细菌纤维素/聚乙烯醇/聚丙烯酰胺复合水凝胶的性能表征北大核心

背景:随着高分子水凝胶材料应用领域的扩展而对其性能提出了更高要求,研制和开发性能更为优良的高分子水凝胶材料已成为目前的研究热点。目的:比较细菌纤维素改性前后的聚乙烯醇/聚丙烯酰胺水凝胶的力学性能,为其用于伤口敷料提供理论依据。方法:实验利用细菌纤维素为增强材料,采用冷冻-熔融法,在细菌纤维素网络中引入聚乙烯醇/聚丙烯酰胺水凝胶,制备了细菌纤维素/聚乙烯醇/聚丙烯酰胺复合水凝胶,采用红外光谱、扫描电镜、热重分析、力学性能测试等手段对凝胶的结构和性能进行表征。结果与结论:①通过扫描电镜和红外光谱图可以看到聚乙烯醇和聚丙烯酰胺结合到了细菌纤维素上,说明制备出了细菌纤维素/聚乙烯醇/聚丙烯酰胺复合水凝胶;②细菌纤维素增强复合凝胶的热稳定性、拉伸强度明显提高,而断裂伸长率较细菌纤维素增强前下降;③聚丙烯酰胺浓度为1.0%时,复合水凝胶的拉伸强度和断裂伸长率最大分别为331.79 kPa和105.33%,聚乙烯醇浓度为3.5%时,复合水凝胶的断裂伸长率最大为46.25%,而拉伸强度随聚乙烯醇浓度的增加而增加;④结果表明,细菌纤维素的引入明显提高了水凝胶材料的力学性能,增强了其稳定性,该复合水凝胶有望用作伤口敷料。     

人工软骨材料——聚乙烯醇水凝胶的研制

聚乙烯醇溶液于－２０℃左右的温度下冷冻６－１２ｈ,室温下颌化１－２ｈ,上述过程反复进行１－３次,然后对试样进行真空脱水处理,制得一种人工软骨材料－ＰＶＡ水凝胶。     

人工髓核材料-聚乙烯醇水凝胶/聚乙烯纤维复合物的生物相容性研究*

目的评估人工髓核材料聚乙烯醇水凝胶／聚乙烯纤维复合物的生物相容性。方法根据ISO10993-1标准，采用细胞毒性试验（琼脂扩散法）、皮内刺激试验、Ame’s致突变试验、微核试验和体内植入（360天）试验对聚乙烯醇水凝胶／聚乙烯纤维复合物的生物相容性进行评估。结果聚乙烯醇水凝胶／聚乙烯纤维复合物的细胞毒性评分小于Ⅰ级，细胞生长无明显抑制现象，对皮内无刺激作用，Ames致突变试验为阴性，微核出现率为3．48‰，无致突变反应。体内植入符合植入材料生物学评价要求。结论聚乙烯醇水凝胶／聚乙烯纤维复合物具有良好的生物安全性，是一种无毒、对皮肤及肌肉、椎间隙无刺激作用的生物医用材料，在动物体内不引起排异反应，可应用于临床。     

聚丙烯酰胺水凝胶的不良事件分析研究

目的:聚丙烯酰胺水凝胶注射隆乳术不良事件发生原因及防治方法。方法:对39例聚丙烯酰胺水凝胶隆乳术出现的并发症进行分析、调查。结果:聚丙烯酰胺水凝胶隆乳术不良事件多在1年内发生,其中硬结的发生率最高,达87%,其次是胸大肌内凝胶滞留、胸大肌炎、感染、血肿、皮下凝胶移位等。结论:聚丙烯酰胺水凝胶注射隆乳术不良事件多与手术者操作不规范及患者术后护理不当有关,应加强手术者的操作规范及术后护理的宣教工作,患者也应当到正规医院进行手术。     

人工髓核材料-聚乙烯醇水凝胶/聚乙烯纤维复合物的生物相容性研究*

目的评估人工髓核材料聚乙烯醇水凝胶/聚乙烯纤维复合物的生物相容性。方法根据ISO10993-1标准,采用细胞毒性试验(琼脂扩散法)、皮内刺激试验、Ame's致突变试验、微核试验和体内植入(360天)试验对聚乙烯醇水凝胶/聚乙烯纤维复合物的生物相容性进行评估。结果聚乙烯醇水凝胶/聚乙烯纤维复合物的细胞毒性评分小于Ⅰ级,细胞生长无明显抑制现象,对皮内无刺激作用,Ames致突变试验为阴性,微核出现率为3.48‰,无致突变反应。体内植入符合植入材料生物学评价要求。结论聚乙烯醇水凝胶/聚乙烯纤维复合物具有良好的生物安全性,是一种无毒、对皮肤及肌肉、椎间隙无刺激作用的生物医用材料,在动物体内不引起排异反应,可应用于临床。     

人工髓核材料(半晶聚乙烯醇水凝胶弹性体)的研制

研制一种可替代椎间盘髓核并恢复其功能的生物医用材料 ,探讨半晶聚乙烯醇水凝胶弹性体材料临床应用的可行性。聚乙烯醇 (PVA)水溶液在 - 2 0℃下冷冻 6～ 12 h,室温下融化 1～ 2 h,上述过程重复 1～ 3次 ,然后对试样进行真空脱水 ,制得人工髓核材料 (半晶 PVA水凝胶弹性体 )。差示扫描量热法 (DSC)和力学性能试验研究了 PVA水溶液浓度、真空脱水和 γ射线辐照对水凝胶 PVA的结晶度和力学性能的影响     

人工髓核材料-聚乙烯醇水凝胶的溶胀性能研究

利用冷冻-解冻法制得聚乙烯醇(PVA)水凝胶弹性体,研究了其用于人工髓核材料的溶胀特性,以及聚乙烯醇浓度、溶胀温度、溶胀体系的pH值对其溶胀性能的影响,采用扫描电镜对其微观形貌进行了观察,并对其溶胀动力学进行了探讨。结果表明,聚乙烯醇水凝胶是一种多孔网状结构,网络孔径大小与水凝胶中聚乙烯醇的含量有关;增加聚乙烯醇的浓度,提高溶胀温度以及溶胀体系的pH值,其平衡溶胀率减小;通过溶胀动力学方程对其溶胀过程进行了描述,水凝胶中聚乙烯醇的含量,试样尺寸以及溶胀体系的pH值,是溶胀速率快慢的重要影响因素。     

制备表面图案化的聚丙烯酰胺-丙烯酸水凝胶

背景:聚丙烯酰胺水凝胶具备良好的生物相容性,但力学性能较差,影响了其在生物材料领域的应用。目的:通过微模塑图形化压印制备具有特殊尺寸的聚丙烯酰胺-丙烯酸水凝胶。方法:依次将不同体积的聚丙烯酰胺溶液、丙烯酸与过硫酸铵溶液混合,加入含有微模塑图形化印章的孔板中,制备聚丙烯酰胺-丙烯酸水凝胶:A组聚丙烯酰胺溶液1.4 mL,丙烯酸0.1 mL;B组聚丙烯酰胺溶液1.3 mL,丙烯酸0.2 mL;C组聚丙烯酰胺溶液1.2 mL,丙烯酸0.3 mL;D组聚丙烯酰胺溶液1.1 mL,丙烯酸0.4 mL;E组聚丙烯酰胺溶液1.0 mL,丙烯酸0.5 mL;F组聚丙烯酰胺溶液0.9 mL,丙烯酸0.6 mL。6组过硫酸铵溶液均为50 L。光镜下观察水凝胶的图案化结构,电子万能试验机检测水凝胶的力学性能。结果与结论:光镜显示各组水凝胶表面的条纹清晰可见;丙烯酸的加入有效改良了水凝胶的力学性能,随着丙烯酸比例的不断增加,水凝胶的力学性能逐渐增强。结果表明,聚丙烯酸-丙烯酰胺水凝胶具有良好的力学性能,有望在组织工程损伤修复领域具有良好的应用前景。     

聚乙烯醇/羟基磷灰石复合水凝胶软骨植入材料的研究

研究了用于人工关节软骨假体的聚乙烯醇水凝胶和羟基磷灰石复合材料的结构与性能，系统讨论了含水量、羟基磷灰石含量等对其拉伸强度，压缩强度，黏弹性、润滑性等生物力学性能的影响，观察和比较了复合材料的徽观形貌。研究表明羟基磷灰石在聚乙烯醇水凝胶中分散均匀，良好相容，使复合材料的力学强度和润滑性能提高。     

Fabrication and characterization of phlorotannins/poly (vinyl alcohol) hydrogel for wound healing application

Abstract

Phlorotannins (PH) derived from brown algae have been shown to have biological effects. However, the application of PH in biomedical materials has not been investigated. Here, we investigated the effects of PH on normal human dermal fibroblast (NHDF) proliferation and fabricated a composite hydrogel consisting PH and poly (vinyl alcohol) (PVA) (PVA/PH) by a freezing-thawing method for wound healing applications. Cell proliferation was significantly higher in the PH-treated (0.01 and 0.02%) cells than in non-treated cells. Based on the mechanical properties, the PVA/PH hydrogel had a significantly increased swelling ratio and ultimate strain compared to the PVA hydrogel, but the ultimate tensile strength and tensile modulus were decreased. Additionally, cell attachment and proliferation on the composites were evaluated using NHDFs. The results showed that after 1 and 5 days, cell attachment and proliferation were significantly increased on the PVA/PH hydrogel compared with that on the PVA hydrogel. The findings from this study suggest that the PVA/PH hydrogel may be a candidate biomedical material for wound healing applications.     

Preparation and characterization of pH-sensitive hydrogel of chitosan/poly(acrylic acid) co-polymer

A pH-sensitive co-polymer hydrogel of chitosan/poly(acrylic acid) (CS/PAAc) was prepared by irradiating the aqueous solution mixture of chitosan and acrylic acid with 60Co gamma-ray irradiation. The effect of the composition of chitosan and AAc on the properties of the hydrogel, such as swelling ratio and pH-sensitivity, were determined. Fourier Transform Infrared (FT-IR) spectrometry was applied in the attenuated total reflectance (ATR) mode for analyzing the structure change of the hydrogels after the treatment in different pH buffer solutions.     

Preparation and characterization of alkylated poly(vinyl alcohol) hydrogels using alkyl halides

A poly(vinyl alcohol) hydrogel coated onto polyethylene was partially alkylated by reaction with an alkylhalide (C⁴, C⁸, or C¹⁸) in the presence of a deprotonating agent (sodium ethoxide or potassium tertbutoxide). Surface coverage determined by X-ray photoelectron spectroscopy (XPS) was respectively ~ 34, 25, and ~ 8% for the C₄, C₈, and C₁₈ modified surfaces. Statistically significant differences were observed in the fraction of C₈ and C₁₈ grafted alkyl groups as a function of depth (i.e. take-off angle) indicating the presence of a verticle composition gradient. All three surfaces showed maximal surface coverage of alkyl groups after 1 h reaction. At this reaction time, no further coverage was observed beyond a base/PVA ratio twenty times greater than the stoichiometric ratio. The advancing contact angle data exhibted an increase in hydrophobicity that correlated with the degree of coverage obtained by XPS: 90 ± 1, 83 ± 0.5, and 71 ± 1 deg for C₄, C₈ and C₁₈ alkylated PVA, and 55 ± 2 deg for PVA respectively. Large contact angle hysteresis was observed on all three surfaces consistent with surface heterogeneity.     

Preparation and characterization of pH-sensitive hydrogel of chitosan/poly(acrylic acid) co-polymer

A pH-sensitive co-polymer hydrogel of chitosan/poly(acrylic acid) (CS/PAAc) was prepared by irradiating the aqueous solution mixture of chitosan and acrylic acid with ⁶⁰Co γ-ray irradiation. The effect of the composition of chitosan and AAc on the properties of the hydrogel, such as swelling ratio and pH-sensitivity, were determined. Fourier Transform Infrared (FT-IR) spectrometry was applied in the attenuated total reflectance (ATR) mode for analyzing the structure change of the hydrogels after the treatment in different pH buffer solutions.     

Preparation and ESCA characterization of poly(vinyl chloride) surf ace-grafted with heparin-complexing poly(amido amine) chains

By a simple process poly(amido-amine) chains have been grafted on the surface of poly(vinyl chloride). Grafted poly(vinyl chloride) is able to adsorb heparin, thus providing potentially non-thrombogenic surfaces. The grafting of poly(amido-amine), and the heparin adsorption have been studied by ESCA. It has been found that the total amount of grafted poly(amido-amine) depends on the molecular weight of the poly(amido-amine) used in the grafting reaction, but the amount of heparin adsorbed on the grafted material is relatively independent of the length of the poly(amido-amine) grafted chains.     

Radiation processed hydrogel of poly (vinyl alcohol) with biodegradable polysaccharides

Poly(vinyl alcohol) (PVA) can be modified to polymer hydrogels by radiation crosslinking and can be used in different biomedical applications. A study was done on the optimization of ingredients concentration for preparing good quality PVA hydrogels with natural polysaccharides. The synthesized hydrogels were also characterized by measuring the different physical properties e.g. gel fraction, swelling and absorption rate. Besides these, sterility test were also performed. Good quality hydrogels were obtained from PVA and natural polysaccharides solutions with 27 kGy radiation dose. There is an influence of natural polysaccharides on the gel fraction of hydrogel. The increase in the amount of polysaccharide causes a decrease in gel fraction that is decrease in the crosslinking density of PVA hydrogel network. The prepared hydrogels were found to be sterile.     

Transparent poly(vinyl alcohol) hydrogel with high water content and high strength

To develop a transparent poly(vinyl alcohol) (PVA) hydrogel with high water content and high strength, we studied the physical gelation of PVA solutions and found that low temperature crystallization of PVA solutions in mixed solvents consisting of water and a water-miscible organic solvent yields transparent gels. The strength and transparency of the PVA hydrogel is dependent on both the type of organic solvent and the mixing ratio of water/organic solvent. A mixed solvent from water/dimethyl sulfoxide resulted in the highest transparency and the highest tensile strength among the water/organic solvent combination studied. A plausible mechanism is proposed for the formation of transparent and strong hydrogels on the basis of the results obtained.     

Porous nano-hydroxyapatite/poly(vinyl alcohol) composite hydrogel as artificial cornea fringe: characterization and evaluation in vitro

A nano-hydroxyapatite/poly(vinyl alcohol) (n-HA/PVA) composite hydrogel was employed as artificial cornea fringe to improve biocompatibility for the firm fixation between material and surrounding host tissues. The morphology and swelling behavior, as well as mechanical strength of the fringes were characterized. The results showed that the n-HA/PVA fringes had interconnective porous structure, high water content and good mechanical properties. With the aid of cell culture observed by inverted microscopy, scanning electron microscopy (SEM) and MTT test, it was concluded that PVA hydrogel modified with n-HA can improve biocompatibility and has no negative effects on the corneal fibroblasts in vitro. These findings indicate that the porous n-HA/PVA fringe can allow invasion and proliferation of cells, and can function as a fringe for artificial cornea.     

Preparation of fast responsive,temperature-sensitive poly(N-isopropylacrylamide) hydrogel

A new poly(N-isopropylacrylamide) (PNIPA) hydrogel was prepared by decreasing the temperature of polymerization/crosslinking reaction below the freezing point (–18°C). This PNIPA hydrogel shows a large swelling ratio at room temperature and exhibits a fast deswelling and reswelling rate in response to external temperature changes. These properties are attributed to the macroporous and regularly arranged network of this PNIPA hydrogel.     

Effects of solvent dehydration on creep resistance of poly(vinyl alcohol) hydrogel

As a synthetic replacement material for osteochondral defect repair, poly(vinyl alcohol) (PVA) hydrogels offer a great potential due to their high water content and strong mechanical integrity. To survive the high stress environment in the joint space, high creep resistance becomes one of the key requirements for hydrogel implants. We hypothesized that reducing the equilibrium water content (EWC) of hydrogels would improve their creep resistance. We investigated the effect of dehydration of PVA theta-gels in various solvent/solution media followed by rehydration in saline solution. Decreasing EWC increased the creep resistance of PVA theta-gels. The most effective medium was isopropyl alcohol for reducing the EWC and increasing the creep resistance of PVA theta-gels.