(223f) Investigation of Surface-Bound ELP As a Thermoresponsive Polymer Film

Thermoresponsive polymer films have been investigated for their use for a variety of applications in the biomedical field, including wound dressings, tissue scaffolding, and biosensing.[1] Elastin-like polymers (ELP) are a class of genetically engineered thermoresponsive polymer that are modeled after the naturally occurring elastin protein found in the extracellular matrix. ELP are a great thermoresponsive candidate due to their ease of production and tunability; they can be expressed with high yield in Escherichia coli and can be genetically encoded to produce a library of variants. ELP possess a Lower Critical Solution Temperature (LCST), above which they form a condensed, undissolved state and below which they form an extended, solvated state.[2] This transition temperature has been experimentally observed many times in solution. However, surface-bound ELP have yet to be fully characterized in terms of their surface reproducibility, thermoresponsive behavior, and electrochemical drift. We use Electrochemical Impedance Spectroscopy (EIS) and quartz crystal microbalance (QCM) to monitor the thermoresponsive behavior of surface-bound ELP. Specifically, we measure the response from two ELP-modified surfaces: a thiol-bonded gold electrode surface and a covalently bonded carboxyphenyl film on glassy carbon electrodes. In addition, we compare surface modification reproducibility of the two surfaces and normalize for the inherent drift that occurs in EIS. Finally, we discuss our progress in using non-faradaic EIS to understand the thermoresponse of ELP surfaces.

Support was provided, in part, by a National Science Foundation EPSCoR award (#2119237).

[1] M.A. Ward, T.K. Georgiou, Thermoresponsive polymers for biomedical applications, Polymers (Basel). 3 (2011) 1215–1242. https://doi.org/10.3390/polym3031215.

[2] M.A. Morales, W.A. Paiva, L. Marvin, E.R.M. Balog, J.M. Halpern, Electrochemical characterization of the stimuli-response of surface-immobilized elastin-like polymers, Soft Matter. 15 (2019) 9640–9646. https://doi.org/10.1039/c9sm01681c.