June 04, 2012
3-Million-Fold Improvement In Immunoassay Sensitivity

Why make small steps forward when really big steps are possible? Princeton researchers have developed a way to make immunoassays for biomarkers (e.g. blood proteins for cancer or Alzheimer's) 3 million times for sensitive. So far fewer molecules need be present to detect a medical condition. Earlier detection becomes possible.

The breakthrough involves a common biological test called an immunoassay, which mimics the action of the immune system to detect the presence of biomarkers the chemicals associated with diseases. 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 laboratory. 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. A major goal in immunoassay research is to improve the detection limit.

The Princeton 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, the scientists were able to drastically increase the fluorescence signal compared to conventional immunoassays, leading to a 3-million-fold improvement in the limit of detection. That is, the enhanced immunoassay would require 3 million times fewer biomarkers to be present compared to a conventional immunoassay. (In technical terms, the researchers measured an improvement in the detection limit from 0.9 nanomolars to 300 attomolars.)

This technique doesn't just enable earlier detection. It also enables detection of compounds that never reach high concentrations. So expect more biomarkers to be found with this technique and for .

These researchers are now going to compare the sensitivity of this approach for cancers and Alzheimer's in hopes of earlier stage detection.

As next steps in his research, Chou said he is conducting tests to compare the sensitivity of the D2PA-enhanced immunoassay to a conventional immunoassay in detecting breast and prostate cancers. In addition he is collaborating with researchers at Memorial Sloan-Kettering Cancer Center in New York to develop tests to detect proteins associated with Alzheimer's disease at a very early stage.

"You can have very early detection with our approach," he said.

The scaling of biotechnology to work at very small scales is yielding rapid advances just as scaling down of semiconductor devices enabled computers to become both cheaper and more powerful at the same time. It is this trend toward smaller scale devices that gives me the most optimism about how soon we will get advances in biotechnology that will enable the development of rejuvenation therapies.

Share |      Randall Parker, 2012 June 04 08:50 PM  Biotech Assay Tools

PacRim Jim said at June 4, 2012 11:25 PM:

Humans are designed to ignore about 95% of the raw data inputted via the senses, and even the afferent data streams from our proprioceptors are ignored at the conscious level.
What will life be like when we become aware of the floods of background data unique to each of us?
It seems that we ultimately will design implantable biostats that will maintain thousands of internal levels within desired ranges, to keep us frozen at a certain age.
Will we still be Homo sapiens?

Nanonymous said at June 5, 2012 7:46 PM:

All this does is reduce the amount of material needed for an assay. That generally is not limiting - not in diagnostics, anyway. What matters much more in immunoassays is 1) signal/noise, 2) false positives. The new signal amplification does not result in a very different signal to noise ratio and changes absolutely nothing with regard to false positives. So, an interesting development but not anywhere near the hype.

NJSteve said at June 6, 2012 6:16 PM:

This is good as long as markers at extremely low levels are not universally present and actual disease develops only with other unknown factors. I guess we'll be finding out soon.

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