Abstract
Antimicrobial photodynamic therapy (APDT) has been considered to treat skin diseases infected by drug resistant microorganisms. In this work, attempts were made to study the effectiveness of APDT with protoporphyrin IX (PPIX) in the presence of gold nanoparticles (GNPs) or hydrogen peroxide (H2O2) against the human bacterial pathogen,Staphylococcus aureus. To photoactivate the PPIX, xenon light source was used at 626 nm. The bactericidal effect was analyzed by standard plate counting method. Attemptswere also made to study whether fluorescence spectroscopy can be used to characterize the damage at protein level. Results of the study revealed that PPIX with H2O2 has showed higher bactericidal effect than that of PPIX alone and PPIX with GNPs. From fluorescence spectroscopic characterization it was found that protein damage is one of the reasons of bactericidal effect as there is a considerable change in the intensity of emission and fluorescence lifetime of tryptophan present in the microorganism between pre and post APDT. Key words: Photodynamic therapy, hydrogen peroxide, gold nanoparticles,Staphylococcus aureus, antimicrobial photodynamic therapy.
Highlights
Staphylococcus aureus is one of the serious human pathogens, which causes a wide range of diseases such as wound infections, syptic arthritis, osteomyelitis and endocarditis (Chopra, 2003; Gemmell, 2004)
Attempts were made to study the effectiveness of Antimicrobial photodynamic therapy (APDT) with protoporphyrin IX (PPIX) in the presence of gold nanoparticles (GNPs) or hydrogen peroxide (H2O2) against the human bacterial pathogen, Staphylococcus aureus
From fluorescence spectroscopic characterization it was found that protein damage is one of the reasons of bactericidal effect as there is a considerable change in the intensity of emission and fluorescence lifetime of tryptophan present in the microorganism between pre and post APDT
Summary
Staphylococcus aureus is one of the serious human pathogens, which causes a wide range of diseases such as wound infections, syptic arthritis, osteomyelitis and endocarditis (Chopra, 2003; Gemmell, 2004). Methicillinresistant S. aureus (MRSA) strains are considered to be the most dangerous, as they cause and develop infections efficiently and they are exhibit resistant to all types of β-lactam antibiotics and other antimicrobials (Nakonieczna et al, 2010). Many studies are focused on the development of new treatment modalities to treat the drug drug resistant pathogenic microorganisms such as MRSA. Photodynamic therapy (PDT) is most commonly used for various oncological applications, it has been considered for many non-oncological applications (Wilson, 2004). Antimicrobial PDT (APDT) is one of the non-oncology applications. The activation of the PS leads to the generation of reactive oxygen species (ROS) results in cytotoxic effect
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