Ex vivo assessment of blue laser-activated berberine-loaded nanoniosomes in enhancing photodynamic therapy against Streptococcus mutans biofilm on tooth enamel.

BACKGROUND

Dental caries is a biofilm-mediated disease primarily caused by Streptococcus mutans, which produces extracellular polysaccharides via glucosyltransferases such as GtfB, promoting biofilm formation and cariogenicity. Photodynamic therapy (PDT) has gained attention as a promising alternative to conventional antimicrobials. This study investigates the efficacy of blue laser-activated berberine-loaded nanoniosomes (nNios@Ber) in enhancing PDT against S. mutans biofilms formed on tooth enamel.

MATERIALS AND

METHODS

An ex vivo model using human tooth enamel slabs was employed to cultivate S. mutans biofilms. Berberine was encapsulated in nanoniosomes (nNios@Ber) to improve stability and delivery. Following determination of minimum inhibitory concentration (MIC) of nNios@Ber, biofilms were treated with various concentrations of nNios@Ber combined with blue laser irradiation (405 ± 10 nm) to activate PDT. Additionally, quantitative real-time PCR was used to quantify gtfB gene expression.

RESULTS

The MIC of nNios@Ber against S. mutans was found to be 15.6 μg/mL. All PDT-treated groups showed significant reductions in biofilm viability and a dose-dependent downregulation of gtfB expression. Specifically, gtfB expression decreased by 4.8-, 5.7-, and 7.4-fold in the 2 × MIC, 4 × MIC, and 8 × MIC nNios@Ber plus blue laser groups, respectively (P < 0.05). Neither nNios@Ber nor laser alone produced statistically significant effects (P > 0.05). These findings confirm that nNios@Ber's anti-biofilm efficacy is enhanced when photoactivated by blue laser.

CONCLUSION

Blue laser-activated nNios@Ber significantly inhibit S. mutans biofilm formation and virulence gene expression, offering an effective and targeted approach for caries management. This photoactivated nNios@Ber enhances the photodynamic activity, providing a promising adjunct or alternative to conventional antimicrobial agents such as CHX in oral healthcare.