Nanoparticle Synthesis for Antimicrobial Applications

Nanoparticles composed of metals such as silver, copper, zinc and gold have emerged as potent antimicrobial agents owing to their ability to disrupt microbial membranes, generate reactive oxygen species and release biocidal ions. Synthesis methods span physical approaches (for example, laser ablation and sputtering), chemical reduction (using agents such as sodium citrate or borohydride) and biological or “green” routes that employ plant extracts, microorganisms or biopolymers to mediate nucleation and growth. Control over size, shape and surface chemistry is achieved by varying reaction parameters (pH, temperature, precursor concentration and capping agents), yielding particles from a few to several tens of nanometres. Surface functionalisation can enhance stability, target specificity and integration into composite materials such as hydrogels, polymer matrices or coatings for medical devices, textiles and water-treatment systems. The global rise in multidrug-resistant pathogens has intensified interest in nanoparticle-based disinfectants and wound-care products, uniting materials science, microbiology and engineering to translate laboratory synthesis into practical antimicrobial technologies.

Research from Nature Portfolio

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Research from all publishers

A recent study demonstrated a green synthesis of silver nanoparticles using Citrus limon zest extract as both reducing and stabilising agent. By optimising the extract-to-metal ratio and incubation time, researchers obtained spherical nanoparticles around 15–25 nm in diameter with high colloidal stability. The bio-derived surface compounds acted as capping agents, endowing the particles with pronounced antibacterial activity against Escherichia coli and Staphylococcus aureus as well as antifungal efficacy. Stability under physiological conditions and antioxidant properties further support their application in wound dressings and topical formulations.

Another investigation employed a statistical design of experiments to optimise chemical reduction parameters for silver nanoparticle synthesis. By tuning pH, silver nitrate, sodium citrate and sodium borohydride concentrations, the team produced monodisperse particles averaging under 10 nm. The optimised nanoparticles exhibited significantly lower minimum inhibitory concentrations against a panel of Gram-positive and Gram-negative bacteria while maintaining acceptable cytotoxicity profiles in mammalian cell assays. This work underlines the importance of systematic process control to enhance antimicrobial potency and biocompatibility.

A complementary study explored the relationship between particle size and antibacterial performance. Silver nanoparticles of varying diameters (5–50 nm) were synthesised by adjusting reducing-agent strength and characterised via transmission electron microscopy and UV–visible spectroscopy. Smaller particles generated greater reactive oxygen species and induced more extensive membrane damage in Vibrio natriegens, yielding lower bacteriostatic and bactericidal thresholds. These findings reinforce the link between nanoscale dimensions and enhanced antimicrobial action, guiding the design of next-generation disinfectant materials.

Nanoparticle Synthesis for Antimicrobial Applications publication trend

The graph below shows the total number of articles in nanoparticle synthesis for antimicrobial applications across all publications each year (not limited to Nature Index journals).

Technical terms

Green synthesis: A biocompatible method that uses plant extracts or microorganisms to reduce metal ions into nanoparticles without harsh chemicals.

Surface plasmon resonance: The collective oscillation of electrons at the nanoparticle surface when excited by light, used for size characterisation and sensor applications.

Zeta potential: The electric potential at the slipping plane of a particle in suspension, indicating colloidal stability against aggregation.

Capping agent: A molecule adsorbed on the nanoparticle surface that controls growth, prevents agglomeration and imparts functionality.

Minimum inhibitory concentration (MIC): The lowest concentration of an antimicrobial agent that prevents visible growth of a microorganism.

References

1. Green Synthesis of Silver Nanoparticles Using Aqueous Citrus limon Zest Extract: Characterization and Evaluation of Their Antioxidant and Antimicrobial Properties. Nanomaterials (2022).
2. Optimization of silver nanoparticle synthesis by chemical reduction and evaluation of its antimicrobial and toxic activity. Biomaterials Research (2019).
3. Antibacterial activity of silver nanoparticles of different particle size against Vibrio Natriegens. PLOS ONE (2019).