Facile fabrication of pure zinc with calcium phosphate composite coatings: regulating zinc ion release for improving cellular compatibility

Zinc and its alloy counterparts are earmarked as advanced materials for crafting degradable medical equipment. The swift release of zinc ions from implants, leading to elevated local concentrations, can significantly influence cell differentiation. To tackle this, CaHPO 4 coatings were applied to pure zinc through a hydrothermal technique at temperatures of 100, 130, and 160 °C. Characterization of the coatings revealed CaHPO 4 as the dominant phase irrespective of the temperature. Immersion tests indicated that CaHPO 4 coatings could diminish zinc ion release and pH levels. All coated samples displayed superior corrosion resistance to pure zinc. Cytocompatibility studies indicated that coatings developed at the higher temperatures of 130 and 160 degrees Celsius supported cell survival and modulated the expression of osteogenic genes such as ALP, OCN, and RUNX2. Consequently, the CaHPO 4 coating can substantially enhance the controlled release of zinc ions and the cytoaffinity of pure zinc.