It is important to detect lower concentrations of disease (like various cancers) markers in human bodily fluids reliably. The ability to detect lower analyte concentration would allow us to identify the onset of diseases in their early stages and start treatment process.
In an effort to make a device that could measure lower concentrations of protein, researchers of Dutta group at the University of Wyoming have developed a microfluidic device in which the analyte protein molecules are preconcentrated infront of membrane inside the channel. Enzyme Linked Immunosorbent Assay (ELISA) was performed on the same channel and the signal generated from the enzyme reaction was increased by a factor of 200.
In their current work reported, they have shown a reduction in the smallest detectable concentration of the tumor marker CA 199-9 and Blue tongue Viral antibody by over 2 orders of magnitude compared to immunoassays without preconcentration. This led to the improvement in the lowest analyte concentration detectable (LOD) by a factor of 20. Their device only required ~5 uL analyte and other solutions to complete the assay in contrast to conventional microtiter plate based assayed (~100uL).
There are several methods to amplify the ELISA signal and some of them involve preconcentration of enzyme reaction product (e.g resorufin) molecules. Dutta groups new method is unique in terms of preconcentrating target analyte-proteins. They used photopolymerized semipermeable membrane fabricated inside bonded glass microchip for preconcentrating analytes.
Details of this work has been published recently in Analytical Chemistry journal.