https://doi.org/10.17113/ftb.63.02.25.8925

Article in press

Agro-Waste Driven Green Synthesis and Characterization of Silver Nanoparticles Using Oryza sativa and Spent Coffea robusta

Nallusamy Nithiskanna¹, Nurul Affifah Mohd Kamal Rufadzil¹, Jasvini Bala Murally^1#, Liam Jing Zhi^1#, Wan Nor Dalila Wan Fauzi², Hawa Dalily Mohd Jefri², Amirul Al-Ashraf Abdullah³, Seeram Ramakrisha⁴ and Sevakumaran Vigneswari^1,5*

¹Institute of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

²Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

³School of Biological Science, Universiti Sains Malaysia, Pulau Pinang, Malaysia

⁴Center for Nanotechnology and Sustainability, National University of Singapore, 119260 Singapore

⁵Ocular Infections and Antimicrobials Research Group, Singapore Eye Research Institute, Singapore

Copyright © 2024 This is a Diamond Open Access article published under CC-BY licence. Copyright remains with the authors, who grant third parties the unrestricted right to use, copy, distribute and reproduce the article as long as the original author(s) and source are acknowledged.

Article history:

Received: 29 October 2024

Accepted: 30 April 2025

Keywords:

agro-waste; green synthesis; Oryza sativa; spent Coffea robusta; silver nanoparticles  

The content of this publication has not been approved by the United Nations and does not reflect the views of the United Nations or its officials or Member States.

Summary:

Research background. Agricultural waste was utilised to synthesise silver nanoparticles (AgNPs) via green synthesis, a sustainable alternative to traditional synthesis techniques that use hazardous chemicals and extensive processing. AgNPs were produced from spent coffee grounds, Coffea robusta, and rice husks, Oryza sativa, both prevalent agricultural wastes rich in bioactive substances including proteins, flavonoids, and phenolic acids, which act as natural reducing agents.

Experimental approach. The formation and stability of AgNPs were confirmed using various methods. UV-Vis spectroscopy displayed surface plasmon resonance (SPR) peaks at 450 nm, signifying AgNP formation, while FTIR identified functional groups responsible for the bio-reduction and stabilisation of nanoparticles. XRD confirmed the crystalline, face-centred cubic structure. Zeta potential analysis showed stable dispersion, and particle size analysis highlighted consistent sizing. The antibacterial activity of AgNPs was assessed by testing their effectiveness against both Gram-positive and Gram-negative bacteria.

Results and conclusions. Synthesis of AgNPs from spent coffee grounds and rice husks rich in biomolecules served as effective reducing and stabilizing agents. FTIR analysis identified functional groups involved in nanoparticle reduction and stabilization, while XRD verified their face-centred cubic (FCC) crystalline structure. Zeta potential measurements demonstrated stable dispersions, with particle sizes of approximately 187 nm spent coffee ground-AgNPs and 198 nm for rice husk-AgNPs. The synthesized AgNPs also exhibited strong antibacterial activity against both gram-positive and Gram-negative bacteria.

Novelty and scientific contribution. The green synthesis approach for AgNPs utilising agriculture waste such as spent coffee grounds and rice husks as natural reducing and stabilizing agents. This study highlights the innovative use of biomolecule-rich materials, producing stable AgNPs with strong antibacterial properties, and establishes a sustainable foundation for advancing nanotechnology applications.

 
^#Both authors contributed equally.