Facile Green, Room-Temperature Synthesis of Gold Nanoparticles Using Combretum erythrophyllum Leaf Extract: Antibacterial and Cell Viability Studies against Normal and Cancerous Cells.

Olufunto T Fanoro,Oluwatobi S Oluwafemi,Vuyo Mavumengwana,Rodney Maluleke,Sundararajan Parani,Thabang C Lebepe,Jose R Varghese

doi:10.3390/antibiotics10080893

Abstract

We herein report a facile, green, cost-effective, plant-mediated synthesis of gold nanoparticles (AuNPs) for the first time using Combretum erythrophyllum (CE) plant leaves. The synthesis was conducted at room temperature using CE leaf extract serving as a reducing and capping agent. The as-synthesized AuNPs were found to be crystalline, well dispersed, and spherical in shape with an average diameter of 13.20 nm and an excellent stability of over 60 days. The AuNPs showed broad-spectrum antibacterial activities against both pathogenic Gram-positive (Staphylococcus epidermidis (ATCC14990), Staphylococcus aureus (ATCC 25923), Mycobacterium smegmatis (MC 215)) and Gram-negative bacteria (Proteus mirabilis (ATCC 7002), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13822), Klebsiella oxytoca (ATCC 8724)), with a minimum inhibition concentration of 62.5 µg/mL. In addition, the as-synthesized AuNPs were highly stable with exceptional cell viability towards normal cells (BHK- 21) and cancerous cancer cell lines (cervical and lung cancer).

Highlights

Gold nanoparticles (AuNPs) have drawn countless attention [1,2,3] due to their unique properties such as their surface plasmon resonance, wavelength tunability, low-cytotoxicity, competent bioconjugation, enhanced permeability, and retention (EPR) assimilation
For the lower volume of Combretum erythrophyllum (CE), it took a little more time to produce the purple colour (40 s for 1.0 mL CE and 2 min 36 s for 0.5 mL CE). This difference in time for the observation of the colour change signifies that the rate of reduction of the Au3+ ions is faster with the increase in the extract concentration
The time at which the colour change was observed was taken as 0 min, and further aliquots were collected to monitor the growth of the AuNPs

Summary

Introduction

Gold nanoparticles (AuNPs) have drawn countless attention [1,2,3] due to their unique properties such as their surface plasmon resonance, wavelength tunability, low-cytotoxicity, competent bioconjugation, enhanced permeability, and retention (EPR) assimilation These properties offer a prospect for their use in cancer therapeutics, antibiotics, and drug delivery [4,5,6,7]. Plant extracts contain different phytochemicals or biomolecules like flavonoids, terpenes, phenols, lectins, alkaloids, tannins, quinones [18], carbohydrates, lipids, reductases proteins, polyphenolic, vitamins [19,20], and among others They can serve as both reducing and stabilizing agents, thereby eliminating the use of chemical reagents in the synthesis of AuNPs. they can serve as both reducing and stabilizing agents, thereby eliminating the use of chemical reagents in the synthesis of AuNPs These phytochemicals or biomolecules can prevent the agglomeration of nanoparticles(NPs), reduce their toxicity, and increase their bio-assimilation [13,21]. Several plants, seed, flower, and leaf extracts such as Alcea rosea [15], Scutellaria barbata [22], dragon fruit [23], Lonicera japonica [24], and Salix Alba [25] have been used for the biosynthesis of AuNPs

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Results

Conclusion