Hemocompatibility,cytotoxicity, and genotoxicity of poly(methylmethacrylate)/nanohydroxyapatite nanocomposites synthesized by melt blending method

The aim of this study was to show the hemocompatibility, cytotoxicity, and genotoxicity of nanocomposites that were synthesized with different molecular weights of poly(methyl methacrylate) (PMMA) and different concentrations of nanohydroxyapatite (nHAp). Different techniques to characterize the nanocomposites were used. The cytotoxicity and genotoxic effects of the polymers and nanocomposites on human lymphocytes were determined by acid phosphatase assay, viability test, and comet assay. Moreover, hemocompatibility test was performed. It was found that all of the PMMA/nHAp nanocomposites are highly hemocompatible and biocompatible, none of the nanocomposites showed a cytotoxic effect, and nHAp addition decreased the genotoxicity.     

Formulation,optimization, hemocompatibility and pharmacokinetic evaluation of PLGA nanoparticles containing paclitaxel

Objective: Paclitaxel (PTX)-loaded polymer (Poly(lactic-co-glycolic acid), PLGA)-based nanoformulation was developed with the objective of formulating cremophor EL-free nanoformulation intended for intravenous use.

Significance: The polymeric PTX nanoparticles free from the cremophor EL will help in eliminating the shortcomings of the existing delivery system as cremophor EL causes serious allergic reactions to the subjects after intravenous use.

Methods and results: Paclitaxel-loaded nanoparticles were formulated by nanoprecipitation method. The diminutive nanoparticles (143.2?nm) with uniform size throughout (polydispersity index, 0.115) and high entrapment efficiency (95.34%) were obtained by employing the Box–Behnken design for the optimization of the formulation with the aid of desirability approach-based numerical optimization technique. Optimized levels for each factor viz. polymer concentration (X1), amount of organic solvent (X2), and surfactant concentration (X3) were 0.23%, 5?ml %, and 1.13%, respectively. The results of the hemocompatibility studies confirmed the safety of PLGA-based nanoparticles for intravenous administration. Pharmacokinetic evaluations confirmed the longer retention of PTX in systemic circulation.

Conclusion: In a nutshell, the developed polymeric nanoparticle formulation of PTX precludes the inadequacy of existing PTX formulation and can be considered as superior alternative carrier system of the same.     

多级结构超疏水钛合金表面制备及性能

本文以Ti6Al4V钛合金为基材,利用微弧氧化和水热法在钛合金表面形成微纳复合多级粗糙结构,进一步通过氟化处理得到具有多级结构的超疏水钛合金表面。利用傅里叶变换红外光谱、能谱仪和场发射扫描电子显微镜等对材料表面结构和组成进行了系统的表征。利用水接触角对材料表面润湿性能进行了分析。因此,通过表面多级粗糙结构的构建以及低表面能处理,能够实现超疏水表面的构建。血小板黏附和溶血率测试结果表明材料表面具有较好的血液相容性。材料表面修饰前后耐腐蚀性能测试表明,超疏水结构能有效地降低材料表面与血液和腐蚀液的接触面积,进而降低材料表面与血细胞的相互作用,同时可以有效提高材料表面的耐腐蚀性能。     

7047584余辉等离子体对PVC吸附FIB的抑制作用

为改善聚氯乙烯(PVC)的抗凝血性,采用余辉等离子体修饰PVC表面,通过扫描电子显微镜(SEM)、接触角、X射线光电子能谱分析(XPS)和散射比浊法等方法,研究了余辉等离子体和放电区等离子体修饰前后的PVC表面形貌、亲水性和化学成分的变化,分析了余辉等离子体和放电区等离子体对PVC吸附血浆中纤维蛋白原(FIB)的影响.结果表明,余辉等离子体对PVC的刻蚀作用较弱,余辉等离子体修饰PVC的亲水性更强,其表面生成了更多的含氧官能团,对纤维蛋白原的抑制吸附明显,表现出好的血液相容性.     

Influence of Human Jaw Periosteal Cells Seeded β-Tricalcium Phosphate Scaffolds on Blood Coagulation

Tissue engineering offers auspicious opportunities in oral and maxillofacial surgery to heal bone defects. For this purpose, the combination of cells with stability-providing scaffolds is required. Jaw periosteal cells (JPCs) are well suited for regenerative therapies, as they are easily accessible and show strong osteogenic potential. In this study, we analyzed the influence of uncoated and polylactic-co-glycolic acid (PLGA)-coated β-tricalcium phosphate (β-TCP) scaffolds on JPC colonization and subsequent osteogenic differentiation. Furthermore, interaction with the human blood was investigated. This study demonstrated that PLGA-coated and uncoated β-TCP scaffolds can be colonized with JPCs and further differentiated into osteogenic cells. On day 15, after cell seeding, JPCs with and without osteogenic differentiation were incubated with fresh human whole blood under dynamic conditions. The activation of coagulation, complement system, inflammation, and blood cells were analyzed using ELISA and scanning electron microscopy (SEM). JPC-seeded scaffolds showed a dense cell layer and osteogenic differentiation capacity on both PLGA-coated and uncoated β-TCP scaffolds. SEM analyses showed no relevant blood cell attachment and ELISA results revealed no significant increase in most of the analyzed cell activation markers (β-thromboglobulin, Sc5B-9, polymorphonuclear (PMN)-elastase). However, a notable increase in thrombin-antithrombin III (TAT) complex levels, as well as fibrin fiber accumulation on JPC-seeded β-TCP scaffolds, was detected compared to the scaffolds without JPCs. Thus, this study demonstrated that besides the scaffold material the cells colonizing the scaffolds can also influence hemostasis, which can influence the regeneration of bone tissue.     

Polycarbonateurethane films containing complex of copper(II) catalyzed generation of nitric oxide

Nitric oxide (NO) is a well known potent antiplatelet agent, and its continuous release will effectively prevent the adhesion of platelets on artificial blood vessel walls. In this paper, polycarbonateurethane (PCU) with lipophilic Cu(II)‐complex (Cu(II)‐DTTCT) blending films were prepared and used as catalyst to generate NO from nitrite. The mechanical properties of PCU films blended with Cu(II)‐DTTCT were characterized by tensile strength measurement. The tensile stress and Young's modulus of PCU films blending with Cu(II)‐DTTCT increased, however, the elongation at break decreased compared with corresponding PCU films. The NO generation was investigated in vitro in the presence of NaNO₂ and ascorbic acid in PBS (pH = 7.4) at 37°C. The flux of NO generation was quantitatively measured by Griess assay. NO flux and velocity increased with the increase of NaNO₂ concentration, the concentration of ascorbic acid in PBS and the amount of Cu(II) in the films. The loss of Cu(II) from blending film surfaces was found during the in vitro NO generation experiments, which resulted in the decrease of NO flux in the second run. The PCU film could catalyze continually generation of NO for two days, which will provide a promising approach that enable endogenous NO generation on the surface of the medical devices. The generation of biologically active level of NO at the blood/polymer interface can reduce the risk of thrombosis on the implants. Polycarbonateurethane films with NO generation function may be used as high thromboresistant blood contacting materials or coating. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

模糊血液相容度法在生物材料血液相容性评价中的应用

针对制作人工心脏瓣膜所采用的生物碳素梯度涂层材料，分析了材料表面与血液间的相互作用；采用体外动态凝血时间、溶血率和血小板消耗率对所制备材料进行了血液相容性单因素评价及模糊数学综合评价，提出了模糊血液相容度(FHCD)的概念并进行了综合评判。结果表明，所制备的梯度涂层材料综合血液相容性(FHCD为0．70—0．80)优于碳／氮离子注入的钛合金、等离子体化学气相沉积碳及碳化钻和氮化钻涂层等对比材料，接近公认血液相容性优良的低温各向同性碳(FHCD为0．72—0．82)。     

Study of hemocompatibility and endothelial cell interaction of tecoflex-based electrospun vascular grafts

Abstract

Ensuring long-term functioning and efficient endothelialization of small diameter vascular grafts (VG) is an urgent task of tissue engineering. A solution may be to use electrospun VGs prepared from blends polyurethane with gelatin and/or bivalirudin. Here, properties of 3D matrices were explored by SEM, contact angle measurements and IR spectroscopy, and their interaction with blood and endothelial cells was studied. Introduction of gelatin into matrices enhanced adhesion and proliferation of endotheliocytes and enabled adhesion of platelets, whereas bivalirudin inhibited platelet adhesion while having no negative effect on the adhesion and proliferation of endothelial cells.     

Versatile Antibacterial Materials: An Emerging Arsenal for Combatting Bacterial Pathogens

Antibacterial materials that prevent bacterial infections and mitigate bacterial virulence have attracted great scientific interests. In recent decades, the bactericidal polymers have been presented as promising candidates to combat bacterial pathogens, mainly based on the construction of bactericidal cationic polymers, functionalization with biocidal agents, and formation of bacterial‐repelling layers. However, these established strategies have inherent disadvantages because they often overlook important features such as their biocompatibility and biosafety, especially for biomedical applications. In recent years, many efforts have been made focusing on the development of multifunctional antibacterial materials to meet the elaborate requirements for medical devices and public hygiene products. Herein the recent advances in developing multifunctional materials for their antibacterial activities together with other functions including “kill‐and‐release” capability, hemocompatibility, cell proliferation promoting properties, and coagulation promoting ability for wound dressing are highlighted. In addition, the outlooks on the remaining challenges that should be addressed in the field of multifunctional antibacterial materials are also described.     

In vitro biocompatibility and antimicrobial activity of chitin monomer obtain from hollow fiber membrane

This study for the first time shows the effective utilization and production of chitin monomers at laboratory level, with immense potential for its biomedical application. Low molecular weight (LMW) N-acetylglucosamine (GlcNAc) is prepared by depolymerization of chitin using chemical method coupled with a physical separation method. A novel filtration strategy exploiting polysulfone hollow fiber membrane is used for the preparation of GlcNAc particles with 94% yield within 8.5 ± 0.5 h. This high efficiency is analyzed using high-pressure liquid chromatography. The GlcNAc obtained was further analyzed using dynamic light scattering, first derivative Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The antimicrobial properties of GlcNAc, chitin, and GlcNAc/chitin mixture were investigated using minimal inhibitory concentration against S. aureus and E. coli. Bacteriostatic property was exhibited by high molecular weight chitin, while GlcNAc and GlcNAc/chitin mixture (LMW) demonstrated bactericidal activity. Blood biocompatibility below 0.25 g/ml and cytocompatibility with NIH3T3 fibroblast cells and the proliferative efficacy suggested its utilization and suitability of these particles in biological applications.