Biocompatible/ Bioresorbable Polymer Based Silver Nanaomaterial Coatng for Chronic Indwelling Medical Devices and Bioscaffolds for Tissue Regrowth

Abstract

The objective of this study is to synthesize and characterize antimicrobial, bio-polymer based silver nanomaterials composite coatings, for use in chronic indwelling medical devices, and bioscaffolds. The coatings and bioscaffolds are comprised of novel biomass mediated silver nano particles (SNP) that are biocompatible, highly concentrated, highly pure, cost-effective, polydispersed and compatible with a range of polymer systems applicable for use with existing chronic indwelling medical devices. This thesis is divided into three main chapters. In Chapter 1, detailed review on the need for antimicrobial nanocomposite coatings for chronic indwelling medical devices along with different SNP synthesis and characterization methods is provided. In Chapter 2 a comprehensive description of biocompatible/bioresorbable poly (L-lactide) (PLLA) based thin film coatings comprised of novel 25-75 nm silver nano particles SNP is provided. The particle and film morphology is characterized using Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and UV-Visible Spectroscopy. The release rate of SNP is profiled by Thermogravimetric Analysis (TGA) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). These coatings, suitable for chronic indwelling devices, drastically reduce the microbial biofilm formed by Staphylococcus aureus and Escherichia coli by 3-5 log reduction. This chapter details the synthesis of PLLA cast-coatings and the procedure to embed SNP, an antimicrobial agent, at a range of concentrations to identify an optimal SNP concentration of 700-800 ppm that efficacious and non-cytotoxic to human epithelial carcinoma cells (HeLa). Chapter 3 explains the procedure of making biocompatible/bioresorbable PLLA-PEG co-polymer block bioscaffolds designed to degrade and resorb at a controlled rate while providing a suitable substrate for tissue regrowth. The antimicrobial properties of these porous bioscaffolds are tested across varying concentrations of biomass mediated SNP, to determine an efficacious antimicrobial concentration. The bioscaffolds are efficacious as it reduces the Staphylococcus aureus and Escherichia coli biofilm by 92.5- 99.9%, respectively, at an antimicrobial SNP concentration of 800ppm.