Green Synthesis of Chromium Oxide Nanoparticles for Antibacterial, Antioxidant Anticancer, and Biocompatibility Activities

Abstract

This study deals with the green synthesis of chromium oxide (Cr₂O₃) nanoparticles using a leaf extract of Abutilon indicum (L.) Sweet as a reducing and capping agent. Different characterization techniques were used to characterize the synthesized nanoparticles such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-VIS) spectroscopy. The X-ray diffraction technique confirmed the purity and crystallinity of the Cr₂O₃ nanoparticles. The average size of the nanoparticles ranged from 17 to 42 nm. The antibacterial activity of the green synthesized nanoparticles was evaluated against four different bacterial strains, E. coli, S. aureus, B. bronchiseptica, and B. subtilis using agar well diffusion and a live/dead staining assay. The anticancer activities were determined against Michigan Cancer Foundation-7 (MCF-7) cancer cells using MTT and a live/dead staining assay. Antioxidant activity was investigated in the linoleic acid system. Moreover, the cytobiocompatibility was analyzed against the Vero cell lines using MTT and a live/dead staining assay. The results demonstrated that the green synthesized Cr₂O₃ nanoparticles exhibited superior antibacterial activity in terms of zones of inhibition (ZOIs) against Gram-positive and Gram-negative bacteria compared to plant extracts and chemically synthesized Cr₂O₃ nanoparticles (commercial), but comparable to the standard drug (Leflox). The green synthesized Cr₂O₃ nanoparticles exhibited significant anticancer and antioxidant activities against MCF-7 cancerous cells and the linoleic acid system, respectively, compared to chemically synthesized Cr₂O₃ nanoparticles. Moreover, cytobiocompatibility analysis displayed that they presented excellent biocompatibility with Vero cell lines than that of chemically synthesized Cr₂O₃ nanoparticles. These results suggest that the green synthesized Cr₂O₃ nanoparticles' enhanced biological activities might be attributed to a synergetic effect. Hence, green synthesized Cr₂O₃ nanoparticles could prove to be promising candidates for future biomedical applications.

Keywords: Abutilon indicum (L.) Sweet; Cr2O3; antibacterial; anticancer; antioxidant; biocompatibility; green synthesis.

Figure 1

The schematic presentation for the green synthesis of Cr₂O₃ nanoparticles using Abutilon indicum (L.) Sweet leaf extract.

Figure 2

UV–Visible spectra of (a) plant leaf extract, (b) Cr₂O₃ nanoparticles. FTIR of (c) plant extract and (d) Cr₂O₃ nanoparticles.

Figure 3

(a) XRD, (b) SEM, scale bar = 1 µm, (c) TEM, (d) DLS particle size distribution, (e) EDX and (f) XPS analysis of green synthesized Cr₂O₃ nanoparticles.

Figure 4

The antibacterial activity of (a) Abutilon indicum (L.) Sweet leaf extract, (b) chemically synthesized Cr₂O₃ nanoparticles, (c) green synthesized Cr₂O₃ nanoparticles in terms of zones of inhibition (ZOIs) at different concentration levels against different bacteria compared to standard drug (d). (Note: Tukey based heterogeneous lower-case letters represent significant pairs).

Figure 5

Live/dead bacterial cell images—live cells stained with green (SYTO-9) while dead cells stained with red (PI) (scale bar = 50 µm).

Figure 6

Anticancer activity of green synthesized Cr₂O₃ nanoparticles in terms of cell viability percentage against MCF-7 cancer cells compared to Abutilon indicum (L.) Sweet leaf extract, chemically synthesized Cr₂O₃ nanoparticles, and standard drug. (Note: Tukey based heterogeneous lower-case letters represent significant pairs).

Figure 7

The morphological alterations in MCF-7 cancer cells after treatment with (b) plant extract, (c) chemically synthesized Cr₂O₃ nanoparticles, and (d) green synthesized Cr₂O₃ nanoparticles. The live/dead MCF-7 cancer cells stained with green and red fluorescent dye respectively after treatment with (f) plant extract, (g) chemically synthesized Cr₂O₃ nanoparticles, and (h) green synthesized Cr₂O₃ nanoparticles. (a) and (e) controls. (Scale bar = 100 µm).

Figure 8

The antioxidant activity of green synthesized Cr₂O₃ nanoparticles in terms of linoleic acid peroxidation percentage compared to plant extract, chemically synthesized Cr₂O₃ nanoparticles, and standard (α-tocopherol). (Note: Tukey based heterogeneous lower-case letters represent significant pairs).

Figure 9

(a) The cytobiocompatibility analysis of green synthesized Cr₂O₃ nanoparticles against Vero cell lines compared to plant extract and chemically synthesized Cr₂O₃ nanoparticles. (Note: Tukey based heterogeneous lower-case letters represent significant pairs). CLSM images of (b) untreated Vero cell lines (control), and treated with (c) plant extract, (d) chemically synthesized Cr₂O₃, and (e) green synthesized Cr₂O₃ nanoparticles (Live cells with green and dead cells with red) (Scale bar = 50 µm).

Figure 10

The leaf extraction preparation and green synthesis of Cr₂O₃ nanoparticles using Abutilon indicum (L.) Sweet leaf extracts.