Sonodynamic excitation of nanomicelle curcumin for eradication of Streptococcus mutans under sonodynamic antimicrobial chemotherapy: Enhanced anti-caries activity of nanomicelle curcumin.

Inactivation of microorganisms related to dental caries has been considered the therapy of choice in the treatment of caries. The proposed study aims to assess the effect of sonodynamic excitation of nanomicelle curcumin (NM@Cur) compared to Cur for eradication of Streptococcus mutans under sonodynamic antimicrobial chemotherapy (SACT).The NM@Cur as a sonosensitizer was synthesized and its morphology, particle size distribution, zeta potential, and physical stability were then determined. After evaluating the Cur and NM@Cur uptake in S. mutans strain, Cur- and NM@Cur-SACT effects were determined on colony forming unit (CFU/mL) and reactive oxygen species (ROS) levels. Additionally, cytotoxicity and apoptotic effects of Cur- and NM@Cur-SACT on human gingival fibroblast (HGF) cells were assessed using MTT assay and flow cytometry analysis, respectively.

Transmission electron microscope, particle size distribution, and zeta potential analysis confirmed successful synthesis of NM@Cur. The finding of this study showed that an incubation time of 5 min to 1 h was sufficient to achieve maximal uptake of Cur and NM@Cur in S. mutans. SACT with Cur at a concentration of 50 mM and ultrasound intensity at 1.56 W/cm² for 1 min significantly reduced the count of S. mutans to 90.8%, compared to control group (P < 0.05), while the count of S. mutans decreased to 99.9% following treatment with the NM@Cur-SACT (P < 0.05), that was also confirmed via fluorescence microscopy. As well as, SACT with 50 mM NM@Cur not only had the least toxicity against HGF cells, but also showed 10.8-fold increase in intracellular ROS production.

Overall, this study revealed that NM@Cur-mediated SACT with the least cytotoxicity and apoptotic effects and the highest cellular uptake, ROS production, and antimicrobial activites could effectively inhibit the growth of the S. mutans in compare with Cur.