阳离子抗菌聚合物

阳离子抗菌聚合物, 作为一种新型抗菌材料, 具有独特的抗菌机理和高效的抗菌活性, 并且能有效解决细菌耐药性问题, 引起了人们的广泛关注。阳离子抗菌聚合物具有有效的抗菌活性, 其抗菌活性受到亲疏水平衡、分子质量、烷基链长度和阴离子等因素的影响。抗菌活性是评价抗菌剂优劣的重要因素之一, 了解和掌握影响抗菌活性的因素, 对于优化或开发更安全、更高效的阳离子抗菌聚合物具有重大意义。本文总结了通过不同作用方式作用于细菌的多种抗菌策略, 依据影响阳离子抗菌聚合物抗菌活性的因素, 总结包括天然阳离子抗菌聚合物、季铵盐类聚合物、N-卤代胺类聚合物、膦盐和锍盐类聚合物、胍盐类聚合物和抗菌水凝胶的研究进展。最后, 对阳离子抗菌聚合物面临的挑战和未来发展方向进行了讨论。     

聚苯乙烯磺酸钠与季鏻盐表面活性剂复合物的结构调控及其抗菌性能

发展非抗生素抗菌策略在减少医疗器械相关的细菌感染并降低对抗生素的过度依赖方面具有重大意义。对医疗器械表面进行功能化,赋予其抗菌性能是非抗生素抗菌所采用的常用方式。聚电解质-表面活性剂复合物的醇溶、水不溶的特点使其在构建抗菌涂层方面具有操作简单、不受器械结构限制的优点,有望应用于各种医疗器械的表面功能化。本文通过构建不同烷基链长季鏻盐表面活性剂与聚苯乙烯磺酸钠聚阴离子复合物,系统研究了复合物在水溶液中的组装行为以及所制备复合物涂层的抗菌性能与表面活性剂组分疏水碳链长度之间的内在关联。通过浊度、等温滴定量热法等测试手段对聚苯乙烯磺酸钠与3种三丁基烷基季鏻盐表面活性剂在水中的组装过程进行了分析,结果表明增加表面活性剂烷基链长将促进聚电解质-表面活性剂复合物形成。通过在常用医疗器械材料表面构建复合物涂层,对比了3种复合物对两种模型菌种的抗菌性能。对于以金黄色葡萄球菌为代表的革兰氏阳性菌,所制备的3种复合物涂层的杀菌率分别为42.9%、99.97%和99.99%,随着表面活性剂烷基链越长而提高;对于大肠杆菌为代表的革兰氏阴性菌,随着表面活性剂烷基链长度增加,单独季鏻盐表面活性剂的抗菌性能增强,而...     

(甲基)丙烯酸氟烷基酯的“活性”/可控聚合

带氟烷基侧链的(甲基)丙烯酸氟烷基酯聚合物是一类具有独特表面性能和光学特性的氟聚合物,传统的自由基共聚合由于无法调节聚合物的微细结构和氟原子的分布,限制了该类聚合物在更广领域的应用.活性聚合为聚合物分子设计和合成提供了一个有效方法,利用活性聚合方法可以获得预期结构和性能的含氟嵌段聚合物材料.由于引入了氟烷基侧链,(甲基)丙烯酸氟烷基酯的活性聚合又有其特殊性,本文针对它的活性阴离子聚合、基因转移聚合、活性自由基聚合等方面作一综述.     

低表面能侧基含氟聚合物*

含氟聚合物材料具有优异的热稳定性、极低的表面能、强化学稳定性和生物相容性等,在功能涂料、织物整理、微电子、汽车以及航空航天等领域具有很好的应用前景。本文综述了侧基含氟聚合物的主链、全氟烷基链、主链与全氟烷基链段间连接基团的结构对聚合物表面性能的影响,并总结了环境友好型低表面能侧基含氟聚合物的研究进展。     

液膜型阴离子洗涤剂离子选择性电极的试制

近十年来,国际上曾对阴离子洗涤剂离子选择性电极开展了不少研究,如采用十六烷基吡啶、三辛基甲基铵、Ferrorin、Hyamine、结晶紫等阳离子染料为配对阳离子,分别试制了十二烷基硫酸根,辛基硫酸根和十二烷基苯磺酸根离子选择性电极。但是这些电极的稳定性和重现性都不够好,至多只能用作电位滴定的指示电极,用于直接电位法的尚未见有报导。我们试验了长碳链的季铵阳离子三庚基十二烷基铵与阴离子洗涤耕十二烷基苯磺酸形成的离子对化合物作为电极的活性材料,试制了新的液膜型阴离子洗涤耕     

水溶性壳聚糖降血脂作用的化学机理 (II)水溶性壳聚糖及其氨化衍生物对硬脂酸钠、十二烷基硫酸钠结合能力

体外测定了水溶性壳聚糖及其氨化衍生物对硬脂酸钠、十二烷基硫酸钠的结合能力及其影响因素．结果表明，水溶性壳聚糖结合硬脂酸钠、十二烷基硫酸钠的能力主要取决于其阳离子化程度．修饰后的壳聚糖对硬脂酸钠、十二烷基硫酸钠结合能力的增强，说明引入更多的胺基或铵基有利于对硬脂酸钠、十二烷基硫酸钠的结合，氨基上烷基与硬脂酸钠、十二烷基硫酸钠碳链之间也应当产生疏水相互作用．     

亲核性氟源在碳碳不饱和键选择性氟化官能化反应中的应用

含氟化合物表现出的特殊理化和生物活性使得其在药物、农用化学品和材料科学等领域有着广泛而重要的应用,因此,含氟化合物的高效制备不仅成为了合成化学的研究热点之一,而且极大地推动了相关领域的蓬勃发展.其中,在有机分子内直接引入氟原子的方法主要有亲电氟化和亲核氟化.相较于亲电氟化,亲核氟化反应所用的氟化试剂通常廉价易得,所需的反应条件也比较温和.作者课题组借助过渡金属催化、可见光氧化还原催化和可见光促进策略,拓展了亲核性氟源在碳碳不饱和键选择性氟化官能化反应中的应用,合成了一系列结构新颖的含氟化合物.在该研究评论中将对此做出小结,并对该领域值得关注的研究方向进行简要的展望.     

含氟β-氨基酸及其衍生物的合成进展

含氟β-氨基酸及其衍生物具有特殊的生理活性, 其合成方法的研究近年来受到广泛关注. 以直接氟化法和间接氟化法分类, 概述了含氟β-氨基酸及其衍生物的合成方法及最新研究进展, 对一些已知化合物的生理活性及药用价值作了初步归纳.     

不同类型表面活性剂对纳米SiO2流体粘度的影响

系统地研究了不同类型的表面活性剂对低浓度纳米SiO2流体粘度的影响规律,并在此基础上深入探讨了不同碳链长度的阳离子和非离子表面活性剂对纳米SiO2流体粘度的影响。结果表明,阴离子表面活性剂十二烷基苯磺酸钠(SDBS)对纳米流体粘度的影响较小,其相对粘度值维持在1.23左右;而阳离子表面活性剂十四烷基三甲基溴化铵(TTAB)、十六烷基三甲基溴化铵(CTAB)、十八烷基三甲基溴化铵(OTAB)、十六烷基氯化吡啶(CPC)、非离子表面活性剂OP-8、OP-10和两性离子表面活性剂DXS14、DXS18对纳米流体粘度的变化影响较大,其最大相对粘度值分别能达到3.42、1.82和8.87。同时也发现,阳离子表面活性剂碳链越长,纳米流体最高粘度值越大,且纳米流体最高粘度所对应的表面活性剂浓度均在其临界胶束浓度值附近。     

新型含氟聚醚链修饰的咪唑离子液体的合成及其热稳定性

含氟聚醚链修饰的咪唑与碘代烷烃经季铵化反应高产率地制备了4个新型的含氟聚醚链修饰的咪唑碘盐(3a ～3d);通过3的复分解反应合成了一系列新型的含氟聚醚链修饰的咪唑离子液体盐(4a ～4d,5a～5d),其结构经1 H NMR,19F NMR,IR和元素分析确证.热重分析研究表明,4和5具有较高的热稳定性.     

Molecular dynamics in fluorinated side-chain maleimide copolymers as studied by broadband dielectric spectroscopy

A series of alternating maleimide (MI) copolymers with fluorinated side chains have been investigated using broadband dielectric spectroscopy. The side chains consist of fluoroalkane (–C _x F_2x+1, x=1, 7, 9) end groups connected to the main chain via methylene spacers. The experiments were carried out in a frequency range of 0.1 Hz to 10 MHz and at temperatures between 120 K and 500 K. The fluorinated MI copolymers show a fast sub-T _g (β) relaxation characterized by an Arrhenius-type temperature dependence with activation energy in the range of 30–37 kJ/mol. Two more processes (α and δ-like) are observed, corresponding to independent relaxations of the main chain and the fluoroalkane domains respectively. For shorter side chains, the δ-like process is not observed but instead another relaxation process, α _S , occurs at temperatures higher than either the α and δ-like processes. When compared with unfluorinated MI copolymers, the fluorinated MI copolymers show the δ-like process and a slower β-relaxation unlike their unfluorinated counterparts. A model to explain the molecular origin of the four processes is proposed, supplemented by differential scanning calorimetry and published WAXS/SAXS data.     

The structure–activity relationship of some hexacoordinated dimethyltin(IV) complexes of fluorinated β‐diketone/β‐diketones and sterically congested heterocyclic β‐diketones

The study was focused on the structure–activity relationship of some newly synthesized hexacoordinated dimethyltin(IV) complexes of fluorinated β‐diketone/β‐diketones and sterically congested heterocyclic β‐diketones. These complexes were screened for their antibacterial activity against a Gram‐negative bacterium (Pseudomonas aeruginosa) and Gram‐positive bacteria (Streptomyces griseus, Staphylococcus aureus, Bacillus subtilis) and the results were compared with those of a standard antibacterial drug. Some of the complexes were also screened for their antifungal activity against various fungi (Aspergillus niger, A. flavus, Trichoderma viride, Fusarium oxysporum) and were found to be active. These new hexacoordinated complexes of dimethyltin(IV) were generated by reactions of dimethyltin(IV) dichloride and sodium salts of fluorinated β‐diketone/β‐diketones and sterically congested heterocyclic β‐diketones in 1:1:1 molar ratio in refluxing dry benzene. Plausible structures of these complexes were suggested with the aid of physicochemical and spectroscopic studies. ¹¹⁹Sn NMR spectral data revealed the presence of a hexacoordinated tin centre in these dimethyltin(IV) complexes. Copyright © 2015 John Wiley & Sons, Ltd.     

Compatibilization of laser generated antibacterial Ag- and Cu-nanoparticles for perfluorinated implant materials

The production of silver and copper particles by laser ablation in an organic solvent and their in situ functionalization with amphiphilic copolymers bearing fluorinated side chains is presented. Aside the stabilization of the particles, the fluorinated side chains render the modified particles compatible with a perfluorinated matrix, which results in a homogeneous distribution of the particles in the matrix. The incorporation of silver particles in perfluorinated matrices is of special interest for the preparation of antibacterial composites, e.g. PTFE, which might be applied in antibacterial implants, e.g. antibacterial vascular prostheses. Laser ablation in liquids as a general method to produce charged nanoparticles of any metal is hence combined with sophisticated surface active compounds.     

Bis-Thiourea Bearing Aryl and Amino Acids Side Chains and Their Antibacterial Activities

Abstract

A series of symmetrical 1,3-bis thiourea 1a–e and 1,4-bis thiourea derivatives 2a–e have been successfully synthesized from the reactions of amines with 3-acetylbenzoyl isothiocyanate and 4-acetylbenzoyl isothiocyanate, respectively. All the synthesized compounds were characterized by FT-IR spectroscopy and ¹H and ¹³C NMR spectroscopy. The compounds were screened for their antibacterial activity by turbidimetric method using gram-negative bacteria (E. coli ATCC 8739) using turbidimetric method. The newly synthesized bis-thiourea derivatives bearing aryl side chains showed good antibacterial activity against E. coli. The effect of the molecular structure of the synthesized compounds on the antibacterial activity is discussed.     

Silver nanoparticle‐decorated multiwalled carbon nanotube/pramipexole nanocomposite: Synthesis,characterization and application as an antibacterial agent

This work reports the preparation of multiwalled carbon nanotube/pramipexole/Ag (CNT/pra/Ag) as a novel antibacterial agent, in which pramipexole groups are utilized as linkers to secure Ag nanoparticles to carbon nanotube surfaces without agglomeration. The resulting CNT/pra/Ag sample was characterized by performing transmission and scanning electron microscopy, wavelength‐ and energy‐dispersive X‐ray, X‐ray diffraction, Fourier transform infrared, inductively coupled plasma and Raman measurements. Using this approach, monodisperse spherical Ag nanoparticles in CNT/pra/Ag have narrow size distributions with average diameters of ca 3–8 nm. The antibacterial activity of CNT/pra/Ag was investigated against bacterial species Staphylococcus aureus , methicillin‐resistant S. aureus , Pseudomonas aeruginosa and Escherichia coli using the paper‐disc diffusion method and by determining the minimal inhibitory concentration. CNT/pra/Ag showed better inhibitory activity towards Gram‐positive bacteria than Gram‐negative bacteria in this study, which indicates its potential as an antibacterial material for laboratory and medical purposes.     

Isolation and structural elucidation of novel antimicrobial compounds from maggots of Chrysomyis megacephala Fabricius

The excretions/secretions from the maggot of Chrysomyis megacephala Fabricius are traditionally used to treat serious infections in China. In this study, bioassay-guided fractionation led to the isolation of three novel antibacterial compounds (1–3), including important fluorinated compounds (3 and 5), together with other nine known compounds from 70% methanol extract of C. megacephala. The structures of the new compounds were elucidated by NMR spectroscopic analysis and high-resolution mass spectroscopy. The antibacterial activities of the isolated compounds were evaluated using agar disc diffusion method. New compounds 1 and 2 exhibited moderate activity against Bacillus subtilis with a minimum inhibitory concentration (MIC) of 250 μg mL^? 1. The most active compounds 3 and 5 displayed a broad spectrum of antimicrobial activity with an MIC of 125 μg mL^? 1 against G⁺ and G^?  bacteria. The structure of the above-mentioned novel compounds and their antimicrobial activities are herein reported for the first time from the natural product of insects.     

Biosynthesis and characterization of Dillenia indica-mediated silver nanoparticles and their biological activity

Dillenia indica L. is a traditional medicinal plant well known for its ability to cure various human diseases. In the current study, silver nanoparticles have been synthesized by simple and eco-friendly method using Dillenia indica extract. The green synthesized nanoparticles were characterized by Fourier transform infrared (FTIR), UV–visible spectroscopy, Atomic force microscopy (AFM), High-resolution transmission electron microscopy (HR-TEM), Zeta Potential and Size Distribution. UV–visible and FTIR spectra, AFM, HR-TEM and Zeta Potential readings and size distribution conformed that the synthesized silver particles were in the size of nano. The green synthesized silver nanoparticles were subjected for antibacterial activity against Gram-positive bacteria Enterococcus faecalis and Gram-negative bacteria Escherichia coli by agar well diffusion method. The synthesized AgNPs exhibited significant inhibition of 27 and 16 mm against the test bacteria at 0.25 mg/ml. Further the antibacterial activity was confirmed by live and dead cell assay by fluorescence microscopy and morphological changes of bacteria were studied by Scanning electron microscope (SEM). The study recommends that the synthesized silver nanoparticles using Dillenia indica extract have potential application in inhibition of bacteria owing to their potent antibacterial activity.     

Peroxidase-Mimetic Copper-Doped Carbon-Dots for Oxidative Stress-Mediated Broad-Spectrum and Efficient Antibacterial Activity

Carbon dots (CDs) have recently emerged as antibacterial agents and have attracted considerable attention owing to their fascinating merits of small size, facile fabrication, and surface functionalization. Most of them are involved in external light activation or hybridization with other functional nanomaterials. Herein, we present peroxidase-like Cu-doped CDs (Cu-CDs) for in vitro antibacterial applications. The unique peroxidase-mimicking property of the Cu-CDs was demonstrated by tetramethylbenzidine chromogenic assay, electron paramagnetic resonance spectra, and hydroxy radical probe. Escherichia coli and Staphylococcus aureus were chosen as representative gram-negative/positive models against which Cu-CDs exhibited superior antimicrobial activity even at a dosage down to 5 μg/mL. A possible mechanism of action was that the Cu-CDs triggered a catalytic redox reaction of endogenous H₂O₂ and glutathione depletion in the bacteria cells, with subsequent oxidative stress and membrane disruption. This work provides a new strategy for the design of microenvironment-responsive antimicrobial nano-agents.     

Carbon quantum dots decorated on ZnO nanoparticles: An efficient visible-light responsive antibacterial agents

Zinc oxide@carbon quantum dots (ZnO@CQDs) nanocomposite was prepared via a facile hydrothermal method. Characterization of the obtained samples was carried out by Scanning electron microscopy-EDX(SEM–EDX), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Photoluminescence (PL), and Fourier transformed infrared spectroscopy (FT-IR). These results revealed that we have prepared ZnO@CQDs nanocomposite successfully. Our study revealed that the antibacterial efficiency (against S.aureus and E.coli) under visible light irradiation of as prepared ZnO@CQDs nanocomposite was higher than pure ZnO nanoparticles. The ZnO@CQDs nanocomposite showed excellent antibacterial activity against Gram-negative and Gram-positive bacteria with a minimal inhibitory concentration (6–8 mg/mL) against to E.coli and S.aureus. We also tested the light response of ZnO@CQDs under UV–vis light, by calculating its band gap data, after decorated with CQDs, the band gap of the pure ZnO can significantly decreased from 2.57 eV to 2.50 eV. The ZnO decorated by CQDs can both enhance the light absorption and suppress photogenerated electron–hole's recombination which results in the enhancement of antibacterial properties.     

Surprising Antibacterial Activity and Selectivity of Hydrophilic Polyphosphoniums Featuring Sugar and Hydroxy Substituents

There is currently an urgent need for the development of new antibacterial agents to combat the spread of antibiotic‐resistant bacteria. We explored the synthesis and antibacterial activities of novel, sugar‐functionalized phosphonium polymers. While these compounds exhibited antibacterial activity, we unexpectedly found that the control polymer poly(tris(hydroxypropyl)vinylbenzylphosphonium chloride) showed very high activity against both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus and very low haemolytic activity against red blood cells. These results challenge the conventional wisdom in the field that lipophilic alkyl substituents are required for high antibacterial activity and opens prospects for new classes of antibacterial polymers.