Effect of Chitosan Coating on the Properties of Poly(glycolic acid-lactic acid)Thread-Embedding Material

Poly( glycolic acid-lactic acid)( PGLA) threadembedding material was modified by chitosan coating which could improve the rigidity,hydrophilicity and moisture absorption of the material,and produced better stimulation effect. Thus,this kind of thread-embedding materials which can be buried into acupuncture points to produce a long-time stimulation is popular in the acupuncture and moxibustion therapies. The variation tendencies of diameter,weight, hydrophilicity, and flexibility of the samples under the change of chitosan coating concentration,coating time and coating times were studied respectively. The results showed that the hydrophilicity,weight,and rigidity after coating rose in a certain range with the increase of coating time,coating times and coating concentration. The coating time had little influence on the diameter of fiber.

In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

Kinetic of Adsorption of Urea Nitrogen onto Chitosan Coated Dialdehyde Cellulose under Catalysis of Immobilized Urease

The adsorption of urea nitrogen onto chitosan coated dialdehyde cellulose (CDAC) under catalysis of immobilized urease in gelatin membrane (IE) was studied in batch system. The pseudo first-order and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model.

Effect of Chitosan Coating on Properties of Polyactic Acid Thread-Embedding Material

Thread-embedding materials buried into acupuncture points to produce a long-time stimulation is a method which has been widely applied in the acupuncture and moxibustion therapies for diseases treating and they should have excellent properties of good biocompatibility,biodegradability and moderate rigidity.Polyactic acid(PLA) as the thread-embedding material had some shortcomings such as poor hydrophilicity and slowly biodegradable speed.In this paper,PLA thread-embedding material was modified by chitosan coating which could improve rigidity,hydrophilicity and moisture absorption and thus produce better stimulation effect.The variation tendency of diameter,mass,hydrophilicity,and initial modulus of the sample under the change of chitosan coating concentration,coating time and coating times were studied respectively.The results showed that the hydrophilicity,mass,and initial modulus after coating rose in a certain range when the coating time,coating times and coating concentration increased,while the changing of coating had little impact on fiber diameter.

Extending Shelf Life of Chilled Pork by Combination of Chitosan Coating With Spice Extracts

The effects of spices（cinnamon,rosemary,clove）extracts and chitosan on microbiological growth,drip loss,color,and lipid oxidation of fresh chilled meat stored for 28 days at 4℃were investigated.There were four treatments：control,coated with spices（cinnamon 1.5 g·L^-1＋rosemary 1.5 g·L^-1＋clove 1.0 g·L^-1）,coated with 0.5%chitosan,coated with spices and chitosan.Chitosan coating resulted in significant inhibition of microbial growth（P〈0.05）,while the lowest microbial counts were obtained in the samples containing both chitosan and spices,indicating a possible synergistic effect.Chitosan and its combinations with spices also showed the most intense antioxidative effect when compared to the controls（P〈0.05）.Meanwhile,chitosan coating could decrease water loss and keep better color of chilled meat.The combined spice extracts and chitosan coating could effectively extend the shelf life of chilled meat.

Application of a chitosan coating as a carrier for natamycin to maintain the storage quality of ground cherry(Physalis pubescens L.)

Ground cherry(Physalis pubescens L.) is a kind of berry fruit favored by consumers in China; however, this fruit is particularly vulnerable to physiological senescence and pathogen attack during the traditional cold storage period. In order to maintain storage quality, a 1.5%(w/w) chitosan(CS) water solution containing 50 mg/L of natamycin(NA) was introduced. After all treatments were completed, the fruit was stored at 0°C and sampled every 10 d. At each sampling date, the following tests were performed: mold and yeast analyses; enzyme activity and content analyses which included superoxide dismutase(SOD), ascorbate peroxidase(APX), and malondialdehyde(MDA); and color analysis. In addition, a sensory evaluation was carried out for quality assessment at the end of the storage period. The results showed that the application of a chitosan coating combined with natamycin(CSNA) enhanced the activity of superoxide dismutase(SOD) and ascorbate peroxidase(APX), reduced the physiological rate of senescence, and inhibited pathogen attack. Thus, CSNA treatment can maintain ground cherries at an acceptable level of storage quality for 50 d.

Development and assessment of a multifunctional chitosan-based coating applied on AZ31 magnesium alloy: Corrosion resistance and antibacterial performance against Klebsiella Pneumoniae

This work presents a simple method to functionalise the surface of AZ31 magnesium alloy by applying a duplex MgF_(2)/chitosan coating,which improves its corrosion resistance and provides it with some antibacterial performance.First,the effect of three chitosan solutions with different concentrations on the growth of the bacteria Klebsiella pneumoniae in nutritive medium(TSB)was evaluated by absorbance kinetics experiments,where the chitosan solution at 2%(m/V)was selected for the coating preparation.Before coating application,the AZ31 substrate was pretreated with hydrofluoric acid for 48 hours in order to form a MgF_(2)conversion layer.Subsequently,the coating was applied to the pretreated substrate through the dry-casting method.Samples of the alloy in each surface condition(bare,pretreated,and pretreated+coated with chitosan)were exposed to simulated body fluid(SBF)for 21 days at 37°C,with the solution renewed every 24 hours and the wastes stored.The surfaces were characterised by SEM-EDS,and XPS after the immersion tests,whereas the stored solutions were employed to measure the change in the Mg-ions concentration.Electrochemical impedance spectroscopy and potentiodynamic polarisation were performed in each surface condition to compare their corrosion resistance in SBF.The antibacterial activity of the functionalised surfaces was evaluated by the plate counting method and compared with bare samples.All results were correlated and demonstrate that the modified surface of AZ31 achieved a higher corrosion resistance when it was exposed to SBF,as well as a reduction of the bacterial growth during in vitro tests.

Electrochemical Generation of Zn-Chitosan Composite Coating on Mild Steel and its Corrosion Studies

A Zinc-Chitosan composite coating was generated on mild steel from zinc sulphate-sodium chloride electrolyte by electrodeposition. The electrolyte constituents were optimized for good composite coating. The corrosion resistance behavior of the composite was examined by weight loss, polarization and impedance methods using 3.5 wt% NaCl neutral solution as medium. Separate polarization profiles were recorded for composite coating and compared with zinc coated sample. SEM images of coatings were recorded for the pure and composite coating.

Development of temperature indicator prototype: Cardpaper coated with chitosan intelligent films

An intelligent and biodegradable material pack- aging was developed based on a natural and thermal-sensitive pigment. Anthocyanin (ATH, 0.50 g/100g) was incorporated into chitosan matrix films (2 g/100g) forming a chitosan intelligent film (C-ATH). The system is able to indicate the variation of temperature during distribution and storage chain of industrial products. The novelty of this work was an alternative packaging material that it is biodegradable and could inform any temperature variations on the range of 40?C - 70?C, by irreversible visual colour changes. The effects of temperature (10?C, 30?C and 50?C) and luminosity (0, 500 and 1000 l×) were analyzed on C-ATH using an experimental design of 2 variables, measuring the colour parameters (L*, a*, b*) and mechanical properties (tensile strength, elongation break and Young’s modulus) as responses. C-ATH suspensions were applied as a coating on cardpaper surface forming a temperature indicator prototype (TIP). C-ATH darkened after being exposed to temper- atures above 50?C and luminosity of 1000 lx for 72 hours. TIP was obtained, without bubbles or defects, with reduced water absorption capacity. Irreversible visual colour change was verified on TIP exposed at 40?C independently of luminosity, turned gradually yellow. Chitosan suspensions containing ATH and applied as a coated on card paper sheets could be an alternative of biode-gradable material for packaging system that indicates efficiently temperature changes. This indicator system has potential application temperature range of 40?C to 70?C, such as food, pharmaceuticals, biological, agricultural and others products, that are highly dependent of storage temperature conditions.

Pharmacokinetic Evaluation of Chitosan-Succinyl-Prednisolone Conjugate Microparticles as a Colonic Delivery System: Comparison with Enteric-Coated Conjugate Microparticles

In the previous study, chitosan-succinyl-prednisolone conjugate microparticles (MP) were found to exhibit good efficacy and reduced toxicity nearly as well as their Eudragit L-coated microparticles (MP/EuL). This proposes a question whether enteric-coating of MP is necessary or not. Although MP/EuL were already examined for their pharmacokinetic and gastrointestinal behaviors, MP have not been done yet. Therefore, in this study, MP were evaluated by investigating pharmacokinetic features in detail. MP with the in vitro features equivalent to those of the previous conjugate microparticles could be produced more readily in the modified preparative method. Pharmacokinetic and gastrointestinal behaviors of MP were investigated by intragastric dosing (5 mg PD eq./kg) to rats with 2,4,6-trinitrobenzenesulfonic acid-induced ulcerative colitis. The plasma concentration was suppressed extensively in MP as well as MP/EuL, supporting the reduction of PD systemic toxic side effects. However, the plasma level increased gradually up to 7 h in MP, but not in MP/EuL. At 8 h after dosing, MP were detected in the stomach to a fair extent, and free PD was found there, indicating that MP were subjected to trapping in the stomach probably due to positive charge of chitosan molecules. For MP, such prolonged localization and slow release of PD in the stomach were probably associated with the gradual increase in plasma concentration. Therefore, MP/EuL were evaluated to be superior to MP for effective targeting to ulcerative colitis. It is concluded that enteric-coating is very important for the targeting system using MP.

Preparation of gastro-resistant pellets containing chitosan microspheres for improvement of oral didanosine bioavailability

The purpose of this work was to introduce a new concept of coated pellets containing chitosan microspheres loaded with didadosine for oral administration,aiming at reducing the frequency of administration and improving the bioavailability by a suitable release profile.Chitosan microspheres were produced under fiuidized bed,followed by extrusion and spheronization to obtain pellets with a mean diameter of about 1 mm.The pellets were then coated with Kollidon VA64 and Kollicoat MAE100P in water dispersion to depict a sustained release profile.Conventional hard gelatine capsules were loaded with these pellets and tested in vitro for their release profile of didadosine.Dissolution testing confirmed that chitosan microsphere pellets provides appropriate sustained release up to 2 h behavior for didanosine.

Biomimetic Mineralizated and Nano-Ag Loadedgraphene Oxide/Chitosan Hybrid Scaffold for Osteoinduction and Antibacterium

Graphene oxide (GO) is a graphene derivatives that has oxygen-containing functional groups on the graphene basal plane, such as hydroxyl, carbonyl, epoxy and carboxyl groups. GO is considered as a promising material for biological applications owing to its excellent surface functionalizability, high specific suface area and good biocompatibility. In this study, GO/chitosan hybrid scaffolds were prepared for tissue engineering. Nano silver was loaded into the scaffold to improve its antibacterial ability and biomimetic Ca-P coatings were deposited on the scaffold surface to enhance its osteoconductivity. First, GO was prepared by the chemical oxidization of graphite. Secondly, nano-Ag loaded GO was prepared by chemical reducing Ag ions in GO solutions. Then, nano-Ag loaded GO solution was mixed with CS solution to form GO-CS gel. Chitosan (CS) and GO were crosslinked by electrostatic interactions between oxygen-containing functional groups of GO and NH2 groups of CS. The gel were freeze dried to produce nano-Ag loaded GO/CS hybrid porous scaffolds. Finally, the as-prepared scaffolds were immersed the into a supersaturated calcium phosphate solution (SCPS) for 7 days to deposite CaP coatings on the surface of the micropores. SEM images showed that nano-Ag uniformly distributed in the scaffold and the CaP covered most of the scaffold surfaces. In vitro cell culture and antimicrobial test indicated the biomimetic mineralized Ag-CS-GO scaffolds have good osteoconductivity and bactericidal ability.

壳聚糖和植物乳杆菌CM-3复合涂膜剂在草莓保鲜中的应用研究

为了开发适合草莓采后果实的新型涂膜保鲜技术,探究壳聚糖溶液与不同菌体浓度的植物乳杆菌CM-3(0、0.5、1、2 g/100 mL)复合涂膜对室温贮藏草莓(20±1)℃的保鲜效果。结果表明:相比于未涂膜的空白处理和壳聚糖单一涂膜,壳聚糖和0.5 g/100 mL乳酸菌菌体复合涂膜的保鲜效果最佳。经8 d贮藏后,与对照相比,草莓腐烂率和失重率分别减少了20%和0.74%;硬度、可溶性固形物含量、可滴定酸含量和Vc含量分别提高了56.85%、15.19%、5.33%和10.36%。壳聚糖和一定浓度的乳酸菌菌体复合涂膜可以显著抑制草莓的腐败变质,有效地延缓果实品质和营养价值的损失。

壳聚糖-水飞蓟素复合保鲜涂膜的制备及其在猪肉保鲜中的应用

为天然复合保鲜涂膜的进一步开发和应用,该文以壳聚糖为成膜基质,以水飞蓟素为主要抑菌剂并以基于壳聚糖质量的0%、2%、4%、6%、8%的添加量制备壳聚糖-水飞蓟素复合保鲜涂膜。通过测定复合保鲜涂膜的DPPH自由基清除率、zeta电位以及流变特性来探究不同水飞蓟素添加量对保鲜涂膜性能表征的影响,同时测定猪肉不同冷藏期间的pH、汁液流失率,挥发性盐基氮(total volatile basic nitrogen,TVB-N)、硫代巴比妥酸(thiobarbituric acid reactive substances,TBARS)、菌落总数以及感官评价来探究不同水飞蓟素添加量对猪肉冷藏保鲜效果的影响。结果表明,随着水飞蓟素添加量的增加,各组保鲜涂膜抗氧化活性显著增加,且zeta电位均大于30 mV,表现出典型的非牛顿剪切变稀流体行为,具有较好的稳定性。其中8%水飞蓟素添加量的保鲜涂膜对猪肉的冷藏保鲜效果的提升最佳,冷藏12 d后,与对照组相比,2%、4%、6%、8%水飞蓟素添加量的保鲜涂膜使猪肉的pH分别降低15.92%、19.39%、21.56%、23.30%,汁液流失率减少19.58%、22.76%、31.33%、39.16%,TBARS降低25.97%,39.75%、58.35%、64.90%,TVB-N降低23.50%、30.56%、47.71%、52.35%。由此可见,壳聚糖-水飞蓟素复合保鲜涂膜可延缓冷藏猪肉品质的劣变,可作为一种优良的可食性涂膜应用于食品保鲜。

壳聚糖与芫荽精油复合涂膜在草莓常温贮藏中的应用

该研究以芫荽精油与1%的壳聚糖复合制备不同浓度的保鲜液,对新鲜且品质优良的草莓进行浸泡涂膜保鲜,以超纯水为对照组,通过测定贮藏期间草莓的感官品质以及各理化指标,探究该复合保鲜液对草莓常温贮藏效果的影响。结果表明,与纯水组相比芫荽精油与壳聚糖复合涂膜有利于草莓保鲜,且精油浓度越高保鲜效果也越好。在贮藏第8天时,芫荽精油浓度为0.18%的保鲜组草莓腐烂率低于30%,失重率、丙二醛含量分别比对照组低62.5%和39.7%,VC含量与可滴定酸含量分别是对照组的1.9、2.1倍,差异显著,表明较高浓度的芫荽精油涂膜有助于草莓保持良好的感官品质和营养价值。

西兰花采后霉变控制技术研究

西兰花花球采后贮运过程中易出现真菌霉变现象,严重影响其商品品质。为降低贮运过程中西兰花真菌霉变发生情况,本研究采用不同温度、乙醇浓度、壳聚糖涂膜浓度等对西兰花进行处理。单因素试验结果表明,45℃热激处理效果最佳,3 d病斑面积为6%;最适的乙醇处理浓度为30%,处理3 d后病斑面积仅为3.4%;壳聚糖涂膜浓度1.5%和2%均有很好的抑菌效果,3 d后病斑面积分别为7.3%和4.5%,且无显著差异,综合考虑采用1.5%的壳聚糖浓度处理最为适宜。45℃热激+1.5%壳聚糖和30%乙醇+45℃热激处理西兰花的霉变病害控制效果表明,两个组合处理均能有效控制病害发生;30%乙醇+45℃热激处理组,能降低乙醇残留,更加绿色安全,且保绿抗霉变效果更好。

复配天然保鲜剂对鸭肉保鲜效果的影响

为提高鸭肉产品的质量和延长保鲜期,满足人们对美味和安全食品的需求,选取壳聚糖、茶多酚、溶菌酶和乳酸链球菌素4种保鲜剂对鸭肉进行涂膜处理,采用单因素试验和响应面分析法,对4种保鲜剂的复配添加量进行优化。结果表明:添加1.12 g/100 mL壳聚糖、0.55 g/100 mL茶多酚、0.19 g/100 mL溶菌酶和0.69 g/100 mL乳酸链球菌素条件下,4℃冷藏鸭肉保鲜期为12 d,菌落总数为5.810(lg(CFU/g)),低于国家标准,保鲜期比对照组延长7 d。

壳聚糖基涂膜技术在草莓贮藏保鲜中的应用

草莓作为一种高营养、高价值的水果,其易腐性一直是贮藏和运输过程中的主要挑战。为了延长草莓的保鲜期,减少因贮藏不当造成的损耗,壳聚糖基涂膜技术作为一种天然、安全、环保的保鲜方法,逐渐受到广泛关注。本文通过研究壳聚糖基涂膜技术在草莓贮藏保鲜中的最新研究进展,详细探讨壳聚糖基涂膜技术的保鲜机制、配方优化途径及壳聚糖基涂膜技术类型,以期为草莓保鲜技术的发展提供参考。

壳聚糖荧光防伪印花涂料的制备及其应用性能

为解决纺织品印染中常用有机荧光防伪印花涂料发光强度低、耐光漂白性弱等问题,以壳聚糖(CS)为生物基高分子涂料代表,采用不同物质的量的聚集诱导发光(AIE)分子四苯基乙烯(TPE)对CS进行荧光标记,制备出一系列具有不同标记率的TPE-CS荧光涂料。测定了TPE-CS防伪涂料的荧光强度、耐光漂白性、热稳定性等,并对棉织物进行防伪印花。结果表明:与目前较常用的聚集诱导荧光猝灭(ACQ)分子标记CS荧光涂料相比,TPE-CS显示出优异的荧光发射性能和耐光漂白性能;当TPE-CS的标记率仅为1.43%(摩尔分数)时,该防伪涂料溶液(1 000 mg/L)的相对荧光强度超过1 090;溶液在强紫外光下曝露1 h后,相对荧光强度仍能达到光漂白前的94.9%。

壳聚糖/明胶/植酸复合阻燃涂料的制备及性能

【目的】为提高木材的阻燃性能,扩展生物基阻燃材料在木材中的应用,制备壳聚糖/明胶/植酸全生物基可膨胀复合阻燃涂料,并且探索其在木材上的应用性能。【方法】以壳聚糖和明胶为成膜物质,水为溶剂,按照壳聚糖、明胶和植酸质量比3∶2∶(0~1.5)制备可膨胀复合阻燃涂料;将其涂覆于木材表面后制备木材的阻燃涂层(CGPx)。利用扫描电子显微镜和傅里叶变换红外光谱观察涂层的形貌结构以及元素分布;使用铅笔硬度仪和附着力检测评估涂层的硬度以及附着力;采用热重测试、可燃耐火测试和锥形量热测试综合评估处理材的热稳定性和阻燃性能;最后采用扫描电子显微镜和傅里叶变换红外光谱分析残炭的形貌结构和元素分布,并分析阻燃机理。【结果】CGPx在木材上表现出优良的附着力和硬度,其中CGP1.5组附着力等级达到1级,铅笔硬度达到7H。CGPx木材表现出优良的热稳定性,其中CGP1.5组残炭率达到44.2%。在可燃耐火测试中,CGPx木材表现出优异的耐火性能。在锥形量热测试中,CGP1.5组热释放速率峰值下降了34.3%,速率峰值出现时间推迟至284 s,总热释放量下降了15.5%,CO和CO_(2)释放速率也有所降低,同时火灾指数为0.189,火焰增长指数为0.708。木材的阻燃性能得到增强。【结论】使用全生物基阻燃涂料涂覆木材的处理方法,有效提高了木材的热稳定性与阻燃性能,丰富了绿色可持续的木材阻燃体系。