Electrochemical Reduction of Diazonium Salts onto Carbon Electrodes for a Robust Electrochemical Aptamer-Based Sensor

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Lars Olivan Ryan White


By Lars Olivan, Chemistry

Advisor: Ryan White

Presentation ID: PM_D38


Electrochemical, aptamer-based (E-AB) sensors provide high specificity and sensitivity while allowing real-time measurement of target analytes. The point-of-care (POC) application of these E-AB sensors can replace more expensive, time consuming and complicated methods. E-AB sensors employ aptamers as the biorecognition element which are single stranded DNA or RNA sequences that are selected to bind a specific target. Aptamers can be immobilized onto different substrates such as gold and platinum. A common approach for aptamer immobilization is using self-assembled monolayer chemistry on a gold electrode. However, the stability of the gold-thiol bond is not ideal for fieldable devices because it is not stable to air drying or when stored for long periods of time. Alternatively, covalent bonding to carbon electrodes has been shown to be capable of forming strong carbon-carbon covalent bonds and offers rich surface chemistry. The rich chemistry offered by carbon substrates, for example glassy carbon electrodes (GCE), can be exploited by the reduction of diazonium salts onto the GCEs forming a strong carbon-carbon covalent bond. The carbon-carbon covalent bond can usually only be removed by mechanical polishing and can be stored for several months without breaking. Here, we introduce a diazonium and electrochemically reduce it onto GCEs. The modification parameters, deposition time and diazonium salt concentration, are optimized to provide a monolayer or near-monolayer coverage. A maleimide group allows for maleimide-thiol coupling chemistry to immobilize thiolated DNA aptamers for E-AB sensor fabrication on GCEs. This surface chemistry provides a framework for the fabrication of E-AB sensors on GCEs. 


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PM Poster Session -- Great Hall -- D: New Frontiers