Effect of photodynamic therapy with imipenem and gentamicin-derived carbon dots on the expression of quorum sensing and virulence genes in Pseudomonas aeruginosa

The capability of Pseudomonas aeruginosa to cause various severe infections is linked to the production of various virulence factors, regulated by quorum sensing. The objective of this study was to assess the effect of sub-lethal doses of antimicrobial photodynamic inactivation (sAPDI), employing carbon dots (CDs) derived from gentamicin and imipenem, on the expression of genes in two key quorum sensing systems (the rhl and las systems) and on the genes responsible for producing elastase (lasB), protease (lasA), rhamnolipid (rhlA), and pyocyanin (phzM) in P. aeruginosa. CDsGEN-NH2, and CDsIMP-NH2 were synthesized from gentamicin and imipenem precursors through the hydrothermal method. The Conjugation of imipenem to CDsGEN-NH2 (CDsGEN-IMP) and gentamicin to CDsIMP-NH2 (CDsIMP-GEN) was done. The study evaluated the effect of sAPDI at sub-minimum biofilm inhibitory concentrations (sub-MBIC) of CDs, combined with a sub-lethal dose of UVA light, on the expression of QS and virulence encoding genes using real-time quantitative polymerase chain reaction (RT-qPCR). Following treatment with sAPDI, there was a notable decline in the expression levels of QS and virulence genes compared to the control (P < 0.05). Conversely, treatment with sub-MBIC concentrations of CDs and a sub-lethal dose of UVA light irradiation alone did not significantly alter the expression of these genes relative to the control group (P > 0.05). The findings indicate that sAPDI, employing CDs sourced from imipenem and gentamicin combined with UVA light exposure, leads to a decrease in the expression of genes related to quorum sensing and virulence in P. aeruginosa.