Investigating of the anticancer activity of salen/salophen metal complexes based on graphene quantum dots: Induction of apoptosis as part of biological activity.

This research work is the first report on the synthesis and stabilization of [Fe-Salophen] and [Fe-Salen] complexes by two methods of surface modification and anchoring of synthesized Schiff base ligand on the surface of graphene quantum dots (GQDs). The GQDs contain oxygenated functional groups that can act as non-radiative electron-hole recombination centers. Therefore removing these oxygen functional groups may improve quantum yield by reducing or deactivating the surface. In this work, GQDs with the amine functional group were synthesized with a quantum yield of 37.48%. The physicochemical properties of GQDs were investigated by Ultraviolet-visible (UV-Vis) and fluorescence spectroscopies, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Powder X-ray diffraction (PXRD), Transmission electron microscope (TEM). The synthesis of GQDs-[Fe-Salen] and GQDs-[Fe-Salophen] was evaluated by FT-IR, Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Energy dispersive X-Ray analysis (EDX) analyses. Then, using MTT- assay, annexin V-FITC/PI, DAPI staining and cellular uptake assays, the biochemical activity of these complexes on the MCF7 cell line was investigated. The results shows that GQDs-[Fe-Salen] and GQDs-[Fe-Salophen] affect the survival of MCF7 cancer cells and, by nuclear fragmentation cause 35.77% and 19.41% of early apoptosis in cells, respectively. Also was found cellular uptake of GQDs-[Fe-Salen] is higher than that of GQDs-[Fe-Salophen].

Multispectroscopic studies of the interaction of calf thymus DNA with the anti-viral drug, valacyclovir.

The present study investigated the binding interaction between an antiviral drug, valacyclovir and calf thymus DNA (CT-DNA) using emission, absorption, circular dichroism, viscosity and DNA melting studies. In fluorimetric studies, thermodynamic enhancement constant (K(D)) and bimolecular enhancement constant (K(B)) were calculated at different temperatures and demonstrated that fluorescence enhancement is not initiated by a dynamic process, but instead by a static process that involves complex DNA formation in the ground state. Further, the enthalpy and entropy of the reaction between the drug and CT-DNA showed that the reaction is exothermic and enthalpy-favored. In addition, detectable changes in the circular dichroism spectrum of CT-DNA in the presence of valacyclovir indicated conformational changes in the DNA double helix following interaction with the drug. All these results prove that this antiviral drug interacts with CT-DNA via an intercalative mode of binding.