Ex Vivo Biosafety and Efficacy Assessment of Advanced Chlorin e6 Nanoemulsions as a Drug Delivery System for Photodynamic Antitumoral Application

Abstract

The photosensitizer (PS) in the Photodynamic Therapy (PDT) field represents a key factor, being directly connected to the therapeutic efficacy of the process. Chlorin e6 is a second-generation photosensitizer, approved by the FDA with the most desired clinical properties for PDT applications, presenting high reactive oxygen species (ROS) generation and proven anticancer properties. However, hydrophobicity is a major limitation, leading to poor biodistribution. To overcome this condition, the present work developed an up-to-date nanoemulsion incorporating Ce6 in a new nanosystem (Ce6/NE). A comprehensive study of physicochemical properties, stability, fluorescence characteristics, the in vitro release profile, in vivo and ex vivo biocompatibility, and ex vivo efficacy was established. The nanoemulsions showed the desired particle size and stability over six months, with no spectroscopic or photophysical alterations. Uptake studies demonstrated the internalization of the Ce6/NE in monolayers, with biocompatibility at the lowest concentrations. The HET-CAM assay, however, revealed a higher biocompatibility range, also indicating Ce6/NE's potential for cancer treatment through antiangiogenic studies. These findings highlight the use of a new promising photosensitizer for PDT modulated with nanotechnology that promotes low toxicity, higher bioavailability, and site-specific delivery.