Improving cytotoxicity against cancer cells by chemo-photodynamic combined modalities using silver-graphene quantum dots nanocomposites

Khaled Habiba,1,2 Joel Encarnacion-Rosado,2,3 Kenny Garcia-Pabon,2,4 Juan C Villalobos-Santos,2,5 Vladimir I Makarov,1 Javier A Avalos,2,6 Brad R Weiner,2,7,8 Gerardo Morell1,2,7 1Department of Physics, University of Puerto Rico – Rio Piedras Campus, 2Molecular Sciences Research Center, University of Puerto Rico, 3Department of Biology, 4Faculty of Education, University of Puerto Rico – Rio Piedras Campus, San Juan, 5Department of Biology, 6Department of Physics, University of Puerto Rico – Bayamon Campus, Bayamon, 7Institute for Functional Nanomaterials, University of Puerto Rico, 8Department of Chemistry, University of Puerto Rico – Rio Piedras Campus, San Juan, PR, USA Abstract: The combination of chemotherapy and photodynamic therapy has emerged as a promising strategy for cancer therapy due to its synergistic effects. In this work, PEGylated silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) were tested as a platform to deliver a chemotherapy drug and a photosensitizer, simultaneously, in chemo-photodynamic therapy against HeLa and DU145 cancer cells in vitro. Ag-GQDs have displayed high efficiency in delivering doxorubicin as a model chemotherapy drug to both cancer cells. The Ag-GQDs exhibited a strong antitumor activity by inducing apoptosis in cancer cells without affecting the viability of normal cells. Moreover, the Ag-GQDs exhibited a cytotoxic effect due to the generation of the reactive singlet oxygen upon 425 nm irradiation, indicating their applicability in photodynamic therapy. In comparison with chemo or photodynamic treatment alone, the combined treatment of Ag-GQDs conjugated with doxorubicin under irradiation with a 425 nm lamp significantly increased the death in DU145 and HeLa. This study suggests Ag-GQDs as a multifunctional and efficient therapeutic system for chemo-photodynamic modalities in cancer therapy. Keywords: multifunctional nanoparticles, silver nanoparticles, cancer therapy, drug delivery, photodynamic therapy, nanocomposite