Biosupramolecular complexes of amphiphilic photosensitizers with human serum albumin and cucurbit[7]uril as carriers for photodynamic therapy

Abstract

In the present work, we evaluated the supramolecular interactions between three photosensitizers, namely toluidine blue O (TBO, positively charged) and two fatty acid conjugates of 6 and 14 carbon atoms chain lengths (TBOC6 and TBOC14), with human serum albumin (HSA) and the macrocycle cucurbit[7]uril (CB[7]), alone or in combination within a biosupramolecular system as potential carriers of photosensitizers for Photodynamic therapy (PDT). Binding studies were carried out using photophysical and calorimetric techniques and accompanied with molecular docking simulations. Amphiphilic photosensitizers, particularly TBOC14, showed stronger binding to HSA and (CB[7]). Comparing the different delivery systems, (CB[7]) had a marginal effect on cell uptake and phototoxicity in HeLa cells, while HSA showed enhanced cell uptake with phototoxicities that depended on the photosensitizer. Despite low cell uptake, the combination of both (CB[7]) and HSA was the most phototoxic, which illustrates the potential of combining these systems for PDT applications.

Keywords: Biosupramolecular; Cucurbit[7]uril; Human serum albumin; Photodynamic therapy; Toluidine blue.