Synergistic Effect of Polydopamine and Gallium Ion Doping on Photothermal and Antibacterial Properties of Hydroxyapatite

Hydroxyapatite (HA) is widely used in biomedical and tissue engineering due to its bioactivity and biocompatibility. Ion doping of HA can improve mechanical, chemical or biological properties, and compositing with other materials can empower the material additional properties such as photocatalytic, photothermal, et al. The incorporation of Ga³⁺ can further increasse the bioactivity and antimicrobial activity of HA, and polydopamine (PDA) has excellent photothermal conversion ability as a photothermal material, which is widely used in anti-tumor and antimicrobial applications. In this study, GaHA (Ga-doped HA) with different doping amounts and different pH hydrothermal environments was prepared by hydrothermal method, and then GaHA@PDA composites were synthesized by coating GaHA with PDA to realize the synergistic antimicrobial effect of Ga³⁺ and PDA. The findings demonstrated that the doping level of Ga³⁺ and surface shape were influenced by the pH and Ga³⁺ concentration of the gallium-containing solution. At a pH of 13, the doping amount of Ga³⁺ in short rod nanoparticles gradually decreases with increasing pH during preparation. Meanwhile the mass fraction of HA is increased from 6.7 to 100%. 1GaHA@PDA has the best photothermal performance. Under the suitable conditions, the solution temperature reach 50 °C, and its photothermal conversion efficiency is high up to 41.2%. And it has good cycle stability. Subsequent in vitro antimicrobial and cellular experiments showed that the prepared GaHA@PDA composites had an antimicrobial rate of more than 99% and no significant cytotoxicity. It shows good biocompatibility and antimicrobial ability. It has promising application prospects in the fields of photothermal antimicrobial and biomedicine.