Fabrication and characterization of hydrophilized porous PLGA nerve guide conduits by a modified immersion precipitation method

Abstract

Nerve guide conduits (NGCs) with selective permeability and hydrophilicity were fabricated using poly(lactic-co-glycolic acid) (PLGA) and Pluronic F127 by a modified immersion precipitation method developed by our laboratory. The hydrophilized porous PLGA tubes as NGCs were fabricated by immersing a water-saturated rod-shape alginate hydrogel into PLGA/Pluronic F127 mixture solution (in tetraglycol). The PLGA/Pluronic F127 mixture was precipitated outside the alginate hydrogel rod by the diffusion of water from the hydrogel rod into PLGA/Pluronic F127 mixture solution. The inner diameter and wall thickness of tubes could be easily controlled by adjusting the diameter of alginate hydrogel rod and immersion time, respectively. It was observed that the tube wall has an asymmetric column-shape porous structure. The inner surface of the tube had nano-size pores ( approximately 50 nm), which can effectively prevent from fibrous tissue infiltration but permeate nutrients and retain neurotrophic factors, while the outer surface had micro-size pores ( approximately 50 microm), which can allow vascular ingrowth for effective supply of nutrients and oxygen into the tube. From the investigations of mechanical property, water absorbabiliy, and model nutrient permeability of the tubes, the hydrophilized PLGA/F127 (3 wt %) tube seems to be a good candidate as a NGC for the effective permeation of nutrients as well as the good mechanical strength to maintain a stable support structure for the nerve regeneration.