Biological evaluation and molecular modelling studies of in vivo synthesized ZnO nanoparticles

Abstract

The ZnO nanoparticle is an excellent candidate for biological applications. It has potential antimicrobial, antioxidant, anticancerous, antidiabetic, anti-inflammatory and wound healing properties because of its biodegradability and biocompatibility. The green method of synthesizing nanoparticles is gaining popularity as it is cost effective and reduces the impact of toxic substances. In the present work, Eichhornia crassipes was used as the plant source for the synthesis of ZnO nanoparticles. It is an invasive aquatic macrophyte that is utilized to exploit its phytoaccumulation property. The goal of the current study was to evaluate the ability of a living plant to transform the accumulated metal into metal nanoparticles in vivo. The formation of ZnO nanoparticles was confirmed by UV–visible spectrophotometry, EDX analysis, FTIR, XRD and HRTEM. A strong absorption peak (300 nm) and an excitonic peak (243 nm) obtained in the UV spectrophotometric analysis confirmed the formation of ZnO nanoparticles. The presence of strong signals for zinc and oxygen in the extracted nanoparticles was identified by EDX analysis. The presence of proteins, alkaloids, flavonoids and phenolics were identified using FTIR and are contributed to the formation of ZnO nps by the reduction reaction. XRD analysis revealed the hexagonal phase wurtzite structure of ZnO with a crystalline size of 16.89 nm. HRTEM analysis revealed that the particles were spherical and agglomerated in nature with an average size of 16 nm which is consistent with the XRD results. The ZnO nanoparticles were evaluated for their antibacterial activity against pathogenic bacterial strains such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae. The antibacterial activity of the ZnO nanoparticles was found to increase with their increasing concentration. The anticancerous activity of ZnO nanoparticles was also evaluated and exhibited a dose-dependent cytotoxicity against MCF-7 cells, which was further confirmed with molecular docking studies. Overall, a rapid, economical and ecofriendly approach for extracting ZnO nanoparticles was established, which can be employed as a potential therapeutic agent, particularly in nanomedicine for bacterial and cancer treatment.