壳聚糖磺化衍生物的制备及抑菌性能研究

在进一步提高脱乙酰度的基础上 ,分别对壳聚糖进行直接磺化、羟丙基改性后再磺化以及黄原酸化。它们反应的最佳条件分别为 :1克壳聚糖、甲酰胺 10ml、氯磺酸 4ml、反应温度 70℃、反应时间 4小时 ;2克羟丙基壳聚糖、氯磺酸5ml、甲酰胺 2 0ml、反应温度 70℃、反应时间 3小时 ;1克壳聚糖、NaOH溶液 5ml、浓度 30 %、CS2 12ml、反应温度 80℃、反应时间 6小时。另外 ,对壳聚糖及其磺化衍生物的抗菌性也进行了研究。     

壳聚糖衍生物抗菌塑料制备与性能评价

采用水相悬浮聚合法合成壳聚糖接枝苯乙烯（CTS-g-St）抗菌剂，机械共混法制备了以LDPE为基体的抗菌塑料，采用红外光谱分析抗菌剂，扫描电镜观察材料断面，定量抗菌实验对抗菌塑料抗菌活性进行了测定，并测试了材料的力学性能。结果表明：苯乙烯单体成功接枝到壳聚糖分子上；改性壳聚糖与树脂间具有很好的相容性；抗菌剂添加量为2份时，抗菌塑料对大肠杆菌、枯草杆菌在24h、48h抗菌率均超过90％；抗菌剂的加入对材料力学性能无不良影响。     

Preparation, characterization and antimicrobial activity of chitosan/layered silicate nanocomposites

Chitosan/layered silicate nanocomposites with different ratios were successfully prepared via solution-mixing processing technique. Unmodified Ca²⁺-rectorite and organic rectorite modified by cetyltrimethyl ammonium bromide were used. Their structures were characterized by XRD, TEM and FT-IR techniques. The results showed that chitosan chains were inserted into silicate layers to form the intercalated nanocomposites. The interlayer distance of the layered silicates in the nanocomposites enlarged as its amount increased. When the weight ratio between chitosan and organic rectorite was 12:1, the largest interlayer distance of 8.24 nm was obtained. However, with further increase of its amount, the interlayer distance of the layered silicates in the nanocomposites reduced. In vitro antimicrobial assay showed that pristine rectorite could not inhibit the growth of bacteria, but chitosan/layered silicate nanocomposites had stronger antimicrobial activity than pure chitosan, particularly against Gram-positive bacteria. With the increase of the amount and the interlayer distance of the layered silicates in the nanocomposites, the nanocomposites showed a stronger antibacterial effect on Gram-positive bacteria, while the nanocomposites showed a weaker antibacterial effect on Gram-negative bacteria. The lowest minimum inhibition concentration (MIC) value of the nanocomposites against Staphylococcus aureus and Bacillus subtilis was 0.00313% (w/v), and the relative inhibition time (RIT) against B. subtilis with concentration of 0.00313% (w/v) was >120 h.     

壳聚糖接枝甲基丙烯酸甲酯在抗菌塑料中的应用

采用水相悬浮聚合法制备了接枝壳聚糖,红外光谱、XRD及扫描电镜分析证明了甲基丙烯酸甲酯单体成功接枝到壳聚糖分子上,机械共混法制备了以LDPE为基体的抗菌塑料,并通过定量抗菌实验对抗菌塑料抗菌活性进行了测定。结果表明:改性壳聚糖与树脂间具有很好的相容性;抗菌剂添加量为3份时,抗菌塑料对大肠杆菌、枯草杆菌在24h.48h抗菌率均超过90%。此外,抗菌剂的加入对材料力学性能无不良影响。     

Antibacterial and anti-mildew behavior of chitosan/nano-TiO2 composite emulsion

A novel chitosan/nano-TiO₂ composite emulsion (CTCE) was prepared by inverse suspension technology, and its multi-function properties were studied. As can be seen from the results, the gauze treated with chitosan/nano-TiO₂ composite emulsion showed excellent antibacterial activities against Escherichia coli, Aspergillus niger and Candida albicans that the bactericidal ratios could reach 99.96%, 100% and 78.3% after 24 h, respectively. At the same time, the chitosan/nano-TiO₂ composite emulsion could really kill the bacteria, not just inhibit its growth, and the bactericidal ratio for E. coli could reach 70.3% after 1 h. The bactericidal ratio for E. coli reached 98.8% at 27 °C compared with 58.7% at 18 °C after 8 h due to the activity of bacteria being weakened at low temperature. Furthermore, the antibacterial ability of antibacterial gauze was hardly influenced with the increase of storage time, which could be reused for up to 8 times without loss of antibacterial ability. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.     

Preparation and antibacterial properties of polycaprolactone/quaternized chitosan blends

This article is a preliminary study on antibacterial blends of polycaprolactone, chitosan and quaternized chitosan by melt processing. Blends were characterized, mechanical test and antibacterial evaluation against Escherichia coli and Staphylococcus aureus, were conducted. Results showed that the antibacterial potential of chitosan was limited in blends and polycaprolactone/chitosan did not show significant antibacterial effect compared with neat polycaprolactone (PCL). Inhibition rates of polycaprolactone/quaternized chitosan were 39.2％–99.9％ against Escherichia coli, while inhibition rate was 40.9％–99.9％against Staphylococcus aureus. When quaternized chitosan (QCTS) content was up to 20％, blends exhib-ited 99.9％inhibition rates against both two types of bacteria.     

Preparation and characterization of nanocomposites based on chitosan with ZnO-Curcumin

The present paper studied the possibility to obtain nanocomposites of chitosan incorporated with ZnO NP, whose surface has been modified with bioactive compounds. To obtain ZnO nanoparticles, the biogenic method was used and the anchoring of curcumin (CRC) on the surface of the particles was followed. Chitosan-based ZnO-CRC were synthesized using ex-situ method that involves the separate preparation of ZnO particles and their dispersion in the chitosan matrix by mechanical and ultrasonic mixing. The structural and morphological studies of the synthesized samples were carried out using X-ray diffraction, SEM microscopy, FTIR and EDX spectroscopy, and the wetting capacity. The XRD analysis revealed wurtzite crystalline structure of ZnO, anchoring of curcumin to the oxide surface, with an average crystallite size about 18.7 nm. The morphological study shows that the particles have spherical formations, with dimensions in the nanometric range and a relatively uniform distribution of ZnO particles in the matrix. Elemental composition of samples was identified using EDX analysis. Contact angle was measured to evaluate the hydrophilic and/or hydrophobic character of the surfaces. The results demonstrate that the synthesized materials have morpho-structural and wetting characteristics that allow the extension of applicability in biotechnological fields as coating systems.     

PP-R管材专用抗菌母料的制备

采用载银无机抗菌剂制得PP-R管材专用抗菌母料,研究了抗菌母料对PP-R管材的抗菌性能、力学性能、耐光性、安全卫生性的影响。结果表明：该抗菌母料属实际无毒级物质;随着抗菌母料的增加,PP-R抗菌管材的抗菌性能增加,当抗菌母料的质量分数为4％时,即抗菌剂在PP-R管材中的质量分数为1％时,PP-R抗菌塑料的性价比最佳;表面处理过的抗菌剂在PP-R中分布均匀、无团聚现象,与PP-R基体树脂具有良好的相容性。添加4％抗菌母料的PP-R抗菌管材对大肠杆菌、金黄色葡萄球菌等细菌的抗菌率都达到99％以上,具有高效、广谱抗菌性能;经55℃的去离子水浸泡16h后,抗菌性能下降较小,具有长效抗菌性能;通过240h的光老化实验后,平均色差为1．36,无明显变色,光老化性能优良;力学性能与空白PP-R管材相当,卫生安全性能符合国家有关食品卫生检验标准。     

Preparation, characterization and antimicrobial activity of quaternized carboxymethyl chitosan and application as pulp-cap

Quaternized carboxymethyl chitosan (QCMC) was prepared from which carboxymethyl chitosan (CMC) was prepared from chitosan first, then N-quaternary ammonium group was introduced by the reaction of CMC with 2, 3-epoxypropyl trimethylammonium. The structures of the derivatives were characterized by FT-IR, XRD, ¹³C NMR, ¹H NMR and gel permeation chromatography. In vitro antimicrobial activities of QCMC were evaluated against Escherichia coli, which is a Gram-negative bacterium, and Staphylococcus aureus, which is a Gram-positive bacterium. In compared with carboxymethyl chitosan (CMC) and quarternary chitosan (QC) of the same degree of substitusion (DS), we found that QCMC has stronger antimicrobial activity. Then we went deep into study of the relationship between their structure and antimicrobial activity, found that the DS of CMC do little effect to their antimicrobial activity, but as the increase of their DS of quaternization or the decrease of their molecular weight, the antimicrobial activity of QCMC become stronger. QCMC was complexed with calcium hydroxide as pulp-cap. Animal experiment results indicated that QCMC can strongly induce reparative dentine formation and showed a better ability in dentin inducing compared with calcium hydroxide.     

Preparation of Some Eco-friendly Corrosion Inhibitors Having Antibacterial Activity from Sea Food Waste

Chitosan is one of the important biopolymers and it is extracted from exoskeletons of crustaceans in sea food waste. It is a suitable eco-friendly carbon steel corrosion inhibitor in acid media; the deacetylation degree of prepared chitosan is more than 85.16 %, and the molecular weight average is 109 kDa. Chitosan was modified to 2-N,N-diethylbenzene ammonium chloride N-oxoethyl chitosan (compound I), and 12-ammonium chloride N-oxododecan chitosan (compound II) as soluble water derivatives. The corrosion inhibition efficiency for carbon steel of compound (I) in 1 M HCl at varying temperature is higher than for chitosan and compound (II). However, the antibacterial activity of chitosan for Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Candida albicans is higher than for its derivatives, and the minimum inhibition concentration and minimum bacterial concentration of chitosan and its derivatives were carried out with the same strain.     

Antibacterial activity of V- doped rod-like MgO crystals decorated with nanoflake layer

In present study, we report a V doping fabrication method for obtaining rod-like MgO crystals decorated with a nanoflake layer. This novel structure has only been minimally reported in literature. Pure MgO and Mg₂V₂O₇–MgO composite materials were obtained by precipitation and impregnation methods, with vanadium added concentrations of 0–9%. The influence of V doping on crystal structure and particle morphology of MgO was investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis demonstrated that MgO has a cubic structure, while X-ray photoelectron spectroscopy (XPS) revealed that V⁵⁺ exists on the surface of MgO. The specific surface areas and pore sizes of MgO composites were calculated by BET and BJH analysis. These techniques revealed that specific surface area and pore size of MgO increased due to vanadium doping. The antibacterial effects of Mg₂V₂O₇–MgO composite materials against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were assessed using a bacterial killing/colony-forming unit (CFU) assay and bacteriostatic ring method. Our results demonstrate that V doping dramatically improved antimicrobial properties of MgO, with 7 mol% doping inducing the best antibacterial activity. The antibacterial mechanisms of Mg₂V₂O₇–MgO composite material were also proposed.     

抗菌塑料的制备及应用研究进展

概述了抗菌塑料中使用的抗菌剂及其抗菌机理,以及抗菌塑料的制备。介绍了目前普遍采用的一些评价抗菌性能的方法。就目前抗菌塑料研究中存在的问题提出了解决办法,并对抗菌塑料的发展进行了展望。     

Magnetic chitosan microspheres: preparation and characterization

In this study, magnetic chitosan microspheres were prepared in a well shaped spherical form with a size range of 100 to 250 μm (size distribution ±15 to ±40 μm, respectively) by the suspension cross-linking technique for use in the application of magnetic carrier technology. The magnetic material (i.e. Fe₃O₄) used in the preparation of the magnetic chitosan microspheres was prepared by precipitation from FeSO₄ and Fe₂(SO₄)₃ solutions in basic medium and then ground to the desired size (i.e. 1–5 μm). The morphological and magnetic properties of the microspheres were characterized by different techniques (i.e. SEM, optical microscopy, magnetometry). The results demonstrated that the stirring rate of the suspension medium and the Fe₃O₄/chitosan ratio are the most effective parameters for the size/size distribution and the magnetic quality of the microspheres, while the chitosan molecular weight (MW) has no significant effect on these properties for the given MW range (i.e. 150 to 650 kDa). The best magnetic quality of the magnetic chitosan microspheres is around 9.1 emu/g microsphere at 10 kG magnetic field intensity.     

抗菌型高抗冲聚苯乙烯的制备

采用机械共混法和热本体聚合法制备抗菌型高抗冲PS（HIPS）,通过定性和定量试验对抗菌型HIPS的抗菌活性进行了测定与分析。结果表明,用机械共混法和热本体聚合法制得的抗菌型HIPS都具有强抗菌活性,抗菌率分别达95％和99％以上;在热本体聚合法中,对所用PSK-11中的抗菌组分的表面处理能有效地提高产物在短接触时间下的抗菌活性;通过这两种方法制备的抗菌型HIPS未产生变色,在放置3年后对大肠杆菌和金黄色葡萄球菌的抗菌率均超过99％,表现出优异的抗菌稳定性、持久性。     

Preparation and characterization of blend membranes of polyurethane and superfine chitosan powder

A novel kind of asymmetric blend membranes with superfine chitosan powder (SCP) and biomedical polyurethane was prepared by immersion precipitation phase inversion method. Effects of different SCP content on the morphology and properties of the blend membranes were investigated. The result showed that SCP content had little influence on the cross-section structure of the blend membranes, and the cross-section presented a cellular structure. WAXD results revealed that the aggregated structure of SCP remained. With an increment of SCP content, the pore diameter and porosities of blend membranes increased firstly, and then decreased. While, the water absorption rate and water vapor transmission rate were improved remarkably with increasing SCP content. The mechanical testing results indicated that with an increment of SCP ratio, mechanical properties presented a descending trend, whereas all blend membranes exhibited the good elasticity.     

抗菌功能塑料的制备与性能评价

采用抗菌母料YK-3、WK-11、WK—B及其复合物,用机械共混法制备了以PE、PP、PVC、ABS为基体的抗菌功能塑料。通过定性和定量的抗菌试验对各种抗菌塑料的抗菌活性进行了测定。结果表明,所制备的抗菌PE、PP、PVC、ABS对大肠杆菌和金黄色葡萄球菌均表现出强抗菌性,即抗菌率均达到或超过99％;在纤维级PP中只加1％的YK-3时,其抗菌率便超过99％;此外,抗菌功能塑料在加工过程中不会产生变色。所制备的抗菌塑料具有稳定而持久的抗菌活性特性。     

Structural characterization and antimicrobial activity of chitosan (CS‐40)/nisin complexes

A complex of chitosan (CS‐40) and nisin (CS‐40/nisin) was prepared and characterized with Fourier transform infrared spectroscopy and thermal analysis (thermogravimetry, differential thermogravimetry, and differential scanning calorimetry). The results show that the complex formed mainly by electrostatic interaction between the protonated amino group in CS‐40 backbone with the carboxylate ion of nisin. Minimum inhibitory concentrations (MICs) were evaluated against Gram‐positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Bacillus stearothermophilus), Gram‐negative bacteria (Escherichia coli, Salmonella enteritidis, and Proteus vulgaris), and fungi (Fusarium oxysporum). The results show that the CS‐40/nisin solution did inhibit or even more strongly inhibited the growth of all the tested microorganisms, whereas CS‐40 did not inhibit the growth of F. oxysporum and nisin did not inhibit the growth of Gram‐negative bacteria (E. coli, S. enteritidis, and P. vulgaris). The relative inhibition times of CS‐40/nisin solutions with different concentrations and ratios of CS‐40 and nisin were also investigated against the seven microorganisms. The results showed that CS‐40/nisin solutions with CS‐40/nisin concentration ratios of 0.05/0.005, 0.05/0.0025, 0.05/0.00125, and 0.025/0.0001% had higher antimicrobial activity against all tested bacteria and fungi. The relationship between complex formation and antimicrobial activity is discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Self-aggregation and antibacterial activity of N-acylated chitosan

Chitosan was selectively N-acylated with acetic, propionic and hexanoic anhydrides under homogeneous condition to prepare N-acetyl chitosan (NACS), N-propionyl chitosan (NPCS) and N-hexanoyl chitosan (NHCS), respectively. NACSs with different N-acetylation degrees were obtained by controlling the degree of N-acetylation. The chemical structures of N-acylated chitosans including degree of deacetylation (DD), weight-average molecular weight (M_w), radius of gyration (〈S₂〉_Z^1/2) and crystal structure were studied by FTIR, GPC-LLS and X-ray diffraction techniques. Aggregation behavior of N-acylated chitosan was investigated by rheometer. Intramolecular aggregation of NPCS and NACS was stronger with NPCS stronger than NACS. The effect of concentration of polymer, concentration of salt and temperature on self-aggregation of NACS and NPCS was investigated. Hydrophobic interaction of N-acylated chitosan substituted with longer acyl chains was stronger. With moderate DD, intramolecular aggregation occurs predominantly. In vitro antibacterial activity test of N-acylated chitosans was evaluated against two Gram-positive bacteria and two Gram-negative bacteria. Relative inhibition time (RIT) of NHCS with concentration of 1 mg/ml against Escherichia coli and Pseudomonas aeruginosa was more than 2-6 times longer than that of NACS and NPCS. N-acylated chitosan with lower DD had inhibitory effect on the growth of bacteria than that with moderate DD. The results showed that intermolecular aggregation characteristic of N-acetylated chitosans with low DD may help in forming bridge to interact with bacterial cell.