Aluminum phthalocyanine hydroxide-loaded thermoresponsive biomedical hydrogel: A design for targeted photosensitizing drug delivery

Abstract Dermatological formulations can enable a more efficient therapy by directly delivering the active ingredient to the action site. Photodynamic therapy is a promising technique to eliminate the microorganism in wounds. The present work aims to obtention a dermatological bioadhesive and stimuli-responsive platform that efficiently solubilizes aluminum phthalocyanine hydroxide (AlPcOH) photosensitizer. A better formulation for dermatological application was obtained after evaluation of the formulation polymeric composition and mechanical characterization. Ex-vivo permeation and complete rheological assays were carried out. The photodynamic potential of AlPcOH was evaluated quantitatively and qualitatively. AlPcOH was shown to be incorporated mostly in monomeric form when subjected to the solid dispersion method. Satisfactory results were achieved for the formulation composed of 0.05, 20, and 0.20 % w/w of AlPcOH, F127 and Carbopol. This formulation was easily administered and presented adequate retention at the application site. Furthermore, the system showed a gelation temperature of 29.1 °C, ensuring the preparation, filling, and administration in the bodýs temperature. The nanostructured thermo-responsive platform promoted AlPcOH skin permeation effects and demonstrated a high capacity to generate reactive oxygen species (ФΔ1O2 for AlPcOH of 0.68 in ethanol). All the information provided in this study supports the potential of the AlPcOH-containing platform designed to treat wounds aggravated by microbial infections. It suggests future in vitro and in vivo applications of the platform developed.