Cholera affects more than 200,000 people annually, mainly in developing countries, and causes about 5,000 deaths. Many involve infants, children, and the elderly. Scientists are reporting the development of a key advance that could provide a fast, simple test to detect the toxin that causes the disease.
Cause
J. Manuel Perez and colleagues note that cholera is an intestinal infection from food or water contaminated with the bacterium Vibrio cholerae. It produces a toxin that can cause severe diarrhea, which can lead to rapid dehydration and death. Prompt treatment thus is essential, and yet existing tests to diagnose cholera are time-consuming, expensive, and require the use of complex equipment. To detect the disease at a faster rate scientists use nanoparticles of iron oxide and dextran.
Iron oxide nanoparticles
Iron oxide nanoparticles have superparamagnetic properties and potential applications in many fields, although Cu, Co and Ni are highly magnetic materials, they have limited applications due to their toxicity and susceptibility to oxidation. There are two main forms of iron oxide nanoparticles, they are magnetite (Fe3O4) or its oxidized form maghemite (γ-Fe2O3).
Applications of iron oxide nanoparticles include multi-tera bit storage device, catalysis, sensors, and a platform for high-sensitivity biomolecular magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. In addition, these applications require special surface modification of iron oxide nanoparticles. Some of the common surface coating agents that are being used for this purpose are long chain fatty acids, alkyl amines and diols.
Dextran
Dextran is a water-soluble polysaccharide of glucose (dextrose) produced by the action of Leuconostoc mesenteroides on sucrose. Dextran is used in various fields such as pharmaceutical, photographic, and agricultural industries. Several preparations of dextran are used as anticoagulants.The versatile use of dextran products relates to the favorable properties such as it is neutral and water soluble, easily filtered, biocompatible, biodegradable and stable for more than 5 years. The scientists describe a method to do a better and faster test. The new method uses specially prepared nanoparticles of iron oxide coated with sugar dextran.
Mechanism
To achieve this, they looked for specific characteristics of the cholera toxin receptor (GM1) found on cells' surface in the victim's gut, and then they introduced these features to their nanoparticles. When the magnetic nanoparticles are added to water, blood, or other fluids to be tested, the cholera toxin binds to the nanoparticles in a way that can be easily detected by instruments. The test hardware can be turned into portable gear that health care workers could use in the field, the scientists say. The approach also shows promise for treating cholera intoxication.