-g-(PS-alt-PLLA))-b-PDMA with V-shaped side chains of PS and PLLA. In this macromolecule, PDMA formed the hydrophilic coil blocks while the bottlebrush polymer of PA-g-(PS-alt-PLLA) formed the hydrophobic rod block. Self-assembly of the amphiphilic PDMA-b-(PA-g-(PS-alt-PLLA))-b-PDMA was subsequently investigated in selective solvents. Due to the unique coil-rod-coil molecular structure, this triblock bottlebrush copolymer self-assembled into sheet-like micelles or vesicles in the selective solvents of THF/methanol or THF/ethanol, respectively. In these self-assemblies, the coil hydrophilic PDMA block formed the dispersing shell to keep their dispersion while the rigid hydrophobic bottlebrush block aggregated into the sheet-like cores to maintain stability of the self-assemblies. The PS and PLLA side chains with V-shaped structure along the middle blocks microphase-separated inside the aggregated micellar sheet or vesicle wall, in which the isolated PLLA microdomain was surrounded by the continuous PS microdomain. Furthermore, the selective hydrolysis of PLLA microdomain left the nanopores inside the cores of micelles and vesicles. It has been demonstrated the hydrolysis rate was heavily depended on the morphology of the self-assemblies, where the hydrolysis of PLLA microdomains of sheet-like micelles was much faster than that of the corresponding vesicles.
Fabrication and Structural Control of Hollow Nanonetwork-structured Polystyrene and Carbon Materials
2018, 0(7): 930-938
doi: 10.11777/j.issn1000-3304.2018.18044
Abstract:
As an important class of novel porous materials, nanonetwork-structured polymer and carbon materials have an unique three-dimensional (3D) interconnected hierarchical porous structure, and thus hold considerable promise in a spectrum of applications including energy, adsorption, separation, catalysis, medicine, and so on. This study focuses on the innovative structure design, controllable fabrication and structure-property relationship of novel nanonetwork-structured polystyrene and carbon materials. Hollow nanonetwork-structured polystyrene (HNNS-PS), with hollow microporous PS spherical network unit was designed and fabricated on molecular-level by combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and Friedel-Crafts hypercrosslinking reaction. The 3D nanonetwork structure was controlled by precisely tuning the molecular weight of PS. Gel permeation chromatography (GPC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen adsorption were used to characterize the structure and morphology of HNNS-PS, and intelligent gravimetric analyzer (IGA) was used to determine the adsorption capacity of HNNS-PS towards toluene vapor. Additionally, the inheritance of 3D nanonetwork structure during carbonization was realized by tuning the heating rate. It is found that, by utilizing the SI-ATRP technique, one was able to precisely tune the PS molecular weight and to fabricate SiO2-g-PS building blocks with different PS molecular weight, i.e., SiO2-g-PS-22.4k, SiO2-g-PS-46.9k and SiO2-g-PS-94.4k. As the molecular weight of PS went up from 2.26 × 104 to 4.69 × 104 and 9.44 × 104, the diameter of the nanospheres increased from 196 nm to 223 and 282 nm. After the Friedel-Crafts hypercrosslinking reaction and silica etching, HNNS-PS with different PS molecular weight was obtained. Due to the introduction of the micropores, the diameter of the network units increased to 263, 280 and 332 nm, respectively. As the molecular weight of PS went up, the Brunauer-Emmett-Teller surface area (SBET) of HNNS-PS increased from 346 m2 g−1 to 390 and 450 m2 g−1. HNNS-PS had a high adsorption capacity of up to 534 mg g−1 towards toluene vapor at 25 °C. In addition, when the heating rate was low (1 or 2 K min−1) during carbonization, the as-prepared carbon materials could preserve their 3D nanonetwork structure morphologies with SBET up to 696 m2 g−1, which paved the way for the design and fabrication of 3D nanonetwork structured carbon materials, and thus would have important theoretic significance and application value.
As an important class of novel porous materials, nanonetwork-structured polymer and carbon materials have an unique three-dimensional (3D) interconnected hierarchical porous structure, and thus hold considerable promise in a spectrum of applications including energy, adsorption, separation, catalysis, medicine, and so on. This study focuses on the innovative structure design, controllable fabrication and structure-property relationship of novel nanonetwork-structured polystyrene and carbon materials. Hollow nanonetwork-structured polystyrene (HNNS-PS), with hollow microporous PS spherical network unit was designed and fabricated on molecular-level by combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and Friedel-Crafts hypercrosslinking reaction. The 3D nanonetwork structure was controlled by precisely tuning the molecular weight of PS. Gel permeation chromatography (GPC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen adsorption were used to characterize the structure and morphology of HNNS-PS, and intelligent gravimetric analyzer (IGA) was used to determine the adsorption capacity of HNNS-PS towards toluene vapor. Additionally, the inheritance of 3D nanonetwork structure during carbonization was realized by tuning the heating rate. It is found that, by utilizing the SI-ATRP technique, one was able to precisely tune the PS molecular weight and to fabricate SiO2-g-PS building blocks with different PS molecular weight, i.e., SiO2-g-PS-22.4k, SiO2-g-PS-46.9k and SiO2-g-PS-94.4k. As the molecular weight of PS went up from 2.26 × 104 to 4.69 × 104 and 9.44 × 104, the diameter of the nanospheres increased from 196 nm to 223 and 282 nm. After the Friedel-Crafts hypercrosslinking reaction and silica etching, HNNS-PS with different PS molecular weight was obtained. Due to the introduction of the micropores, the diameter of the network units increased to 263, 280 and 332 nm, respectively. As the molecular weight of PS went up, the Brunauer-Emmett-Teller surface area (SBET) of HNNS-PS increased from 346 m2 g−1 to 390 and 450 m2 g−1. HNNS-PS had a high adsorption capacity of up to 534 mg g−1 towards toluene vapor at 25 °C. In addition, when the heating rate was low (1 or 2 K min−1) during carbonization, the as-prepared carbon materials could preserve their 3D nanonetwork structure morphologies with SBET up to 696 m2 g−1, which paved the way for the design and fabrication of 3D nanonetwork structured carbon materials, and thus would have important theoretic significance and application value.
2018, 0(7): 939-948
doi: 10.11777/j.issn1000-3304.2018.18056
Abstract:
Nano-scale hydrated ferric oxide (HFO) of high specific surface area and reactivity exhibits specific affinity toward arsenate owing to the abundant surface hydroxyl groups. Nevertheless, the ultrafine particle of nano-HFO tend to agglomerate and thereafter significantly limits its large-scale application in water treatment due to the excessive hydraulic pressure drop and difficult operation from the reaction systems. In comparison with macroporous ion exchangers, gel-type ones are more cost effective, though their utilization as hosts to support nanoparticles is intensively compromised by relatively poor pore structure, high swelling rate and weak mechanical strength. In this study we prepared a nanocomposite adsorbent HFO-201 × 4 via ion exchange/in situ deposition method by using a gel resin-201 × 4 as the host of nano-HFO. The main objective of this study is to compare the structural features, physical and chemical properties of the nanocomposite to a macroporous resin-based nanocomposite HFO-201, and to evaluate their different adsorption property toward As(V). The results indicate that nano-HFO immobilized in HFO-201 × 4 was acicular, quite different from the spherical particles in HFO-201. Other structure properties of both composites, such as crystal form, pore structure, mechanical strength and swelling ratio, are quite similar. The maximum adsorption capacity of HFO-201 × 4 was slightly higher than that of HFO-201, while HFO-201 × 4 exhibited superior adsorption toward trace As(V) over HFO-201 in terms of adsorption capacity and kinetics, possibly arising from higher site density of HFO-201 × 4 (1.47 mmol/g) than HFO-201 (0.88 mmol/g). From the breakthrough curves of two separate fixed beds packed with both composites, the effective working capacity of HFO-201 × 4 was nearly twice of HFO-201. The exhausted HFO-201 × 4 could be efficiently regenerated for cyclic runs. This study demonstrates that gel-type anion exchange resins could serve as promising hosts for fabrication of similar nanocomposite for water decontamination.
Nano-scale hydrated ferric oxide (HFO) of high specific surface area and reactivity exhibits specific affinity toward arsenate owing to the abundant surface hydroxyl groups. Nevertheless, the ultrafine particle of nano-HFO tend to agglomerate and thereafter significantly limits its large-scale application in water treatment due to the excessive hydraulic pressure drop and difficult operation from the reaction systems. In comparison with macroporous ion exchangers, gel-type ones are more cost effective, though their utilization as hosts to support nanoparticles is intensively compromised by relatively poor pore structure, high swelling rate and weak mechanical strength. In this study we prepared a nanocomposite adsorbent HFO-201 × 4 via ion exchange/in situ deposition method by using a gel resin-201 × 4 as the host of nano-HFO. The main objective of this study is to compare the structural features, physical and chemical properties of the nanocomposite to a macroporous resin-based nanocomposite HFO-201, and to evaluate their different adsorption property toward As(V). The results indicate that nano-HFO immobilized in HFO-201 × 4 was acicular, quite different from the spherical particles in HFO-201. Other structure properties of both composites, such as crystal form, pore structure, mechanical strength and swelling ratio, are quite similar. The maximum adsorption capacity of HFO-201 × 4 was slightly higher than that of HFO-201, while HFO-201 × 4 exhibited superior adsorption toward trace As(V) over HFO-201 in terms of adsorption capacity and kinetics, possibly arising from higher site density of HFO-201 × 4 (1.47 mmol/g) than HFO-201 (0.88 mmol/g). From the breakthrough curves of two separate fixed beds packed with both composites, the effective working capacity of HFO-201 × 4 was nearly twice of HFO-201. The exhausted HFO-201 × 4 could be efficiently regenerated for cyclic runs. This study demonstrates that gel-type anion exchange resins could serve as promising hosts for fabrication of similar nanocomposite for water decontamination.
2018, 0(7): 949-958
doi: 10.11777/j.issn1000-3304.2018.18078
Abstract:
The structure-property relationship of reversible crosslinked high performance polymer with self-healing and recyclable properties has attracted significant attention in the past decades. Herein, a thermally reversible crosslinked epoxy resin (DAERs) based on Diels-Alder covalent bonds was designed and prepared, where furan functional groups were incorporated into the side chains of linear epoxy resin and then cross-linked by maleimide. Different characterization techniques were used to investigate the structure-property relationship of DAERs. In situ variable-temperature 13C solid-state NMR was used to follow the evolution of dynamic Diels-Alder bonds in non-soluble cross-linked networks of DAERs, providing clear evidence of the cycling process of the DA reaction via displaying the consumption, appearing and disappearing of free furan group resonances in the network at different temperatures. NMR results provided a molecular level understanding of their equilibrated structure, and the reversible reconstruction and disconnection of the cross-link networks. Thermal behavior of DAERs was measured by repeated DSC cycles to verify the reversible temperature dependence of the DA and RDA reaction. Repeated endothermic and exothermic transition of DAERs during successive thermal cycles were observed, indicating the presence of RDA and DA reactions, respectively. The DSC results clearly demonstrated the capability of DAERs as a thermal re-mendable and recyclable material. The results of both DSC and DMA experiments indicated that the DA cross-linkage enhanced the glass transition and DA/retro-DA transition temperatures, and the heat-resistance of the materials increased with increasing cross-link density. Especially, DMA is a powerful and sensitive tool to distinguish the overlapped glass transition and DA/RDA temperatures. Tensile experiments indicated that the mechanical property also increased with the increase in crosslink density, and the synthesized DAERs exhibited good comprehensive mechanical properties, including high stiffness, strength, and toughness, and had good solvent and heat resistance. These materials can be easily thermally recycled, and this makes the material eco-friendly, with great potential for industrial applications.
The structure-property relationship of reversible crosslinked high performance polymer with self-healing and recyclable properties has attracted significant attention in the past decades. Herein, a thermally reversible crosslinked epoxy resin (DAERs) based on Diels-Alder covalent bonds was designed and prepared, where furan functional groups were incorporated into the side chains of linear epoxy resin and then cross-linked by maleimide. Different characterization techniques were used to investigate the structure-property relationship of DAERs. In situ variable-temperature 13C solid-state NMR was used to follow the evolution of dynamic Diels-Alder bonds in non-soluble cross-linked networks of DAERs, providing clear evidence of the cycling process of the DA reaction via displaying the consumption, appearing and disappearing of free furan group resonances in the network at different temperatures. NMR results provided a molecular level understanding of their equilibrated structure, and the reversible reconstruction and disconnection of the cross-link networks. Thermal behavior of DAERs was measured by repeated DSC cycles to verify the reversible temperature dependence of the DA and RDA reaction. Repeated endothermic and exothermic transition of DAERs during successive thermal cycles were observed, indicating the presence of RDA and DA reactions, respectively. The DSC results clearly demonstrated the capability of DAERs as a thermal re-mendable and recyclable material. The results of both DSC and DMA experiments indicated that the DA cross-linkage enhanced the glass transition and DA/retro-DA transition temperatures, and the heat-resistance of the materials increased with increasing cross-link density. Especially, DMA is a powerful and sensitive tool to distinguish the overlapped glass transition and DA/RDA temperatures. Tensile experiments indicated that the mechanical property also increased with the increase in crosslink density, and the synthesized DAERs exhibited good comprehensive mechanical properties, including high stiffness, strength, and toughness, and had good solvent and heat resistance. These materials can be easily thermally recycled, and this makes the material eco-friendly, with great potential for industrial applications.
