Enhancement of 5-aminolevulinic acid phototoxicity by encapsulation in polysaccharides based nanocomplexes for photodynamic therapy application

Polysaccharides based nanocomplexes have been developed for encapsulation, controlled delivery and to enhance the phototoxicity of the photosensitizer 5-aminolevulinic acid for application in photodynamic therapy. The nanocomplexes were prepared by coacervation in a solvent free environment using chitosan as polycation while alginic and polygalacturonic acid as polyanions. The complexes showed average dimension in the range 90-120 nm, good stability in simulated physiological media and high drug encapsulation efficiency, up to 800 mu g per mg of carrier. Release studies demonstrate the possibility to tune the overall release rate and the intensity of the initial burst by changing the external pH. Cytotoxicity and photocytotoxicity tests confirmed the not toxicity of the used polysaccharides. Cell viability results confirmed the improvement of 5-aminolevulinic acid photo toxicity when loaded into the carrier compared to the free form. No effect of the irradiation on the nanocomplexes structure and on the release kinetics of the drug was observed. The results demonstrate that the prepared formulations have suitable properties for future application in photodynamic therapy and to ameliorate the therapeutic efficacy and overcome the side-effects related to the use of the photosensitizer 5-aminolevulinic acid.