PHEMA-PLLA semi-interpenetrating polymer networks: A study of their swelling kinetics, mechanical properties and cellular behavior

Semi-interpenetrating polymer networks (semi-IPNs) have attracted much attention in recent years as biomaterials with a high potential in tissue engineering and controlled drug release. In this article, semi-IPNs were synthetized by free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in the presence of poly(L-lactic acid) (PLLA) with contents of 5,10 and 20 wt.% at high temperature (150 degrees C). The study focused on the analysis of thermal and mechanical properties, wettability, swelling kinetics in buffered solutions of different pH, and biocompatibility using fibroblasts of human embryonic skin. Segregation of the components in different microdomains was verified by morphological analysis through scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) results revealed that the poly(2-hydroxyethyl methacrylate) (PHEMA) network is amorphous and the PLLA is semi-crystalline. Mechanical analysis provided Young's modulus values in the range 240-370 MPa in tensile tests, and storage modulus (E') values at 37 degrees C, 1 Hz, in the range 800-1200 MPa. Equilibrium water uptake measurements displayed material dependence on composition and pH. Swelling kinetics presented good agreement with a second-order diffusion process in all media. No sample present cytotoxicity and the cell migration process occupied many semi-IPNs pores closing them and indicating good cellular recognition. In overall, these networks can be considered for their application as scaffolds for bone defects augmentation and subchondral cartilage repair. (C) 2016 Published by Elsevier Ltd.