Rose Bengal (RB) is a photosensitizer dye used for eradicating cancer and microbial cells. Intralesional 10% RB (PV-10®) demonstrated to kill locoregional and metastatic melanoma, in the absence of light, by direct tumor ablation and indirect tumor death thanks to a specific immune response [1]. Nevertheless, RB is only employed in ophthalmic diagnostic because the biopharmaceutical profile limits its therapeutic use [2,3]. Since formulating RB delivery systems has proven to overcome its limits [4], this work focuses on the development of RB lipid-based nanocarriers to treat melanoma via topical application in the absence of light. Solid lipid nanoparticles (SLNs), obtained by solvent emulsification-evaporation, and transfersomes (TFs) obtained by modified reverse evaporation (REV), were prepared both blank and RB-loaded. Dimensional properties, physical stability and the interaction between RB and lipids were evaluated. For blank SLNs, 90 s of sonication at 70% US amplitude allowed to obtain a homogenous polydispersity index (PI=0.225) and stable formulation without phase separation or aggregation. About blank TFs, we obtained the best dimensional stability by REV technique: after three months, size increased from 244 nm to 497.35 nm while TFs prepared by another technique increased from 236.23 nm to 747.4 nm. Moreover, leader TFs were prepared employing ethanol instead of an initial toxic solvent mixture obtaining a safe and more homogeneous system (PI=0,166 vs PI=0.43). Dimensional studies on loaded nanosystems revealed SLNs were 130 nm-sized and TFs 230 nm, both were homogeneous (PI<0.25) and stable after one month. UV-spectrophotometer analysis showed RB maximum absorption wavelength shifted from 549 nm in water to 562 nm when it is formulated in carriers indicating an association with the lipid phase [5]. Cytotoxicity studies on melanoma cells are ongoing; further characterizations and permeation studies are planned. We obtained two stable RB formulations potentially active in eradicating melanoma via dermal delivery.

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