The effect of surface functionalization on cell behavior

Bone-on-a-chip platforms that replicate the native bone microenvironment are indispensable for research of complex physiological conditions. Polydimethylsiloxane (PDMS) has widespread use for these platforms and needs biochemical modification to derive suitable biocompatibility and bioactivity for bone research. In this study, PDMS surfaces were coated with Hydroxyapatite (HA) using immobilization and biomineralization techniques with the aid of small molecules, namely Aspartic Acid (AA), Glutamic Acid (Glu), and Citric Acid (CA). The effectiveness of biomineralization and immobilization techniques and the impact of small molecules on HA deposition on PDMS surfaces were investigated by chemical and morphological analysis of the surfaces, besides in vitro cell culture studies. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS) spectra confirmed that the small molecule modification on both PDMS and onto nHA particles was achieved successfully. X-ray Diffraction (XRD) patterns showed characteristic peaks of HA deposited by either biomineralization or immobilization on PDMS surfaces, which were also observed with scanning electron microscopy (SEM). The interaction of human fetal human osteoblasts cells (hFOB 1.19) with HA-deposited PDMS surfaces was evaluated with in vitro cell culture studies, which revealed increased cell viability across all groups, with HA deposited on AAPDMS surfaces being the most stimulating group. Overall, it is further worthy of study on the effect of small molecules on HA deposition to the PDMS substrates, especially for those mimicking chemical and morphological features of the bone surface