Washington, Oct 11 : Scientists at Yale University have created nanowire sensors with simple microprocessor electronics, which are not only sensitive but also specific enough to be used for point-of-care (POC) disease detection, says a new report.
Highly specific antigens like signatures of bacteria, viruses or cancer cells, are used as detectors for activating immune cells.
On activation, T cells produce acid, and generate a tiny current in the nanowire electronics, signalling the presence of a specific antigen. The system can detect as few as 200 activated cells.
Previous studies have reported that the nanowires could detect generalized activation of this small number of T cells.
In the new report, scientists have shown that the nanowires can identify activation from a single specific antigen even when there is substantial background "noise" from a general immune stimulation of other cells.
"Imagine I am the detector in a room where thousands of unrelated people are talking - and I whisper, 'Who knows me?' I am so sensitive that I can hear even a few people saying, 'I do' above the crowd noise. In the past, we could detect everyone talking - now we can hear the few above the many," said senior author Tarek Fahmy, Yale assistant professor of biomedical engineering.
The authors said that such level of sensitivity and specificity is unprecedented in a system that uses no dyes or radioactivity.
Another exciting aspect of this detection system, according to the scientists, is its speed - producing results in seconds - and its compatibility with existing CMOS electronics.
"We simply took direction from Mother Nature and used the exquisitely sensitive and flexible detection of the immune system as the detector, and a basic physiological response of immune cells as the reporter. We coupled that with existing CMOS electronics to make it easily usable," said postdoctoral fellow and lead author, Eric Stern.
The scientists believe that the system has huge potential in POC diagnostic centers in the US and in underdeveloped countries where healthcare facilities and clinics are lacking.
Stern said that it could be as simple as an iPod-like device with changeable cards to detect or diagnose disease. Also, he believes that the system produces no false positives - a necessity for POC testing.
"Instruments this sensitive could also play a role in detection of residual disease after antiviral treatments or chemotherapy. They will help with one of the greatest challenges we face in treatment of disease - knowing if we got rid of all of it," said Fahmy.
The study is published in Nano Letters.