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On the horizon is a new approach for food pathogen screening that is far faster than current commercial methods. Scientists are reporting the technique in the ACS journal Analytical Chemistry.
Conventional methods to detect harmful bacteria in food are reliable and inexpensive, but they can be complicated, time consuming and thus allow contamination to go undetected. Sibani Lisa Biswal’s team set out to develop a faster method to catch unwanted microbes before they can make people sick.
They used an array of tiny “nanomechanical cantilevers,” anchored at one end, kind of like little diving boards. The cantilevers have peptides attached to them that bind to Salmonella. When the bacteria bind to the peptides, the cantilever arm bends, creating a signal. The screening system rapidly distinguished Salmonella from other types of bacteria in a sample. One of the peptides was even more specific than an antibody, which is considered the gold standard. That peptide could tell eight different types of Salmonella apart from each other. The researchers stated that the technique could be applied to other common food pathogens.
Specific binding between analytes and receptors causes surface stress that bends the microcantilevers. The deflection of the cantilevers, which is tens of nanometres, is measured using electronic readout from stress-induced changes in the MOSFET drain current. This approach offers low noise, high sensitivity and direct readout, and could be used to detect DNA hybridization, protein binding and other assays in a multiplexed and parallel manner. © G. S. SHEKHAWAT, S-H. TARK AND V. P. DRAVID