The overall goal of this research is to develop a new point-of-care system for early detection and
characterization of cardiac markers to aid in diagnosis of acute coronary syndrome. The envisioned final technology
platform incorporates functionalized gold colloidal nanoparticles trapped at the entrance to a nanofluidic device
providing a robust means for analyte detection at trace levels using surface enhanced Raman spectroscopy (SERS).
To discriminate a specific biomarker, we designed an assay format analogous to a competitive ELISA. Notably, the
biomarker would be captured by an antibody and in turn displace a peptide fragment, containing the binding epitope
of the antibody labeled with a Raman reporter molecule that would not interfere with blood serum proteins. To
demonstrate the feasibility of this approach, we used C-reactive protein (CRP) as a surrogate biomarker. We
functionalized agarose beads with anti-CRP that were placed outside the nanochannel, then added either
Rhodamine-6-G (R6G) labeled-CRP and gold (as a surrogate of a sample without analyte present), or R6G labeled
CRP, gold, and unlabeled CRP (as a surrogate of a sample with analyte present). Analyzing the spectra we see an
increase in peak intensity in the presence of analyte at characteristic peaks for R6G specifically, 1284 and1567 cm-
1. Further, our results illustrate the reproducibility of the Raman spectra collected for R6G-labeled CRP in the
nanochannel. Overall, we believe that this method will provide the advantage of sensitivity and narrow line widths
characteristic of SERS as well as the specificity toward the biomarker of interest.