Preparation,Bioactivities and Applications in Food Industry of Chitosan-Based Maillard Products: A Review

Chitosan, a biopolymer possessing numerous interesting bioactivities and excellent technological properties, has received great attention from scientists in different fields including the food industry, pharmacy, medicine, and environmental fields. A series of recent studies have reported exciting results about improvement of the properties of chitosan using the Maillard reaction. However, there is a lack of a systemic review about the preparation, bioactivities and applications in food industry of chitosan-based Maillard reaction products (CMRPs). The presence of free amino groups in chitosan allows it to acquire some stronger or new functional properties via the Maillard reaction. The present review aims to focus on the current research status of synthesis, optimization and structural identification of CMRPs. The applications of CMRPs in the food industry are also discussed according to their biological and technological properties such as antioxidant, antimicrobial activities and inducing conformational changes of allergens in food. Some promising directions for future research are proposed in this review, aiming to provide theoretical guidance for the further development of chitosan and its derivatives.     

Investigation of Parameters Influencing Tubular-Shaped Chitosan-Hydroxyapatite Layer Electrodeposition

Tubular-shaped layer electrodeposition from chitosan-hydroxyapatite colloidal solutions has found application in the field of regeneration or replacement of cylindrical tissues and organs, especially peripheral nerve tissue regeneration. Nevertheless, the quantitative and qualitative characterisation of this phenomenon has not been described. In this work, the colloidal systems are subjected to the action of an electric current initiated at different voltages. Parameters of the electrodeposition process (i.e., total charge exchanged, gas volume, and deposit thickness) are monitored over time. Deposit structures are investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The value of voltage influences structural characteristics but not thickness of deposit for the process lasting at least 20 min. The calculated number of exchanged electrons for studied conditions suggests that the mechanism of deposit formation is governed not only by water electrolysis but also interactions between formed hydroxide ions and calcium ions coordinated by chitosan chains.     

Formulation of Piperine–Chitosan-Coated Liposomes: Characterization and In Vitro Cytotoxic Evaluation

The present research work is designed to prepare and evaluate piperine liposomes and piperine–chitosan-coated liposomes for oral delivery. Piperine (PPN) is a water-insoluble bioactive compound used for different diseases. The prepared formulations were evaluated for physicochemical study, mucoadhesive study, permeation study and in vitro cytotoxic study using the MCF7 breast cancer cell line. Piperine-loaded liposomes (PLF) were prepared by the thin-film evaporation method. The selected liposomes were coated with chitosan (PLFC) by electrostatic deposition to enhance the mucoadhesive property and in vitro therapeutic efficacy. Based on the findings of the study, the prepared PPN liposomes (PLF3) and chitosan coated PPN liposomes (PLF3C1) showed a nanometric size range of 165.7 ± 7.4 to 243.4 ± 7.5, a narrow polydispersity index (>0.3) and zeta potential (−7.1 to 29.8 mV). The average encapsulation efficiency was found to be between 60 and 80% for all prepared formulations. The drug release and permeation study profile showed biphasic release behavior and enhanced PPN permeation. The in vitro antioxidant study results showed a comparable antioxidant activity with pure PPN. The anticancer study depicted that the cell viability assay of tested PLF3C2 has significantly (p < 0.001)) reduced the IC₅₀ when compared with pure PPN. The study revealed that oral chitosan-coated liposomes are a promising delivery system for the PPN and can increase the therapeutic efficacy against the breast cancer cell line.     

Copper Nanoparticles In鄄Situ Anchored on Nitrogen鄄Doped Carbon for High鄄Efficiency Oxygen Reduction Reaction Electrocatalyst北大核心CSCD

Compared with noble metal platinum (Pt)-based catalysts, inexpensive non-noble metal electrocatalysts have attracted extensive attention for oxygen reduction reaction (ORR). Herein, chitosan as a kind of biomass resource rich in nitrogen and carbon was used to prepare nitrogen-doped carbon (N-C) and N-C in-situ anchored by copper nanoparticles (Cu/N-C). The as-obtained N-C and Cu/N-C nanoparticles were successfully used as non-noble eletrocatalysts tested for ORR. Compared with the N-C, the Cu/N-C showed the high surface area of 607.3 m2窑g-1 with the mean pore size of 2.5 nm and the pore volume of 0.40 cm3窑g-1. The most positive Gibbs free energy change was the rate determining step for ORR process with the 4e mechanism, where the value of the Cu (111)/N-C(-0.39 eV) was lower than that of the N-C(-0.26 eV). The Cu/N-C exhibited superior onset and half-wave potentials (0.96 V and 0.84 V, respectively) in alkaline media (0.1 mol窑L-1 KOH), all of which are much better than those measured for N-C and commercial Pt/C. Furthermore, the Cu/N-C showed superior methanol crossover avoidance and oxygen reduction stability. © 2021 Authors. All rights reserved.     

氮掺杂碳原位锚定铜纳米颗粒用于高效氧还原反应催化剂

与贵金属铂基电化学氧还原反应（ORR）催化剂相比,廉价的非贵金属催化剂引起了广泛的关注。本文以壳聚糖作为一种富含氮和碳元素的生物质资源,利用碳浴法成功制备了氮掺杂碳原位负载铜纳米颗粒（Cu/N-C）催化剂。纯壳聚糖碳化得到的样品N-C的比表面积为67.5 m²·g^-1、平均孔径0.14 nm、平均孔体积8.00 m²·g^-1,与之相比,Cu/N-C比表面积可达607.3 m²·g^-1、平均孔径为2.5 nm、平均孔体积为0.40 cm³·g^-1。通过密度泛函理论（DFT）进行计算表明,Cu(111)/N-C的自由能值低于N-C,更有利于氧还原催化进行。在0.1 mol·L^-1 KOH的介质中,Cu/N-C不仅表现出优异的起始和半波电势（分别为0.96 V和0.84 V）,而且还表现出了优异的抗甲醇性能和稳定性,并且Cu元素掺杂量达到1.67wt.%。     

Synthesis of a Novel Chitosan/Basil Oil Blend and Development of Novel Low Density Poly Ethylene/Chitosan/Basil Oil Active Packaging Films Following a Melt-Extrusion Process for Enhancing Chicken Breast Fillets Shelf-Life

An innovative process for the adsorption of the hydrophobic Basil-Oil (BO) into the hydrophilic food byproduct chitosan (CS) and the development of an advanced low-density polyethylene/chitosan/basil-oil (LDPE/CS_BO) active packaging film was investigated in this work. The idea of this study was the use of the BO as both a bioactive agent and a compatibilizer. The CS was modified to a CS_BO hydrophobic blend via a green evaporation/adsorption process. This blend was incorporated directly in the LDPE to produce films with advanced properties. All the obtained composite films exhibited improved packaging properties. The film with 10% CS_BO content exhibited the best packaging properties, i.e., 33.0% higher tensile stress, 31.0% higher water barrier, 54.3% higher oxygen barrier, and 12.3% higher antioxidant activity values compared to the corresponding values of the LDPE films. The lipid oxidation values of chicken breast fillets which were packaged under vacuum using this film were measured after seven and after fourteen days of storage. These values were found to be lower by around 41% and 45%, respectively, compared with the corresponding lipid oxidation values of pure LDPE film.     

The effect of zirconium phosphonate with different functional groups on the structure and properties of chitosan film

Three types of zirconium phosphonate (org‐ZrP) with different functional groups (―COOH, ―SO₃H, ―NO₂) were prepared first and then added into chitosan (CS) matrix, respectively. The effect of these functional groups on structure, morphologies, and mechanical properties of chitosan films was investigated. The Fourier transform infrared spectroscopy revealed that org‐ZrP had intensely interacted with chitosan in the composites because of introducing functional groups on the fillers. The composite films filled with zirconium sulfophenylphosphonate exhibited the best mechanical properties among the three org‐ZrP fillers. These differences of reinforcement effect appeared to be caused by the difference of interfacial interactions between the org‐ZrP fillers and matrix. The stronger the interfacial interactions are, the better the reinforcement effect is. In addition, the moisture uptake (Mu) of CS/org‐ZrP‐n composite films depended on the hydrophilic property of functional groups. It was found that zirconium nitrophenyl phosphonate showed the best moisture barrier property due to its poor absorbability for water molecules. Copyright © 2014 John Wiley & Sons, Ltd.     

基于N-羧甲基壳聚糖钆基磁共振造影剂的制备及性能

通过在DTPA配体上修饰N-羧甲基壳聚糖(NCMCS)增加配体的分子量,构建配合物Gd-(DTPA-NCMCS)。测定了Gd-(DTPA-NCMCS)及对照组Gd-DTPA与Gd-(DTPA-CS)不同浓度的弛豫时间T1,拟合了配合物的纵向弛豫率r1,结果表明Gd-(DTPA-NCMCS)纵向弛豫能力明显强于Gd-DTPA,也高于配合物Gd-(DTPA-CS),浓度梯度的体外加权成像图清晰地观察到配合物Gd-(DTPA-NCMCS)比Gd-DTPA、Gd-(DTPA-CS)对应水溶液的信号更强。MTT法测定了Gd-(DTPA-NCMCS)的IC50值为568μmol·L-1,表现出良好的生物相容性。Gd-(DTPA-NCMCS)可作为潜在的磁共振造影剂。     

壳聚糖/乙炔黑修饰电极上萘酚异构体的电化学行为及同时测定

制备了壳聚糖/乙炔黑复合修饰电极(CS-AB/GCE),采用SEM和交流阻抗法对其进行表征。并利用循环伏安法(CV)研究了萘酚异构体(α-N和β-N)在该修饰电极上的电化学行为,对实验条件进行了优化。结果表明,在p H 7.0的PBS缓冲液中,α-N和β-N在该修饰电极上均出现一不可逆氧化峰,且在20~200m V/s范围内,其峰电流与扫速呈线性关系,表明电极过程是受吸附控制的不可逆过程。计算了电极过程的部分动力学参数,优化了差分脉冲伏安法(DPV)的实验参数,并对α-N和β-N进行同时测定,发现二者的微分氧化峰电流值与其浓度在2.5×10-6~1.0×10-4mol/L范围内呈良好的线性关系(rα-N=0.996;rβ-N=0.998)。α-N和β-N的检出限(S/N=3)分别为3.4×10-7mol/L和2.4×10-7mol/L。采用该法对实际水样进行检测,得到α-N和β-N的加标回收率分别为96.7%~105.1%和98.8%~103.9%。     

Wound healing improvement by curcumin‐loaded electrospun nanofibers and BFP‐MSCs as a bioactive dressing

Wound healing, one of the most complex processes of the body involving the cooperation of several important biomolecules and pathways, is one of the major therapeutic and economic issues in regenerative medicine. The present study aimed to introduce a novel electrospun curcumin (Cur)‐incorporated chitosan/polyvinyl alcohol/carbopol/polycaprolactone nanofibrous composite for concurrent delivery of the buccal fat pad‐derived mesenchymal stem cells (BFP‐MSCs) and Cur to a full‐thickness wound on the mouse model. Scaffolds were characterized structurally using scanning electron microscopy (SEM), fluorescence microscopy imaging and Fourier‐transform infrared spectroscopy, and toxicity of the scaffolds was also evaluated after BFP‐MSC seeding by SEM imaging and 3‐(4,5 dimethyiazol‐2‐1)‐2‐5‐diphenyl tetrazolium bromide (MTT) assay. Then, its influence on the wound‐healing process was investigated as a wound dressing for a full‐thickness skin defect in mouse model. Results demonstrated that the designed composite scaffolds have the capability for cell seeding and support their growth and proliferation. Macroscopic and histopathological characteristics were evaluated at the end of the 7 and 14 days after surgery, and their results showed that our designed scaffold groups accelerated the wound‐healing process compared with the control group. Among those, scaffold/Cur, scaffold/Cur/BFP‐MSC and scaffold/BFP‐MSC groups demonstrated more wound repair efficacy. These results indicated that the combined grafts can be used to improve the wound‐healing process, and therefore, the electrospun nanofibers presented in this study, Cur and BFP‐MSC together, were demonstrated to have promising potential for wound‐dressing applications.