Breakthrough can boost lab test's sensitivity

Washington - A breakthrough in nanotechnology would boost a lab test's sensitivity more than three-million-fold, vastly improving early detection of cancer, Alzheimer's disease and other disorders, a study reveals.

It involves a common biological test called an immunoassay, which mimics the action of the immune system to detect the presence of biomarkers - the chemicals linked with diseases.

It would enable doctors to detect the lowest ever concentrations of telltale markers than was previously practical, the journals Nanotechnology and Analytical Chemistry reported.

Simply stated, the immunoassay would require three million times fewer biomarkers to be present compared to an existing conventional immunoassay.

"This advance opens many new and exciting opportunities for immunoassays and other detectors, as well as in disease early detection and treatment," said Stephen Chou, professor of engineering at Princeton, who led the research team.

"Furthermore, the new assay is very easy to use, since for the person conducting the test, there will be no difference from the old one - they do the procedure in exactly the same way," added Chou, according to a university statement.

When biomarkers are present in samples, such as those taken from humans, the immunoassay test produces a fluorescent glow (light) that can be measured in a lab. The greater the glow, the more of the biomarker is present.

However, if the amount of biomarker is too small, the fluorescent light is too faint to be detected, setting the limit of detection.

Princeton University researchers tackled this limitation by using nanotechnology to greatly amplify the faint fluorescence from a sample.

By fashioning glass and gold structures so small they could only be seen with a powerful electron microscope, scientists were able to drastically increase the fluorescence signal compared to conventional immunoassays, leading to a three-million-fold improvement in the limit of detection.

That is, the enhanced immunoassay would require three million times fewer biomarkers to be present compared to a conventional immunoassay.