微波辐射法合成壳寡糖/有机累托石纳米复合材料及性能研究

采用高效快速的微波辐射法制备了壳寡糖/有机累托石(CTOOR)纳米复合材料,其中壳聚糖(CTS)经酶解处理得到低分子量壳寡糖(CTO),累托石(REC)用Gemini 18-3-18进行有机改性。用场发射扫描电子显微镜(FESEM)、红外光谱(FT-IR)、X射线衍射(XRD)、Zeta电位分析表征了该纳米复合材料的微观形态和结构,比较了其与单一组分CTO热稳定性和抗菌性能的差异。结果表明,CTO插层进入有机累托石(OREC)层间,扩大了其层间距;CTO与OREC发生氢键和静电的相互作用;CTOOR的热稳定性及抗菌能力均优于CTO。     

壳聚糖衍生物改性磷酸锆自组装纳米材料的 制备及抑菌性能研究

以α-ZrP为载体,通过微波辐射法,将3种水溶性壳聚糖衍生物羧甲基壳聚糖、N-三甲基壳聚糖季铵盐和N-对苯甲氧基甲基壳聚糖季铵盐插层进入α-ZrP层间,制备得到3种壳聚糖衍生物/磷酸锆纳米复合抑菌材料。通过红外光谱、X射线衍射、扫描电镜、透射电镜、电动电位分析和热重分析,对纳米复合材料的组成、结构和热稳定性进行表征。X射线衍射及电动电位分析实验结果表明:相较于α-ZrP,壳聚糖衍生物/磷酸锆纳米复合材料的层间距随着壳聚糖衍生物插层而明显增大,壳聚糖衍生物的正电性越强,复合材料的层间距越大,这表明壳聚糖衍生物与α-ZrP通过离子交换、氢键结合,已经成功地插层进入α-ZrP层间。热重分析结果显示复合材料的热稳定性较天然壳聚糖有显著提高。抑菌试验结果表明,复合材料对大肠杆菌和金黄色葡萄球菌都具有很好的抑菌效果。     

季铵盐壳聚糖抗菌纸的性能研究

以季铵盐壳聚糖为抗菌剂处理普通成纸,制备了包装用抗菌纸。采用抑菌圈法评价了该抗菌纸对大肠杆菌和金黄色葡萄球菌的抑制效果,研究了季铵盐壳聚糖的浓度对抗菌纸厚度、抗张强度、耐破度和抑菌性能的影响。结果表明,抗菌纸的抗张强度及耐破度均较原纸有所增加,厚度没有明显变化,能满足包装需求,且具有良好的抗菌性能,其抗菌效果随季铵盐壳聚糖浓度的增加而增强,并且相同季铵盐壳聚糖浓度下的抗菌纸对金黄色葡萄球菌的抑菌效果要好于大肠杆菌。     

壳聚糖/有机锂皂石纳米复合材料的制备及抗菌性能研究

采用离子交换法将季铵盐及壳聚糖插层到锂皂石层间, 制备锂皂石基二次插层复合物。所制备的两种二次插层复合物的层间距相比于纯的锂皂石分别增加了0.276 nm和0.262 nm。用大肠杆菌(E. coli)和金黄色葡萄球菌(S. cereus)为模拟体系对二次插层复合物的抗菌性进行了检验, 利用抑菌环和平板计数法测定两种二次插层复合物的抗菌能力。抗菌结果显示, 细菌与两种复合物接触24 h后, 锂皂石/十四烷基三甲基溴化铵/壳聚糖对大肠杆菌的抗菌率可达100%, 对S.cereus的抗菌率可达85%以上, 锂皂石/十六烷基三甲基溴化铵/壳聚糖对大肠杆菌和金黄色葡萄球菌的抗菌率均可达99%以上。采用扫描电镜法及β-半乳糖苷酶活性考察了两种复合物对大肠杆菌和金黄色葡萄球菌抑菌过程及机理, 结果表明: 复合物首先通过表面带的正电荷将表面带负电的细菌吸附到材料表面, 随后借助有机物阳离子的疏水作用, 穿透细菌细胞膜, 从而达到杀菌效果。     

累托石/大豆蛋白纳米复合材料的性能研究

利用累托石制备累托石/大豆蛋白纳米复合材料,并对材料的结构和性能进行测试和表征,结果表明,累托石/大豆蛋白复合材料在保持韧性的同时,其力学性能得到了明显的提高;一定量的累托石与大豆蛋白通过溶液插层复合形成了剥离/插层结构。     

有机累托石/聚脲弹性体纳米复合材料的制备及性能研究

利用有机纳米累托石对聚脲弹性体进行改性,制备了粘土/聚脲纳米复合材料,采用红外光谱(FTIR)分析了改性体系的结构变化,X-射线衍射(XRD)和透射电镜(TEM)分析了粘土在纳米复合材料中的解离情况,研究了有机累托石添加量对聚脲性能的影响。结果表明,有机累托石以物理共混的形式分散在聚脲中,聚脲可以插入粘土层间,使层间距变大;纳米复合材料在有机累托石添加量为5wt%时具有较优的综合性能,拉伸强度和断裂延伸率分别提高了72.9%和8.7%,初始分解温度提高了19.7℃,500℃时重量保持率提高了7.6%。     

累托石/聚合物纳米复合材料的新进展

累托石是我国湖北省盛产的铝硅酸盐矿物, 其与蒙脱土极为相似, 但又具有它独特的结构特点, 近年来广泛用于聚合物/层状硅酸盐纳米复合材料的制备. 本文介绍了累托石的结构特性、表面修饰和累托石/聚合物纳米复合材料的结构及制备方法, 总结了累托石/壳聚糖基纳米复合材料及其作为抗菌剂、吸附剂、药物控释材料和基因载体等功能化应用方面的最新研究成果, 并提出了累托石/聚合物纳米复合材料未来的研究方向.     

POSS-NH2自组装改性累托石/EPDM橡胶复合材料的制备与性能研究

以异丁胺基多面齐聚倍半硅氧烷(Aminopropyllsobutyl POSS,POSS-NH2)作为插层剂对累托石(Rectorite,REC)进行有机化处理,并应用于三元乙丙橡胶(Ethylene propylene diene monomer,EPDM)体系,采用机械共混法制备了POSS-NH2自组装改性累托石/三元乙丙橡胶(POSS-REC/EPDM)复合材料。考察了POSS-REC在橡胶体系中的剥离行为、复合材料的微观结构、力学性能及热学性能。结果表明:POSS-REC添加量较低时形成较均一的插层-剥离型纳米复合材料;POSS-REC添加量为3%(质量分数)时,复合材料力学性能和热学性能最佳,与纯EPDM橡胶相比,其拉伸强度提高245.5%,断裂伸长率提高113.3%,热分解温度提高7.7℃。     

季铵盐改性SiO_2纳米颗粒的制备及其抗菌性能

选用季铵盐作为抗菌剂,对纳米SiO2颗粒进行表面改性。对合成的季铵盐进行了FT-IR表征。通过FTIR、接触角、Zeta电位等手段研究了烷基链长度及纳米颗粒尺寸对改性纳米SiO2性能的影响,考察了改性纳米SiO2颗粒的抗菌性能。结果表明季铵盐接枝纳米SiO2颗粒表面带正电,随着烷基链的增长,疏水性渐强。抗菌测试表明,改性后的纳米SiO2对金黄色葡萄球菌有很好的抗菌性,24h可以全部杀死浓度为1.72×106 CFU/mL的金黄色葡萄球菌。     

EVOH/蒙脱土插层型纳米复合材料的研究

将蒙脱土有机化处理,然后将有机化蒙脱土与乙烯-乙烯醇嵌段共聚物(EVOH)通过Brabender流变仪熔融共混,制得纳米复合材料.通过电子透射显微镜、傅里叶变换红外光谱分析,X射线衍射分析等手段对该复合材料进行了结构测试.结果表明:EVOH可以插入有机化蒙脱土片层间;聚乙烯吡咯烷酮改性蒙脱土被EVOH插开的片层距离比季铵盐改性蒙脱土被EVOH插开的片层距离大;有机化蒙脱土在复合材料中比例越小,复合体系中蒙脱土被插开的片层间距越大;当有机化蒙脱土含量为8%时,形成剥离型纳米复合材料;当有机化蒙脱土含量为15%时,形成插层型纳米复合材料.     

Preparation and characterization of new quaternized carboxymethyl chitosan/rectorite nanocomposite

Quaternized carboxymethyl chitosan (QCMC) was intercalated into the interlayer of rectorite (REC) to prepare QCMC/REC nanocomposite. XRD and TEM results revealed that REC was well dispersed in the polymer matrix and obtained the largest interlayer distance when the mass ratio of QCMC to REC was 2:1. FTIR, NMR and zeta-potential analyses showed that the intercalation of QCMC did not destroy the structure of REC layer, but there were hydrogen-bonding and electrostatic interactions between QCMC and REC. Quaternized chitosan (HTCC)/REC nanocomposite was prepared and studied in parallel. The comparative analysis of the two biopolymer/clay nanocomposites indicated that the free volume and positive charge density of biopolymers were important factors that affected the intercalation of biopolymer into clay. At last, thermal analysis indicated that QCMC/REC nanocomposites had obviously higher thermal stability in comparison with QCMC. This study shows that the combination with clay materials is a functional way to expand the possible application of QCMC as drug controlled-release carriers, antimicrobial agent and pulp-cap.     

Biopolymer/montmorillonite nanocomposite: preparation, drug-controlled release property and cytotoxicity

In order to combine the advantages of a biopolymer with clay in a drug delivery system, the hot intercalation technique was used to prepare quaternized chitosan/montmorillonite (HTCC/MMT) nanocomposites. Transmission electron microscopy (TEM), x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) results revealed that HTCC chains entered into the interlayer of MMT, and the interaction between them has taken place. This is the basis of the advantage combination. Then the HTCC/MMT nanocomposites were modified to prepare the nanoparticles, whose drug-controlled release behaviours were evaluated. The results suggested that, compared to pure HTCC nanoparticles, certain montmorillonite loadings on quaternized chitosan enhanced the drug encapsulation efficiency of the nanoparticles and slowed the drug release from the nanocomposites. Finally, a study of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) indicated that the nanocomposites are not cytotoxic. Therefore, the HTCC/MMT nanocomposites are of great potential in the biomedical field.     

Preparation of silver nanoparticles with antimicrobial activities and the researches of their biocompatibilities

Silver nanoparticles were prepared by chemical reduction method using chitosan as stabilizer and ascorbic acid as reducing agent in this work. The silver/chitosan nanocomposites were characterized in terms of their particle sizes and morphology by using UV spectrophotometer, nano-grainsize analyzer, and transmission electron microscopy. Antibacterial activities of these nanocomposites were carried out for Staphylococcus aureus and Escherichia coli. The silver nanoparticles exhibited significantly inhibition capacity towards these bacteria. Detailed studies on the biocompatibility of the silver/chitosan nanocomposites were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell adhesion test. The results indicated that these silver/chitosan nanocomposites were benefit for the proliferation and adhesion of L-929 cells, and the biocompatibilities between the nanocomposites and the cells would become better with the culturing days. We anticipated that these silver/chitosan nanocomposites could be a promising candidate as coating material in biomedical engineering and food packing fields wherein antibacterial properties and biocompatibilities are crucial.     

累托石纳米晶层的高压剥离研究

首次采用物理方法高压制备了酚醛树脂(PF)/累托石(REC)粘土和酚醛树脂(PF)/有机改性累托石(OREC)粘土纳米复合材料,以X射线衍射(XRD)、透射电子显微镜(TEM)及红外光谱(IR)分析了复合材料的物相和显微结构。结果表明,不通过层间高分子聚合反应,在常温高压下,由聚合物分子插入粘土层间,可以形成剥离型树脂/粘土纳米复合材料。在100M Pa和500M Pa下,复合材料中的OREC完全剥离,而REC只有部分被剥离。     

Electrospun nano composites of poly(vinyl pyrrolidone)/ nano-silver for antibacterial materials

Poly(vinyl pyrrolidone) (PVP) and nanosilver are promising candidates for biomedical applications because of their biocompatibility and antibacterial efficacy, respectively. In this research, three kinds of nanosilver particles (NSPs) were prepared using the seed mediate growth method and added to electrospinning solutions. PVP/NSPs composites were prepared by electrospinning of 10 wt% PVP solutions that contained NSPs in ethanol. The electrospinability of PVP/NSPs nanowebs in ethanol was investigated according to three different concentrations of NSPs. The Electrospun PVP/NSPs nanocomposites were photocross-linked to improve their water stability. The antibacterial efficacy of the PVP/NSPs nanocomposites was assessed against three types of bacteria; Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. The photocross-linked PVP/NSPs nanocomposites had high water stability and significant antibacterial efficacy against all three types of bacteria. Therefore, these composites could be applied as antimicrobial materials.     

低聚壳聚糖复配体系对皮肤致病菌的体外抗菌活性研究

采用药敏纸片法和对倍稀释法分别考察了低聚壳聚糖与茶树油对化脓性链球菌、表皮葡萄球菌、金黄色葡萄球菌和大肠杆菌的抑菌性和最小抑菌浓度(MIC);采用定量法测定了低聚壳聚糖和茶树油复配体系的杀菌率,并与单组分杀菌率进行对比。结果表明:低聚壳聚糖和茶树油对4种实验菌均有抑菌性的MIC分别为0.5g/L和7.50mL/L;0.5g/L低聚壳聚糖与7.50mL/L茶树油复配后,对4种实验菌均有优异的杀菌率,复配体系明显优于单组分杀菌效果,其20min杀菌率均达到100%。     

Preparation and characterization of a quaternized chitosan

A novel method was developed to obtain N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (HTCC) using glycidyl trimethyl ammonium chloride (GTMAC) and chitosan in a homogeneous system. The factors affecting the degree of substitution (DS) of HTCC, including the amount of perchloric acid, the reaction temperature, and the reaction time, were especially investigated. Under optimal conditions (i.e., with 2.0, 1.9, and 15 g of chitosan, perchloric acid, and GTMAC, respectively), chitosan was pre-reacted with GTMAC at 60 °C, and then the reaction was continued at 80 °C for 8 h. The as-produced HTCC had a DS of 86.9%. Its structure was characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Moreover, it had a good solubility in water within a wide pH range. Besides, the composite was formed from HTCC loaded on bentonite surface.     

Synergistic antibacterial activity of chitosan-silver nanocomposites on Staphylococcus aureus

The approach of combining different mechanisms of antibacterial action by designing hybrid nanomaterials provides a new paradigm in the fight against resistant bacteria. Here, we present a new method for the synthesis of silver nanoparticles enveloped in the biopolymer chitosan. The method aims at the production of bionanocomposites with enhanced antibacterial properties. We find that chitosan and silver nanoparticles act synergistically against two strains of Gram-positive Staphylococcus aureus (S.?aureus). As a result the bionanocomposites exhibit higher antibacterial activity than any component acting alone. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations of the chitosan-silver nanoparticles synthesized at 0?°C were found to be lower than those reported for other types of silver nanoparticles. Atomic force microscopy (AFM) revealed dramatic changes in morphology of S. aureus cells due to disruption of bacterial cell wall integrity after incubation with chitosan-silver nanoparticles. Finally, we demonstrate that silver nanoparticles can be used not only as antibacterial agents but also as excellent plasmonic substrates to identify bacteria and monitor the induced biochemical changes in the bacterial cell wall via surface enhanced Raman scattering (SERS) spectroscopy.     

Synthesis and characterization of quaternized carboxymethyl chitosan/poly(amidoamine) dendrimer core–shell nanoparticles

With the aim to develop a novel water-soluble modified chitosan nanoparticle with tuned size and improved antibacterial activity, quaternized carboxymethyl chitosan/poly(amidoamine) dendrimers (CM-HTCC/PAMAM) were synthesized. Firstly low-generation amino-terminated poly(amidoamine) (PAMAM) dendrimers were prepared via repetitive reactions between Michael addition and amidation, which were then employed for modifying quaternized carboxymethyl chitosan (CM-HTCC). Prior to the reaction of CM-HTCC with PAMAM, carboxylic groups in CM-HTCC were activated with EDC/NHS in order to enhance the reaction efficiency. FT-IR, ¹H NMR, elemental analysis and XRD were performed to characterize CM-HTCC/PAMAM dendrimers. Turbidity measurements showed that CM-HTCC/PAMAM dendrimers had good water-solubility. TEM images indicated that CM-HTCC/PAMAM dendrimers existed as smooth and spherical nanoparticles in aqueous solution. The results of antibacterial activity explored that CM-HTCC/PAMAM dendrimer nanoparticles displayed higher antibacterial activity against Gram-negative bacteria Escherichia coli (E. coli), whereas they showed much less efficiency against Gram-positive bacteria Staphylococcus aureus (S. aureus) compared to quaternized chitosan (HTCC).     

C6位选择性氧化竹浆纤维的壳聚糖改性处理

采用H_3PO_4/HNO_3-NaNO_2氧化体系对竹浆纤维C6位进行选择性氧化,然后与壳聚糖溶液交联反应制备生态的抗菌壳聚糖改性竹浆纤维。固相CP/MAS 13 C核磁共振分析显示,H_3PO_4/HNO_3-NaNO_2已将竹浆纤维C6位上的伯羟基选择性氧化成羧基,且红外光谱和扫描电镜测试表明,壳聚糖的氨基与氧化竹浆纤维分子上的羧基发生酰胺化反应,壳聚糖分子通过C-N化学键共价交联在竹浆纤维上,并在竹浆纤维表面形成壳聚糖薄膜。通过分析H_3PO_4/HNO_3-NaNO_2氧化和壳聚糖处理过程中竹浆纤维羧基含量、机械强力、壳聚糖含量等指标,得出最佳工艺参数。Kjeldahl定氮分析得出壳聚糖在氧化竹浆纤维上的最大含量为3.92%。壳聚糖接枝竹浆纤维的断裂强度变化不明显,但其断裂伸长率降低。抗菌试验结果显示,与壳聚糖处理的原竹浆纤维抗菌性相比,壳聚糖改性竹浆纤维对大肠杆菌和金黄色葡萄球菌的抗菌效果明显提高,抑菌率均在96%以上,且壳聚糖改性竹浆纤维具有良好的抗菌耐洗涤性能。