Synthesis of Functional Silver Nanoparticles and Microparticles with Modifiers and Evaluation of Their Antimicrobial, Anticancer, and Antioxidant Activity.

Erum Dilshad,Qaisar Mansoor,Qaisar Maqbool,Khairul Fikri Tamrin,Mehmoona Bibi,Nadeem Ahmed Sheikh,Muhammad Nawaz

doi:10.3390/jfb11040076

Abstract

An accumulating body of evidence reports the synthesis and biomedical applications of silver nanoparticles. However, the studies regarding the use of maleic acid and citric acid in the synthesis of nano-sized silver particles (AgNPs) and micro-sized silver particles (AgMPs) as well as their antibacterial, antifungal, and anticancer activities have not been reported. In the current study, we synthesized AgNPs and AgMPs using maleic acid and citric acid as capping agents and have characterized them by UV-Vis, energy-dispersive X-Ray spectroscopy (EDS), X-Ray diffraction (XRD), and scanning electron microscope (SEM) analysis. The capped silver particles were examined for their antimicrobial activity and cytotoxicity against bacteria, fungi, and brine shrimp. Additionally, the anticancer activity of these particles was tested against human breast and liver cancer cell lines. The free radical scavenging activity of capped silver particles was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. SEM analysis revealed a round plate-like morphology of maleic acid capped particles with an average size of 39 ± 4 nm, whereas citric acid capped particles display flower-shaped morphology with rough surfaces and an average size of 250 ± 5 nm. The uncapped AgMPs were hexagonal with 500 ± 4 nm size. EDS and XRD analysis confirmed the presence of Ag and face-centered cubic crystalline nature, respectively. Functionally, capped silver particles exhibited antibacterial activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis, and Micrococcus luteus) and Gram-negative bacteria (Salmonella setubal, Enterobacter aerogenes, and Agrobacterium tumefaciens). The bactericidal activity was more active against Gram-negative bacteria with minimum inhibitory concentration (MIC) as low as 5 ppm as compared to 25 ppm for Gram-positive. Similarly, the silver particles demonstrated antifungal activity by inhibiting the growth of five fungal strains (Mucor species, Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, and Fusarium solani) up to 50% at the concentration of 500 ppm. Additionally, these particles showed substantial toxicity against brine shrimp and also significantly inhibited the proliferation of breast cancer (MCF7) and liver cancer (HePG2) cell lines (IC50 8.9–18.56 µM). Uncapped AgMPs were less effective, inhibiting only the proliferation of MCF7 cells with IC50 46.54 µM. Besides cytotoxicity, these particles acted as potential antioxidants, showing free radical scavenging up to 74.4% in a concentration-dependent manner. Taken together, our results showed that the modifiers affect the shape and size of silver particles and may, in part, contribute to the antimicrobial and antioxidant activity of silver particles. However, the contribution of maleic acid and citric acid in enhancing the antimicrobial, anticancer, and antioxidant potential independent of silver nano and microparticles needs to be studied further. In vivo experiments may determine the therapeutic effectiveness of silver particles capped with these modifiers.

Highlights

The need for achieving materials of preferred morphology and architecture at a nanometric scale holds great importance largely because methods used in manufacturing influence the therapeutic properties of nanoparticles strongly [1,2]
The synthesis was further confirmed by UV-Vis spectrum analysis, which showed a strong, broad peak at 400 nm, whereas the broadening of the peak indicates the formation of polydispersed AgNPs and AgMPs (Figure 1A)
Our results showed that the modifiers act as stabilizers, and they may be involved in enhancing the antimicrobial and anticancer potential of nanoparticles, and may, in part, contribute to the antioxidant activity of nanoparticles to scavenge or remove the free radicals (Figure 7)

Summary

Introduction

The need for achieving materials of preferred morphology and architecture at a nanometric scale holds great importance largely because methods used in manufacturing influence the therapeutic properties of nanoparticles strongly [1,2]. Silver nanoparticles (AgNPs) have emerged as a playful delivery platform in the field of nanotechnology These important materials have attained considerable interest lately because of their good conductivity [4], chemical stability [5], catalytic [6], and antimicrobial activity [7,8]. It has been shown that AgNPs exhibit strain-specific antimicrobial activity against different pathogenic bacterial strains [9], as well as against toxigenic species of fungi [10,11] Due to their distinctive features, these nanoparticles have prognostic applications against various diseases, such as those caused by bacteria, fungi, and viruses, including tuberculosis, acquired immunodeficiency syndrome, and retinal neovascularization [12]. It has been shown that the silver content of AgNPs in rat tissues gradually decreases during the 4-month recovery period, indicating tissue clearance of the accumulated silver [17]

Methods

Results

Conclusion