Tumoricidal and Bactericidal Properties of ZnONPs Synthesized Using Cassia auriculata Leaf Extract

Abstract

In this work, we aimed to synthesize zinc oxide nanoparticles (ZnONPs) using an aqueous extract of Cassia auriculata leaves (CAE) at room temperature without the provision of additional surfactants or capping agents. The formation of as-obtained ZnONPs was analyzed by UV-visible (ultraviolet) absorption and emission spectroscopy, X-ray photoemission spectroscopy (XPS), X-ray diffraction analysis (XRD), energy dispersive X-ray diffraction (EDX), thermogravimetric analysis/differential thermal analysis (TGA-DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The XRD results reflect the wurtzite structure of as-prepared ZnONPs, which produced diffraction patterns showing hexagonal phases. The SEM images indicate that the morphology of as-prepared ZnONPs is composed of hexagonal nanostructures with an average diameter of 20 nm. The HR-TEM result shows that the inter-planar distance between two lattice fringes is 0.260 nm, which coincides with the distance between the adjacent (d-spacing) of the (002) lattice plane of ZnO. The fluorescence emission spectrum of ZnONPs dispersed in ethanol shows an emission maximum at 569 nm, revealing the semiconductor nature of ZnO. As-obtained ZnONPs enhanced the tumoricidal property of CAE in MCF-7 breast cancer cells without significant inhibition of normal human breast cells, MCF-12A. Furthermore, we have studied the antibacterial effects of ZnONPs, which showed direct cell surface contact, resulting in the disturbance of bacterial cell integrity.

Keywords: Cassia auriculata; X-ray photoemission spectroscopy (XRD) pattern; anticancer property; zinc oxide nanoparticles (ZnONPs).

Figure 1

(A) The absorption and (B) emission spectra of as-obtained ZnONPs.

Figure 2

XRD diffraction pattern of as-grown ZnONPs obtained using aqueous extract of C. auriculata leaves.

Figure 3

Energy-dispersive X-ray diffraction spectrum of ZnONPs under study.

Figure 4

The SEM image of as-obtained ZnONPs using Cassia auriculata leaf extract.

Figure 5

The X-ray photoemission spectra show (a) Zn 2p and (b) O 1s of as-obtained ZnONPs.

Figure 6

TGA/DTA graph showing the decomposition of as-obtained ZnONPs.

Figure 7

(a) TEM and (b) HR-TEM images with SAED (inset) of as-obtained ZnONPs.

Figure 8

Zone of inhibition graph by ZnONPs against selected bacterial strains.

Figure 9

A comparative display of growth curves of test bacteria in the absence and presence of synthesized ZnONPs. Experiments were performed in triplicate.

Figure 10

Cytotoxicity of CAE and ZnONPs on breast cancer MCF-7 cells. Results are reported as mean ± SEM for n = 3, and a p- value of <0.05 was considered to be significant; *p = <0.033, **p = <0.002, ***p = <0.001, ns = not significant.

Figure 11

Cytotoxicity of CAE and ZnONPs on normal human breast MCF-12A cells. Results are reported as mean ± SEM for n = 3, and a p-value of <0.05 was considered to be significant; *p = <0.033, **p = <0.002, ***p = <0.001, ns = not significant.