Green synthesized silver nanoparticles from Moringa: Potential for preventative treatment of SARS-CoV-2 contaminated water

Adebayo J. Bello, Omorilewa B. Ebunoluwa, Rukayat O. Ayorinde, Nneka Onyepeju, Joseph O. Shaibu, Adeniyi R. Adewole, Abeebat O. Adewole, Olusegun Adedeji, Ololade O. Akinnusi, Olajumoke B. Oladapo, Temitope S. Popoola, Oluwamodupe M. Arotiba, Joseph B. Minari, Luqman A. Adams, Joy Okpuzor, Mujeeb O. Shittu

Posted on: 14 November 2024

Preprint posted on 14 October 2024

Moringa power! Cost-effective, eco-friendly silver nanoparticles could revolutionize SARS-CoV-2 water decontamination in developing regions. Safer, cleaner water ahead and a sustainable win for global health.

Selected by Safieh Shah, Benjamin Dominik Maier

Categories: bioengineering, cell biology, ecology, epidemiology, microbiology, molecular biology, plant biology

Background

The emergence of SARS-CoV-2 has underscored the critical need for effective antiviral agents, particularly in the realm of water purification. Contaminated water sources can serve as reservoirs for various pathogens, including viruses like SARS-CoV-2, which pose significant public health risks (1).

Traditional methods for water disinfection such as chlorination have their limitations, including the potential formation of harmful by-products for humans. Therefore, the exploration of alternative disinfection strategies is imperative. Alternatively, green chemistry approaches are methods of chemical synthesis that aim to reduce or eliminate the use and generation of hazardous substances. In this study, Moringa oleifera leaf extracts are used to synthesize silver nanoparticles. Moringa trees are native to South Asian countries as well as some African countries.

This eco-friendly method minimizes toxic chemicals and waste, making the process more sustainable and safer for the environment.

Preprint Figure 2: Scanning Electron Microscopy showing the particle size of the biosynthesized nanoparticles. Reproduced under a CC-BY 4.0 International license

The size and shape of silver nanoparticles are effective against microbes because of their small size and large surface area. These properties help them move easily through cell membranes and reach the target areas, boosting their antimicrobial power, while their positive surface charge helps them disrupt bacterial membranes more effectively. These are examples of how their physicochemical properties play a crucial role in determining the overall effectiveness and behavior of the nanoparticles in different environments. In this context, the use of nanoparticles, especially those synthesized through green chemistry approaches, offers a promising avenue due to their unique physicochemical properties and potential for broad-spectrum antimicrobial activity.

This preprint explores the synthesis, characterization, and application of biogenic silver nanoparticles (AgNPmo) derived from Moringa oleifera leaf extracts. The study primarily aims to investigate the antimicrobial and antiviral efficacy of these nanoparticles, with a specific focus on SARS-CoV-2, the causative agent of COVID-19.

Key findings

Synthesis of Silver Nanoparticles

The authors employed Moringa oleifera leaf extracts to synthesize biogenic silver nanoparticles (AgNPmo), leveraging the plant’s inherent reducing and stabilizing agents. The synthesis process involved mixing aqueous extracts of Moringa oleifera leaves with a silver nitrate solution, followed by incubation at room temperature. The color change from colorless to brown indicated the formation of AgNPmo.

Characterization of AgNPmo

Characterization of the synthesized nanoparticles was conducted using a suite of techniques, including UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffractometry (XRD). These analyses confirmed the successful synthesis of AgNPmo, revealing their spherical morphology as well as their crystalline nature. The UV-Vis spectroscopy showed a characteristic absorption peak around 430 nm, indicative of the presence of silver nanoparticles. FTIR analysis confirmed the presence of biomolecules from Moringa oleifera that capped and stabilized the nanoparticles. SEM images displayed uniform spherical nanoparticles with an average size of 20-30 nm, while XRD patterns confirmed their crystalline structure.

Antimicrobial and Antiviral Activity

The nanoparticles demonstrated significant antimicrobial activity against clinical bacterial isolates (Pseudomonas aeruginosa and Staphylococcus aureus) and low cytotoxicity on Vero cells (kidney epithelial cell line derived from the African green monkey). In vitro studies showed that AgNPmo effectively reduced SARS-CoV-2 viral load, after 48-hours of incubation and at low concentrations.

What I like about the preprint

I appreciate the innovative approach of using green synthesis for producing silver nanoparticles, which is both cost-effective and environmentally friendly. The dual antimicrobial and antiviral properties of AgNPmo make it a promising candidate for addressing waterborne infections, especially in resource-limited settings. The study’s findings could have significant implications for public health, particularly in preventing the spread of SARS-CoV-2 through contaminated water.

Future directions

Future research could focus on scaling up the production of AgNPmo and conducting in vivo studies to assess its efficacy and safety in animal models. It would also be valuable to explore the long-term stability and potential environmental impact of these nanoparticles which is beyond the scope of this current study.

Questions for the authors

How can the synthesis process be optimized for larger-scale production?
What should AgNPmo be used in conjunction with to effectively reduce and clean water from SARS-CoV-2 virus?
Does this current low concentration and reduced viral load of SAE-CoV-2 have any clinical significance in terms of preventing actual infection?
Are there other potential applications for AgNPmo beyond water purification for this particular virus?
Does the addition of AgNPmo interfere with the estimation of the COVID-19 prevalence from wastewater measurements?