Antimicrobial resistance is a significant threat to public health. In response, scientists are developing functional nanoparticles to target and eliminate resistant bacteria. These advanced materials are being explored for use in medicine, sanitation, and food safety, offering new strategies to combat infections.1
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What Are Antimicrobial Nanoparticles?
Antimicrobial nanoparticles are materials with exceptional antimicrobial properties, capable of controlling bacterial, viral, and fungal infections. Thanks to their unique physicochemical attributes, they have proven to be more effective than traditional antimicrobial agents.
Researchers have developed various nanoparticle-based antimicrobial systems, including polymeric nanoparticles, dendrimers, and inorganic nanoparticles, for use in healthcare. Studies have shown their ability to treat and detect bacterial infections by enabling targeted drug delivery, responsive therapies, and rapid bacterial detection.2
Nanoparticles made from gold, silver, titanium dioxide, zinc oxide, and copper oxide are widely used in antimicrobial coatings for medical devices, wound dressings, water purification systems, and food packaging to prevent bacterial contamination and extend shelf life.3
Mechanism of Action
Antimicrobial nanoparticles interact efficiently with the DNA of harmful microorganisms. Their high surface area increases contact with bacterial cells, enhancing their ability to interfere with essential functions.
They attack bacteria through multiple pathways, including breaking down cell walls, disrupting membranes, oxidizing proteins, inhibiting cell division, damaging nucleic acids, and generating reactive oxygen species (ROS). Together, these mechanisms make them powerful tools against resistant infections.
Cell Membrane Disruption
When antimicrobial nanoparticles come into contact with bacteria, they attach to the cell wall and membrane. Metal-based nanoparticles typically carry a positive charge, allowing them to electrostatically bind to the negatively charged bacterial surface.
This interaction disrupts the membrane, creating pores and holes that cause leakage. These structural changes also lead to cytoplasmic shrinkage and membrane detachment, ultimately resulting in membrane rupture.4
Formation of Reactive Oxygen Species
Antimicrobial nanoparticles produce reactive oxygen species (ROS), which are highly reactive oxygen-based molecules that disrupt bacterial functions. This is a powerful mechanism for combating microorganisms.
When antimicrobial nanoparticles interact with bacteria, they accelerate ROS production, leading to the deactivation of respiratory enzymes. This process generates hydroxyl radicals (HO•), superoxide anions (O₂⁻), and hydrogen peroxide (H₂O₂), which collectively damage cellular components and inhibit bacterial survival.
ROS also induce oxidative stress, damaging key bacterial macromolecules such as DNA and disrupting essential biological processes, ultimately leading to cell death.5
Excessive ROS exposure harms microbial biomolecules and organelle structures due to their high oxidation potential. This damage includes protein carbonylation, DNA and RNA breakage, enzyme inhibition, and membrane disruption, which can result in necrosis or even mutagenesis.
In short, ROS are highly reactive and can degrade cellular structures, causing significant damage to bacterial cell walls and membranes.
Intracellular Targeting
Intracellular bacteria survive and multiply within host cells, adapting to adverse microenvironments and developing mechanisms to evade the immune system. Conventional antimicrobial materials often struggle to eliminate these microbes, but antimicrobial nanoparticles have shown success in penetrating and destroying them.
Antimicrobial nanoparticles kill intracellular bacteria by first penetrating bacterial membranes, often by forming ion transport channels. Their small size and large surface area enhance their ability to breach cell walls and membranes. Once inside, they cause protein denaturation and shear genetic material within the microbial cell, ultimately leading to bacterial eradication.
Antimicrobial Nanoparticles in Action: Applications Across Industries
Antimicrobial nanoparticles made from various organic and inorganic materials are being developed for industrial applications. Silver-based nanoparticles are commonly found in cosmetics, textiles, and healthcare, including in the treatment of ulcers, diabetic wounds, and infectious burns. Along with their antimicrobial effects, they also have anti-inflammatory properties.
Why is silver antimicrobial? Explained in a minute I Chemniverse
Gold-based antimicrobial nanoclusters are used for imaging, microbe detection, and other biomedical applications. In therapeutic settings, they are functionalized with surface ligands to enhance antimicrobial activity.7 Their potential anti-malarial and anti-HIV properties make them a focus of pharmacological research.
Titanium nanoparticles are widely used in dental applications, including restorative treatments and high-strength dental implants. TiO₂ nano-fillers are also added to biomaterials to improve antimicrobial performance.8
In water purification, antimicrobial nanoparticles help remove dyes, heavy metals, and harmful microbes from untreated wastewater.9 They are also used in antimicrobial coatings for wastewater treatment and food packaging, preventing bacterial and fungal growth while ensuring safety and environmental protection.
What’s Preventing Wider Use of Antimicrobial Nanoparticles?
The use of antimicrobial nanoparticles is expanding significantly, but several challenges need to be addressed.
One concern is the potential for microbial resistance. Some experts warn that bacteria, viruses, and fungi may adapt to these nanoparticles over time through evolutionary changes. Understanding how resistance develops and designing stronger, more effective nanoparticles will be critical to ensuring their long-term success.
Another challenge is the lack of comprehensive data on the long-term biocompatibility and cytotoxicity of antimicrobial nanoparticles. Assessing their potential risks is essential to minimizing harmful side effects and ensuring their safe use in medicine, industry, and environmental applications.
Regulatory oversight is also a key issue. A standardized framework for the approval, monitoring, and disposal of antimicrobial nanoparticles is needed. While some countries have regulations in place, a globally recognized standard would provide consistency in cytotoxicity testing and environmental safety. Proper disposal methods must also be established, as these materials could pose biohazard risks if not managed correctly.2
So, What Comes Next?
Future research will focus on expanding in vivo studies, as in vitro experiments alone do not provide a complete picture of how antimicrobial nanoparticles function in living systems.
A key area of interest is nanoparticle toxicity, particularly neurotoxicity, as limited studies have explored whether these particles can cross the blood-brain barrier and their potential effects on the nervous system.
Researchers are also working to map out the precise mechanisms by which nanoparticles enter bacterial cells, improving their design for targeted antimicrobial action.
Another emerging focus is the development of biogenic nanoparticles—nanoparticles synthesized using environmentally friendly reducing agents. This approach aims to create safer, more sustainable antimicrobial materials while maintaining strong antibacterial properties.10
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References and Further Reading
- Yılmaz G. et. al. (2023). Antimicrobial Nanomaterials: A Review. Hygiene. 3(3). 269-290. Available at: https://doi.org/10.3390/hygiene3030020
- Mondal, S. et. al. (2024). Antimicrobial nanoparticles: current landscape and future challenges. RSC Pharmaceutics. 388-402. Available at: https://doi.org/10.1039/D4PM00032C
- Elbourne, A. et. al. (2017). Nano-structured antimicrobial surfaces: From nature to synthetic analogues. Journal of Colloid and Interface Science, 508, 603-616. Available at: https://doi.org/10.1016/j.jcis.2017.07.021
- Girma, A. et. al. (2023). Alternative mechanisms of action of metallic nanoparticles to mitigate the global spread of antibiotic-resistant bacteria. The Cell Surface, 10, 100112. Available at: https://doi.org/10.1016/j.tcsw.2023.100112
- Lam, P. et. al. (2020). The role of reactive oxygen species in the biological activity of antimicrobial agents: An updated mini review. Chemico-Biological Interactions, 320, 109023. Available at: https://doi.org/10.1016/j.cbi.2020.109023
- Chen, Y. et. al. (2023). Nanomaterials against intracellular bacterial infection: from drug delivery to intrinsic biofunction. Frontiers in Bioengineering and Biotechnology, 11, 1197974. Available at: https://doi.org/10.3389/fbioe.2023.1197974
- Yougbare, S. et. al. (2019). Antimicrobial gold nanoclusters: Recent developments and future perspectives. International journal of molecular sciences, 20(12), 2924. Available at: https://doi.org/10.3390/ijms20122924
- Song W. et. al. (2019). Application of Antimicrobial Nanoparticles in Dentistry. Molecules. 24(6):1033. Available at: https://doi.org/10.3390/molecules24061033
- Hossain, F. et. al. (2014). Antimicrobial nanomaterials as water disinfectant: applications, limitations and future perspectives. Science of the total environment, 466, 1047-1059. Available at: https://doi.org/10.1016/j.scitotenv.2013.08.009
- Chakraborty, N. et al. (2022). Nanobiotics against antimicrobial resistance: harnessing the power of nanoscale materials and technologies. J Nanobiotechnol. 20. 375. Available at: https://doi.org/10.1186/s12951-022-01573-9
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