Preparation of Porous Ga-Doped TiO₂ Composite Aerogel and Its Bactericidal Activity against Escherichia coli and Staphylococcus aureus

In this work, a novel strategy for preparing Ga-doped TiO₂ composite aerogel antibacterial agent through the sol–gel method and supercritical technology is demonstrated. The specific surface area of the samples is as high as 175 m² g⁻¹ and exhibits a 3D network structure with a multistage pore distribution. The obtained antibacterial agent combines the phototoxicity of TiO₂, photo-independent toxicity of Ga³⁺, and structural properties of aerogels, showing a synergistic antibacterial effect. On the one hand, TiO₂ produces reactive oxygen species in the presence of light, thus destroying the structure of bacteria. On the other hand, Ga³⁺ competitively replaces Fe³⁺ and hinders the metabolic process of bacteria. Moreover, the structural properties of aerogels promote superior antimicrobial performance of antibacterial agents. Their antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria are mainly investigated through the inhibition zone and natural colony counting method. In the results, it is shown that the structure and bactericidal activity of TiO₂ aerogel is effectively optimized with Ga³⁺ doping. The maximum zone of inhibition of the composite aerogel against E. coli and S. aureus is 17.5 and 16 mm, and the bactericidal rate is as high as 98.57% and 96.60%, which exhibit outstanding bactericidal performance.