Photodynamic Inactivation of Staphylococcus epidermidis: Application of PEGylated Gold Nanoparticles

Nowadays, implant-related infections are considered as one of the major dangers for human health, and a novel method to ablate the related pathogens is therefore crucial. In this paper, potentials of PEGylated gold nanoparticles to load methylene blue and consequently enhance its effectiveness in photodynamic inactivation of Staphylococcus epidermidis (PTCC1114) were investigated. According to our experimental results, it was shown that PEGylated gold nanoparticles have the ability to load and preserve optical properties of methylene blue. Our studies demonstrated that photodynamic inactivation of the bacteria in an in vitro model using a red laser (630 nm and 100 mW/cm2) and methylene blue or methylene blue-PEGylated gold nanoparticles showed a superiority for the PEGylated gold nanoparticles conjugated with methylene blue. In fact, conjugation of MB with the PEGylated gold nanoparticles avoids dimer formation through preventing direct contact between MB and cellular or plasma components. Based on the results of this paper, PEGylated gold nanoparticles are proposed to improve the photodynamic inactivation of implant-related infections.