Release of fluorescent markers from phase‐separated gelatin‐maltodextrin hydrogels

Genipin‐crosslinked gelatin‐maltodextrin phase‐separated hydrogels consisting of gelatin‐continuous or bicontinuous microstructures were developed to regulate swelling and release behavior of four fluorescent markers of varying molecular weights [(fluorescein (332 Da) and FITC‐dextrans (FD) (4000–250,000 Da)]. Bicontinuous hydrogels showed significantly greater swelling than gelatin‐continuous hydrogels under all conditions (at pH 1.5 and 7.4 and three genipin/gelatin crosslinking ratios) (P < 0.05). With both microstructures, fluorescein showed the largest release rate and total release followed by FD 4000 Da, FD 40,000 Da, and FD 250,000 Da (P < 0.05). Marker molecular weight, pH, and crosslink ratio all affected the rate and amount of release. The mode of transport for the solvent and all markers was Fickian or slightly anomalous, with diffusional exponent (n) values ranging from 0.35 to 0.64. These results demonstrated that with the proper combination of crosslink density, solvent pH, and microstructure, hydrogels with a specified swelling behavior may be developed. This, coupled with a marker of appropriate size, can lead to controllable levels and rates of release. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization of cross-linked polyampholytic gelatin hydrogels through the rubber elasticity and thermodynamic swelling theories

A new approach is proposed to characterize polyampholytic gelatin hydrogels, cross-linked covalently with glutaraldehyde. An experimental methodology involving simple mechanical extension and compression and equilibrium swelling tests is developed to estimate relevant microstructural parameters and electrokinetic properties of this type of hydrogel, for different cross-linker to gelatin mass ratios. The polyampholytic cross-linked matrices are studied here in the framework of the rubber elasticity and thermodynamic swelling theories. The main purposes of this work are the estimations of average mesh size and toughness of the swollen hydrogels, and the determination of the feasibility of polyion complexation between cross-linked gelatin chains and bioactive macromolecules to be delivered through hydrogel biodegradation.     

明胶的改性及其在制革业中的应用

简述了明胶改性的途径，重点对改性明胶在制革业中的应用进行了综述。     

水产动物明胶的研究进展

根据近年来国内外水产动物明胶的研究现状,本文对水产动物明胶的提取工艺,水产动物明胶的胶凝特性、成膜性、乳化性及发泡性,以及水产动物明胶在食品、化妆品及生物医学领域中的应用进行了综述。     

Use of proteins to minimize the physical aging of EUDRAGIT sustained release films

The objective of this study was to investigate the influence of two proteins, albumin and type B gelatin, on the physical aging of EUDRAGIT® RS 30 D and RL 30 D coated theophylline pellets. The physicomechanical properties of sprayed films, thermal properties of cast films, influence of proteins on the zeta potential and particle size of the dispersion, and the release of proteins from cast films under simulated dissolution conditions were investigated. The release rate of theophylline decreased significantly over time from pellets coated with an acrylic dispersion containing 10% albumin when there was no acidification of the acrylic dispersion; however, when pellets were coated with an acidified EUDRAGIT®/albumin dispersion, the theophylline release rate was stable for dosage forms stored in the absence of humidity. The drug release rate was faster for pellets coated with acrylic dispersions containing 10% gelatin compared to the albumin-containing formulations. When sprayed films were stored at 40°C/75% RH, the water vapor permeability decreased significantly for both EUDRAGIT® films and those containing EUDRAGIT® and albumin; however, there was no significant change in this parameter when 10% gelatin was present. Albumin was released from the acrylic films when the pH of the dissolution media was below the isoelectric point of the protein while no quantitative release of gelatin was observed in pH 1.2 or 7.4 media. The effect of gelatin to prevent the decrease in drug release rate was due to stabilization in water vapor permeability of the film. Acidification of the polymeric dispersion resulted in electrostatic repulsive forces between albumin and the acrylic polymer, which stabilized the drug release rate when the dosage forms were stored in aluminum induction sealed containers at both 40°C/75% RH and 25°C/60% RH.     

采用“梯度升温法”提取鱼鳞明胶及其理化特性的研究

以草鱼鳞为原料提取明胶,首先采用单因素试验明确了明胶提取温度为60℃～80℃,时间为6h。在此基础上采用60℃～70℃～80℃三段式加热的梯度升温法提取草鱼鳞明胶,并以恒温提取法(60℃、70℃和80℃)为对照组,对所制备的明胶理化特性进行了比较研究。实验表明,梯度升温法所得明胶相比市售明胶和对照组,含有更多的高分子量组分(130～250ku),使其具有更高的凝胶强度,傅里叶变换红外光谱显示梯度升温法所得明胶具有明胶特有的典型酰胺带,其溶胶-凝胶点和热变性温度居于恒温提取法60℃组和80℃组之间,但提取率和凝胶强度均相对较高,且灰分含量低于0.20%,脂肪含量低于0.60%。综上所述,采用梯度升温法提取明胶兼顾了提取率和明胶品质,具有较好的应用前景。     

温度对石墨/明胶共混复合膜性能的影响

以明胶为基体,甘油为增塑剂,石墨为增强相,制备易溶解的生物大分子功能性复合膜,通过共混的方法制备一系列的石墨/明胶复合膜,并测试复合膜在不同温度下各浓度复合膜的抗拉强度、断裂伸长率、吸水性、水蒸气透过率、SEM等的性能来判断膜的性能。抗拉强度整体趋势随着石墨含量的增加呈现为先增加后减小的趋势,在35℃(抗拉强度范围在49MPa～85MPa)和-10℃(23MPa～40MPa)时较大但断裂伸长率较低,35℃(断裂伸长率范围在13%～34%)和-10℃(5%～55%);断裂伸长率趋势随着石墨含量的增加先增加后减少的趋势,在10℃(70%～112%)和0℃(48%～110%)时较好,但抗拉强度在10℃(6MPa～10MPa)和0℃(0.5MPa～6MPa)时较差;吸水性中随着温度的升高,空白样的吸水率受温度影响增加最快,同温度下随着石墨含量的增加吸水率降低,吸水率起到了抑制的作用;温度越高WVP越大,少量石墨加入(0.5%、3%、5%)对WVP有利;水溶性:35℃25℃5℃15℃,高温有利于溶解,低温有利有疏水保护层的形成。     

3种不同二氧化硅对螺旋藻片可压性的影响

目的研究不同二氧化硅对螺旋藻片可压性的影响,选出最适合制备螺旋藻片的二氧化硅。方法以硬度、脆碎度和主压力为主要评价指标,关联工序总混、包衣的工艺顺应性作为辅助评价指标,分别采用沉淀法二氧化硅、凝胶法二氧化硅和气相法二氧化硅制备螺旋藻片,对比分析螺旋藻片的可压性,确认螺旋藻片的质量参数。结果二氧化硅对螺旋藻片的可压性是:沉淀法二氧化硅气相法二氧化硅凝胶法二氧化硅,沉淀法二氧化硅不符合螺旋藻片的工艺要求,气相法二氧化硅分散性较差。结论螺旋藻片中优先使用凝胶法二氧化硅,其可压性最佳。