Targeted Photodynamic Therapy: Gluconamide-Modified Cellulose Nanocrystals as Efficient Photosensitizer Delivery Platforms Against Gram-Negative Bacteria

Antimicrobial Photodynamic Therapy (aPDT) is an emerging strategy to fight against resistant pathogenic bacteria, which is considered a serious health problem. In this work, we described the functionalization of cellulose nanocrystals (CNC) with two photosensitizers (PS): one cationic and the other anionic, Rose Bengal (RB) and Toluidine Blue O (TBO), respectively, together with a specific target, gluconamide, as potential nanosystem for a PDT against Gram-negative bacteria such as Escherichia Coli (E. coli). The nanosystems loaded with the photosensitizers (PS@CNC) are chemically and photophysically characterized and tested in E. coli bacteria comparing their cyto- and phototoxicity with the PSs in solution. The resultant PS@CNC have reduced the inherent cytotoxicity of PSs in dark conditions maintaining their phototoxicity activity under green and red irradiation for RB@CNC and TBO@CNC, respectively. The presence of gluconamide as the target has improved the phototoxic of the nanosystem.