Evaluation of 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 deactivating different strains of bacteria. Ag NPs were synthesized by pulsed laser ablation technique in different aqueous solutions like 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, when 532nm wavelength is used, the average size was found to be 4nm, 7nm, and 10nm respectively. The synthesized Ag NPs were characterized using a transmission electron microscopy (TEM), UV-vis, and photoluminescence (PL) spectra. These Ag NPs were combined with MB and used to deactivate the Gram-negative bacteria, Escherichia coli (E. coli), and Gram-positive bacteria, Staphylococcus aureus (S. aureus). MB and Ag NPs combination was found to possess higher antimicrobial activity in comparison to MB and Ag NPs alone. Within 6 min of irradiation time with 660 nm LED, the MB/Ag NPs deactivated entire similar to 10(8) CFU/mL concentrated S. aureus and E. coli, bacteria. 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.