Green synthesis of ZnO-TiO2/RGO nanocomposites using Senna surattensis extract: a novel approach for enhanced anticancer efficacy and biocompatibility

Abstract

The purpose of the present study is to enhance the anticancer and biocompatibility performance of TiO₂ NPs, ZnO NPs, ZnO-TiO₂ (NCs), and ZnO-TiO₂/reduced graphene oxide (RGO) NCs against two types of human cancer (HCT116) and normal (HUVCE) cells. A novel procedure for synthesizing ZnO-TiO₂/RGO NCs has been developed using Senna surattensis extract. The improved physicochemical properties of the obtained samples were investigated using different techniques such as XRD, TEM, SEM, XPS, FTIR, DLS and UV-visible spectroscopy. XRD results showed that the addition of ZnO and RGO sheets affects the crystal structure and phase of TiO₂ NPs. SEM and TEM images displayed that the TiO₂ NPs and ZnO NPs were small with uniform spherical morphology in the prepared ZnO-TiO₂/RGO NCs. Besides, it is shown that ZnO-TiO₂ NCs anchored onto the surface of RGO sheets with a particle size of 14.80 ± 0.5 nm. XPS data confirmed the surface chemical composition and oxidation states of ZnO-TiO₂/RGO NCs. Functional groups of prepared NPs and NCs were determined using FTIR spectroscopy. DLS data confirmed that the addition of ZnO and RGO sheets improves the negative surface charge of the prepared pure TiO₂ NPs (−22.51 mV), ZnO NPs (−18.27 mV), ZnO-TiO₂ NCs (−30.20 mV), and ZnO-TiO₂/RGO NCs (−33.77 mV). Optical analysis exhibited that the bandgap energies of TiO₂ NPs (3.30 eV), ZnO NPs (3.33 eV), ZnO-TiO₂ NCs (3.03 eV), and ZnO-TiO₂/RGO NCs (2.78 eV) were further enhanced by adding ZnO NPs and RGO sheets. This indicates that the synthesized samples can be applied to cancer therapy and environmental remediation. The biological data demonstrated that the produced ZnO-TiO₂/RGO NCs show a more cytotoxic effect on HCT116 cells compared to pure TiO₂ NPs and ZnO-TiO₂ NCs. On the other hand, these NCs displayed the lowest level of toxicity towards normal HUVCE cells. These results indicate that the ZnO-TiO₂/RGO NCs have strong toxicity against HCT116 cells and are compatible with normal cells. Our results show that the plant extract enhanced the physicochemical properties of NPs and NCs compared with the traditional chemical methods for synthesis. This study could open new avenues for developing more effective and targeted cancer treatments.