A gel track-assisted light-driven micromotor system moving on complex solid substrates for visually targeted biofilm eradication and dental caries prevention

Biofilms-induced dental caries poses significant challenges in oral healthcare. Current treatments, involving mechanical removal and pharmacological interventions, often result in enamel damage and drug resistance, highlighting the need for safer alternatives. Although have exhibited potential for antimicrobial applications, most micro/nano motors are confined to liquid environments and cannot operate on solid substrates, creating a bottleneck in the field. In this study, we introduce a laser-driven micromotor system (MSM) with visual guidance, specifically designed for navigation on complex solid substrates. The system consists of a graphene aerogel micromotor integrated with a temperature-sensitive gel that allows for biofilm visualization. This system enables the targeted removal of biofilms from complex surfaces, such as teeth infected with Streptococcus mutans . In addition to directional propulsion guided by light irradiation, the MSM converts light into heat, triggering a thermogenic gel-sol phase transition in the gel, which creates a controlled pathway for micromotor movement. The plaque-disclosing agent in the gel visualizes bacterial biofilms, guiding precise ablation. Comprehensive characterization demonstrated that MSM is biocompatible and effectively disrupts bacterial membranes and interferes with bacterial metabolism, leading to the eradication of biofilms without damaging the underlying tooth structure. MSM provides new perspectives for dental caries treatment and offers promising solution for light-driven micromotor movement on solid substrates.