Electrochemically Tagging Elastin-like Polymers-Modified Au Surfaces

Abstract

We are exploring Elastin-like-Polymer (ELP) as a transducing enhancement element for biosensors. While previous work in our lab has investigated surface-bound ELP conformational state with electrochemical impedance spectroscopy to understand its stimuli-response, we would like to use ELP as an electrically active transducer in sensor applications. To achieve this, we must understand how much of the ELP is covalently attached to the electrode and functionalize the electrochemically-inert ELP with a faradaic tag. We present a proof-of-concept model for modifying the C-terminus of the ELP with Toluidine Blue O, an electrically active phenothiazine compound. Our system uses simple and accessible conjugation chemistry for this purpose and is conducted in aqueous solution. Further, reducing the thiol bonds will remove the covalently-bound ELP from the electrode surface to obtain an estimate of the ELP surface coverageThus far, we have successful decoupled the thiol-gold bond using the cyclic voltammetry reduction technique.. Electrochemical impedance spectroscopy confirmed that the modified electrode after thiol desorption returned to a similar state compared to a bare electrode. Additionally, we successfully measured an electrochemical signal attributed to the Toluidine Blue O tag conjugated to ELP based on its redox properties (Figure 1). We intend to further expand this work by refining the conjugation protocol, comparing various tags and conjugation chemistries, and relating surface coverage to desorption amounts of covalently bound ELP. Acknowledgements: The authors would like to acknowledge the financial support from the College of Medicine at Drexel University, NSF (CBET 1638896), the Collaborative Research Excellence Initiative Pilot Research Program at the University of New Hampshire, and the Hamel Center of Undergraduate Research at the University of New Hampshire. The authors also would like to acknowledge the assistance of Dr. Balog’s laboratory and Dr. Halpern’s laboratory.