Researchers at Pittsburg State University in Pittsburg, KS, have developed a hybrid nanosensor to detect bacterial contamination from E. coli or other pathogens at concentrations as low as one colony-forming unit and to do it more quickly than existing methods.
The nanosensor uses a combination of magnetic relaxation and fluorescence measurements to both detect and quantify broad-spectrum contaminations in samples ranging from aquatic reservoirs to commercially produced food, according to an abstract posted Sept. 4 by the American Chemical Society in its ACS Infectious Diseases.
The method was developed by PSU Chemist Tuhina Banerjee, PSU Assistant Professor of Chemistry Santimukul Santra, and their colleagues Shoukath Sulthana, Tyler Shelby, Blaze Heckert, Jessica Jewell, Kalee Woody, Vida Karimnia and James McAfee.
In lab tests of milk samples, the nanosensor could detect varying concentrations of E. coli O157:H7 in less than an hour, the researchers reported. They also used it to analyze E. coli levels in untreated lake water, which they noted serves as a source of household water in some developing countries.
In addition, the researchers said that the device could be customized to detect a wide range of pathogens other than E. coli.
While conventional bacterial detection methods such as polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA) and fluorescent immunoassays are useful, they require sophisticated instruments and extensive sample preparation and have long readout times, the research report said.
Commonly used methods to test food for microbes can take up to 24 hours to get results, which is often too slow to catch tainted products before they reach the consumer. Magnetic resonance can detect very low levels of bacteria, but it isn’t as effective when pathogens are at higher concentrations. Fluorescence is the opposite, which is why the PSU researchers wanted to combine the two techniques.
E. coli O157:H7 “presents a serious threat to human health and sanitation and is a leading cause in many food- and waterborne ailments,” the researchers stated. With a simpler and more sensitive diagnostic technique, its presence in food or water might be more quickly detected and potential illnesses averted.