Phototoxic Potential of Different DNA Intercalators for Skin Cancer Therapy: In Vitro Screening.

Photodynamic therapy is a minimally invasive procedure used in the treatment of several diseases, including some types of cancer. It is based on photosensitizer molecules, which, in the presence of oxygen and light, lead to the formation of reactive oxygen species (ROS) and consequent cell death. The selection of the photosensitizer molecule is important for the therapy efficiency; therefore, many molecules such as dyes, natural products and metallic complexes have been investigated regarding their photosensitizing potential. In this work, the phototoxic potential of the DNA-intercalating molecules-the dyes methylene blue (MB), acridine orange (AO) and gentian violet (GV); the natural products curcumin (CUR), quercetin (QT) and epigallocatechin gallate (EGCG); and the chelating compounds neocuproine (NEO), 1,10-phenanthroline (PHE) and 2,2'-bipyridyl (BIPY)-were analyzed. The cytotoxicity of these chemicals was tested in vitro in non-cancer keratinocytes (HaCaT) and squamous cell carcinoma (MET1) cell lines. A phototoxicity assay and the detection of intracellular ROS were performed in MET1 cells. Results revealed that the IC50 values of the dyes and curcumin in MET1 cells were lower than 30 µM, while the values for the natural products QT and EGCG and the chelating agents BIPY and PHE were higher than 100 µM. The IC50 of MB and AO was greatly affected by irradiation when submitted to 640 nm and 457 nm light sources, respectively. ROS detection was more evident for cells treated with AO at low concentrations. In studies with the melanoma cell line WM983b, cells were more resistant to MB and AO and presented slightly higher IC50 values, in line with the results of the phototoxicity assays. This study reveals that many molecules can act as photosensitizers, but the effect depends on the cell line and the concentration of the chemical. Finally, significant photosensitizing activity of acridine orange at low concentrations and moderate light doses was demonstrated.

Engineering dual-stimuli responsive poly(vinyl alcohol) nanofibrous membranes for cancer treatment by magnetic hyperthermia.

The development of new cancer treatment options, such as multifunctional devices, allows for a more personalized treatment, avoiding the known severe side effects of conventional options. In this context, on-demand drug delivery systems can actively control the rate of drug release offering a precise control of treatment. Magnetically and thermally controlled drug delivery systems have been explored as on-demand devices to treat chronic diseases and cancer tumors. In the present work, dual-stimuli responsive systems were developed by incorporating Fe3O4 magnetic nanoparticles (NPs) and poly(N-isopropylacrylamide) (PNIPAAm) microgels into electrospun polymeric fibers for application in cancer treatment. First, Fe3O4 NPs with an average diameter of 8 nm were synthesized by chemical precipitation technique and stabilized with dimercaptosuccinic acid (DMSA) or oleic acid (OA). PNIPAAm microgels were synthesized by surfactant-free emulsion polymerization (SFEP). Poly(vinyl alcohol) (PVA) was used as a fiber template originating fibers with an average diameter of 179 ± 14 nm. Stress tests of the membranes showed that incorporating both microgels and Fe3O4 NPs in electrospun fibers increases their Young's modulus. Swelling assays indicate that PVA membranes have a swelling ratio of around 3.4 (g/g) and that the presence of microgels does not affect its swelling ability. However, with the incorporation of Fe3O4 NPs, the swelling ratio of the membranes decreases. Magnetic hyperthermia assays show that a higher concentration of NPs leads to a higher heating ability. The composite membrane with the most promising results is the one incorporated with DMSA-coated NPs, since it shows the highest temperature variation, 5.1 °C. To assess the membranes biocompatibility and ability to promote cell proliferation, indirect and direct contact cell viability assays were performed, as well as cell adhesion assays. Following an extract method viability assay, all membrane designs did not reveal cytotoxic effects on dermal fibroblasts and melanoma cancer cells, after 48 h exposure and support long-term viability. The present work demonstrates the potential of dual-stimuli composite membranes for magnetic hyperthermia and may in the future be used as an alternative cancer treatment particularly in anatomically reachable solid tumors.

Liposomes encapsulating methylene blue and acridine orange: An approach for phototherapy of skin cancer.

Photodynamic therapy uses photosensitizer molecules for the photo-mediated treatment of several diseases such as cancer and skin disorders. However, most of the photosensitizer molecules present problems such as aggregation and low solubility in physiological environments which hinders the treatment efficacy. To overcome these problems, the development of stable liposomes loading photosensitizing molecules as delivery systems can be explored as promising alternatives to enhance cellular uptake and the therapy's efficacy. In this work, liposomes composed by different lipids with or without surfactants were characterized for the encapsulation of photosensitizer molecules such as Methylene Blue (MB) and Acridine Orange (AO). Liposomes were produced by the thin-film hydration method followed by extrusion to reduce particle size and were characterized by Dynamic Light Scattering and Atomic Force Microscopy. Encapsulation efficiency was evaluated as well as the release profile of these molecules from the liposome systems. Cytotoxicity and phototoxicity studies were performed on keratinocytes with and without carcinoma. Results showed that liposome's stability depends on the composition of lipids regardless of the presence of surfactants. Most stable liposomes were those with cholesterol plus the surfactants Span® 80 or sodium cholate that were able to provide higher stability for the liposomes considering the MB and AO encapsulation. Encapsulation efficiency (EE) studies revealed that AO had greater affinity for the vesicles presenting high EE (>98%) while for MB the encapsulation was, in general, moderate (between 63% and 86%). Greater phototoxicity was observed for MET1 squamous cell carcinoma (SCC) cells treated with AO liposomes, achieving similar half-maximal inhibition concentration (IC50) as for the free drug. Finally, two different possible approaches were found, namely, MB-liposomes with potential as a cytotoxic agent for cancer cells; and AO liposomes with a great phototoxicity potential at very low concentrations.