Academic journal article The American Biology Teacher

Bacteria Buster: Testing Antibiotic Properties of Silver Nanoparticles

Academic journal article The American Biology Teacher

Bacteria Buster: Testing Antibiotic Properties of Silver Nanoparticles

Article excerpt


Nanoscale science and engineering are disciplines that examine the unique behaviors and properties of materials that emerge at the size range of 1 to 100 nanometers (a billionth of a meter). Nanobiotechnology is a sub-discipline of nanoscience that has arisen more recently. It refers to harnessing unique behaviors and properties at the nanoscale to manipulate materials for applications in biology (NNI, 2001). Already nanobiotechnology is impacting the fields of healthcare and biomedical engineering, and promises to be critical in advances in other related fields. Even though it spans multiple science disciplines, the abstract nature of nanoscience in general can challenge instructors to find practical ways to teach about this concept in the classroom (for additional ideas see, Nanoscale Science: Activities for Grades 6-12).

This article describes a quick and simple laboratory investigation utilizing nanotechnology in a biological context. It is most appropriate for high school or undergraduate students. It addresses biology content standards in both personal and community health as well as the future challenges of science and technology to society. This activity requires a limited amount of materials and yields visible results. The investigation has two basic objectives: 1) make students aware of nanotechnology and its potential biological interface, and 2) have students examine and explore the accuracy of claims made about emerging technologies. The activity itself is something that we believe many instructors will recognize, but we hope that our proposed approach will offer a new perspective on an old activity.

* Bacteria & Silver Nanoparticles

The misuse and overuse of antibiotics in today's society have lead to the evolution of dangerous new strains of antibiotic-resistant bacteria. For example, methicillin-resistant Staphylococcus aureus (MRSA) outbreaks have become a concern in many hospitals due to the microbes' resistance to all but the most potent antibiotics (Gupta & Silver, 1998). Outbreaks of antibiotic-resistance bacteria fuel incentives to develop new effective bacteriacidal agents (Morones et al., 2005).

Silver is toxic to a wide range of microorganisms including many that cause human disease (Liau et al., 1997). Silver nanoparticles are especially potent when reduced to the size range of 5-to-50 nanometer clusters. Studies with silver nanoparticles in this size range have been shown to kill common bacteria such as E. coli, V. cholera, and S. typhus (Morones et al., 2005). The effectiveness of silver as an antibiotic has already led to its widespread use in wound dressings and catheters (Margaret et al., 2006; Samuel & Guggenbichler, 2004).

Despite the effectiveness of silver as an antimicrobial agent, questions remain as to whether microbes like bacteria will develop resistance to silver (similar to that seen with modern antibiotics). Whether bacteria could develop resistance to silver nanoparticles will depend on the mechanism by which silver works to kill bacteria. Numerous models have been suggested including deactivation of certain bacterial enzymes, disruption of gene replication, and limitation of cellular membrane function (summarized in Morones et al., 2005). However, the true mechanism for silver's antibacterial action remains uncertain.

Nanoparticle silver is already being used in numerous antibiotic applications, just a few of which are listed below (Gupta Silver, 1998):

* Hospital surfaces and sterile instrumentation

* Agricultural sites (such as chicken farms) to reduce infectious agents in the environment

* Sterilize recycled water aboard the MIR space station

* Medical wrappings to treat burns and various infections

* Silver-threaded socks and underwear to reduce odor caused by bacteria.

As with all new technology, the potential benefits might be associated with risks. …

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