Effect of bore fluid composition on poly(lactic-co-glycolic acid) hollow fiber membranes fabricated by dry-jet wet spinning

Abstract

Poly(lactic-co-glycolic acid) (PLGA) is a widely used polymeric biomaterial due to its excellent biocompatibility and biodegradation. Asymmetric PLGA hollow fiber membranes (HFMs) have been extensively used as porous tubular scaffolds for tissue engineering, e.g. for nerve conduits and artificial blood vessels. PLGA HFMs are generally fabricated through a dry-jet wet spinning process, and the porous morphology of PLGA HFMs induced by polymer/solvent/nonsolvent ternary phase inversion plays a key role in their biomedical performance. In this study, PLGA was dissolved in dimethyl sulfoxide (DMSO) as the dope fluid, and deionized water with different DMSO contents was used as the bore fluid. The influence of bore fluid composition on the HFM morphology and performance was investigated by measuring phase separation time, porosity, mechanical properties, and in vitro hydrolytic degradation. The results indicated that with increased bore fluid DMSO content, the inner and outer diameters, as well as the wall thickness of the HFMs, decreased significantly; also, the inner surface became more porous and the inner surface pore size and porosity increased. Cross-sectional SEM images showed that the middle layer of the five-layered microstructure gradually changed from large voids to finger-like microvoids when the DMSO content in bore fluid increased from 0% to 60%. Furthermore, the HFMs resulting from higher DMSO content in bore fluid had a lower porosity, a faster degradation rate, a higher Young's modulus, and a lower suture retention strength. More importantly, the in vitro cell culture on the inner surface of PLGA HFMs showed that PC12 cells cultured on HFMs prepared with 60% DMSO bore fluid exhibited better cell adhesion, longer neurite length, and alignment along the HFM longitudinal axis. A ternary phase diagram and the Flory-Huggins theory were applied to analyze HFM morphological formation. The study contributes to understanding of the mechanism of HFM porous morphology formation and should guide potential application of PLGA HFMs as tissue engineering scaffolds.