Extrudable salicylic acid-based poly(anhydride-esters) for injectable drug releasing applications

Abstract

Injectable biomaterials have attracted more and more interest owing to their advantages over traditional open surgeries: minimal invasive procedure and ease of handling. Commonly used synthetic injectable polymers exhibited low drug loading and poor biodegradability. In this work, we describe a novel series of degradable copolymers comprising salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) subunits suitable for injectable drug releasing applications. By tuning the rheology properties, these salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) copolymers may function as injectable drug delivery vehicles that deliver salicylic acid at the injury site. These copolymers were designed to have glass transition temperatures (Tg) below 0ºC, resulting in extrudable polymers that behave like viscous fluids at room temperature. Salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) copolymers of different ratios (2:1, 1:1, and 1:2 salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol)) were synthesized and characterized by nuclear magnetic resonance and Fourier-transform infrared spectroscopies. Their shear viscosities were determined both at room and physiological temperatures. The in vitro drug release profiles, cytotoxicity, and anti-inflammatory activities were assessed. The shear viscosities were found to compare favorably with current injectable barrier materials on the market.