CAPTISOL®/PORPHYRIN NANOCOMPLEXES WITH ANTIMICROBIAL PHOTODYAMIC PROPERTIES

The development of new biocompatible delivery systems enabling controlled release of phototherapeutic agents is one of the most active areas in the field of nanomedicine. Antimicrobial photodynamic therapy (aPDT) is a promising approach to treat bacterial infections that are recalcitrant to antibiotics. Following our previous investigation on nanophototherapeutics [1], here we propose the design and characterization of a novel photosensitizing nanosystem based on the marketed cyclodextrin CAPTISOL® (sulphobutylether-beta-cyclodextrin, SBE-beta-CD) to fabricate efficient biocompatible system for aPDT. Firstly, interaction studies were carried out in order to investigate the complexation between CAPTISOL® with the tetracationic water soluble meso-tetrakis(N-methylpyridinium- 4-yl)porphine (TMPyP). Nanocomplexes based on CAPTISOL® and TMPyP (NanophotoCapitsol) were prepared in aqueous media and characterized by complementary spectroscopy and microscopic techniques such as UV/vis, fluorescence spectroscopy, AFM and scanning-near field optical luminescence (SNOL), thus investigating complex stoichiometry, stability constant, photophysical and morphological properties. Furthermore, size and z- potential were measured by Dynamic Light Scattering and Electrophoretic Light Scattering. Release and stability studies were performed in physiological conditions pointing out the role of CAPTISOL® to sustain the photosensistizer release. Finally, photoantimicrobial activity of the NanophotoCapitisol vs free porphyrin were investigated against Gram-negative Pseudomonas aeruginosa ATCC 27853, showing as the proposed nanosystems can control the time-release of porphyrin to photokill Gram-negative bacterial cells.