Advances in SERS Based Point of Care Diagnostic Assays

In the development of next generation bioassays designed for detecting the emergence and spread of diseases in point-of-care (POC) and remote settings, more rapid and portable analytical methods are required. Colloidal based SERS bioassays have distinct advantages for use in portable diagnostic systems over surface sensors.  Nanoparticles in solution allow for both a freely diffusing sensor surface and a high surface area to volume ratio.  Therefore colloidal systems are not impacted by mass transfer limitations, allowing for the rapid analysis of small sample volumes.  In addition, paramagnetic capture assay schemes provide both separation and concentration mechanisms, minimizing signals from non-specific interactions.  Recent developments in our laboratory in the fabrication of gold-coated magnetic nanoparticles provide an additional alternative single nanoparticle assay scheme.  The nanoparticles function as SERS substrates while simultaneously allowing for manipulation by a magnetic field.  Detection strategies have been demonstrated for the sensitive detection of Rift Valley Fever virus and West Nile virus nucleic acids and proteins in multiplexed formats. In addition, we have demonstrated the advantages of using antibody fragments over IgGs as a more compact recognition element in our immunoassay schemes.