| dc.description.abstract | Myocardial infarction (MI) is a critical disease that affects a large population and has a high rate of mortality. Development of a point-of-care (POC) system for the detection of a biomarker panel composed of cardiac troponin I (cTnI), copeptin, and heart-type fatty acid-binding protein (h-FABP), is better than detection of a single biomarker because it can achieve an improved diagnosis of MI and a rapid rule-out of the non-MI patients in the field. Further, using a multiplex POC testing approach is more efficient for detecting a biomarker panel, because it requires a less total volume of sample, shorter analysis time, and lower total cost.
In this work, surface-enhanced Raman spectroscopy (SERS), a sensitive optical modality, was used as the transduction mechanism for the detection of the biomarkers for MI. Assays developed on paper-based microfluidic platforms were used to achieve the recognition of the biomarker and afforded the ability to be low cost and user-friendly. A silica shell nanoparticle was first developed to provide a stable and strong SERS signal. Using this SERS active particle, a single biomarker assay for the detection of cTnI was developed. To enhance the sensitivity, the paper-based microfluidic platform was improved by designing a localized dissolvable delay to tune the flow rate in the paper channel. In addition, a horizontal motion mechanical valve was designed to automatically finish the multiple steps in the assay. However, the sensitivity of the assay still needs to be improved. To overcome this, a new SERS active particle using a Raman reporter molecule (RRM) as a spacer to form a nanometer gap between a gold core and a gold shell was developed. The nanometer gap largely enhanced the SERS signal; the gold shell protects the RRM and ensures a stable SERS signal. Using the improved SERS active particle, a multiplexed assay for detection of the biomarker panel (cTnI, copeptin, h-FABP) was developed. The signal from each biomarker on a single test line was resolved by using separate peaks from different RRMs in SERS active particles. The detection ranges of the assay successfully covered the clinically relevant range of the three biomarkers. | |
