Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences (NILES) - Department of Laser Applications in Medical and Biological

The growing emergence of microbial resistance to antibiotics represents a worldwide challenge.Antimicrobial photodynamic inactivation (aPDI) has been introduced as an alternative technique, especially when combined with nanotechnology.Therefore, this study was designed to investigate the therapeutic merits of combined aPDI and nanoemulsion in infections caused by resistant bacterial strains. Cationic zinc (II) phthalocyanine nanoemulsions (ZnPc-NE) were prepared using isopropyl myristate (IPM) as oil phase, egg phosphatidylcholine (egg PC) as emulsifier, and N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB).Nanoemulsions were characterized for particle size, polydispersity, zeta potential, viscosity, and skin deposition.The in-vitro aPDI was investigated on human resistant pathogens; gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and gram-negative multidrug-resistant strain of Escherichia coli (MDR E. coli), under different experimental conditions. In addition, in-vivo model of abrasion wound infected by MDR E. coli was induced in rats to investigate the therapeutic potential of the selected formulation. It was evident that the selected ZnPc formulation (20% IPM, 2% egg PC and 0.5% CTAB) displayed a particle size of 209.9 nm, zeta potential +73.1 mV, and 23.66% deposition of ZnPc in skin layers. Furthermore, the selected formulation combined with light achieved almost 100% eradication of the two bacterial strains, with superior bacterial load reduction and wound healing properties in-vivo, compared to either the nanoemulsion formulation or laser alone.This delineates that ZnPc nanoemulsion improved antimicrobial photodynamic therapy in inactivating resistant bacterial infections and introduced a promising therapeutic means of treating serious infections, and could be applied in diseases caused by other bacterial strains

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