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- Combination of chemotherapy and Au-nanoparticle photothermy in the visible light to tackle doxorubicin resistance in cancer cellsPublication . Pedrosa, Pedro; Mendes, Rita; Cabral, Rita; Martins, Luisa; Baptista, Pedro; Fernandes, AlexandraDespite great advances in the fight against cancer, traditional chemotherapy has been hindered by the dose dependent adverse side effects that reduce the usable doses for effective therapy. This has been associated to drug resistance in tumor cells that often cause relapse and therapy failure. These drawbacks have been tackled by combining different therapeutic regiments that prevent drug resistance while decreasing the chemotherapy dose required for efficacious ablation of cancer. In fact, new metallic compounds have been in a continuous development to extend the existing chemotherapy arsenal for these combined regimens. Here, we demonstrate that combination of a metallic compound (TS265), previously characterized by our group, with photothermy circumvents cells resistant to Doxorubicin (DOX). We first engendered a colorectal carcinoma cell line (HCT116) highly resistant to DOX, whose viability was diminished after administration of TS265. Cancer cell death was potentiated by challenging these cells with 14 nm spherical gold nanoparticles followed by laser irradiation at 532 nm. The combination of TS265 with photothermy lead to 65% cell death of the DOX resistant cells without impacting healthy cells. These results support the use of combined chemotherapy and photothermy in the visible spectrum as an efficient tool for drug resistant tumors.
- Evaluation of cell toxicity and DNA and protein binding of green synthesized silver nanoparticlesPublication . Da Costa Ribeiro, Ana Paula; Anbu, S; Alegria, Elisabete; Fernandes, Alexandra; Baptista, Pedro; Mendes, Rita; Matias, A. S.; Mendes, M.; Guedes Da Silva, M. Fátima C.; Pombeiro, ArmandoSilver nanoparticles (AgNPs) were prepared by GREEN chemistry relying on the reduction of AgNO3 by phytochemicals present in black tea extract. AgNPs were fully characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy ((UV-vis)), X-ray diffraction (XRD) and energy dispersive absorption spectroscopy (EDS). The synthesized AgNPs induced a decrease of the cell viability in a dose-dependent manner with a low IC50 (0.5 +/- 0.1 mu M) for an ovarian carcinoma cell line (A2780) compared to primary human fibroblasts (IC50 5.0 +/- 0.1 mu M). The DNA binding capability of CT (calf thymus) DNA was investigated using electronic absorption and fluorescence spectroscopies, circular dichroism and viscosity titration methods. Additionally, the AgNPs strongly quench the intrinsic fluorescence of BSA, as determined by synchronous fluorescence spectra.