SYNTHESIS AND CHARACTERIZATION OF LYSOZYME-COATED AND Ag-ENCAPSULATED POLYDOPAMINE NANOPARTICLES WITH POTENT ANTIBACTERIAL ACTIVITY

In recent years there has been a great interest in the antibacterial activity of polydopamine nanoparticles (PDA-NPs), especially of those containing metals. We have recently demonstrated that Ag-containing PDA-NPs exhibit potent antibacterial and antibiofilm activities against a variety of bacteria, including gram-positive S. aureus and S. mutans, and gram-negative E. coli and P. aeruginosa. In this study, we report the synthesis and antibacterial activity of PDA-NPs containing the antibacterial enzyme Lysozyme on their shell and encapsulating Agº nanoparticles in their core. The new PDA-NPs were characterized using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), which confirmed the presence of Ag in the core of the particles. The presence of Lysozyme on the shell of the PDA-NPs was confirmed with immuno-staining method using fluorescence activated cell sorting (FACS) while inductively coupled plasma AES (ICP) was used to determine the amount of Ag metal in the PDA-NPs core. The hybrid PDA-NPs demonstrated higher antibacterial activity and lower cell toxicity as compared to commercially available antibacterial Ag-NP, which is associated most probably from the synergistic effect of the membrane active Lysozyme and encapsulated Ag-NPs. The high antibacterial activity of the hybrid PDA-NPs with their lower toxicity suggest that PDA-NPs could be used as multi-functional antimicrobial platform against wide-range of bacteria with limited resistance development. These particles can be applied in coating of gauze bandages surfaces and possibility of bio-medical devices such as catheters with antibacterial and antibiofilm activity to prevent infections.