Development of an electrochemical surface-enhanced raman spectroscopy aptasensor for the early detection of acute myocardial infarction

Abstract

A common cardiovascular disease is acute myocardial infarction (AMI), which is characterized as an ischemic event within the myocardium that results in irreparable damage to the heart. Unfortunately, current clinical methods lack sensitivity or are too time consuming to diagnose AMI events effectively. A common biomarker that is specific to AMI is the protein cardiac troponin I (cTnI). cTnI is a good protein biomarker for diagnosing AMI because it is part of the troponin complex which breaks down and is released into the blood stream when AMI events occur. The goal of this thesis was to build an aptamer-based biosensor (aptasensor) specific to cTnI using an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) detection platform. EC-SERS was first used to prepare, optimize, and characterize a ternary (three component) monolayer consisting of an aptamer that specifically binds to cTnI, and two alkane thiols which backfill the surface and limit non-specific adsorption. Once optimized, the ternary monolayer was tested for blocking efficiency of non-target analytes, which was found to block >99% of non-target signal. This research also developed a new method for verifying the presence of the aptamer after the monolayer had been prepared using deuterated thiols. Finally, the ternary monolayer was tested for its aptasensing capabilities for the determination of cTnI, where no signal was detected for cTnI due to distance dependence issues that are a limitation of SERS techniques. Future work is needed to extend the applicability of SERS to aptamer-based sensors.