Antimicrobial photodynamic inactivation of fungal biofilm using amino functionalized mesoporus silica-rose bengal nanoconjugate against Candida albicans

Candida albicans is an opportunistic fungal pathogen that causes both superficial and systemic infection and an important candidate that contribute to high morbidity and mortality rates in immunocompromised patients. The ability of C albicans to switch from yeast to filamentous form and thereby forming biofilms make them resistant to most of the antifungal drugs available today. Thus the development of more effective antifungal drugs are essential and crucial at this point of time. Antimicrobial photodynamic therapy is an alternative modality to treat such biofilm forming resistant strains. This study aims to investigate the enhanced efficiency of newly synthesized MSN-RB conjugate as an antimicrobial photosensitizer for antimicrobial photodynamic therapy against C albicans. Functionalization of MSN with amino groups was performed to increase the dye loading capacity. Conjugation process of MSN-RB was confirmed using different techniques including UV-Vis spectroscopy, Fluorescent spectroscopy and FTIR analysis. A low power green laser 50 mW irradiation was applied (5 min) for activation of MSN-RB conjugate and RB against C albicans biofilm and planktonic cell. The comparative study of MSN-RB conjugate and free RB on aPDT was evaluated using standard experimental procedures. Antibiofilm efficacy was determined using biofilm inhibition assay, cell viability, EPS quantification and CLSM studies. The results revealed that MSN-RB conjugate has a significant antimicrobial activity (88.62 +/- 3.4%) and antibiofilm effect on C albicans when compared to free dye after light irradiation. The MSN-RB conjugate based aPDT can be employed effectively in treatment of C albicans infections. (C) 2018 The Authors. Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.