Antibacterial Activity of Pulsed Laser Synthesized Silver Nanoparticles Combined with Methylene Blue for Prosthetic Joint Infection

Photosensitizing agents play an essential role in deactivation process of multidrug resistant pathogens and tumor treatments. In this work, methylene blue (MB) functionalized silver nanoparticles (Ag NPs) are used as an effective photodynamic therapy (PDT) agent for prosthetic joint infection (PJI). Ag NPs were synthesized by pulsed laser ablation technique in different aqueous solutions such as polyvinylpyrrolidone (PVP), citrate and polyvinyl alcohol (PVA) at different wavelength and power. With 1064nm wavelength, Ag NPs average size distribution in citrate, PVP, and PVA were found to be 6nm, 10nm, and 12nm respectively. Further, with 532nm wavelength it was found to be 4nm, 7nm, and 10nm respectively. The synthesized Ag NPs were characterized in depth using a transmission electron microscopy (TEM), UV–vis, and photoluminescence (PL) spectra. These Ag NPs were combined with MB and used to deactivate Escherichia coli, a Gram-negative bacterium, and Staphylococcus aureus, a Gram-positive bacterium. MB and Ag NPs combination was found to possess higher antimicrobial activity and thus were more effective in killing both Gram –positive and Gram-negative bacteria in comparison to MB and Ag NPs alone. Within 6 min of irradiation time with 660 nm LED, the MB/Ag NPs deactivated entire bacterial population containing ~10⁸ CFU/mL of E.coli. Thus, MB/Ag NPs used in PDT could be effective in killing bacterial pathogens in open wounds, prosthetic joint infections, in vivo cancer and tumor treatments. We are further exploring the effect of magnetic field during the silver nanoparticle synthesis on particle size and distribution.