Effects of poly(lactic-co-glycolic acid) (PLGA) degradability on the apatite-forming capacity of electrospun PLGA/SiO2-CaO nonwoven composite fabrics

Abstract

We investigated the effects of poly(lactic-co-glycolic acid) (PLGA) degradability on the apatite-forming ability of electrospun PLGA/SiO 2-CaO gel composite fabric. Two PLGA copolymer compositions with low and high degradability were used in experiments. A nonwoven polymer/ceramic composite fabric composed of randomly mixed microsized biodegradable PLGA fibers and nanosized bioactive SiO2-CaO gel fibers was prepared using a simultaneous electrospinning method. A 17 wt.% PLGA solution was prepared using 1,1,3,3-hexafluoro-2-propanol as a solvent, while the SiO2-CaO gel solution was prepared via a condensation reaction following hydrolysis of tetraethyl orthosilicate under acidic conditions. PLGA and SiO2-CaO gel solutions were spun simultaneously with two separate nozzles under electric fields of 1 and 2 kV/cm using two syringe pumps with flow rates of 7.5 and 5 mL/h, respectively. As controls, low and high degradable PLGA and SiO 2-CaO gel nonwoven fabrics were also made by the same methods. The five nonwoven fabrics that were produced were exposed to simulated body fluid (SBF) for 1 week. SBF exposure resulted in the deposition of a layer of apatite crystals on the surfaces of both the SiO2-CaO gel and the low degradable PLGA/SiO2-CaO gel composite fabrics, but not on the low and high degradable PLGA or the high degradable PLGA/SiO2-CaO gel composite fabrics. The results are explained in terms of the acidity of the PLGA degradation products, which could have a direct influence on apatite dissolution.