A rapid, near infrared, whole blood immunoassay using metal nanoshells

The development of a rapid, whole blood immunoassay with the capacity to detect various analytes would greatly benefit point-of-care or public health applications, where there is a strong demand for the rapid, high throughput screening of blood-borne species. Immunoassays, with their high affinity/specificity, show the most promise for implementing such a system. Nevertheless, conventional methods, such as the enzyme linked immunosorbent assays (ELISAs), have failed to develop a robust, rapid, whole blood assay, as they require time-consuming sample purification, incubation, and rinsing steps prior to analysis. We have used a new class of optically-active nanoparticles called metal nanoshells to develop a new rapid, near-infrared (NIR) immunoassay capable of detecting very low concentrations of analytes in whole blood within minutes without any sample preparation.