Iridium Oxide Nanomonitors for Real-Time Health Monitoring Systems

An innovative lab-on-a-chip device based on iridium oxide (IrOx) nanowires was designed, fabricated, and developed for real-time “point-of-care” diagnostics. The turnaround time in detection and the need for expensive equipment for analysis have considverably limited rapid and “point-of-care” diagnosis. This research demonstrates the potential of IrOx nanowires toward early disease diagnosis by detecting proteins that are disease markers. The device designed is based on electrical detection of protein biomarkers wherein a single capture immunoassay is built onto a vertically aligned IrOx nanowire platform. Detection of two inflammatory proteins, C-reactive protein (CRP) and myeloperoxidase (MPO) (Calbiochem, La Jolla, CA), that are biomarkers of cardiovascular diseases is demonstrated individually and concurrently. The performance metrics of the device in response to the two biomarkers in pure form and in serum samples were evaluated and compared with standard enzyme-linked immunosorbent assay (ELISA). The methodology that has been adopted is based on measuring real-time impedance changes because of the protein binding event through electrochemical impedance spectroscopy and calibrating its change in magnitude with concentration of proteins. We have demonstrated limit of detection up to 500 pg/mL for protein MPO and I ng/mL for CRP with cross-reactivity of less than 8% of selective binding of these two inflammatory biomarkers.