Cell Adhesion and Interactions with Biomaterials

The related phenomena of biocompatibility and biodegradation are of major concern in the selection of synthetic polymers for use as implantable biomedical devices. These properties are largely determined by the consequences of the cellular interactions that occur at the polymer/tissue interface during inflammation. Using an in vivo cage implant system, in conjunction with surface analysis techniques, we have investigated the variation in the cellular events that occurred on a polyetherure-thaneurea and a cytotoxic polyvinyl chloride). Quantitative and qualitative information that describe the cellular response to polymer implantation will be presented. From the results, a chronological sequence has been established which suggests that the important events follow cellular adhesion, and include cell spreading over a polymer surface accompanied by lysosomal degranulation of the adherent cells.     

The Role of Bloom Index of Gelatin on the Interaction with Retinal Pigment Epithelial Cells

Biocompatible materials are of considerable interest in the development of cell/drug delivery carriers for therapeutic applications. This paper investigates the effects of the Bloom index of gelatin on its interaction with retinal pigment epithelial (RPE) cells. Following two days of culture of ARPE-19 cells with gelatin samples G75-100, G175, and G300, the in vitro biocompatibility was determined by cell proliferation and viability assays, and glutamate uptake measurements, as well as cytokine expression analyses. The mitochondrial dehydrogenase activity in the G300 groups was significantly lower than that of G75-100 and G175 groups. The Live/Dead assays also showed that the gelatin samples G300 induced mild cytotoxicity. In comparison with the treatment of gelatins with low Bloom index, the exposure to high Bloom strength gelatins markedly reduced the glutamate uptake capacity of ARPE-19 cells. One possible explanation for these observations is that the presence of gelatin samples G300 with high viscosity in the medium may affect the nutrient availability to cultured cells. The analyses of pro-inflammatory cytokine IL-6 expression at both mRNA and protein levels showed that the gelatins with low Bloom index caused less cellular inflammatory reaction and had more acceptable biocompatibility than their high Bloom strength counterparts. These findings suggest that the Bloom index gives influence on cellular responses to gelatin materials.     

钛基表面PDLLA/ZnO纳米阵列材料的制备及生物学性能

采用水热生长法,在钛基表面制备高度有序、尺寸可控的氧化锌纳米棒阵列,再通过静电吸附的方法在其表面自组装一层具有良好生物相容性的聚乳酸生物涂层。利用SEM,MTT,LDH方法对细胞形态和生物活性进行表征。结果表明,氧化锌阵列上细胞形态呈圆形,无铺展现象。而经聚乳酸修饰过的材料表面MC3T3细胞外基质铺展较好,细胞分泌的丝状伪足嵌入了阵列结构的空隙中,并且表面细胞数量最多,细胞活性明显高于氧化锌纳米棒及纯钛片。结果表明,聚乳酸涂层提高了氧化锌阵列的生物相容性,为细胞生长提供适宜的微环境,有效促进了细胞的黏附与增殖。     

AZ91HP镁合金激光熔凝层的耐蚀性和生物相容性

为提高医用AZ91HP镁合金的耐蚀性和生物相容性,采用激光熔凝技术对镁合金进行熔凝处理。结果表明,AZ91HP镁合金熔凝层相组成为α-Mg和β-Mg17Al12,凝固组织为典型的树枝晶。模拟体液中腐蚀速率结果表明,熔凝层的耐蚀性较原始镁合金显著提高。在Hank’s中浸泡21 d后,可清楚看到一些絮状物沉积在熔凝层表面;能谱分析结果表明,絮状物中Ca,P比约为1.33,接近羟基磷灰石中Ca,P比(1.67)。原始镁合金的凝血酶原时间(PT)值为11.025 s,激光熔凝层的PT值为12.025 s,熔凝层具有较好的抗凝血性。细胞毒性实验结果表明,培养1 d后,在原始镁合金周围细胞出现破碎和固缩,极少数贴壁细胞。熔凝层表面则存在许多粘附细胞,熔凝层细胞死亡率较原始镁合金大有降低。     

Influence of chain length of diol on the swelling behavior of citric acid based pH sensitive polymeric hydrogels: A green approach

Synthesis of pH‐sensitive hydrogels of citric acid with varying diol units viz., 1,2 Ethane diol, 1,4 butane diol, and 1,6 hexane diol along with methacrylic acid towards the solventless green approach. The formations of the hydrogels were identified using FTIR spectroscopy. Thermal characterization (thermo gravimetric analysis, differential thermal analysis (DTA), and differential scanning calorimetry) and morphology of the synthesized hydrogels have been investigated. Swelling studies of hydrogels in various pH ranging from 4.0 to 10.0 have been investigated. The results of the swelling studies implied that percentage of swelling comparatively higher at neutral pH (7.4) than at acidic and alkaline pH. The inverse relationship was noticed, where ascending the diol units of hydrogel in swelling equilibrium. The hydrogels with the increasing chain length show a noticeable pH sensitivity and which could be considered as smart hydrogel. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41403.     

In vivo bioactivity of herbal‐drug‐incorporated nanofibrous matrixes

Aloe‐vera‐incorporated polycaprolactone nanofibrous matrixes were prepared by an electrospinning method. These developed matrixes were evaluated for their water absorption capacity, water vapor permeability, and contact angle, and, in an in vivo animal model, wound‐healing ability. The incorporation of the herbal drug made the matrixes hydrophilic with improved water retention and permeability properties. The in vivo studies were carried out in a rat model and showed improved results with respect to healing. Thus, this study confirmed that the developed matrixes could be used for wound‐healing applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42178.     

Carbohydrate crosslinked biocompatible polyurethanes: Synthesis,characterization, and drug delivery studies

A series of novel polyurethanes (PUs) with carbohydrate crosslinkers was synthesized. The drug loading and release kinetics were studied by using lamotrigine as a model drug. The polymers were designed in such a way that the drug release was tailored by differences in the stoichiometry of polymers. All the PUs were characterized for thermal and morphological properties by using differential scanning calorimetry and thermogravimetric analysis and scanning electron microscope , respectively. The encapsulation of drug inside PU matrix was confirmed via Fourier transform ‐ infrared (FT‐IR) spectra and scanning electron microscope . The kinetics and release mechanisms were observed to be a function of stoichiometric parameters such as type of crosslinker, polyol/crosslinker ratio and polyol/chain extender ratio. All the PUs were observed to be non‐cytotoxic in normal lung cell line L132. The synthesized PUs exhibited good mechanical strength, tunable release rates and biocompatibility that can be utilized in biomedical applications like wound dressing, biomedical implants , and drug delivery carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42223.     

In vitro degradation of starch/PVA films and biocompatibility evaluation

A series of starch/PVA (SP) films with the thickness of 0.05–0.1 mm were cast by solvent method. The swelling and degradation behaviors in simulated blood fluid (SBF) and simulated saliva fluid (SSF) within 30 days were investigated. In vitro biocompatibility was also evaluated. Research purpose of this work was to supply basic data for SP films' potential application in guide tissue regeneration (GTR) technology. It took 10–20 min for different samples to reach to their maximum water absorption and 30 min to lever off. The weight loss of all samples decreased rapidly in the first day in both of SBF or SSF, and then it changed slightly in SSF but decreased step by step in SBF. The mechanical properties of the wet SP films were satisfied with the requirement of GTR membrane. No matter in SBF or SSF, although the mechanical properties decreased rapidly in the first day, they changed slightly after that. Cytotoxicity and L929 fibroblasts attachment test proved that the SP film possesses excellent cell affinity. Hemolysis ratios of all samples were less than 5%. All results demonstrated that SP film is a promising candidate in GTR treatment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Antibacterial oil‐based polyurethane films for wound dressing applications

As an alternative to petroleum‐based polyol, hydroxyl containing material was prepared from linseed oil for polyurethane synthesis. Hexamethylene di‐isocyanate (HMDI) and/or 4, 4′‐methylene diphenyl di‐isocyanate (MDI) were used as isocyanate source. The polymerization reaction was carried out without catalyst. Polymer films were prepared by casting‐evaporation technique. The MDI/HMDI‐based polyurethane and its films had higher T_g and better thermal property than that of the HMDI‐based one because of the existence of benzene ring in the polymer chain. Static water contact angle was determined to be 74° and 77.5° for HMDI and MDI/HMDI‐based films, respectively. Water adsorption was found to be around 2.6–3.6% for both films. In vitro degradation of polyurethanes in phosphate buffered saline at 37°C was investigated by gravimetric method. Fourier transform infrared spectroscopy and scanning electron microscopy were used for confirmation of degradation on the polymer surface. The degradation rate of the HMDI‐based polyurethane film was found higher than that of the MDI/HMDI‐based film. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films, and the polyurethane films investigated here was not cytotoxic. Silver‐containing films were prepared using Biocera A® as filler and were screened for their antibacterial performance against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and/or Bacillus subtilis. The films prepared with and without Biocera A® exhibited antibacterial activity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

改性剂对n-HA/NRL复合医用乳胶膜结构与性能的影响

将经不同改性剂改性后的纳米羟基磷灰石(n-HA)与天然胶乳(NRL)复合,制备n-HA/NRL复合医用乳胶膜。采用IR、TEM和SEM进行表征,结果表明,n-HA的粒径在20~60 nm之间,长径比在2.5～3.5之间,复合乳胶膜表面结构形态明显改善。n-HA和NRL两相间界面作用增强,复合乳胶膜表观交联密度及综合力学性能明显提高。