Fluorescence-based detection and imaging techniques are convenient to use to detect and image various biological species of interest but suffer from poor sensitivity. When a patient carries low levels of antigens in the blood or urine, the fluorescent signal can be weak, making visualization and diagnosis difficult. This method is not always preferred when sensitivity is a key requirement.
A recently developed fix uses metal nanostructures to increase the fluorescence intensity by 100 times in these diagnostic tests. The solution devised by researchers from Washington University in St. Louis and the Air Force Research Laboratory at Wright-Patterson Air Force Base offers an inexpensive approach to enhance the sensitivity of fluorescence technology.
Enzyme-based amplification and other techniques applied to boost the signal require extra steps that prolong the overall operation time, and expensive read-out systems in some cases. The new plasmonic patch, consisting of a 1 square centimeter piece of flexible film with embedded nanomaterials, incurs no changes to testing protocols. The sample is prepared in the usual manner after which the patch is applied over the top followed by scanning.
The gold nanorods or other plasmonic nanostructures absorbed on the film function as antennae. The design concentrates light into a tiny volume around the fluorescence-emitting molecules and is likened to a magnifying glass for light that improves visualization.
Costing only about five cents per application, the patch can prove useful in research as well as medical diagnostics. The device could be combined with a microarray to enable simultaneous detection of tens to hundreds of analytes in a single experiment.
The research is published in Light: Science and Applications.