effect of antimicrobial photodynamic therapy using indocyanine green doped with chitosan nanoparticles on biofilm formation-related gene expression of aggregatibacter actinomycetemcomitans

Objectives: eradication of aggregatibacter actinomycetemcomitans (a. actionmycetemcomitans), as an opportunistic periodontopathogen, and inhibition of its virulence factor expression require a new adjunctive therapeutic method. in this study, we accessed the expression level of rcpa gene, as a virulence factor associated with a. actinomycetemcomitans biofilm formation, following treatment by antimicrobial photodynamic therapy (apdt) using indocyanine green (icg) doped with chitosan nanoparticles (cs-nps@icg). materials and methods: cs-nps@icg was synthesized and examined using scanning electron microscopy (sem). a. actinomycetemcomitans atcc 33384 strain was treated with cs-nps@icg, as a photosensitizer, which was excited with a diode laser at the wavelength of 810 nm with the energy density of 31.2 j/cm². quantitative real-time polymerase chain reaction (qrt-pcr) was performed to determine the changes in rcpa gene expression level. results: synthetized cs-nps@icg was confirmed via sem. the results revealed that cs-nps@icg-mediated apdt could significantly decrease rcpa gene expression to 13.2-fold (p<0.05). there was a remarkable difference between apdt using csnps@ icg and icg (p<0.05). the diode laser, icg, and cs-nps@icg were unable to significantly downregulate rcpa gene expression (p>0.05). conclusion: apdt with cs-nps@icg leads to a decrease of the virulence factor of a. actinomycetemcomitans and can be used as an adjunct to routine treatments for successful periodontal therapy in vivo.