Orange Peel Extract-Mediated Green Synthesis of PEG-Modified ZnO Nanoparticles: Structural Characterization,...

Engineered nanomaterials could potentially interact with biomolecules and intracellular processes, as many biological activities take place at the nanoscale level. Conventional anticancer therapies have several limitations, which warrant the introduction of alternative cancer cell killing agents.

In the present study, we have synthesized ZnO nanoparticles using orange peel extract and encapsulated them inside polyethylene glycol (PEG), a biocompatible polymer (PEG-ZnO-OP). Different characterization techniques were performed to ensure the proper synthesis of the nanoparticles. The biocompatibility was assessed by the MTT assay using normal fibroblast cells, 3T3L1, hemolysis assay, and zebrafish embryo studies. Finally, the anticancer activity in vitro was estimated by the MTT assay in the lung cancer cell line.

The hydrodynamic diameter and zeta potential were 43 nm and -20 mV, respectively, showing an ultrasmall size and moderate stability in an aqueous environment. The XRD data suggested a good crystalline structure; SEM and EDX showed size distribution between 81 nm and 143 nm, and the presence of Zn and O, along with other trace elements, was probably contributed by the orange peel extract. The PEG-ZnO-OP nanoparticles were highly biocompatible up to a dose of 50 μg/mL, as assessed both in vitro and in vivo. Further, the anticancer activity showed a high cell killing effect with an IC50 value of 43.88 μg/ml.

This study demonstrated that our synthesized PEG-ZnO-OP nanoparticles were safe to administer and could cause significant cancer cell killing. Future studies involving the anticancer effect in other cell lines and animal models need further exploration.