Small-Molecule Chemistry Effect on the Functionalization of Polydimethylsiloxane with Hydroxyapatite

Herein, polydimethylsiloxane (PDMS) surfaces are coated with hydroxyapatite (HA) using immobilization and biomineralization techniques with the aid of small molecules, namely, l-aspartic acid (AA), l-glutamic acid, and citric acid, in an effort to develop biointeractive surfaces for bone tissue-related research. The efficacy of biomineralization and immobilization techniques and the impact of small molecules on HA deposition on PDMS surfaces are investigated by chemical and morphological analysis of surfaces, besides in vitro cell culture studies. Characteristic peaks of phosphate groups at wavelengths of 569 and 603 cm⁻¹ in Fourier transform infrared spectroscopy analysis and HA's characteristic patterns identified at 26.1°, 31.7°, and 45.5° in X-ray diffraction analysis demonstrate the successful deposition of HA particles on PDMS surfaces which are also observed on scanning electron microscopy micrographs. The interaction of human fetal osteoblast cells (hFOB 1.19) with HA-deposited PDMS surfaces is evaluated with in vitro cell culture studies, which reveals increased cell metabolic activity and growth across all groups as compared to plain PDMS, with HA deposited on AA-PDMS surfaces through biomineralization being the most stimulating group. Overall, small-molecule effect on deposition of HA on PDMS substrates merits further investigation, particularly on substrates mimicking bone surface chemical and morphological features.