Curcumin Internalization in Streptococcus mutans Biofilms: A Confocal Microscopy Analysis

Streptococcus mutans is one of the main harmful agents to oral health, exhibiting high resistance in its biofilm form. This study evaluated curcumin as a photosensitizer in photodynamic inactivation (PDI), monitoring its internalization time and activity. The biofilm was cultured for 24 h and treated with curcumin activated by two-photon excitation (800 nm). After photodegradation, curcumin continued to penetrate effectively into the biofilms, replacing previously degraded molecules with new ones and constantly generating reactive species (ROS and singlet oxygen) capable of damaging the bacteria. This contrasts with previous studies that reported limitations of natural photosensitizers in this context. Therefore, the principal contribution of this study is the in vitro demonstration of the dynamic efficacy of curcumin in the complex biofilm environment. The use of confocal microscopy was essential to visualize and quantify the effects of curcumin, highlighting its value as an analytical tool in the evaluation of biofilm treatments.