Structural characterization, photothermal effect and biological properties of La/Ga ion co-doped hydroxyapatite coated with polydopamine

Pure hydroxyapatite (HA) and La³⁺/Ga³⁺ co-doped HA were made using a straightforward hydrothermal method and later coated with the photothermal agent polydopamine (PDA). In addition to testing the HA of uncoated PDA in an alkaline environment (pH = 13), the influence of doping quantity and pH on the warming of solid/liquid samples was methodically examined and compared. The results show that among the same series of samples, 1La1GaHA13@PDA (pH = 13, doping amount of 1) has the optimal photothermal heating capacity. Enhancing the photothermal efficiency of the specimens is better achieved through co-doping, and the light absorption ability of the dopamine-modified samples is much stronger than that of the unmodified samples. It is estimated that the photothermal conversion efficiency of 1La1GaHA13@PDA is 67.68 %. E. Coli and S. aureus are used to test the photothermal sterilization performance of various samples. Light irradiation dramatically increases the antimicrobial rate of PDA-coated samples, with 1La1GaHA13@PDA being able to achieve more than 99 % against two types of bacteria. The cellular MTT assay showed that 1La1GaHA13@PDA was able to promote the proliferation of MC3T3-E1 osteoblasts at a low concentration of 50 ug/mL, with good biocompatibility.