Photodynamic inactivation using Pluronic® F-127 conjugated curcumin on the biofilm of Streptococcus mutans

Author(s)

Diego Dantas Lopes dos Santos

• Document type: Master's Dissertation
• Press: Araraquara. 2019-07-16.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2019-03-04
• Advisor: Alessandra Nara de Souza Rastelli

Abstract

Photodynamic inactivation is described as promising therapy in the inactivation of oral microorganisms. Curcumin is a hydrophobic photosensitizer, which can compromise its efficiency. Thus, the development of studies that verify its effect when conjugated to polymeric micelles becomes relevant. The objective of this study was to evaluate the effectiveness of photodynamic inactivation in Streptococcus mutans biofilm using curcumin, conjugated or not, to micelles as photosensitizer, irradiated by LED light. The characterization of the polymeric micelles in the 0.1% and 0.5% concentrations of curcumin was carried out by Zeta Potential, determination of dynamic light scattering, transmission electron microscopy and investigation of the mechanisms involved in the photodynamic reaction. After that, the best concentration to be used in photodynamic inactivation on Streptococcus mutans biofilm was selected. Minimum inhibitory concentrations (MIC), minimal bactericidal (MBC) were determined. Single-species biofilms were induced in 96-well plate. The biofilms were uniformly irradiated with a LED illumination system (Biotable, MMO) at wavelength of 460 nm with dose or energy density of 15 J/cm2. Colony forming units (CFU / mL) from CIM and CBM were obtained. By means of confocal microscopy using BacLight® LIVE/DEAD dye, cell viability in biofilms was evaluated. Different groups were analyzed: FSM+L+ (Photosensitizer conjugate micelles Pluronic + Light), FSD+L+ (Photosensitizer in 10% DMSO + Light), M+L+ (Micelles Pluronic + Light), D+L+ (10% DMSO + Light), FS-L+ (Milli-Q Water+ Light), FSM+L- (Photosensitizer conjugated Pluronic micelles - Light) FSD+L- (Photosensitizer in 10% DMSO - Light), M+L- (Micelles Pluronic - Light), FSL- (Milli-Q Water- Light: Negative control group) and C+L- (Chlorhexidine 0.2%: Positive control group). After evaluating the assumptions of normality and homoscedasticity, the data were submitted to Analysis of Variance (ANOVA) and ANOVA with Welch correction, for multiple comparison was used Post-hoc GamesHowell and Post-hoc of Tukey. Both tests were performed at a significance level of 5%. For the groups treated with light and value of α < 0,05 the results showed that the groups FSM+L+ (3,41log10) and FSD+L+ (1,92log10) were similar (p=0,122) and different from M+L+, D+L+ e FS-L+ (p0,027). The viability of Streptococcus mutans in the presence of curcumin conjugated to micelles was substantially reduced by irradiation with LED light. Thus, it becomes feasible to use Pluronic® F-127 micelles as a viable alternative for curcumin to be used for photodynamic inactivation, without the need for prior incorporation of curcumin to solvents such as ethanol and DMSO. (AU)

• FAPESP's process: 17/17839-4 - Photodinamic inactivation using curcumin conjugated to pluronic ®F-127 on Streptococcus mutans and Candida albicans biofilm
• Grantee: Diego Dantas Lopes dos Santos
• Support Opportunities: Scholarships in Brazil - Master