Self-Assembly of L-Arginine on Electrophoretically Deposited Hydroxyapatite Coatings

In this study, L-Arginine (L-Arg) molecules are self-assembled on HA coatings for potential orthopedic applications. By immersing HA coatings in L-Arg solution in phosphate buffer saline (PBS) with a pH of 7.4 at room temperature for 24 hours, L-Arg assembled on HA. The samples were characterized by using Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Diffraction (XRD), Atomic Force Microscopy (AFM) and ninhydrin assay. The response of human bone marrow derived mesenchymal stem cells (hBMSCs) to HA and L-Arg/HA coatings both in growth and osteogenic differentiation medium are reported. In the growth medium, cells are found to be more spread out on L-Arg/HA coatings than HA coatings. Moreover, cell aggregates which are indicators of differentiation are observed on HA coatings spontaneously in the growth medium and cell aggregates are only observed on L-Arg/HA coatings in the osteogenic differentiation medium. Overall, this study showed that L-Arg self-assembles on HA and it hinders osteogenic differentiation of hBMSCs in the growth medium.