A quick and simple assay, developed from a collaborative effort between researchers at the universities of Montreal and Rome, could one day allow doctors, or even patients themselves, to carry out diagnosis of various diseases and obtain results within minutes –all in the comfort of their homes and offices.
The Montreal team, working with a scientist from Rome, have developed a straightforward, yet highly selective assay for rapid detection of proteins in whole blood, by taking advantage of steric hindrance effects on pairing of complementary DNA strands, as reported in the September issue of the Journal of the American Chemical Society.
Steric effects occur when atoms in close proximity create cost in energy as a result of overlapping electron clouds, which affect reactivity of molecules. In this case, the team capitalized on the effects of steric hindrance caused by the presence of proteins (a relatively larger molecule) on the reactivity of DNA hybridization (a relatively smaller molecule), in a process known as electrochemical steric-hindrance hybridization assay (eSHHA). In the absence of proteins, binding of complementary DNA strands generates a detectable flow of electrical current. However, when proteins such as antibodies are present, steric effects reduce the signal.
Unlike current point-of-care (POC) approaches which simply indicate the presence or absence of target proteins, the signal reduction in eSHHA directly correlates with the concentration of antibodies present, thus allowing precise quantification of targets in a sample. Also, the signal reduction is proportional to the size of the target molecule. In addition, eSHHA confers the advantage of no detectable signal drift during the first few minutes of immersion in whole blood, in contrast to conventional DNA-based electrochemical assays.
In summary, eSHHA offers rapid detection of multiple target molecules in complex matrices, for example whole blood, with high specificity and sensitivity. It is the advent of this kind of rapid, cheap, and straightforward POC approaches that revolutionize diagnostic testing, by bringing such tests conveniently and immediately to patients, and hence allowing faster and more efficient clinical management.
Study in Journal of The American Chemical Society: A Highly Selective Electrochemical DNA-Based Sensor That Employs Steric Hindrance Effects to Detect Proteins Directly in Whole Blood
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