Indocyanine Green Loaded PLGA Film Coated Coronary Stents for Photo-Triggered in situ Biofilm Eradication

Abstract

Biofilm formation is a major impeding factor for successful angioplasty. Bacteria dwelling in the biofilm are resistant to most systemically administered antibodies necessitating stent removal which is often not a suitable option for patients suffering from coronary artery disease. In the quest to develop a suitable system for combating biofilm development on stents, we have formulated a stable titanium surface modification based on electrostatic interactions and investigated in situ. For this purpose, surface activated titanium was modified with amine rich (3-Aminopropyl)-triethoxysilane (APTES) to enable coating with a photosensitising drug containing polymer (Indocyanine green (ICG)/ poly(lactic-co-glycolic acid) [PLGA]) solution. The surface modifications were characterised using scanning electron microscopy and confocal microscopy together with antibacterial studies were used to qualitatively and quantitatively determine the antibacterial effect respectively. IR (810 nm) laser was used to trigger ICG leading to a dramatic reduction (99.96%) in bacterial viability inside the biofilm. The polymer, PLGA used in this study is a widely explored biocompatible and biodegradable polymer thereby making it an excellent choice for coating materials intended for use in biological systems. Indocyanine green on the other hand is a well-documented diagnostic agent and has gained much popularity in the recent past as a photosensitising agent for use in photodynamic therapy. Using this novel technique the photosensitising ICG could be triggered using IR laser leading to the generation of bacteriostatic reactive oxygen species at the site of irradiation. Due to the inertness of the photosensitising ICG in the absence of IR trigger, risk of antibacterial resistance could be ruled out. In the absence of biofilm formation following stent insertion/angioplasty, the ICG containing PLGA degrades with time. This first of its kind minimally invasive method would help avoid/treat bacterial infections and biofilm formation on coronary stents.