Characterization and in vitro cytotoxicity evaluation of fish scale and seashell derived nano-hydroxyapatite high-density polyethylene composite

Hydroxyapatite (HAp) is the major inorganic component of natural bone which exhibits better biocompatibility with various kinds of cells and tissues, making it an ideal candidate for dental and orthopedic applications. The naturally extracted HAp (Ca10(PO4)6(OH)2) from fish scale and seashell is exactly matched with the chemical composition of bone minerals. Nowadays, soft chemistry is used for the synthesis of bioceramics such as HAp. This is a chemical route that yields more homogeneous solid-state materials. In this study, the extracted powder from fish scale and seashell was heated in the furnace and maintained at 700°C for 3 hours and the powder was naturally cooled. The derived CaO was used for preparing HAp by the microwave irradiation techniques. The HAp was filled with High-Density Polyethylene (HDPE) in the ratio of 10:3 (Matrix 100 g: Filler 30 g) and composite was fabricated by the injection molding. The functional groups present in the HAp-HDPE specimen was identified using Fourier Transform Infrared (FTIR) spectroscopy analysis. The thermal stability of 30 wt. % HAp-HDPE composite was analyzed using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). In vitro cytotoxicity studies were carried out using MG63 cell line. In these studies, five different volumes of liquid extracts of the prepared HAp-HDPE specimen having different concentrations (10, 20, 30, 40, and 50 μl) were allowed to interact with fresh cell culture medium for 24 hours. The cell morphology, cell viability, and the levels of cytotoxicity of the composite specimen were studied as per 10993:12, and ISO 10993:5 test standards.