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.     

Biocompatibility and Mechanical Stability of Nanopatterned Titanium Films on Stainless Steel Vascular Stents

Nanoporous ceramic coatings such as titania are promoted to produce drug-free cardiovascular stents with a low risk of in-stent restenosis (ISR) because of their selectivity towards vascular cell proliferation. The brittle coatings applied on stents are prone to cracking because they are subjected to plastic deformation during implantation. This study aims to overcome this problem by using a unique process without refraining from biocompatibility. Accordingly, a titanium film with 1 µm thickness was deposited on 316 LVM stainless-steel sheets using magnetron sputtering. Then, the samples were anodized to produce nanoporous oxide. The nanoporous oxide was removed by ultrasonication, leaving an approximately 500 nm metallic titanium layer with a nanopatterned surface. XPS studies revealed the presence of a 5 nm-thick TiO₂ surface layer with a trace amount of fluorinated titanium on nanopatterned surfaces. Oxygen plasma treatment of the nanopatterned surface produced an additional 5 nm-thick fluoride-free oxide layer. The samples did not exhibit any cracking or spallation during plastic deformation. Cell viability studies showed that nanopatterned surfaces stimulate endothelial cell proliferation while reducing the proliferation of smooth muscle cells. Plasma treatment further accelerated the proliferation of endothelial cells. Activation of blood platelets did not occur on oxygen plasma-treated, fluoride-free nanopatterned surfaces. The presented surface treatment method can also be applied to other stent materials such as CoCr, nitinol, and orthopedic implants.     

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.     

Improving Blood Compatibility of Polyethersulfone Hollow Fiber Membranes via Blending with Sulfonated Polyether Ether Ketone

Appropriate membrane for blood contacting applications requires hemocompatibility and high permeation flux; it should inhibit proteins or platelets adsorption and still possess high permeability. Aiming to improve the polyethersulfone (PES) hollow fiber membrane hemocompatibility, sulfonated polyether ether ketone (SPEEK) is self‐synthesized in the present research and added to PES in different ratios. Scanning electron microscopy images have revealed significant changes in PES membranes structure after addition of SPEEK, which can influence water permeation property of the membranes. Water contact angles of the membranes have reduced from 75° to 50° after addition of 4 wt% SPEEK. Influence of SPEEK addition on hemocompatibility of the PES membranes is evaluated via protein (bovine serum albumin) adsorption, platelet attachment, and coagulation time (APTT and TT) assays. Obtained results reveal that hemocompatibility of the modified hollow fiber membranes is enhanced as a result of emerging repulsive forces between negative charges on the membranes surface and negatively charge blood components.

     

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。     

TLM钛合金表面白蛋白涂层的制备及抗凝血性研究

为提高医用钛合金Ti-3Zr-2Sn-3Mo-25Nb的抗凝血性能,首先通过溶胶-凝胶法在其表面制备一层TiO2薄膜,再将该TiO2薄膜活化处理,最后通过静电自组装法将牛血清白蛋白固定在TiO2薄膜表面形成抗凝血涂层。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和接触角测试仪研究了该抗凝血涂层的相结构、表面微观形貌和亲水性特征,并通过动态凝血时间法和血小板黏附实验对比研究了白蛋白修饰前后Ti-3Zr-2Sn-3Mo-25Nb合金的抗凝血性能。结果表明,经白蛋白表面修饰处理后,Ti-3Zr-2Sn-3Mo-25Nb合金的抗凝血性能得到了明显的改善。     

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.     

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)。     

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.     

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.