Investigation on biomimetic mineralization and its effect on MG-63 cell behavior on poly L-lactic acid surfaces through poly (2-methacryloyloxyethyl phosphorylcholine) conjugation

Abstract

The purpose of this study was to introduce phosphate groups into orthopedic polymeric material, so that they adsorb calcium ions when in contact with body fluids and form hydroxycarbonate apatite (HCA), thereby encouraging biomimetic mineralization. To this end, poly L-lactic acid (PLLA) discs were conjugated with poly (2-methacryloyloxyethyl phosphorylcholine-co-2-aminoethyl methacrylate hydrochloride) (PLLA/PMPC) to introduce phosphate groups to provide mineralization sites on the surface of PLLA. PLLA discs were treated with NaOH and ethanol to create OH and COOH groups on the surface, then coupled with the amine groups of PMPC in a condensation reaction. For biomimetic mineralization, PLLA/PMPC discs were immersed in simulated body fluid (SBF) for 14 days to induce HCA formation (PLLA-PMPC/HCA). The surface modification was analyzed using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurements, and X-ray Diffraction (XRD). In vitro experiments showed PLLA-PMPC/HCA discs enhanced adhesion and proliferation of MG-63 cells compared to control and PLLA-PMPC discs. HCA formation was found to contribute to fibronectin adsorption, promoting focal adhesion. PLLA-PMPC/HCA discs contributed to increased integrins (α5 and β1) and FAK expression for focal adhesion and induced downstream signaling of the FAK-MAPK and PI3K-AKT pathways for proliferation.