静电纺丝纳米纤维膜固定化酶及其应用*

静电纺丝是一种简单有效的制备聚合物纳米纤维的技术,在组织工程、药物控释和传感器等方面具有广泛的应用。采用静电纺丝技术制备得到的纳米纤维膜具有比表面积大、孔隙率高和易于分离回收等优点,可以作为一种优良的酶固定化载体,目前在酶固定化领域受到了广泛的关注。本文综述了近年来静电纺丝纳米纤维膜固定化酶的研究进展,在阐述静电纺丝纳米纤维膜制备技术的基础上,详细介绍了纳米纤维膜表面担载法和包埋法固定化酶的原理和方法,分析了不同固定化方法的优缺点,并讨论了静电纺丝纳米纤维膜固定化酶的应用前景,对静电纺丝纳米纤维膜固定化酶的发展方向进行了展望。     

静电纺丝纳米纤维薄膜的应用进展

静电纺丝是一种简单而高效制备高分子微纳米纤维的技术,由于设备和实验成本低、纤维产率高、制备出的纤维比表面积比较大、适用性广泛等独特的优势,近些年来备受关注。静电纺丝的应用是静电纺丝研究的最基本动力和终极目标,因此成为研究者一直努力的方向。为了研究静电纺丝应用的研究现状和主要发展方向,本文综述了静电纺丝纳米纤维薄膜几个主要的应用领域,包括组织工程、药物缓释、纳米传感器、能源应用、生物芯片和催化剂负载等,并展望了未来可能的发展方向。     

胶原蛋白静电纺丝纳米纤维研究进展

由于胶原蛋白静电纺丝纳米纤维具有胶原蛋白的生物活性以及纳米结构材料的优异性能,其在生物医学领域的研究和应用开发取得了非常大的进展。本文首先综述了胶原蛋白静电纺丝纳米纤维的研究现状,讨论了胶原蛋白静电纺丝纳米纤维在组织工程、止血及伤口愈合、载药和防粘连等生物医学领域的应用,最后针对胶原蛋白静电纺丝纳米纤维存在的问题及其未来的发展方向进行了展望。     

取向静电纺丝纳米纤维的制备及应用研究进展

简单描述了静电纺丝的基本装置、原理;为制得高性能的取向纳米纤维,对静电纺丝中出现的不稳定性进行了研究,介绍了三种不稳定状况,并分析了其产生原因.列举了通过改变接收装置、控制电场和附加磁场等方法,改进静电纺丝技术来制取连续取向的纳米纤维,并对各种方法进行了简单的评价,指出磁化静电纺丝(MES)是目前制备取向纳米纤维最具有发展前景的方法.简要介绍了取向纳米纤维在生物组织工程领域方面的应用,并对其未来作了展望.     

可控核/壳结构聚合物电纺纤维的制备与应用

核/壳结构纳米纤维是一种兼具核层与壳层优异性能的功能化复合纤维, 通常具有优于核层和壳层自身的性能, 如可控的机械强度和较好的热传导系数等。其特殊的结构极大地提高了纤维的使用价值, 拓宽了纤维的应用领域, 因此, 核/壳结构纳米纤维成为纤维领域的研究热点之一。静电纺丝技术因其简单有效的特点, 近些年来在众多纳米纤维制备技术中一直备受关注, 制备结构和形貌可控的核/壳结构纤维的方法对于指导其在实际中的应用尤为重要。本文系统介绍了以静电纺丝技术制备核/壳结构纳米纤维的方法, 主要包括单喷头相分离法、同轴静电纺丝法、乳液静电纺丝法以及模板法, 重点讨论了影响核/壳结构的主要因素以及核/壳结构对纤维性能的影响。综述了近几年来国内外关于可控核/壳结构电纺纤维制备的研究新进展及其在药物缓释体系、组织工程支架、多功能敷料、污水处理材料、疏水性材料等领域的潜在应用价值。     

生物高分子静电纺丝研究进展

静电纺丝(电纺)技术是一种制备直径为数十纳米到数微米的纳米纤维的有效方法。由于生物高分子具有良好的生物相容性,近年来国内外对生物高分子的电纺制备进行了大量研究。这种生物高分子纳米纤维在组织工程支架、组织修复等方面有独特的优势。本文对生物高分子——多糖、蛋白质、核酸(DNA)的静电纺丝研究进行了总结。     

PHBV纳米纤维的静电纺丝及在生物医用领域的研究进展

聚(3-羟基丁酸酯-3-羟基戊酸酯)(PHBV)纳米纤维具有高比表面积、高孔隙率、生物相容性、生物降解性等优点,可用作生物医用材料。本文综述了基于静电纺丝法制备的PHBV纳米纤维及其在生物医用领域的研究进展,讨论了PHBV纺丝溶液的溶剂、浓度、外加盐类以及聚合物等对PHBV纳米纤维形貌、结构及性能的影响规律,结合目前PHBV纳米纤维在组织工程和药物运输载体的研究现状,重点概述了其亲水改性、力学性能改善、功能化改性的研究进展。最后,对静电纺丝法制备PHBV纳米纤维存在的一些问题进行分析,并对其未来发展趋势和前景进行展望。     

静电纺丝制备醋酸纤维素复合纳米纤维的研究进展

静电纺丝技术就是通过带电聚合物溶液或熔体的喷射来制备纳米纤维,是一种制备纳米纤维材料简单有效的技术。醋酸纤维素(CA)易溶于有机溶剂,常作为纤维素的替代材料应用于静电纺丝领域。本文总结了近年来国内外采用静电纺丝技术制备CA复合纳米纤维的研究新进展,重点介绍了CA/CNTs复合纳米纤维、CA/金属粒子复合纳米纤维、CA/金属氧化物复合纳米纤维、CA基载药复合纳米纤维、CA/PAN复合纳米纤维、CA/PVA复合纳米纤维、CA/CS复合纳米纤维等CA复合纳米纤维的研究进展以及潜在的应用领域。     

静电纺丝法制备三维聚二甲基硅氧烷纳米通道

利用静电纺丝技术构建了新型三维纳米通道系统。 在不同质量分数的聚苯乙烯（PS：Mw=1.3×105）溶液中加入一定量十二烷基磺酸钠（SDS）,于不同电压下进行静电纺丝。 所得纤维在90 ℃加热粘连后,形成三维聚苯乙烯纳米网络模板,然后于聚二甲基硅氧烷(PDMS)预聚体（含10%交联剂）灌注进入上述模板并交联形成网络复合材料,再用二硫化碳超声除去聚苯乙烯纤维。 采用扫描电子显微镜、透射电子显微镜对纤维模板形貌和纳米通道进行了表征。 结果表明,质量分数为10%的PS溶液加入0.5%SDS,在20 kV电压下进行静电纺丝,得到直径为150 nm的纤维。 SDS的加入对纺丝纤维具有平滑作用,使得粘连的纤维模板更易去除,形成的三维纳米通道直径约160 nm,与纤维模板直径一致。 该类型纳米通道可以应用于医学药物载体、纳流控芯片等众多领域。     

静电纺丝法制备纳米抗菌纤维的研究进展

纳米抗菌材料是防止细菌等致病微生物对人们生产、生活的破坏而发展起来的一类新型材料.在纳米抗菌材料的众多制备方法中,静电纺丝是一种成本低,工艺可控的技术,制备的纳米纤维具有比表面积大、孔隙率高、纤维均匀等特点.本文作者首先简述了静电纺丝技术以及该技术制备纳米抗菌纤维材料的特点;接着按照菌剂种类不同,对静电纺丝技术制备的抗菌纤维材料进行归类,将其分为无机抗菌纤维材料、天然抗菌纤维材料和复合抗菌纤维材料3类,并对其研究进展进行了评述;最后对静电纺丝技术制备纳米抗菌纤维的研究现状进行了总结与展望.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.