Microorganism Resistance to Antimicrobial Nanosilver: Cytotoxicity Origins and Molecular Basis of Cell Defence

Antimicrobial nanosilver, one of the earliest and most developed products of nanotechnology has found extensive applications in consumer products, ranging from wound dressings, antibacterial textiles to water and air purification systems and even, baby products. Nanosilver as versatile antimicrobial has proven efficacy against bacteria, yeast, fungi, algae and viruses. Recently, we found that the antimicrobial activity of nanosilver is non-universal and that some bacteria appear to adapt quite rapidly to its presence (Gunawan et al., 2013; featured in the Age and Science Alert). We have found the important natural ability of the commonly-occurring Bacillus species to develop stable resistance to nanosilver upon prolonged exposure. While effectively suppressing the growth of the common household and clinical pathogen Escherichia coli, the prolonged nanosilver exposure caused the nanosilver-tolerant Bacillus sp. to abnormally proliferate and ultimately dominates the microbiota. The project seeks to elucidate the origins and routes of the cellular ROS-mediated nanosilver toxicity (Gunawan et al., 2009; 2013), identifying the nature and target ROS destruction sites of the leached soluble silver and the undissolved silver particulates as well as their intracellular fates. Concurrently, the project also seeks to identify the molecular basis of cell defence to the toxicity at the genomic, RNA (DNA expression) and protein levels. The generated knowledge is transferrable to the fundamental elucidation of the potential cell acquired resistance across the broader range of nanomaterials beyond nanosilver. Importantly, the knowledge is vital for the protection and well-being of Australian and the international community, and the environment.


Development of nanosilver-resistant Bacillus sp. upon extensive nanosilver exposure (Gunawan et al., 2013)

Student undertaking this project will be supervised by Prof Rose Amal and Dr Cindy Gunawan.  The project is carried out in collaboration with the School of Chemistry and School of Biotechnology and Biomolecular Sciences (UNSW) and University of Technology Sydney (UTS). For more details, please contact Dr Cindy Gunawan at c.gunawan@unsw.edu.au or Professor Rose Amal at r.amal@unsw.edu.au 


  1. Gunawan, C., Teoh, W. Y., Marquis, C. P., Amal, R. Small (2013) DOI: 10.1002/smll.201300761
  2. Gunawan, C., Teoh, W. Y., Marquis, C. P., Lifia, J., Amal, R. Small (2009) 5, 341-344; Research Highlights by Chun, A. L. Nat. Nanotechnol. (2009) doi: 10.1038/nnano.2009.18
  3. www.sciencealert.com.au/news/20130805-24354.html
  4. http://www.theage.com.au/national/health/silver-lining-removed-in-medicines-war-with-bacteria-20130518-2jtll.html .95pt; margin-bottom:10.0pt;margin-left:-14.2pt;mso-add-space:auto;text-align:justify; text-indent:-7.1pt;line-height:normal’>Gunawan, C., Sirimanoonphan, A., Teoh, W. Y., Marquis, C. P., Amal, R. J. Hazard. Mater. (2013c) 260, 984-992.