“Evaluation of the potential of sodium alginate films containing curcumin encapsulated in nanoparticles of chitosan associated with photodynamic therapy for the treatment of oral biofilms.”

The oral cavity is colonized by several species of microorganisms, among them, Streptococcus mutans and Candida albicans are the most prevalent and can be found organized in the form of biofilm, which can cause cavities and oral candidiasis. The conventional treatment for the removal of these oral biofilms consists of their mechanical removal associated with the systemic administration of antimicrobials, which causes several side effects to the patient, in addition to being a potential cause of microbial resistance. In this context, alternative therapies have been developed to treat diseases in the oral cavity, including Antimicrobial Photodynamic Therapy (aPDT), which is performed using a photosensitizer, such as curcumin (CUR). However, CUR has the limitation of being a hydrophobic compound and that suffers degradation in light, temperature, and alkaline conditions. One strategy to overcome these limitations is their incorporation into polymeric nanoparticles (NPs), which offer important benefits, such as improved solubility and protection against degradation. The incorporation of NPs_CUR in sodium alginate films (FA) contributes to system adhesion in the oral cavity, optimizing the application of aPDT and the antimicrobial action. This work aims to evaluate the potential of FA containing CUR encapsulated in NPs of chitosan (CS) and sodium alginate (SA) associated with aPDT for the treatment of oral biofilms. The NPs were obtained by the polyelectrolytic complexation method through the concentration of 0.3 mg / mL of QTS and 0.5 mg / mL of ALG with proportions (w/w) of 0.05:1 to 1:1 and were characterized employing the analysis of average hydrodynamic diameter (DHM), polydispersion index (PDI), zeta potential (ZP), scanning electron microscopy (SEM), encapsulation efficiency (EE) and thermal analysis. The FAs were obtained by the solvent casting method using 2% SA and 10% glycerin and were characterized by liquid absorption tests, thickness determination, water vapor permeability (PVA), mechanical properties, and mucoadhesion. An in vitro release test of the final system FA/NPs_CUR, free CUR, and NPs_CUR was performed. The minimum inhibitory (MIC) and bactericidal (CBM) concentrations against S. mutans were also determined and the photodynamic effect on the biofilms of S. mutans and C. albicans and the count of Colony Forming Units (CFU/mL) were evaluated. The NPs were successfully obtained, obtaining adequate results for all the proportions tested, mainly for 0.30: 1 sample with DHM of 181.6 nm, PDI of 0.23, and ZP of - 30.6 mV. The photomicrographs obtained by SEM showed the spherical morphology of the NPs. The incorporation of CUR kept the spherical NP with a size between 200 and 300 nm indicating that there was incorporation, and this can be affirmed by EE where it obtained the value of 32.91 to 80.23%. The FA were successfully obtained and proved to be homogeneous without fissures or bubbles and adequate mechanical and thickness properties, in addition to having PVA and considerable liquid absorption and excellent mucoadhesive properties. The in vitro release test indicates that the release is controlled by diffusion and swelling using the Korsmeyer Peppas model, with a 24-hour release profile of 92.31% for FA/NPs_CUR, 47.77% for free CUR, and 50.79 % for NP_CUR. In the MIC and CBM microbiological assay, a value of 2,175 µg / mL was obtained for free CUR and 8,7 µg / mL for NPs-CUR. The results of CFU / mL in the biofilm assays of C. albicans did not show significant log reduction between the groups tested with treatments with and without light. On the other hand, the UFC / mL assays for the S. mutans biofilm showed a reduction of 3 log10 for the group of tested NPs when compared to treatments without light. Therefore, the results are promising and suggest that the developed system has the potential for the treatment of S. mutans biofilms. (AU)