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2018 Volume 29 Issue 8
2018, 29(8): 1179-1180
doi: 10.1016/j.cclet.2018.07.009
Abstract:
2018, 29(8): 1181-1192
doi: 10.1016/j.cclet.2018.01.045
Abstract:
This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids (CPAs), a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of chiral phosphoric acids have been designed and developed into a privileged class of catalysts in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to November 2017. Meanwhile, catalytic systems which combine metal catalysts and chiral phosphoric acids will not be discussed in this review.
This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids (CPAs), a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of chiral phosphoric acids have been designed and developed into a privileged class of catalysts in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to November 2017. Meanwhile, catalytic systems which combine metal catalysts and chiral phosphoric acids will not be discussed in this review.
2018, 29(8): 1193-1200
doi: 10.1016/j.cclet.2018.02.009
Abstract:
Quinoproteins are an important type of redox enzymes for biological oxidation processes. Inspired by the quinone cofactors, particularly from copper amine oxidases, a number of small molecular quinone catalysts have been developed for C-H functionalizations of amines. Bio-inspired quinone catalysts have significantly expanded the substrate scope to include branched primary amines, secondary amines and tertiary amines, far beyond the scope of quinoproteins. This review summarizes the evolution of quinone catalysts, their mechanism and catalytic applications.
Quinoproteins are an important type of redox enzymes for biological oxidation processes. Inspired by the quinone cofactors, particularly from copper amine oxidases, a number of small molecular quinone catalysts have been developed for C-H functionalizations of amines. Bio-inspired quinone catalysts have significantly expanded the substrate scope to include branched primary amines, secondary amines and tertiary amines, far beyond the scope of quinoproteins. This review summarizes the evolution of quinone catalysts, their mechanism and catalytic applications.
2018, 29(8): 1201-1208
doi: 10.1016/j.cclet.2018.05.041
Abstract:
Chiral organobases occupy a significant position in asymmetric organocatalysis. The general types of chiral organobases include tertiary amines, amidines, guanidines, cyclopropenimines, and iminophosphoranes, etc. These organobases are demonstrated to be effective organocatalysts to promote divers kinds of base-initiated reactions in excellent yields and stereoselectivities. In previous reports, several groups have summarized each kind of chiral organobases in different reviews. To the aim of understanding the whole of them in one review, herein, we provide a brief introduction of these chiral organobases in asymmetric catalysis.
Chiral organobases occupy a significant position in asymmetric organocatalysis. The general types of chiral organobases include tertiary amines, amidines, guanidines, cyclopropenimines, and iminophosphoranes, etc. These organobases are demonstrated to be effective organocatalysts to promote divers kinds of base-initiated reactions in excellent yields and stereoselectivities. In previous reports, several groups have summarized each kind of chiral organobases in different reviews. To the aim of understanding the whole of them in one review, herein, we provide a brief introduction of these chiral organobases in asymmetric catalysis.
2018, 29(8): 1242-1250
doi: 10.1016/j.cclet.2018.05.008
Abstract:
Organic-inorganic lead halide based perovskite solar cells (PSCs) have presented a promising prospective in photovoltaic field with current record power conversion efficiency of 22.7%, which is comparable to commercial crystalline silicon cells and even higher than traditional thin film solar cells of CIGS. However, the pressure to enhance device stability under operational condition has driven researches towards development of stable hole transport materials (HTMs) for PSCs. Compared to traditional expensive organic HTMs such as spiro-OMeTAD, there is no doubt that inorganic p-type semiconductors and carbon materials are attractive alternatives that not only possess better stability but also are much cheaper. This review summarized the most recent progress of inorganic hole-transporting materials and carbon materials that have been developed for PSCs. The most recent advancement of device performance using these HTMs was demonstrated. In addition, the research of using various types of carbon materials as additives in HTMs to enhance device performance and stability or as electrical contact in HTM-free PSC was also demonstrated. The effectiveness of each type of materials on mitigating ion migration and degradation of PSC induced by humidity, illumination light intensity and high temperature is discussed. This timely review sheds light on the approaches to tackle the stability issue of PSCs to push the technology towards commercialization through material engineering of HTM.
Organic-inorganic lead halide based perovskite solar cells (PSCs) have presented a promising prospective in photovoltaic field with current record power conversion efficiency of 22.7%, which is comparable to commercial crystalline silicon cells and even higher than traditional thin film solar cells of CIGS. However, the pressure to enhance device stability under operational condition has driven researches towards development of stable hole transport materials (HTMs) for PSCs. Compared to traditional expensive organic HTMs such as spiro-OMeTAD, there is no doubt that inorganic p-type semiconductors and carbon materials are attractive alternatives that not only possess better stability but also are much cheaper. This review summarized the most recent progress of inorganic hole-transporting materials and carbon materials that have been developed for PSCs. The most recent advancement of device performance using these HTMs was demonstrated. In addition, the research of using various types of carbon materials as additives in HTMs to enhance device performance and stability or as electrical contact in HTM-free PSC was also demonstrated. The effectiveness of each type of materials on mitigating ion migration and degradation of PSC induced by humidity, illumination light intensity and high temperature is discussed. This timely review sheds light on the approaches to tackle the stability issue of PSCs to push the technology towards commercialization through material engineering of HTM.
2018, 29(8): 1209-1211
doi: 10.1016/j.cclet.2018.03.003
Abstract:
The chiral N-heterocyclic carbene-catalyzed[4 + 2] annulation of α-chloroaldehydes and aurones was developed, giving the corresponding benzofuran-fused dihydropyranones in good to high yields with good diastereoselectivities and excellent enantioselectivities. The catalytic cycle features with the generation of enolate from chloroaldehdye and its following[4 + 2] cycloaddtion with aurones.
The chiral N-heterocyclic carbene-catalyzed[4 + 2] annulation of α-chloroaldehydes and aurones was developed, giving the corresponding benzofuran-fused dihydropyranones in good to high yields with good diastereoselectivities and excellent enantioselectivities. The catalytic cycle features with the generation of enolate from chloroaldehdye and its following[4 + 2] cycloaddtion with aurones.
2018, 29(8): 1212-1214
doi: 10.1016/j.cclet.2018.01.039
Abstract:
A catalytic asymmetric brominative dearomatization reaction of benzofuran derivatives was achieved by using hydroquinidine 1, 4-phthalazinediyl diether[(DHQ)2PHAL] as the catalyst and N-bromoacetamide (NBAc) as the brominating reagent. A series of brominated spiro[benzofuran-2, 5'-oxazoles] bearing two contiguous stereogenic centers were obtained in high yields (up to 99%) with excellent enantioselectivity (up to 97% ee).
A catalytic asymmetric brominative dearomatization reaction of benzofuran derivatives was achieved by using hydroquinidine 1, 4-phthalazinediyl diether[(DHQ)2PHAL] as the catalyst and N-bromoacetamide (NBAc) as the brominating reagent. A series of brominated spiro[benzofuran-2, 5'-oxazoles] bearing two contiguous stereogenic centers were obtained in high yields (up to 99%) with excellent enantioselectivity (up to 97% ee).
2018, 29(8): 1215-1218
doi: 10.1016/j.cclet.2018.01.047
Abstract:
A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1, 4-dithiane-2, 5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities (85%-98% ee and 84%-95% ee).
A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1, 4-dithiane-2, 5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities (85%-98% ee and 84%-95% ee).
2018, 29(8): 1219-1222
doi: 10.1016/j.cclet.2017.12.024
Abstract:
The amphiphilic derivatives of L-histidine with different alkyl chains, NIPCA, UIPCA, and TIPCA, have been designed and their self-assembly behaviors with citric acid were investigated. All L-histidine derivatives can form hydrogels with citric acid, and exhibit the increasing gelation ability and mechanical strength with the increasing chain length. The gelation ability is considered to be affected by the synergistic effect of electrostatic interaction, hydrogen bonding and hydrophobic interaction. The hydrogels exhibit excellent releasing selectivity for charged dyes in aqueous solution, enlightening people to utilize this kind of hydrogels as intelligent carriers to separate the mixtures of charged dyes.
The amphiphilic derivatives of L-histidine with different alkyl chains, NIPCA, UIPCA, and TIPCA, have been designed and their self-assembly behaviors with citric acid were investigated. All L-histidine derivatives can form hydrogels with citric acid, and exhibit the increasing gelation ability and mechanical strength with the increasing chain length. The gelation ability is considered to be affected by the synergistic effect of electrostatic interaction, hydrogen bonding and hydrophobic interaction. The hydrogels exhibit excellent releasing selectivity for charged dyes in aqueous solution, enlightening people to utilize this kind of hydrogels as intelligent carriers to separate the mixtures of charged dyes.
2018, 29(8): 1223-1225
doi: 10.1016/j.cclet.2018.06.007
Abstract:
Tetrahydrobenzo[5 ]helicenediol (THB-[5]HDIOL) derivatives as additives for the efficient prolinecatalyzed asymmetric List-Lerner-Barbas (LLB) aldol reactions of bulky aldehyde substrates was described. It was found that with dibromo-substituted helical diols P-4a/M-4a as additives, the prolinecatalyzed LLB aldol reaction of 9-anthraldehyde and acetone gave the product in 83% yield and 99% ee. Transition state models revealed an edge-to-face π-π stacking between the anthracenyl group in TS(R) and the phenyl group of the additive, which might result in the high enantioselectivity.
Tetrahydrobenzo[
2018, 29(8): 1226-1232
doi: 10.1016/j.cclet.2018.02.007
Abstract:
Frustrated Lewis pairs (FLPs) emerge as a new type of bifunctional metal-free catalysts for reversible H2 activation, which is important for the storage and liberation of H2 or further controllable utilizing chemical fuels via hydrogenation/dehydrogenation. Herein, a DFT study was conducted to understand the geometric factors and electronic effects of FLPs on reversible H2 activation. The Lewis base group mainly contributes to the proton attachment, and influences the kinetics of the H2 activation. The Lewis acid group mainly relates to the hydride attachment, and affects more significantly on the thermodynamics of H2 activation. The dimer and quenched structure of FLPs also have a degree of influence on the performance of catalyzed H2 activation. A series of FLPs with para-substituted phenyl derivatives as LA groups were designed and evaluated. The results indicate that the variation of LA groups has significant impact on thermodynamic energy of dihydrogen adducts but insignificant effect on kinetics. Moreover, we found the thermodynamic energy of products has a good linear relationship with Hammett substituent constants. The solvent effect on H2 activation was also studied, and polar solvent is beneficial for zwitterionic products. These results should provide deeper insight to understand the relation between FLPs structure and reactivity, which is critical for rational design of more efficient FLPs catalysts for reversible H2 activation.
Frustrated Lewis pairs (FLPs) emerge as a new type of bifunctional metal-free catalysts for reversible H2 activation, which is important for the storage and liberation of H2 or further controllable utilizing chemical fuels via hydrogenation/dehydrogenation. Herein, a DFT study was conducted to understand the geometric factors and electronic effects of FLPs on reversible H2 activation. The Lewis base group mainly contributes to the proton attachment, and influences the kinetics of the H2 activation. The Lewis acid group mainly relates to the hydride attachment, and affects more significantly on the thermodynamics of H2 activation. The dimer and quenched structure of FLPs also have a degree of influence on the performance of catalyzed H2 activation. A series of FLPs with para-substituted phenyl derivatives as LA groups were designed and evaluated. The results indicate that the variation of LA groups has significant impact on thermodynamic energy of dihydrogen adducts but insignificant effect on kinetics. Moreover, we found the thermodynamic energy of products has a good linear relationship with Hammett substituent constants. The solvent effect on H2 activation was also studied, and polar solvent is beneficial for zwitterionic products. These results should provide deeper insight to understand the relation between FLPs structure and reactivity, which is critical for rational design of more efficient FLPs catalysts for reversible H2 activation.
2018, 29(8): 1233-1236
doi: 10.1016/j.cclet.2018.01.003
Abstract:
This paper reports a computational study elucidating reaction mechanism for amide bond formation from esters and amines catalyzed by acetic acid. Two optional mechanisms (namely, classic stepwise and concerted acyl substitution mechanisms) have been studied. Calculation results establish the reaction energy profiles of both mechanisms and locate all the intermediates and transition states in both catalytic cycles. Our results propose that the concerted acyl substitution mechanism may be more likely wherein the formation of C-N bond and the cleavage of C-O bond occur concurrently without the need of rehybridization of the carbonyl carbon. This is also consistent with the fact that no significant racemization/epimerization were observed in the amide products when asymmetric esters and/or amines were used as the reactants, because concerted acyl substitution mechanism precludes the intermediacy of tetrahedral adducts and the accompanying generation/elimination of new chiral centers. Further discussion implies that the concerted acyl substitution mechanism may widely occur in related amidation reactions in the presence of different types of coupling reagents.
This paper reports a computational study elucidating reaction mechanism for amide bond formation from esters and amines catalyzed by acetic acid. Two optional mechanisms (namely, classic stepwise and concerted acyl substitution mechanisms) have been studied. Calculation results establish the reaction energy profiles of both mechanisms and locate all the intermediates and transition states in both catalytic cycles. Our results propose that the concerted acyl substitution mechanism may be more likely wherein the formation of C-N bond and the cleavage of C-O bond occur concurrently without the need of rehybridization of the carbonyl carbon. This is also consistent with the fact that no significant racemization/epimerization were observed in the amide products when asymmetric esters and/or amines were used as the reactants, because concerted acyl substitution mechanism precludes the intermediacy of tetrahedral adducts and the accompanying generation/elimination of new chiral centers. Further discussion implies that the concerted acyl substitution mechanism may widely occur in related amidation reactions in the presence of different types of coupling reagents.
2018, 29(8): 1237-1241
doi: 10.1016/j.cclet.2018.03.018
Abstract:
Phosphoric acid catalysis is a powerful tool for the construction of new C-C bonds because of its unique LUMO-lowering activity. Theoretical calculations were employed to investigate phosphoric acidcatalyzed asymmetric conjugate addition of indolizines to α, β-unsaturated ketones. The calculation results showed that this transformation proceeds via a reaction pathway involving nucleophilic addition, deprotonation-aromatization, and tautomerization. The computational results showed that deprotonation-aromatization is the rate-determining step and the enantioselectivity-determining step. The S-configured product was preferentially generated via a pathway starting from the s-cis conjugated ketone, whereas the s-trans isomer led to a side product with the R configuration. Non-covalent interaction analysis showed that the enantioselectivity is mainly caused by bond-rotation strain in the transition states of the deprotonation-aromatization step.
Phosphoric acid catalysis is a powerful tool for the construction of new C-C bonds because of its unique LUMO-lowering activity. Theoretical calculations were employed to investigate phosphoric acidcatalyzed asymmetric conjugate addition of indolizines to α, β-unsaturated ketones. The calculation results showed that this transformation proceeds via a reaction pathway involving nucleophilic addition, deprotonation-aromatization, and tautomerization. The computational results showed that deprotonation-aromatization is the rate-determining step and the enantioselectivity-determining step. The S-configured product was preferentially generated via a pathway starting from the s-cis conjugated ketone, whereas the s-trans isomer led to a side product with the R configuration. Non-covalent interaction analysis showed that the enantioselectivity is mainly caused by bond-rotation strain in the transition states of the deprotonation-aromatization step.
2018, 29(8): 1251-1253
doi: 10.1016/j.cclet.2018.06.025
Abstract:
Steroidal drugs have wide indications such as anti-inflammation, anti-tumor, endocrine regulation, fertility management. Phytosterol is the main starting materials for the industrial synthesis of steroid drugs. Microbial transformation of phytosterol is a simple and environmentally friendly process. Efficient microbial strains for industrial phytosterol transformation are critical for the commercial success. To this end, a 96-well plate based method was developed to discriminate the mixture of 4-androstene-3, 17-dione, androsta-1, 4-diene-3, 17-dione, and bisnoraldehyde, with different ratio of the 3 components in the mixture, which mimics the sterol bioconversion products by using the Mycobacterium neoaurum. The M. neoaurum bioconversed broth test using phytosterol as substrate also found that the spectrum methodology can evaluate the relative content of different compounds. The method is practical, high throughput and can replace the conventional HPLC-based assay for rapid selection of desired microbial strains.
Steroidal drugs have wide indications such as anti-inflammation, anti-tumor, endocrine regulation, fertility management. Phytosterol is the main starting materials for the industrial synthesis of steroid drugs. Microbial transformation of phytosterol is a simple and environmentally friendly process. Efficient microbial strains for industrial phytosterol transformation are critical for the commercial success. To this end, a 96-well plate based method was developed to discriminate the mixture of 4-androstene-3, 17-dione, androsta-1, 4-diene-3, 17-dione, and bisnoraldehyde, with different ratio of the 3 components in the mixture, which mimics the sterol bioconversion products by using the Mycobacterium neoaurum. The M. neoaurum bioconversed broth test using phytosterol as substrate also found that the spectrum methodology can evaluate the relative content of different compounds. The method is practical, high throughput and can replace the conventional HPLC-based assay for rapid selection of desired microbial strains.
2018, 29(8): 1254-1256
doi: 10.1016/j.cclet.2017.10.022
Abstract:
Ryanodine receptors (RyRs) activator has become one class of popular insecticide because of its unique mode of action. In order to find more new RyRs activators as insecticidal agents, a series of 18 novel chiral anthranilic diamides were designed by introducing the D-alanine acid and D-serine acid esters as well as trifluoroethoxyl group into the anthranilic diamide skeleton and synthesized successfully based on anthranilic diamide and FKI-1033 structures. The structures of the title compounds Ⅰa-i and Ⅱa-i were confirmed by melting points, 1H NMR, 13C NMR, elemental analysis and specific optical rotation analysis. The preliminary bioassay results indicated that most of the title compounds exhibited considerable larvicidal activities against oriental armyworm at 10 mg/L, especially Ⅰb, Ⅰe and Ⅱh showed remarkable insecticidal activities at 0.5 mg/L. The larvicidal activity against diamondback moth of Ⅰa and Ⅱd were 80% and 90% respectively at 0.0001 mg/L, which was similar to that of chlorantraniliprole. The relationship between structure and insecticidal activity was analyzed to reveal a possible co-regulated effect of the chiral amino acid ester, halogen atom or cyano group, and trifluoroethyloxyl group of the skeleton structures of the title compounds, which will provide useful information for guiding the design and discovery of new RyRs activators and insecticidal agrochemicals.
Ryanodine receptors (RyRs) activator has become one class of popular insecticide because of its unique mode of action. In order to find more new RyRs activators as insecticidal agents, a series of 18 novel chiral anthranilic diamides were designed by introducing the D-alanine acid and D-serine acid esters as well as trifluoroethoxyl group into the anthranilic diamide skeleton and synthesized successfully based on anthranilic diamide and FKI-1033 structures. The structures of the title compounds Ⅰa-i and Ⅱa-i were confirmed by melting points, 1H NMR, 13C NMR, elemental analysis and specific optical rotation analysis. The preliminary bioassay results indicated that most of the title compounds exhibited considerable larvicidal activities against oriental armyworm at 10 mg/L, especially Ⅰb, Ⅰe and Ⅱh showed remarkable insecticidal activities at 0.5 mg/L. The larvicidal activity against diamondback moth of Ⅰa and Ⅱd were 80% and 90% respectively at 0.0001 mg/L, which was similar to that of chlorantraniliprole. The relationship between structure and insecticidal activity was analyzed to reveal a possible co-regulated effect of the chiral amino acid ester, halogen atom or cyano group, and trifluoroethyloxyl group of the skeleton structures of the title compounds, which will provide useful information for guiding the design and discovery of new RyRs activators and insecticidal agrochemicals.
2018, 29(8): 1257-1260
doi: 10.1016/j.cclet.2017.12.001
Abstract:
A glucosidic indole-lignan conjugate with a novel carbon skeleton, named isatindolignanoside A (1), was isolated from an aqueous extract of the Isatis indigotica roots "ban lan gen". Its structure was elucidated by comprehensive analysis of spectroscopic data, including J- and NOESY correlation-based configurational analysis, circular dichroism (CD) data, enzyme hydrolysis, and theoretical ECD calculation. In a preliminary assay, compound 1 showed antiviral activity against Coxsackie virus B3. This compound is the first example of natural product having a structural feature of conjugation between indole and lignan units, and its biosynthetic pathway is postulated.
A glucosidic indole-lignan conjugate with a novel carbon skeleton, named isatindolignanoside A (1), was isolated from an aqueous extract of the Isatis indigotica roots "ban lan gen". Its structure was elucidated by comprehensive analysis of spectroscopic data, including J- and NOESY correlation-based configurational analysis, circular dichroism (CD) data, enzyme hydrolysis, and theoretical ECD calculation. In a preliminary assay, compound 1 showed antiviral activity against Coxsackie virus B3. This compound is the first example of natural product having a structural feature of conjugation between indole and lignan units, and its biosynthetic pathway is postulated.
2018, 29(8): 1261-1263
doi: 10.1016/j.cclet.2017.11.042
Abstract:
A new cytotoxic salannin-class limonoid alkaloid, azadiramide A (1), was isolated from seeds of Azadirachta indica A. Juss. Its structure was elucidated by extensive analysis of spectroscopic data and quantum chemical calculation. Compound 1 is a rare salannin-class limonoid alkaloid. To our best knowledge, only two compounds belonging to this type were so far found. It showed inhibitory activity against human breast cancer MDA-MB-231 cell line with IC50 value of 2.70 0.63 μmol/L.
A new cytotoxic salannin-class limonoid alkaloid, azadiramide A (1), was isolated from seeds of Azadirachta indica A. Juss. Its structure was elucidated by extensive analysis of spectroscopic data and quantum chemical calculation. Compound 1 is a rare salannin-class limonoid alkaloid. To our best knowledge, only two compounds belonging to this type were so far found. It showed inhibitory activity against human breast cancer MDA-MB-231 cell line with IC50 value of 2.70 0.63 μmol/L.
2018, 29(8): 1264-1268
doi: 10.1016/j.cclet.2017.11.043
Abstract:
N-(2-Hydroxybenzyl) cysteine derivatives were recently disclosed to be efficient crypto-thioesters for native chemical ligation (NCL). To elucidate the mechanism of the relevant N-to-S acyl transfer process as well as the origin of the acceleration effect of the phenol substitutes, a density functional theory (DFT) study was performed. It was found that the N-to-S acyl transfer of N-(2-hydroxybenzyl) cysteine derivatives involve four major steps:concerted nucleophilic addition of thiolate/proton transfer, inversion of an amine moiety, water-assisted proton transfer and C-N bond cleavage. The phenol substitutes promote the nucleophilic addition of thiolate by protonating the carbonyl oxygen atom synergistically and the proton transfer from hydroxyl to amide nitrogen atom is the rate-determining step of the N-to-S acyl transfer. By contrast, changing the phenolic hydroxyl to methoxyl was found to significantly slow down the nucleophilic addition of thiolate and thus hinders the N-to-S acyl transfer overall. These computational results are consistent with the observation of previously reported control experiments, by which our proposed mechanism is further validated.
N-(2-Hydroxybenzyl) cysteine derivatives were recently disclosed to be efficient crypto-thioesters for native chemical ligation (NCL). To elucidate the mechanism of the relevant N-to-S acyl transfer process as well as the origin of the acceleration effect of the phenol substitutes, a density functional theory (DFT) study was performed. It was found that the N-to-S acyl transfer of N-(2-hydroxybenzyl) cysteine derivatives involve four major steps:concerted nucleophilic addition of thiolate/proton transfer, inversion of an amine moiety, water-assisted proton transfer and C-N bond cleavage. The phenol substitutes promote the nucleophilic addition of thiolate by protonating the carbonyl oxygen atom synergistically and the proton transfer from hydroxyl to amide nitrogen atom is the rate-determining step of the N-to-S acyl transfer. By contrast, changing the phenolic hydroxyl to methoxyl was found to significantly slow down the nucleophilic addition of thiolate and thus hinders the N-to-S acyl transfer overall. These computational results are consistent with the observation of previously reported control experiments, by which our proposed mechanism is further validated.
2018, 29(8): 1269-1272
doi: 10.1016/j.cclet.2017.10.006
Abstract:
A simple and efficient method for preparation of imines by the oxidative coupling of benzyl alcohols with aromatic amines or aliphatic amines was developed. The reaction was catalyzed by 9-azabicyclo[3.3.1] nonan-N-oxyl (ABNO)/KOH with air as the economic and green oxidant. Under the optimal reaction conditions, a variety of imines were obtained in 80%-96% isolated yields.
A simple and efficient method for preparation of imines by the oxidative coupling of benzyl alcohols with aromatic amines or aliphatic amines was developed. The reaction was catalyzed by 9-azabicyclo[3.3.1] nonan-N-oxyl (ABNO)/KOH with air as the economic and green oxidant. Under the optimal reaction conditions, a variety of imines were obtained in 80%-96% isolated yields.
2018, 29(8): 1273-1276
doi: 10.1016/j.cclet.2017.11.044
Abstract:
A novel organocatalytic cascade process initiated by 1, 6-conjugated addition has been successfully developed. A range of pharmaceutically active 2-amino-4-aryl-4H-chromenes were readily obtained in high yields (88%-99%) and excellent enantiopurities (86%-99% ee). The functionalized para-Quinone methides (p-OMs) could be facilely obtained.
A novel organocatalytic cascade process initiated by 1, 6-conjugated addition has been successfully developed. A range of pharmaceutically active 2-amino-4-aryl-4H-chromenes were readily obtained in high yields (88%-99%) and excellent enantiopurities (86%-99% ee). The functionalized para-Quinone methides (p-OMs) could be facilely obtained.
2018, 29(8): 1277-1280
doi: 10.1016/j.cclet.2017.10.023
Abstract:
In this work, we report the synthesis of holmium(Ⅲ)-doped carbon nanodots (HoBCDs) as fluorescence/magnetic resonance (FL/MR) dual-modal imaging probes via a facile hydrothermal process using citrate acid (CA), branched-polyethylenimine (BPEI) and diethylenetriamine pentaacetic acid hydrate holmium (Ⅲ) dihydrogen salt (Ho-DTPA) as carbon source, passivating reagent and holmium source, respectively. The thus prepared HoBCDs exhibited ultra-small particle size (~4 nm), high water solubility and bright fluorescence with an absolute quantum yield of 8%. Additionally, grey-scaled T1-weighted images of HoBCDs solution appeared to be apparently brighter than that of deionized water and un-doped blue carbon nanodots (BCDs) solution. In addition, in vitro toxicity assay validated superior biocompatibility of HoBCDs. Using HeLa cells as models, HoBCDs-treated cells were observed to emit blue fluorescence located both in plasma and nucleus, and presented positive contrast enhancement in T1-weighted images, suggesting their potentials for practical biomedical applications.
In this work, we report the synthesis of holmium(Ⅲ)-doped carbon nanodots (HoBCDs) as fluorescence/magnetic resonance (FL/MR) dual-modal imaging probes via a facile hydrothermal process using citrate acid (CA), branched-polyethylenimine (BPEI) and diethylenetriamine pentaacetic acid hydrate holmium (Ⅲ) dihydrogen salt (Ho-DTPA) as carbon source, passivating reagent and holmium source, respectively. The thus prepared HoBCDs exhibited ultra-small particle size (~4 nm), high water solubility and bright fluorescence with an absolute quantum yield of 8%. Additionally, grey-scaled T1-weighted images of HoBCDs solution appeared to be apparently brighter than that of deionized water and un-doped blue carbon nanodots (BCDs) solution. In addition, in vitro toxicity assay validated superior biocompatibility of HoBCDs. Using HeLa cells as models, HoBCDs-treated cells were observed to emit blue fluorescence located both in plasma and nucleus, and presented positive contrast enhancement in T1-weighted images, suggesting their potentials for practical biomedical applications.
2018, 29(8): 1281-1283
doi: 10.1016/j.cclet.2018.01.034
Abstract:
Bisphenol A (BPA) plays an important role in metabolic disorders. As a major alternative to BPA, it is unclear whether the exposure of bisphenol S (BPS) may result in lipidome disturbance. Using a mouse model, we investigated the effects of BPS exposure on metabolism and spatial distribution of lipids by using lipidomics analysis and matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry imaging (MSI) in mouse liver tissues. Lipid metabolites displayed significant up-regulation in phosphatidylethanolamines (PE), lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE) and lysophosphatidylserine (LPS) as well as remarkable down-regulation in phosphatidylcholine (PC) and phosphatidylserine (PS) in mouse liver after the exposure at 100μg BPS/kg body weight/day. The obtained results indicated that the lipidome of liver was perturbed significantly in glycerophospholipid (GP) fatty acid remodeling pathway upon the BPS exposure. We applied MSI and multivariate statistical analysis to evaluate the abundance variation of lipid markers in BPS-treated liver sections and to compare with the analytical results from olive oil-treated liver sections. Differential structural lipids with up-regulated PE (20:1/20:4), LPC (20:4), LPE (20:4), LPS (33:4) and down-regulated PC (20:4/22:6) and PS (18:0/22:6), which were related to GP fatty acid remodeling, changed and co-localized in the liver sections. To explore the cause of variation of lipid abundance, expression of enzymes that regulate biosynthesis and metabolism of fatty acid in liver tissues were analyzed. Consistent with the results of liver lipidome and spatial distribution, a decrease in hepatic expression of LPC acyltransferase 1 (LPCAT1), LPCAT2 and LPS acyltransferase and an increase expression of LPCAT3, LPCAT4, LPE acyltransferase 1 (LPEAT1), LPEAT2 and phospholipase A2 s were observed in GP fatty acid remodeling pathway. Our results demonstrated that exposure to BPS could induce the GP fatty acid remodeling, which might be useful in toxicity evaluation for bisphenols-induced hepatic diseases.
Bisphenol A (BPA) plays an important role in metabolic disorders. As a major alternative to BPA, it is unclear whether the exposure of bisphenol S (BPS) may result in lipidome disturbance. Using a mouse model, we investigated the effects of BPS exposure on metabolism and spatial distribution of lipids by using lipidomics analysis and matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry imaging (MSI) in mouse liver tissues. Lipid metabolites displayed significant up-regulation in phosphatidylethanolamines (PE), lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE) and lysophosphatidylserine (LPS) as well as remarkable down-regulation in phosphatidylcholine (PC) and phosphatidylserine (PS) in mouse liver after the exposure at 100μg BPS/kg body weight/day. The obtained results indicated that the lipidome of liver was perturbed significantly in glycerophospholipid (GP) fatty acid remodeling pathway upon the BPS exposure. We applied MSI and multivariate statistical analysis to evaluate the abundance variation of lipid markers in BPS-treated liver sections and to compare with the analytical results from olive oil-treated liver sections. Differential structural lipids with up-regulated PE (20:1/20:4), LPC (20:4), LPE (20:4), LPS (33:4) and down-regulated PC (20:4/22:6) and PS (18:0/22:6), which were related to GP fatty acid remodeling, changed and co-localized in the liver sections. To explore the cause of variation of lipid abundance, expression of enzymes that regulate biosynthesis and metabolism of fatty acid in liver tissues were analyzed. Consistent with the results of liver lipidome and spatial distribution, a decrease in hepatic expression of LPC acyltransferase 1 (LPCAT1), LPCAT2 and LPS acyltransferase and an increase expression of LPCAT3, LPCAT4, LPE acyltransferase 1 (LPEAT1), LPEAT2 and phospholipase A2 s were observed in GP fatty acid remodeling pathway. Our results demonstrated that exposure to BPS could induce the GP fatty acid remodeling, which might be useful in toxicity evaluation for bisphenols-induced hepatic diseases.
2018, 29(8): 1284-1286
doi: 10.1016/j.cclet.2018.01.015
Abstract:
A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and fully validated for determination of arformoterol in rat plasma, lung and trachea tissues. The chromatographic separation was performed on an Agilent XDB C8 column with gradient elution by using acetonitrile and 0.1% formic acid water. The method presented high sensitivity (LLOQ of 1.83 pg/mL for plasma and 3.90 pg/mL for lung and trachea tissue homogenates) and great linearity over the range of 1.83-458 pg/mL for plasma, 13.9-1560 pg/mL for lung and trachea tissue homogenates. No carry over effect and matrix effect were observed. The intra-and inter-day precision/accuracy were within ±15% at three quality control concentration levels. This robust method was successfully applied to the pharmacokinetic, lung and trachea tissue distribution study after inhalation administration of arformoterol tartrate inhalation solution (50 mg/kg). The in vivo information indicate that arformoterol can be rapidly absorbed into blood through respiratory systems, lung and trachea tissue maintain a certain amount of arformoterol in 1 h after dosing.
A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and fully validated for determination of arformoterol in rat plasma, lung and trachea tissues. The chromatographic separation was performed on an Agilent XDB C8 column with gradient elution by using acetonitrile and 0.1% formic acid water. The method presented high sensitivity (LLOQ of 1.83 pg/mL for plasma and 3.90 pg/mL for lung and trachea tissue homogenates) and great linearity over the range of 1.83-458 pg/mL for plasma, 13.9-1560 pg/mL for lung and trachea tissue homogenates. No carry over effect and matrix effect were observed. The intra-and inter-day precision/accuracy were within ±15% at three quality control concentration levels. This robust method was successfully applied to the pharmacokinetic, lung and trachea tissue distribution study after inhalation administration of arformoterol tartrate inhalation solution (50 mg/kg). The in vivo information indicate that arformoterol can be rapidly absorbed into blood through respiratory systems, lung and trachea tissue maintain a certain amount of arformoterol in 1 h after dosing.
2018, 29(8): 1287-1290
doi: 10.1016/j.cclet.2017.10.013
Abstract:
A dual-amplification system is reported to apply in DNA sensing via the assembly of DNA and protein. In this process, the biotinylatedcapature DNA bounded with streptavidin (SA) through the biotinstreptavidin reaction, and then the assembly of DNA and protein was triggered by the linker DNA after the target hybridized with biotinylatedcapature DNA. Sequentially, the 3, 3', 5, 5'-tetramethylbenzidine (TMB) was oxidized by H2O2 under the catalysis of horseradish peroxidase. Based on the variation of the color and the UV-vis absorbance intensities, qualitative and quantitative DNA analyses were realized. This proposed method could detect the target DNA as low as 1.75 pmol/L and discriminate perfectly matched target DNA from the mismatch DNA. What's more, it can be expanded to detect other molecules with a reasonable design of the corresponding DNA sequences.
A dual-amplification system is reported to apply in DNA sensing via the assembly of DNA and protein. In this process, the biotinylatedcapature DNA bounded with streptavidin (SA) through the biotinstreptavidin reaction, and then the assembly of DNA and protein was triggered by the linker DNA after the target hybridized with biotinylatedcapature DNA. Sequentially, the 3, 3', 5, 5'-tetramethylbenzidine (TMB) was oxidized by H2O2 under the catalysis of horseradish peroxidase. Based on the variation of the color and the UV-vis absorbance intensities, qualitative and quantitative DNA analyses were realized. This proposed method could detect the target DNA as low as 1.75 pmol/L and discriminate perfectly matched target DNA from the mismatch DNA. What's more, it can be expanded to detect other molecules with a reasonable design of the corresponding DNA sequences.
2018, 29(8): 1291-1295
doi: 10.1016/j.cclet.2017.11.017
Abstract:
Information concerns endocytosis and autophagic effects of magnetite particles is crucial for understanding the particle-cell interactions. In this work, we investigated the effects of bovine serum proteins on the endocytosis of magnetite spherical particles (MSPs). Autophagic effects of MSPs in breast cancer cells were studied. Light scattering based flow cytometry and microscopy were used for evaluating the uptake potential of MSPs by cells and the cellular autophagosome accumulation. Results showed bovine serum proteins significantly reduced the endocytosis of MSPs by decreasing their adsorption to cell membranes. Additionally, serum proteins had influences on the endocytic mechanisms of MSPs. Autophagosome accumulation could be caused by the internalized MSPs rather than the particles associated with cell membrane. Above fundamental findings promote our understandings upon the interactions of MSPs with cells. Light scattering based methods were proved to be simple and effective. The present work may promote their application in studies upon endocytosis of metallic particles in the future.
Information concerns endocytosis and autophagic effects of magnetite particles is crucial for understanding the particle-cell interactions. In this work, we investigated the effects of bovine serum proteins on the endocytosis of magnetite spherical particles (MSPs). Autophagic effects of MSPs in breast cancer cells were studied. Light scattering based flow cytometry and microscopy were used for evaluating the uptake potential of MSPs by cells and the cellular autophagosome accumulation. Results showed bovine serum proteins significantly reduced the endocytosis of MSPs by decreasing their adsorption to cell membranes. Additionally, serum proteins had influences on the endocytic mechanisms of MSPs. Autophagosome accumulation could be caused by the internalized MSPs rather than the particles associated with cell membrane. Above fundamental findings promote our understandings upon the interactions of MSPs with cells. Light scattering based methods were proved to be simple and effective. The present work may promote their application in studies upon endocytosis of metallic particles in the future.
2018, 29(8): 1296-1300
doi: 10.1016/j.cclet.2018.07.005
Abstract:
It is well known that in biomineralization, the inorganic solids crystallized in the presence of organic phases, which are generally recognized as additives and matrix, leading to the crystal morphology modification. However, the synergy effects of both soluble additive and insoluble matrix on regulating the morphology of synthetic single-crystals are less studied. Here, we examine the morphological revolution of calcite single crystals induced by the additive, citrate (CIT), or/and the matrix, agarose gel network. The agarose gel matrix is inert to the crystal morphology in the sense that the agarose gelgrown calcite crystals maintain in characteristic rhombohedra. In contrast, CIT additives are active in crystal morphology modification and crystals begin to exhibit curved rough surfaces when grown in solution with the concentration of CIT coated Au nanoparticles ([CIT-Au NPs]) of more than 2.25 mg/mL. Interestingly, once agarose gel and CIT-Au NPs are simultaneously introduced, the curved morphological feature emerges at a much lower[CIT-Au NPs] of around 0.2 mg/mL. Increasing the gel concentrations further reduce the[CIT-Au NPs] needed to trigger calcite morphological modification, suggesting that the gel networks reduce the CIT diffusion and thereby enhance the kinetic effects of CIT on crystallization. As such, this work may have implications for understanding the mechanism of hierarchical biominerals construction and provide rational strategy to control single-crystal morphologies.
It is well known that in biomineralization, the inorganic solids crystallized in the presence of organic phases, which are generally recognized as additives and matrix, leading to the crystal morphology modification. However, the synergy effects of both soluble additive and insoluble matrix on regulating the morphology of synthetic single-crystals are less studied. Here, we examine the morphological revolution of calcite single crystals induced by the additive, citrate (CIT), or/and the matrix, agarose gel network. The agarose gel matrix is inert to the crystal morphology in the sense that the agarose gelgrown calcite crystals maintain in characteristic rhombohedra. In contrast, CIT additives are active in crystal morphology modification and crystals begin to exhibit curved rough surfaces when grown in solution with the concentration of CIT coated Au nanoparticles ([CIT-Au NPs]) of more than 2.25 mg/mL. Interestingly, once agarose gel and CIT-Au NPs are simultaneously introduced, the curved morphological feature emerges at a much lower[CIT-Au NPs] of around 0.2 mg/mL. Increasing the gel concentrations further reduce the[CIT-Au NPs] needed to trigger calcite morphological modification, suggesting that the gel networks reduce the CIT diffusion and thereby enhance the kinetic effects of CIT on crystallization. As such, this work may have implications for understanding the mechanism of hierarchical biominerals construction and provide rational strategy to control single-crystal morphologies.
2018, 29(8): 1301-1304
doi: 10.1016/j.cclet.2017.11.040
Abstract:
Novel magnetic core/shell bimetallic Au/Cu nanoparticles (Fe3O4@SiO2-Au/Cu NPs) were prepared using SiO2-coated iron oxide (Fe3O4@SiO2) as a supported material. The magnetic Fe3O4 colloidal nanocrystal clusters (CNCs) as nano-core were modified with a silica coating for improvement stability and superficial area of the Au-Cu particles. The morphological structure and chemical composition of the Fe3O4@SiO2-Au/Cu NPs were characterized with high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analyses. The Au and Cu NPs were deposited on the SiO2 surface in a highly dense and well dispersed manner with an average size of approximately 5 nm. The Fe3O4@SiO2-Au/Cu NPs as magnetic nano-catalysts were applied to the Ullmann coupling reaction of bromamine acid to synthesize 4, 40-diamino-1, 10-dianthraquinonyl-3, 30-disulfonic acid (DAS). The prepared Fe3O4@SiO2-Au/Cu NPs exhibited efficient catalytic activity with higher conversion and selectivity. A bromamine acid conversion of 97.35% and selectivity for DAS of 88.67% were obtained in aqueous medium. The magnetic nano-catalysts can be readily separated from the reaction system and reused. This new nano-catalytic reaction represents a useful and attractive cleaner production system. The new catalyst system has important and potential applications in dye and pigment industry.
Novel magnetic core/shell bimetallic Au/Cu nanoparticles (Fe3O4@SiO2-Au/Cu NPs) were prepared using SiO2-coated iron oxide (Fe3O4@SiO2) as a supported material. The magnetic Fe3O4 colloidal nanocrystal clusters (CNCs) as nano-core were modified with a silica coating for improvement stability and superficial area of the Au-Cu particles. The morphological structure and chemical composition of the Fe3O4@SiO2-Au/Cu NPs were characterized with high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analyses. The Au and Cu NPs were deposited on the SiO2 surface in a highly dense and well dispersed manner with an average size of approximately 5 nm. The Fe3O4@SiO2-Au/Cu NPs as magnetic nano-catalysts were applied to the Ullmann coupling reaction of bromamine acid to synthesize 4, 40-diamino-1, 10-dianthraquinonyl-3, 30-disulfonic acid (DAS). The prepared Fe3O4@SiO2-Au/Cu NPs exhibited efficient catalytic activity with higher conversion and selectivity. A bromamine acid conversion of 97.35% and selectivity for DAS of 88.67% were obtained in aqueous medium. The magnetic nano-catalysts can be readily separated from the reaction system and reused. This new nano-catalytic reaction represents a useful and attractive cleaner production system. The new catalyst system has important and potential applications in dye and pigment industry.
2018, 29(8): 1305-1309
doi: 10.1016/j.cclet.2017.10.042
Abstract:
Mesoporous silicas with different morphologies have attracted great interest in the fields of catalysis, separation and so on. In this study, silica hollow tubes with ordered mesopores were synthesized via a novel sol-gel method with an ionic liquid 1-decyl-3-methylimidazolium chloride ([Dmim]Cl) and a nonionic surfactant P123 (PEO20PPO70PEO20) as the co-template. Coparatively, silica hollow spheres with disordered mesopores were synthesized with only[Dmim]Cl as the template. The template dosage is the key factor in controlling the morphology. The micelles assembly mechanism based on hydrogen bonding interactions is proposed to be responsible for the formation of the final silica morphology and mesostructure.
Mesoporous silicas with different morphologies have attracted great interest in the fields of catalysis, separation and so on. In this study, silica hollow tubes with ordered mesopores were synthesized via a novel sol-gel method with an ionic liquid 1-decyl-3-methylimidazolium chloride ([Dmim]Cl) and a nonionic surfactant P123 (PEO20PPO70PEO20) as the co-template. Coparatively, silica hollow spheres with disordered mesopores were synthesized with only[Dmim]Cl as the template. The template dosage is the key factor in controlling the morphology. The micelles assembly mechanism based on hydrogen bonding interactions is proposed to be responsible for the formation of the final silica morphology and mesostructure.
2018, 29(8): 1310-1312
doi: 10.1016/j.cclet.2017.12.018
Abstract:
ZnO hexagonal bilayer disk-like microstructures are successfully fabricated using a simple solvothermal method assisted with polyvinylpyrrolidone (PVP). The structure and morphology were investigated by Xray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). XRD result indicated that the as-obtained samples were well-crystallized wurtzite hexagonal ZnO structure. SEM images showed that the ZnO hexagonal bilayer disk-like assembles consist of two uniform and smooth disks with an average edge length of 6 μm and thickness of 4 μm. UV-vis spectrum reveals that ZnO sampls show an appreciable red shift and the band gap energy of the obtained ZnO samples were about 3.15 eV. A very strong ultraviolet (UV) emission at the UV region was observed in the photoluminescence (PL) spectrum of the as-prepared ZnO samples tested at room temperature. A possible growth process of the ZnO hexagonal bilayer disk-like microstructures was schematically illustrated.
ZnO hexagonal bilayer disk-like microstructures are successfully fabricated using a simple solvothermal method assisted with polyvinylpyrrolidone (PVP). The structure and morphology were investigated by Xray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). XRD result indicated that the as-obtained samples were well-crystallized wurtzite hexagonal ZnO structure. SEM images showed that the ZnO hexagonal bilayer disk-like assembles consist of two uniform and smooth disks with an average edge length of 6 μm and thickness of 4 μm. UV-vis spectrum reveals that ZnO sampls show an appreciable red shift and the band gap energy of the obtained ZnO samples were about 3.15 eV. A very strong ultraviolet (UV) emission at the UV region was observed in the photoluminescence (PL) spectrum of the as-prepared ZnO samples tested at room temperature. A possible growth process of the ZnO hexagonal bilayer disk-like microstructures was schematically illustrated.
Synthesis of MXene-supported layered MoS2 with enhanced electrochemical performance for Mg batteries
2018, 29(8): 1313-1316
doi: 10.1016/j.cclet.2018.04.023
Abstract:
In this paper, the petal-like MoS2/MXene composite has been successfully synthesized by one-step hydrothermal method. With the combination of few-layer MoS2 nanosheets and the high conductive MXene substrate, the composite exhibits enhanced capacities of 165 mAh/g at 50 mA/g and outstanding rate performance of 93 mAh/g at 200 mA/g as a cathode material of Mg batteries. Simultaneously, MXene with high conductivity and abundant surface functional groups is proved to be a promising substrate for the wider design of high performance electrode materials.
In this paper, the petal-like MoS2/MXene composite has been successfully synthesized by one-step hydrothermal method. With the combination of few-layer MoS2 nanosheets and the high conductive MXene substrate, the composite exhibits enhanced capacities of 165 mAh/g at 50 mA/g and outstanding rate performance of 93 mAh/g at 200 mA/g as a cathode material of Mg batteries. Simultaneously, MXene with high conductivity and abundant surface functional groups is proved to be a promising substrate for the wider design of high performance electrode materials.
2018, 29(8): 1317-1320
doi: 10.1016/j.cclet.2018.05.042
Abstract:
In the fields of tissue engineering and controlled drug release, electro-spun fibers are often required to have structural characteristics such as high porosity and large specific surface area. The traditional scanning electron microscope can observe the microscopic appearance of the sample clearly, but it damage to the polymer electro-spun fiber, and the detection takes a long time. In view of this, we have tested a polarization method to quickly distinguish different morphological features of the samples, such as smooth surface, microporous, and beaded microspheres using the depolarization parameter MMD-△, which is obtained by the Mueller matrix polar decomposition. The preliminary results show that this method is simple, fast, and potentially capable of non-destructive evaluation of the microstructure properties of the object surface.
In the fields of tissue engineering and controlled drug release, electro-spun fibers are often required to have structural characteristics such as high porosity and large specific surface area. The traditional scanning electron microscope can observe the microscopic appearance of the sample clearly, but it damage to the polymer electro-spun fiber, and the detection takes a long time. In view of this, we have tested a polarization method to quickly distinguish different morphological features of the samples, such as smooth surface, microporous, and beaded microspheres using the depolarization parameter MMD-△, which is obtained by the Mueller matrix polar decomposition. The preliminary results show that this method is simple, fast, and potentially capable of non-destructive evaluation of the microstructure properties of the object surface.
