Enhanced photo-ablation effect of positively charged phthalocyanines-detonation nanodiamonds nanoplatforms for the suppression of Staphylococcus aureus and Escherichia coli planktonic cells and biofilms

Abstract

Photodynamic antimicrobial therapy (PACT) is a powerful technic recommended to eliminate life-threatening pathogens that cause localized and superficial infections as pathogens cannot develop resistance to it. For this reason, new positively charged chalcone substituted zinc (3a) and indium (4a) metalated phthalocyanines (Pcs) were synthesized and were π-π interacted with detonation nanodiamonds (DNDs) nanoparticles to form new water soluble nanoplatfoms 3a@DNDs and 4a@DNDs. The conjugates generated high singlet oxygen quantum yields (ΦΔ) in water (1% DMSO, used for PACT studies) with values of 0.46 and 0.47 for 3a@DNDs and 4a@DNDs, respectively. Hence, they were tested for PACT against biofilms of S. aureus and E. coli, as well as their planktonic cells. The quaternized Pcs alone 3a and 4a as well as their nanoconjugates 3a@DNDs and 4a@DNDs were effective PACT agents with log10 CFU > 9 for E. coli and S. aureus. The quaternized derivatives were found to have higher ability to completely suppress both planktonic and biofilms of S. aureus and E. coli in vitro. Therefore, they could be used as appropriate photosensitive agents.