Plasma surface modification strategies for the preparation of antibacterial biomaterials: A review of the recent literature.

Plasma-based strategies offer several advantages for developing antibacterial biomaterials and can be used directly or combined with other surface modification techniques. Direct plasma strategies can be classified as plasma surface modifications that derive antibacterial property by tailoring surface topography or surface chemistry. Nano patterns induced by plasma modification can exhibit antibacterial property and promote the adhesion and proliferation of mammalian cells, creating antibacterial and biocompatible surfaces. Antibacterial effect by tailoring surface chemistry via plasma can be attained by either creating bacteriostatic surfaces or bactericidal surfaces. Plasma-assisted strategies incorporate plasma processes in combination with other surface modification techniques. Plasma coating can serve as a drug-eluting reservoir and diffusion barrier. The plasma-functionalized surface can serve as a platform for grafting antibacterial agents, and plasma surface activation can improve the adhesion of polymeric layers with antibacterial properties. This article critically reviews plasma-based strategies reported in the recent literature for the development of antibacterial biomaterial surfaces. Studies using both atmospheric and low-pressure plasmas are included in this review. The findings are discussed in terms of the trends in material and precursor selection, modification stability, antibacterial efficacy, the choice of bacterial strains tested, cell culture findings, critical aspects of in vitro performance testing and in vivo experimental design.

A study on bone tissue engineering: Injectable chitosan-g-stearic acid putty.

BACKGROUND: Bioengineering products can help bone tissue regeneration. OBJECTIVE: There is an ongoing research for more effective biomaterials in bone regeneration. Chitosan (Ch) grafted stearic acid (Ch-g-Sa) polymer was synthesized and its usability as a putty was evaluated in this study. METHODS: The chemical structure of Ch-g-Sa polymer was investigated using Proton nuclear magnetic resonance (H-NMR) and Fourier-transformed infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Thermal properties of Ch-g-Sa polymer were determined by thermal gravimetric analysis (TGA). Putties containing nano-hydroxyapatite were prepared and in-vitro degradation properties and viscosity of the putties were determined. RESULTS: The cytotoxicity, oxidation effect and osteogenic potential of the putties were investigated on MC3T3 cells while the inflammatory effect of the putties was studied on THP-1 cells. For the determination of the osteogenic effect of the putties, ALP and RUNX2 gene expression of MC3T3 cells were studied. CONCLUSION: Ch-g-Sa/HA putties are promising biomaterials for bone tissue regeneration.

Ti implants with nanostructured and HA-coated surfaces for improved osseointegration.

This study was aimed at comparing the osseointegration of titanium (Ti)-based Küntscher nails (K-nails) and plates with modified nanostructured and hydroxyapatite-coated surfaces in a rat femur model. Material surfaces were first modified via a simple anodization protocol in which the materials were treated in hydrogen fluoride (1% w/w) at 20 V. This modification resulted in tubular titanium oxide nanostructures of 40-65 nm in diameter. Then, hydroxyapatite-deposited layers, formed of particles (1-5) µm, were produced via incubation in a simulated body fluid, followed by annealing at 500°C. Both surface modifications significantly improved cell proliferation and alkaline phosphatase (ALP) activity as compared to the control (non-modified Ti implants). The controls and modified nails and plates were implanted in the femur of 21 male Sprague-Dawley rats. The implants, with surrounding tissues, were removed after 10 weeks, and then mechanical tests (torque and pull-out) were performed, which showed that the modified K-nails exhibited significantly better osseointegration than the controls. Histologic examinations of the explants containing plates showed similar results, and the modified plates exhibited significantly better osseointegration than the controls. Surface nanostructuring of commercially available titanium-based implants by a very simple method - anodization - seems to be a viable method for increasing osseointegration without the use of bioactive surface coatings such as hydroxyapatite.