An electrochemical microdevice has been fabricated to probe biomolecular characteristics under localized temperature control provided by an internal microheater. Measurements with this type of platform have successfully produced thermal profiles of duplex DNA, and show detection capabilities for single nucleotide polymorphisms and ligand-based stabilization. Background noise for electrochemical measurements on immobilized biomolecules has been minimized by using a redox active, methylene blue (MB) tag. Major advantages for our microdevice approach relate to high signal-to-noise ratios, sample volumes less that 10μL, and associated faster equilibration times for heating, which allow faster analysis of melting temperatures. The fabricated device is designed with an embedded platinum microheater, encased in insulating SiO<sub>2 </sub>(Figure 1). One of the key features of the platform is incorporation of a high-quality insulating later which isolates voltage applied to the heater from the surface electrodes, and is thin enough to minimize the temperature difference between the embedded heater and the surface. The surface of the device includes a central gold working electrode, proximal platinum reference electrode, and larger platinum counter electrode. MB is used as a redox probe for implementing a turn-on/off approach: lower current is recorded when biomolecular species locate MB away from the working electrode, and higher current is measured as thermally-induced conformation changes bring the MB closer to the gold surface. Square wave voltammetry has been used to analyze the conformation-dependent current at a specific voltage. The demonstrated feasibility of this low-volume, temperature-controlled technology enables scale up to arrays for electrochemical analysis of biomolecular stability under varied conditions.

Electrochemical studies of bioanalytes using microdevices with embedded microheaters

254th National Meeting (2017)

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