有机相中壳聚糖-海藻酸固定化脂酶的特性

研究了壳聚糖 海藻酸固定化脂酶在有机相反应中的稳定性与活性。考察了凝胶时间、壳聚糖浓度及壳聚糖分子质量对固定化脂酶包埋率与活性的影响 ,确定了适宜 pH值与批反应时间。同时讨论了溶剂极性和操作时间对固定化酶稳定性的影响。测定了固定化脂酶水解橄榄油反应的动力学参数。结果表明 ,壳聚糖 海藻酸聚电解质膜可提高固定化酶的包埋率与稳定性     

氢氧化镧交联壳聚糖微球的微流控制备及其除磷性能

基于微流控技术制备了氢氧化镧[La(OH)₃]交联壳聚糖（CS）微球（La-CS-M）,并对其组成和结构进行表征,探究了微球吸附去除水中磷酸盐的性能和机理。结果表明,La-CS-M成功负载了La（OH）₃,与传统滴落法制备的氢氧化镧交联壳聚糖球（La-CS）相比,其表面和内部具有疏松多孔结构,其体积平均粒径为415.8 μm,孔隙率为89.22%,平均孔径为960.0 nm,pH_pzc约为6.5。La-CS-M在宽pH范围内（3.0~10.0）均保持较高吸附量,\mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{2}-}对La-CS-M吸附性能影响较Cl^-、\mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{-}、\mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}以及腐殖酸（HA）明显。吸附动力学数据符合准二级动力学模型,等温吸附数据符合Langmuir模型且在pH=6.0时最大吸附量为56.48 mg/g。结合XPS表征和吸附数据推测La-CS-M的吸附机理涉及静电吸附和形成内层配合物（通过配位交换或Lewis酸碱作用）。吸附磷酸盐后La-CS-M可通过2.5 mol/L NaOH溶液实现脱附,具有良好的再生性和吸附稳定性。     

呋喃甲醛改性壳聚糖铜、钴螯合物电催化性能

合成了呋喃甲醛改性壳聚糖(FCS).将其与一定pH值的含Co2 、Cu2 硝酸铵溶液反应,制得呋喃甲醛改性壳聚糖金属钴、铜的螯合物(CoFCS、CuFCS),采用红外光谱法(IR)对FCS、CoFCS、CuFCS进行了表征.使CoFCS、CuFCS与碳基体混合,在氩气保护一定温度下热处理后,制成空气电极,通过测试极化曲线和放电曲线,研究了它的电催化性能.结果表明,CoFCS/C和CuFCS/C具有良好的氧气还原电催化性能,且CoFCS/C优于CuFCS/C.     

原位聚合法制备壳聚糖-g-聚丙烯酸/高岭土复合树脂

利用无机粘土矿物与烯类单体的接枝共聚反应制备复合高吸水性树脂,具有改善树脂吸水性能、增强凝胶强度、降低产品成本的优点。以高岭土、壳聚糖和丙烯酸为原料,在水溶液中通过接枝共聚反应合成了壳聚糖接枝共聚丙烯酸/高岭土复合吸水树脂。以丙烯酸量为基准,研究了交联剂、引发剂、壳聚糖、高岭土等与丙烯酸的不同质量比对复合树脂吸水倍率的影响。红外光谱分析结果表明,丙烯酸、壳聚糖和高岭土共同参与了接枝聚合反应。以过硫酸胺为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,丙烯酸中和度为70%,引发剂用量0.3%,交联剂用量为0.05%,壳聚糖与丙烯酸的质量比为0.13,高岭土与丙烯酸质量比为0.13时,高吸水性树脂具有较好的综合吸液性能。     

甲醛溶液吸收-盐酸副玫瑰苯胺分光光度法测定白砂糖中的二氧化硫

本文建立了用甲醛溶液吸收-盐酸副玫瑰苯胺分光光度法测定白砂糖中二氧化硫的方法.该法用甲醛代替汞盐,减少了对环境的污染.样品经处理后加入甲醛,样液中二氧化硫与甲醛生成稳定的羟基甲基磺酸,加氢氧化钠后,与盐酸副玫瑰苯胺作用,生成紫红色化合物,在579 nm处测定其吸光度.白砂糖中二氧化硫浓度在0～60 mg/kg范围内与吸光度值呈良好的线性关系(r=0.9998),检出限为0.81 mg/kg.样品测定的相对标准偏差在2.8%～4.1%,回收率在93.8%～98.6%之间.与国标方法测定结果比较,两者无显著性差异,结果令人满意.     

基于壳聚糖/银离子的可逆温敏水凝胶的制备与性能

以壳聚糖(CS)和Ag NO₃为主要原料,通过CS与Ag⁺的超分子络合作用制备了一系列可逆温敏CS-Ag水凝胶,采用FTIR、XRD、XPS、SEM和EDS对CS-Ag水凝胶的结构和化学状态进行了表征。结果表明,通过同时调节Ag NO₃用量和体系p H可制备具有相同凝胶温度的CS-Ag水凝胶。当CS用量为0.60 g、Ag NO₃用量为0.19 g、体系总体积为21 m L、保持水凝胶p H=4.24时,制备的CS-Ag-19水凝胶凝胶温度为50℃,具有最佳的热可逆性能,至少可循环相变5次,具有室温避光保存5个月的稳定性,并表现出对大肠杆菌良好的抗菌性能。CS-Ag-19的溶胶-凝胶转换是由CS的氨基在不同温度下的超分子相互作用控制,H⁺和Ag⁺在温度、浓度变化的驱动下,对游离氨基的竞争反应(质子化和络合作用)之间的平衡关系使水凝胶具有温敏可逆性。CS-Ag-19水凝胶的可注射和温敏凝胶性能使其具有作为水凝胶抗菌敷料的应用潜力。     

Parameters effect on proton conductivity to obtain chitosan membranes for use as electrolytes in PEMFC

The chitosan biopolymer can be used as a proton‐conducting membrane in proton‐exchange membrane fuel cell. In the forms that they have normally obtained and tested, chitosan membranes typically show poor performance in conduction of protons, requiring modifications in the structure of the biopolymer or blending with other polymers to increase its proton conductivity. The present work investigates the individual properties of chitosan and relates them to the proton conductivity performance of membranes composed of this polymer. Evaluation was made of the effects of variables such as the degree of deacetylation (DD) and the molar mass (Mv) of chitosan membranes without addition of any other polymer. The DD and Mv values of the chitosan used to produce membranes determined the proton conduction, with lower DD and higher Mv resulting in higher conductivity. The thicker membranes presented greater crystallinity, with conductivity between 2.0 × 10^?4 and 1.8 × 10^?3 S cm^?1. The characteristic stages of degradation of the chitosan membranes were in the ranges 200 to 300°C and 500 to 600°C, indicating good thermal stability of the material.     

Solid dispersion adsorbate technique for improved dissolution and flow properties of lurasidone hydrochloride: characterization using 32 factorial design

The aim of the present study was to improve the dissolution and flow properties of lurasidone hydrochloride (LH) by solid dispersion adsorbate (SDA) technique. Solid dispersions (SDs) of LH were prepared by fusion method using Poloxamer P188. The melt dispersion was adsorbed onto the porous carrier Florite (calcium silicate). A 3² factorial design was employed to quantify the effect of two independent variables, namely ratio of carrier (Poloxamer 188) and LH in SD and ratio of adsorbent (Florite) to SD. SDA granules of LH were studied for flow properties and characterized using differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction. Tablets of optimized composition of SDA granules (equivalent to 20?mg of drug) and plain tablets were prepared by direct compression method. The dissolution studies were carried out in Mcllvaine buffer (pH 3.8) as per USFDA guidelines and characterized for parameters such as percent dissolution efficiency, t₅₀, and Q₃₀. Tablets prepared from SDA granules showed almost four-fold increase in cumulative percentage drug release as compared to tablets prepared from plain LH. The value of dissolution efficiency was enhanced from 49.60% for plain tablets to 94.15% for SDA tablets. SDA granules did not show any change in drug release and X-ray diffraction pattern after storage at 40?°C/75% of RH for 3?months, which confirms that Florite prevented conversion of drug from amorphous form to crystalline form improving physical stability of the amorphous state of LH.     

Facile development,characterization, and optimization of new metformin-loaded nanocarrier system for efficient colon cancer adjunct therapy

Purpose: Metformin hydrochloride (MF) repurposing as adjuvant anticancer therapy for colorectal cancer (CRC) proved effective. Several studies attempted to develop MF-loaded nanoparticles (NPs), however the entrapment efficiency (EE%) was poor. Thus, the present study aimed at the facile development of a new series of chitosan (CS)-based semi-interpenetrating network (semi-IPN) NPs incorporating Pluronic^® nanomicelles as nanocarriers for enhanced entrapment and sustained release of MF for efficient treatment of CRC.

Methods: The NPs were prepared by ionic gelation and subsequently characterized using FTIR, DSC, TEM, and DLS. A full factorial design was also adopted to study the effect of various formulation variables on EE%, particle size, and zeta-potential of NPs.

Results: NPs had a spherical shape and a mean particle size ranging between 135 and 220?nm. FTIR and DSC studies results were indicative of successful ionic gelation with the drug being dispersed in its amorphous form within CS-Pluronic^® matrix. Maximum EE% reaching 57.00?±?12.90% was achieved using Pluronic^®-123 based NPs. NPs exhibited a sustained release profile over 48?h. The MF-loaded NPs sensitized RKO CRC cells relative to drug alone.

Conclusion: The reported results highlighted the novel utility of the developed NPs in the arena of colon cancer treatment.