Conjugate of chitosan nanoparticles with chloroaluminium phthalocyanine: Synthesis, characterization and photoinactivation of Streptococcus mutans biofilm

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) using chloroaluminium phthalocyanine (ClAlPc) has high oxidative power allowing for the control of biofilms, especially when the photosensitizer is administered in an appropriate release vehicle. This study aimed to develop/characterize the ClAlPc encapsulated in chitosan nanoparticles (CSNPs), and evaluate its antimicrobial properties against S. mutans biofilms. METHODS: . The aPDT toxicity was verified by dark phototoxicity. The antimicrobial activity was verified by CFU/mL and biofilm was analyzed by scanning electron microscopy (SEM). The number of viable bacteria was analyzed by ANOVA and Tukey HSD tests (α = 0.05). RESULTS: The characterization revealed that the ClAlPc nanoparticles were found in nanometer-scale with adequate photophysical and photochemical properties. The aPDT mediated by ClAlPc + CSNPs nanoconjugate showed a significant reduction in the viability of S. mutans (1log10 CFU/mL) compared to the negative control (PBS, p < 0.05). The aPDT mediated by ClAlPc was similar to PBS (p > 0.05). SEM revealed change in biofilm morphology following the treatment of bacteria with aPDT ClAlPc + CSNPs. Cells were arranged as single or in shorted chains. Irregular shapes of S. mutans were found. CONCLUSION: ClAlPc nanoparticles are considered stable and aPDT mediated by ClAlPc + CSNPs nanoconjugate was effective against S. mutans biofilm.