Chitosan/Sodium Alginate Multilayer pH-Sensitive Films Based on Layer-by-Layer Self-Assembly for Intelligent Packaging

The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.

Smart Colorimetric Corn Starch Films Combined with Anthocyanin-Loaded Glutenin-Carboxymethyl Chitosan Nanocomplexes for Freshness Monitoring of Chilled Pork

In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch matrix and used in the freshness monitoring of chilled pork.The effects of anthocyanin-loaded nanocomplexes on the physical,structural,and functional characteristics of the films were investigated.The addition of anthocyanin-loaded nanocomplexes increased the tensile strength,elongation at break,hydrophobicity,and light transmittance of the films while decreasing their water vapor permeability.This is because new hydrogen bonds are formed between the film components,resulting in a more homogeneous and dense structure.The colorimetric film has a significant color response to pH changes.These films were used in experiments on the freshness of chilled pork,in which the pH changes with changing freshness states.The results show that the colorimetric film can monitor changes in the freshness of chilled pork in real time,where orange,pink,and green represent the fresh,secondary fresh,and putrefied states of pork,respectively.Therefore,the intelligent colorimetric film developed in this study has good application potential in the food industry.

Preparation and Characterization of Chitosan/Carboxymethylated Konjac Glucomannan Blend Films

In order to improve the mechanical and water swelling properties of the chitosan (CS) film, a series of transparent films were prepared by blending 2%(weight) chitosan acetic acid solution with 1.5%(weight) carboxymethylated konjac glucomannan (CMKGM) aqueous solution according to predetermined ratio and drying at 30°C. The morphological structure, miscibility, thermal stability, mechanical properies, and swelling capacity of the blend films were studied by infrared (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron micrograph (SEM), and measurements of the mechanical properties and swelling properties. The results demonstrated that there was strong interaction and good miscibility between CS and CMKGM resulted from intermolecular hydrogen bonding and electrostatic force. The mechanical properties in dry state and wet state, thermostability, and water swelling properties of the blend films were obviously improved. The best values of the tensile strength in the dry and wet state achieved 89 MPa and 49 MPa, respectively, when the CMKGM content was 30%(weight). The CS/ CMKGM blend films provided promising biomedical applications.

Electrochemical study and application on rutin at chitosan/graphene films modified glassy carbon electrode

Graphene（G） was dispersed into 0.5% chitosan（Chit） solution,then the composite films were coated on glassy carbon electrode（GCE）,the electrochemical behavior of rutin on a Chit/G modified GCE was investigated and the electrochemical parameters of rutin were calculated.Rutin effectively accumulated on the Chit/G/GCE and caused a pair of redox peaks at around 408 mV and 482 mV（vs.SCE） in 0.1M phosphate buffer solution（pH 4.0）.Under optimized conditions,the anodic peak current was linear to the rutin concentration in the range of 5×107-1.04×105M.The regression equation was：y 9.9219x-0.0025,r=0.9958.The proposed method was successfully used for the determination of rutin content in tablet samples with satisfactory results.

Mechanical Properties of Collagen Biomimetic Films Formed in the Presence of Calcium,Silica and Chitosan

Using eucollagen solutions from ox hide, we cast collagen films to assess the influence of calcium and silica on the reconstitution of the fibrous structure of collagen. The tensile strength and the breaking elongation of the reconstituted collagen films were measured and analysed. Significant differences were observed between reconstituted collagen films with and without calcium and silica. The breaking elongation of the films obtained in the presence of silica was significantly greater, and the degradation was lower than other films of reconstituted collagen. Collagen and chitosan do not exist together as blends in nature, but the specific properties of each may be used to produce in biomimetic way man-made blends with biomedical applications, that confer unique structural, mechanical （detail） and in vivo properties.

Investigation of Chitosan-PVA Composite Films and Their Adsorption Properties

Viscous aqueous solutions of chitosan and polyvinyl alcohol (PVA) were blended to enhance miscibility and avoid polymer phase separation. The mixtures were drop-casted and air dried to yield composite film materials that were characterized by equilibrium water uptake, physical stability in aqueous solution, and thermal stability. Chitosan/PVA blends have greater thermal stability, unique morphology, and reduced solubility in acidic solution, thus extending the useful pH range for chitosan as a sorbent material. The uptake properties of the films was investigated using methylene blue (MB) and a p-nitrophenol (PNP) dyes, where it was found that each single component polymer has greater uptake toward MB than PNP. A direct relationship between film composition (chitosan:PVA) with solution pH and the uptake of MB was observed. The results are in agreement with electrostatic interactions and contributions due to the hydrophobic effect for such composite materials.

Moisture Sorption Isotherms of Soy Protein IsolatelCarboxymethyl Chitosan Blend Films

Soy protein isolate/carboxymethyl chitosan （SPI/CMCH） blended films incorporated with glycerol were prepared using solution casting to investigate the effects of the SPI and CMCH ratios （100：0, 88：12, 67：33, 50：50, 33：67, 12：88, 0：100） on the water sorption isotherm. The moisture sorption isotherm of the SPI/CMCH blended films was determined using various relative humidity＇s （16%, 35%, 55% and 76% RH） at 25 ± 1℃. The isotherms showed that the equilibrium moisture content （EMC） of the films increased with increasing CMCH content and the EMC value sharply increased above aw = 0.55. Understanding of sorption isotherms is important for prediction of moisture sorption properties of films via moisture sorption empirical models. The Guggenheim-Oswin, Brunauer-Emmett-Teller （BET）, and Anderson-de Boer （GAB） sorption model predictions were tested against the experimental data. The root mean square （RMS） values from the Oswin, BET, and GAB models respectively ranged from 698.54 to 1,557.54, 38.85 to 58.30, and 52.52 to 95.95. Therefore, the BET model was found to be the best-fit model for SPI/CMCH blended films at 25 ± 1 ℃.

Physical Properties of Chitosan Films Obtained after Neutralization of Polycation by Slow Drip Method

The development of new materials from biodegradable constituents is enticing for applications in bioelectronics and biomedicine, due to their considerable durability, versatility and biodegrada-bility. The present work aims to determine the chemical and physical properties of chitosan membranes after neutralization of the polycation solution. This work was divided into two stages: solubilization and neutralization. In the first stage, the chitosan was solubilized with three different concentrations of acetic acid (1%, 0.8% and 0.5%) in order to evaluate whether the acid affected the physical-chemical properties of the films. In the second stage, the chitosan polycation was neutralized with two strong bases (NaOH and KOH) using three different molar concentrations, by the slow drip method for obtaining films with pH values close to neutrality. The characterization of the membranes obtained from casting method showed that the different concentrations of acetic acid did not affect the physical-chemical properties of the films. In contrast, the neutralization process did affect their properties, and in particular, different behaviors were observed depending on the type of base used for neutralization. More ductile and plasticity were obtained in the films when the polycation was neutralized with KOH, whereas the films neutralized with NaOH exhibited a more fragile behavior.

Applicative Study(Part I):The Excellent Conditions to Remove in Batch Direct Textile Dyes(Direct Red,Direct Blue and Direct Yellow)from Aqueous Solutions by Adsorption Processes on Low-Cost Chitosan Films under Different Conditions

In recent years the development of chitosan (CH) based materials as useful adsorbent polymeric matrices is an expanding field in the area of adsorption science. Even though CH has been successfully used for dye removal from aqueous solutions due to its low cost, no considerations have been made about, for example, the effect of changing the pH of chitosan hydrogelor about the dehydrating effect of Ethanol (EtOH) treatment of chitosan film on the dyes removal from water. Consequently in our laboratory we carried out a study focusing the attention, mainly, on the potential use of CH films under different conditions, such as reducing the intrinsic pH, increasing the hydrophobic character by means of ethanol treatment and neutralization of CH films to improve their absorption power. Textile anionic dyes named Direct Red 83:1, Direct Yellow 86 and Direct Blue 78 have been studied with the aim of reducing the contact time of CH film in waste water improving the bleaching efficiency. Neutralized acid CH film and longtime dehydrated one result to be the better films in dye removal from water. Also the reduction of the CH solution acidity during the film preparation determines the decreasing of the contact time improving the results. The effect of initial dye concentration has been examined and the amount of dye adsorption in function of time t, qt (mg/cm2), for each analyzed film has been evaluated comparing the long term effect with the decoloration rate. A linear form of pseudo-first-order Lagergren model has been used and described. The best condition for removing all examined dyes from various dye solutions appears to be the dehydration of a novel projected CH film obtained by means of the film immersion in EtOH for 4 days. Also CH films prepared by well-known literature procedure and neutralized with NaOH treatment appear having an excellent behavior, however the film treatment requires a large quantity of water and time.

Anastomotic stoma coated with chitosan film as a betamethasone dipropionate carrier for peripheral nerve regeneration

Scar hyperplasia at the suture site is an important reason for hindering the repair effect of peripheral nerve injury anastomosis. To address this issue, two repair methods are often used. Biological agents are used to block nerve sutures and the surrounding tissue to achieve phys- ical anti-adhesion effects. Another agent is glucocorticosteroid, which can prevent scar growth by inhibiting inflammation. However, the overall effect of promoting regeneration of the injured nerve is not satisfactory. In this regard, we envision that these two methods can be combined and lead to shared understanding for achieving improved nerve repair. In this study, the right tibial nerve was transected 1 cm above the knee to establish a rat tibial nerve injury model. The incision was directly sutured after nerve transection. The anastomotic stoma was coated with 0.5 × 0.5 cm^2 chitosan sheets with betamethasone dipropionate. At 12 weeks after injury, compared with the con- trol and poly （D, L-lactic acid） groups, chitosan-betamethasone dipropionate film slowly degraded with the shape of the membrane still intact. Further, scar hyperplasia and the degree of adhesion at anastomotic stoma were obviously reduced, while the regenerated nerve fiber structure was complete and arranged in a good order in model rats. Electrophysiological study showed enhanced compound muscle action potential. Our results confirm that chitosan-betamethasone dipropionate film can effectively prevent local scar hyperplasia after tibial nerve repair and promote nerve regeneration.

A Novel Biomolecular Immobilization Matrix Based on Nanoporous ZnO/Chitosan Composite Film for Amperometric Hydrogen Peroxide Biosensor

A novel ZnO/Chitosan composite matrix was developed to fabricate the H2O2 biosensor. This material combined the advantages of inorganic species, ZnO, and organic polymer, chitosan. Horseradish peroxidase immobilized in the material maintained its activity well as the usage of glutaraldehyde was avoided. The activity of enzyme was 7.9 times greater than the cross-linked enzyme. The parameters affecting the fabrication and experimental conditions of biosensors were optimized. With the aid of hydroquinone mediator, the biosensor had a fast response of less than 10 s. The linear range was 5.0×10-6 to 2.0× 10-3 mol/L with a sensitivity of 43.8 μA L/mmol. This matrix can also be used to immobilize other biomolecule.

Preparation and Charactcrization of a Novel PDLLA/Chondroitin Sulfate/Chitosan Asymmetry Film

A novel bioactive and bioresorbable asymmetry film was prepared. The PDLLA membrane was activated by 1, 6-hexanediamine to obtain a stable positive charge surface. Chondroitin sulfate and chitosan were then deposited on activated PDLLA membrane via layer-by-layer （LBL） electro-static assembly （ESA） technique. The deposition process was monitored by UV-Vis absorbance spectroscopy. The composite membrane was frozen lyophilized to form the asymmetry film and characterized by attenuated total reflectic （ATR）-FT-IR, XPS and SEM. The experimental results show that a stable 1, 6-hexanediamine layer on PDLLA substrate based on the aminolysis of the polyester and the layer thickness increase linearly first with the increase of the deposited layers, and then increases slowly due to the layer interpenetration. The test results of ATR-FT- IR and SEM show the asymmetry film is modified uniformly with a dense inner layer and a porous sponge outer tayer.

Preparation of Fe_(3)O_(4) Film by in-situ Oxidative Hydrolysis on Chitosan

The Fe3O4 films were prepared by in-situ oxidative hydrolysis on chitosan. The structures and characteristics of the prepared Fe3O4 films were investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, atom force microscopy （AFM）, vibrating sample magnetometry （VSM） and thermogravimetric-differentia thermal analysis （TG-DTA）. The results show that, （1） the as-synthesized Fe3O4 films are pure Fe3O4 with cubic inverse spinel structure; （2） the network structured film can be obtained at lower temperature, and the compact particle film at higher temperature; （3） the prepared Fe3O4 films are super-paramagnetic, and the saturation magnetization is improved with increasing the reaction temperature, which is 49.03 emu/g at 80℃; （4） the temperature of phase transformation from Fe3O4 to a-Fe2O3 is about 495℃. Besides, the formation mechanism of Fe3O4 film was also proposed.

Influence of Glutaraldehyde on the Properties and Release Kinetic of α-Tocopherol from Chitosan-based Film

A crosslinked chitosan film with α-tocopherol was produced by a solution casting method. The appearance, mechanical properties, morphology, barrier properties and release kinetics of the α-tocopherol were evaluated. The addition of glutaraldehyde and α-tocopherol decreased the lightness and greenness and increased the yellowness of the chitosan-based film. Moreover, it also affected the compatibility of the film due to a decrease in the opacity values. The elongation at break(EB) and tensile strength(TS) values of the film decreased when the glutaraldehyde and α-tocopherol were added. In contrast, the Young’s modulus(YM) values increased. SEM micrographs showed coarse spots and pores on the surface and cross-section of the film when compared with the chitosan film. Based on the results, it was indicated that the chitosan structure was disconnected by the α-tocopherol, and the glutaraldehyde as a crosslinking agent generated a link between the chitosan network, which could be the cause of the reduced flexibility and the increased surface roughness of the film. However, the glutaraldehyde and α-tocopherol did not result in a significant difference in water vapour permeability(WVP) values. The glutaraldehyde influenced the release kinetics of the α-tocopherol as seen by the decrease of the diffusion coefficient values that were calculated using the Fickian diffusion model.

A study of chitosan blend film as a carrier of corneal endothelial cells

In order to evaluate the cytocompatibility and biocompatibility of a new kind of chitosan blend film as a carrier of corneal endothelial cell, rabbit corneal endothelial cells cultured in vitro were breeded onto the film. After a cell monolayer formed, the scanning electron micrography was performed. After inplanted into anterior chamber, slit lamp observation, thickness metering, specular microscopy and HE staining were performed at random time after operation to evaluate the biocompatibility. Inflmmnation in anterior, thickness of cornea, cell density, hexagonality and cell size of the surgical cornea were taken as the indexes of biocompatibility. The cultured cells exhibited a confluent monolayer 10 days after incubation, which proved the satisfactory cytocompatibility of this film. Biocompatibility assay results suggested the implantation feasibility of the film as a carder of corneal endothelial cells.

Adsorption of Toluene on Film Membranes of Chitosan/Nа-CMC

The sorption properties of films on bases of chitosan and sodium carboxyl methylcellulose (Na-CMC) with toluene have been checked. The sorption rate, sorption thermodynamics and isothermal properties of toluene molecules in chitosan/Na-CMC films are analyzed by adsorption-calorimetric method. Thus, it was found that toluene is adsorbed on the chitosan/Na-CMC film by the same patterns of sorption of aromatic compounds, due to the process of penetration of toluene molecules into the network of chitosan macromolecules and this is preceded by the absorption process by the surface of the chitosan/Na-CMC film.

壳聚糖抗菌成膜喷剂在鼻咽癌患者PICC所致接触性皮炎治疗中的应用效果

目的探讨壳聚糖抗菌成膜喷剂在鼻咽癌患者经外周静脉置入中心静脉导管(PICC)置管部位接触性皮炎治疗中的应用效果。方法选取2020-05至2022-04联勤保障部队第909医院因置入PICC所致接触性皮炎的94例鼻咽癌患者为研究对象,其中2020-05至2021-04的46例患者为对照组,2021-05至2022-04的48例患者为观察组。对照组采用地塞米松注射液外涂联合3M透明敷料行PICC换药,观察组采用喷涂壳聚糖抗菌成膜喷剂联合3M透明敷料行PICC换药。对比观察两组患者临床疗效、并发症的发生率、愈合时间、换药次数、患者的自付费用及满意度情况。结果观察组治疗第1周、第2周总有效率(95.83%,100%)均显著高于对照组治疗总有效率(73.91%,89.13%)(P<0.05),观察组愈合时间[(10.43±0.52)d]、换药次数[(3.30±0.69)次]显著短于或少于对照组愈合时间[(18.15±0.33)d]、换药次数[(5.67±0.96)次](P<0.05),观察组患者满意度得分(8.71±0.82)显著高于对照组患者满意度得分(5.67±0.96)(P<0.05),两组患者在导管移位率、脱管率及患者自付费用三方面无明显区别,差异无统计学意义(P>0.05)。结论壳聚糖抗菌成膜喷剂治疗鼻咽癌同步放化疗患者PICC置管部位接触性皮炎效果明显,可减少换药次数,减轻护理工作量,降低局部感染率,提高患者满意度。

新型果蔬可食用复合保鲜膜的制备及其保鲜性能研究

为延长室温下果蔬贮藏期,以草莓为研究对象,壳聚糖、羟乙基纤维素、山茱萸油和CaCl_(2)为膜制剂材料,失重率、可溶性固形物含量和丙二醛含量为评价指标,采用单因素试验和四因素三水平的正交试验,考察复合涂膜对草莓保鲜效果的影响。试验结果表明,1.50%壳聚糖、0.75%羟乙基纤维素、1.20%山茱萸油和1.20%CaCl_(2)制备的复合保鲜膜对草莓的保鲜效果较好,能有效减少果实失重率和可溶性固形物含量损失,有效抑制丙二醛含量的生成和积累。

壳聚糖生物降解薄膜在食品保鲜包装中的应用进展

壳聚糖是天然高分子材料,其来源广,可再生,生物降解性和生物相容性良好,同时也具有优良的成膜性能、抗菌性能和抗氧化性能,在食品保鲜包装领域展现出巨大的应用前景。本文综述了壳聚糖生物降解薄膜的制备方法、改性方法和其在食品保鲜包装中的应用进展,并对壳聚糖生物降解薄膜的未来发展方向进行了展望。今后对壳聚糖食品包装材料的研究,应侧重于降低材料成本,提升材料的安全性;还应加强对新型壳聚糖复合材料的研究,以拓展其应用范围;此外,还应深入研究壳聚糖的保鲜机理和作用方式,从而提升其保鲜效果和适用性。

花青素-壳聚糖基新鲜度指示膜的研究进展

消费者食品安全意识的提高为包装技术带来了新机遇,基于天然色素和生物聚合物的智能包装作为食品包装的最新技术被引入。这类包装可以将食品的状态在包装膜上显示出来,依据膜的颜色变化实时评估食品的新鲜度。近年来,花青素作为指示剂被广泛应用于智能包装膜,其中以壳聚糖为基质的指示膜用于食品的新鲜度监测较多。该文阐述了新鲜度指示膜的组成及监测原理,重点介绍了花青素-壳聚糖基指示膜的物理特性和功能特性及其在食品新鲜度监测中的研究进展,并指出新鲜度指示膜在应用过程中存在的问题,为进一步开发实用且准确的新鲜度指示膜提供一些思路。