罗非鱼鳞胶原蛋白膜抗水性和机械性能研究

以戊二醛作为交联剂对罗非鱼磷胶原蛋白交联改性。研究交联剂对罗非鱼鳞胶原蛋白膜抗水性能和机械性能的影响。通过检测改性后胶原膜的拉伸强度、断裂伸长率、抗水性、吸水率、水接触角等指标来对胶原膜进行表征。结果表明,对胶原膜机械性能影响因素依次为pH值温度戊二醛量;对胶原膜抗水性影响因素依次为戊二醛量pH值温度;当戊二醛的添加量为8%,pH值为2.9,加热温度为40℃时,胶原蛋白膜的机械、抗水综合性能最优,抗拉伸强度为31.32 MPa,断裂伸长率为65.24%,抗水性为34.85%,水接触角为120.24°。     

环境因素对碳钢点蚀临界电势的影响

采用动电势扫描法测定了不同体系中碳钢发生点蚀的临界电势Eb。结果表明 :当Cl- 浓度 <0 .0 1mol/L时 ,随Cl- 浓度增加 ,临界电势负移并与Cl- 浓度成线性关系 ;pH值在 7～ 11之间 ,随pH值增加 ,临界电势正移并与pH值成线性关系 ;随温度增加 ,临界电势负移并与温度成线性关系。     

琼脂粉体系的凝胶质构特性

利用旋转黏度计与质构仪探究不同种类和价态的金属离子(包括氯化钠、氯化钙、氯化铁)和木糖醇、山梨糖醇等小分子多羟基化合物以及其他食品胶体等对琼脂粉体系的凝胶性能影响。结果表明,琼脂粉浓度可以有效影响琼脂粉的黏度与凝胶硬度;金属离子会阻碍琼脂分子的相互作用,导致黏度、硬度和弹性降低,随着价态升高,三价金属离子会使体系形成微小悬浮物,而阻碍凝胶的形成;小分子糖醇的影响很小;加入其他食品胶,能够有效调控琼脂粉体系的黏度、硬度和弹性。     

常见哺乳动物源胶原蛋白的提取及其性能表征

为了评价不同哺乳动物源胶原蛋白理化性能和生物学性能,采用酶法提取从常见哺乳动物猪、鼠、牛中提取胶原蛋白,并对其提取的胶原蛋白氨基酸组成、理化性能和生物相容性进行评价。结果表明,不同来源胶原蛋白氨基酸组成及含量不同;FT-IR图谱显示所提取3种胶原蛋白都较好地维持其三螺旋结构;TG结果表明3种胶原蛋白具有较为相似的热行为,其中猪皮胶原(pig skin collagen,PS-col)对热降解具有更高的稳定性;SEM照片显示鼠尾胶原膜(rat tail collagen,RT-col)具有微粗糙结构表面,猪皮胶原膜表面较为光滑,牛跟腱胶原膜(bovine tendon collagen,BT-col)适中;AFM观察到3种胶原蛋白都呈现胶原纤维束状结构,但不同来源胶原蛋白形成胶原纤维存在差异性;力学性能测试表明牛跟腱胶原能够较好抵抗外界作用力且材料柔性好,猪皮胶原杨氏模量最大,较其它二者不易发生形变,鼠尾胶原力学性能介于二者之间。体外细胞实验结果表明,3种胶原蛋白都具有良好的生物相容性。为优选以胶原基为生物材料满足不同需求匹配提供更多参考。     

新型胶原/聚丙烯酸互穿网络pH敏感水凝胶的制备及性能研究

以Bis为交联剂,采用互穿网络(IPN)技术制备胶原/聚丙烯酸pH敏感水凝胶.研究了不同配比的水凝胶的溶胀动力学、pH敏感性及pH溶胀-退胀特性,并利用傅里叶变换红外光谱法(FTIR)和差示量热扫描法(DSC)对其结构进行表征.结果显示:制备的水凝胶具有较快的溶胀速率,在13min时吸水率可达93%左右;水凝胶有明显的pH敏感性且pH溶胀-退胀可逆性良好.FTIR和DSC结果表明,在保持胶原三股螺旋结构的同时,材料间形成了互穿网络,材料的热稳定性显著提高,从而扩大了材料的应用范围.     

敏感性壳聚糖-聚醚水凝胶的研究

以壳聚糖和聚醚为原料、戊二醛为交联剂合成了壳聚糖-聚醚水凝胶,探讨了壳聚糖-聚醚水凝胶的形成机理,研究了该水凝胶的pH值、酸、碱、盐、温度等敏感性,并通过红外光谱图对其结构进行了分析.结果表明,壳聚糖-聚醚水凝胶具有显著的pH值/温度敏感性,酸、碱、盐的种类和浓度也是影响其溶胀度的重要因素,戊二醛的醛基与壳聚糖分子链上的氨基生成Schiff碱交联,从而形成壳聚糖-聚醚水凝胶三维空间结构.     

生理pH下可控释放胰岛素的温度/葡萄糖双响应可注射复合水凝胶

成功制备了能够在生理pH下快速响应葡萄糖的Alg-g-PNA/Alg-g-PNlPAM可注射复合水凝胶体系.研究了复合体系的温度和葡萄糖响应特性,结果表明,该体系在10℃时为溶胶态,37℃下转变为凝胶态;在pH=7.4条件下,随葡萄糖浓度增加,复合体系的低临界溶解温度(LCST)逐渐升高,葡萄糖响应性良好.考察了复合体系的流体力学特性,结果表明,复合水凝胶体系具有良好的热响应可逆性与自修复性.最后,探究了复合体系的体外药物释放行为,结果表明,48 h内,复合水凝胶在高血糖浓度下胰岛素的累积释放远高于低血糖浓度下胰岛素的累积释放,且能够较好地响应高血糖与正常血糖间的循环交替变化.该复合体系通过简单的环境温度刺激或者葡萄糖浓度刺激即可实现溶胶-凝胶转变,且能够在生理温度和生理pH下及时响应血糖浓度变化,为基于血糖响应的胰岛素体内自调节给药系统的开发提供了一种新策略.     

由沥青制备炭基凝胶的研究

以煤焦油沥青为原料,经过氧化、碱溶制备出水性中间相沥青,着重考察了制备条件对水性中间相沥青在水相中凝胶化的影响。结果表明：氧化温度、浓度和溶胶的pH值对水性中间相沥青的凝胶化有影响;水性中间相沥青（AMP）可以在较宽的pH值范围内形成凝胶。在碱性条件下,氧化温度降低、pH值升高和AMP浓度提高均可缩短炭基凝胶的凝胶时间;以强酸为絮凝剂在酸性条件下水性中间相沥青絮凝为炭基凝胶;在中性条件下,给溶胶中加入乙醇可形成炭基凝胶。     

电沉积非晶态Ni-P合金工艺的优化

为了在亚磷酸-镍盐体系中获得工艺稳定、耐蚀性好、硬度高的非晶态Ni-P镀层,进行了7因素(温度、电流密度、pH值、硫酸镍浓度、氯化镍浓度、亚磷酸浓度、磷酸浓度)3水平正交试验.优选出制备最佳耐蚀性镀层的工艺条件为:10g/L亚磷酸,180g/L硫酸镍,50g/L氯化镍,45mL/L磷酸,pH值1.8,温度65℃,电流密度6 A/dm2;获得最佳镀层硬度的工艺条件为:40g/L氯化镍,10g/L亚磷酸,180g/L硫酸镍,45 mL/L磷酸,pH值2.2,温度65℃,电流密度6 A/dm2.分析了各因素对镀层耐蚀性和硬度的影响,结果表明,pH值和温度对镀层耐蚀性影响较大,而氯化镍和亚磷酸浓度对镀层硬度影响较大.     

重组胶原蛋白与牛源I型胶原蛋白红外光谱研究

用红外光谱分析了重组胶原蛋白和牛源I型胶原蛋白的结构,并用场发射扫描电镜观察了两种胶原蛋白的形貌.结果表明,两种胶原蛋白的红外光谱存在显著差异,牛源I型胶原蛋白的红外光谱呈典型的三螺旋结构特征,而重组胶原蛋白的红外光谱呈变性胶原蛋白特征;重组胶原蛋白的红外光谱在1024 cm-1附近有很强的丝氨酸侧基C-O伸缩振动吸收峰;牛源I型胶原蛋白分子形成胶原纤维,重组胶原蛋白没有纤维存在,重组胶原蛋白与牛源I型胶原蛋白的分子构型和聚集结构不同.研究结果将为胶原基生物医学材料和组织工程支架的设计使用提供理论依据.     

Isolation and characterization of drug delivering potential of type-I collagen from eel fish Evenchelys macrura

Acid soluble collagen (ASC) and pepsin-soluble collagen (PSC) from the outer skin waste of marine eel fish (Evenchelys macrura) were isolated and characterized. The prepared collagen was used to test its effective drug delivering potential in vitro condition. Present results were confirmed as collagen by different physico-chemical techniques like SDS-PAGE, HPLC, FTIR and SEM. Further amino acid analysis corroborates isolation of type I collagen. Both ASC and PSC comprising two different α-chains (α 1 and α 2) were characterized as type I and contained imino acid of 190-200 residues, respectively. The denaturation temperatures (T(d)) of ASC and PSC were 38.5 and 35.0?°C, respectively, which is promising as an advantage for biomedical application due to closeness in T(d) to mammalian collagen. Furthermore, the gel and film forming capability of collagen samples containing implant standard antibiotic was proved to be a suitable drug delivering system.     

From curdlan powder to the triple helix gel structure: an attenuated total reflection-infrared study of the gelation process

Infrared spectroscopy was used to probe the hydration and gelation of curdlan, a linear polysaccharide built from repeating units of (1-->3)-beta-D-glucose. The spectra have been recorded using a temperature-controlled attenuated total reflection (ATR) device. Thermal gelation of curdlan could therefore be followed in situ and in real time. The transformation of the low-set gel, mainly formed with single helices, into a high-set gel, associated with a triple helix structure, could be directly observed. The relative intensities and positions of characteristic absorption bands in the C-O region (1200-850 cm-1) were found to be representative of the gel structure, as they are believed to be sensitive to the helical conformation of the polymer chains. Infrared (IR) spectroscopy is shown to be a useful tool for rapid and efficient characterization of curdlan gels.     

Influence of functionalized nanoparticles on conformational stability of type I collagen for possible biomedical applications

Collagen–nanoparticle interactions are vital for many biomedical applications including drug delivery and tissue engineering applications. Iron oxide nanoparticles synthesized using starch template according to our earlier reported procedures were functionalized by treating them with Gum Arabic (GA), a biocompatible polysaccharide, so as to enhance the interaction between nanoparticle surfaces and collagen. Viscosity, circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR) techniques have been used to study the collagen–nanoparticle interactions. The relative viscosity for collagen–nanoparticle conjugate was found to increase with increase in concentration of the nanoparticle within the concentration range investigated, which is due to the aggregation of protein onto the surface of nanoparticle. The CD spectra for the collagen–nanoparticle at different concentration ratios do not have much variation in the Rpn values (ratio of positive peak intensity over negative peak intensity) after functionalization with GA. The variation of molar ellipticity values for collagen–nanoparticle is due to the glycoprotein present in GA. The collagen triple helical structure is maintained after interaction with nanoparticles. The FTIR spectra of native collagen, Coll–Fs (nanoparticle without functionalization) and Coll–FsG (nanoparticle functionalized with GA) show clearly the amide I, II, III bands, with respect to collagen. The ability of polysaccharide stabilized/functionalized nanoparticles to maintain the collagen properties would help in its biomedical applications.     

Anisotropic elasticity of magnetically ordered agarose gel

The physical properties of agarose gel prepared under strong magnetic fields were investigated. The storage modulus was measured by the reflection method with an ultrasonic pulse. The measurement results of the gel''s elasticity indicate that agarose gel has anisotropic properties. The elasticity and its anisotropy depend on the concentration of the gel and the magnetic field to which it is exposed. The experimental results indicate that the anisotropic network structure of the gel is induced by the exposure to the magnetic field during gelation. The gelation mechanism under a magnetic field is discussed.     

Anisotropic elasticity of magnetically ordered agarose gel

Abstract

The physical properties of agarose gel prepared under strong magnetic fields were investigated. The storage modulus was measured by the reflection method with an ultrasonic pulse. The measurement results of the gel's elasticity indicate that agarose gel has anisotropic properties. The elasticity and its anisotropy depend on the concentration of the gel and the magnetic field to which it is exposed. The experimental results indicate that the anisotropic network structure of the gel is induced by the exposure to the magnetic field during gelation. The gelation mechanism under a magnetic field is discussed.     

Tailoring material properties of a nanofibrous extracellular matrix derived hydrogel

In the native tissue, the interaction between cells and the extracellular matrix (ECM) is essential for cell migration, proliferation, differentiation, mechanical stability, and signaling. It has been shown that decellularized ECMs can be processed into injectable formulations, thereby allowing for minimally invasive delivery. Upon injection and increase in temperature, these materials self-assemble into porous gels forming a complex network of fibers with nanoscale structure. In this study we aimed to examine and tailor the material properties of a self-assembling ECM hydrogel derived from porcine myocardial tissue, which was developed as a tissue specific injectable scaffold for cardiac tissue engineering. The impact of gelation parameters on ECM hydrogels has not previously been explored. We examined how modulating pH, temperature, ionic strength, and concentration affected the nanoscale architecture, mechanical properties, and gelation kinetics. These material characteristics were assessed using scanning electron microscopy, rheometry, and spectrophotometry, respectively. Since the main component of the myocardial matrix is collagen, many similarities between the ECM hydrogel and collagen gels were observed in terms of the nanofibrous structure and modulation of properties by altering ionic strength. However, variation from collagen gels was noted for the gelation temperature along with varied times and rates of gelation. These discrepancies when compared to collagen are likely due to the presence of other ECM components in the decellularized ECM based hydrogel. These results demonstrate how the material properties of ECM hydrogels could be tailored for future in vitro and in vivo applications.     

杂萘联苯聚醚砜酮类材料成膜动力学研究(Ⅱ)凝胶介质对 PPESK凝胶动力学的影响

以杂萘联苯聚醚砜酮(PPESK)/NMP为聚膜液体系,进行了成膜过程凝胶动力学研究;浊点实验表明,随着醇类物质碳原子数目的增多,相图的二相区变小,凝胶过程所需的非溶剂量增多.还考察了不同凝胶浴对PPESK/NMP体系凝胶速度的影响.结果表明,使絮凝值增大的非溶剂,凝胶过程中所需的非溶剂量增多,凝胶速度降低.凝胶浴中加入溶剂使铸膜液和凝胶浴的化学势差降低,使非溶剂和溶剂的传质速度下降,凝胶速度减小.当NMP浓度为80%时,膜结构由指状转变为海绵状结构.     

催化剂对正硅酸乙酯水解-聚合机理的影响

运用溶胶-凝胶法制备SiO₂凝胶,研究了催化剂对正硅酸乙酯的水解-聚合机理及凝胶结构的影响．结果表明催化剂阴离子尺寸导致了不同的水解机理,不同的催化方式及催化剂浓度、pH值、反应水量等对凝胶化时间、结构均有明显影响．     

Collagen Structural Hierarchy and Susceptibility to Degradation by Ultraviolet Radiation

Collagen type I is the most abundant extracellular matrix protein in the human body, providing the basis for tissue structure and directing cellular functions. Collagen has complex structural hierarchy, organized at different length scales, including the characteristic triple helical feature. In the present study, the relationship between collagen structure (native vs. denatured) and sensitivity to UV radiation was assessed, with a focus on changes in primary structure, changes in conformation, microstructure and material properties. A brief review of free radical reactions involved in collagen degradation is also provided as a mechanistic basis for the changes observed in the study. Structural and functional changes in the collagens were related to the initial conformation (native vs. denatured) and the energy of irradiation. These changes were tracked using SDS-PAGE to assess molecular weight, Fourier transform infrared (FTIR) spectroscopy to study changes in the secondary structure, and atomic force microscopy (AFM) to characterize changes in mechanical properties. The results correlate differences in sensitivity to irradiation with initial collagen structural state: collagen in native conformation vs. heat-treated (denatured) collagen. Changes in collagen were found at all levels of the hierarchical structural organization. In general, the native collagen triple helix is most sensitive to UV-254nm radiation. The triple helix delays single chain degradation. The loss of the triple helix in collagen is accompanied by hydrogen abstraction through free radical mechanisms. The results received suggest that the effects of electromagnetic radiation on biologically relevant extracellular matrices (collagen in the present study) are important to assess in the context of the state of collagen structure. The results have implications in tissue remodeling, wound repair and disease progression.