Sensors for detecting chemical biomarkers that indicate a disease have already been applied to some maladies, but they have not proven very effective at discovering low concentrations of those biomarkers, such as when a disease is in its early stages. This is a problem, because often the key to successful treatment is early detection.
Now researchers at the London Centre for Nanotechnology at Imperial College London and the University of Vigo have developed plasmonic nanosensors that could enable early disease detection by picking up biomarker signals at very low concentrations.
The research, which was published in the journal Nature Materials (“Plasmonic nanosensors with inverse sensitivity by means of enzyme-guided crystal growth”), demonstrated a signal-generation mechanism for nanoparticle sensors capable of creating “a signal that is larger when the target molecule is less concentrated.” Earlier this year we saw researchers at Brown University experiment with plasmonics for biosensors to measure glucose levels via saliva rather than blood.
In the initial testing with the new London nanoparticle sensor the researchers looked for the biomarker associated with prostate cancer, called prostate specific antigen (PSA). The nanosensor was capable of detecting PSA in concentrations nine orders of magnitude smaller than today's enzyme-linked immunosorbent assay (ELISA) tests.
The LCN nanosensors are made up of gold nanoparticles that are floating in proteins derived from blood serum. On the surface of the gold nanoparticles are differnet antibodies. One antibody latches onto the PSA when it detects it while the other antibody creates a silver crystal coating that floats on the surface of the nanoparticle when it comes in the presence of the PSA. The silver crystal coating is detected by optical microscopes. The improved “signal-generation mechanism” is that this silver crystal coating is more apparent when the concentration of the PSA is low.
Professor Molly Stevens, senior author of the study from the Departments of Materials and Bioengineering at Imperial College London, notes in a press release: “It is vital to detect diseases at an early stage if we want people to have the best possible outcomes – diseases are usually easier to treat at this stage, and early diagnosis can give us the chance to halt a disease before symptoms worsen. However, for many diseases, using current technology to look for early signs of disease can be like finding the proverbial needle in a haystack. Our new test can actually find that needle. We only looked at the biomarker for one disease in this study, but we’re confident that the test can be adapted to identify many other diseases at an early stage.”
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.