Princeton researchers have developed a nanotechnology application to take routine immunoassays to a new level of detection capability.
The process uses glass and gold nanostructures to amplify the florescence signals emitted from a traditional immunoassay to indicate the presence of the pathogen or biomarker being measured. The researchers were able to dramatically increase the fluorescence signal compared to conventional immunoassays, leading to a 3-million-fold improvement in the limit of detection.
This discovery translates in real terms to improved early detection of disease, given that smaller concentrations of biomarkers for disorders such as Alzheimer’s disease and cancer are now detectable. It also could apply to increased sensitivity for biodefense assays such as for anthrax, ricin and food-borne pathogens.
“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, 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.”
The new artificial nanomaterial developed by the team, called D2PA, is a thin layer of gold nanostructures surrounded glass pillars just 60 nanometers in diameter. The pillars are spaced 200 nanometers apart and capped with a disk of gold on each pillar. The sides of each pillar are speckled with even tinier gold dots about 10 to 15 nanometers in diameter. The unique structure boosts the collection and transmission of light to approximately 1 billion-fold increase in an effect called surface Raman scattering.
The researchers recently published their results in the journals Nanotechnology and Analytical Chemistry. Moving forward, the team is next conducting tests to compare the sensitivity of the D2PA-enhanced immunoassay to a conventional immunoassay in detecting breast and prostate cancers. They are additionally collaborating with researchers at Memorial Sloan-Kettering Cancer Center to develop tests to detect proteins associated with Alzheimer’s disease at a very early stage.
The work was funded by the Defense Advanced Research Project Agency (DARPA) and the National Science Foundation.