Investigating Elastin-like Polymer Surface Thickness with Quartz Crystal Microbalance (QCM)

The quartz crystal microbalance with dissipation (QCM-D) measures the frequency and viscoelasticity on a quartz crystal surface. In order to calculate the thickness of the surface layer, the frequency response is used along with the density of the polymer and viscosity of the solute in the flow system.

One of the layers used by our lab is elastin-like polymer (ELP). ELP is a polypeptide with the general formula (VPGXG)_n, with X being replaced with a specific amino acid (except proline) and n is the number of repeats. ELP has a stimuli-responsive behavior to different environments, such as salt concentrations and temperature. ELP can be modified onto gold surfaces through gold-thiol interactions. Gold is a common substrate for electrochemical biosensors because it is easily conjugatable and acts as an electron-conducting substrate. We successfully modified gold-quartz chips to evaluate the viscoelastic changes of surface-bound ELP during a stimulus response. Data showed that the ELP attached to the gold surface with a thickness of 2.74nm through viscoelastic calculations. Our next step is to measure the difference in thickness and viscoelasticity with temperature changes to better understand surface bound ELP.

Funding support was provided by a National Science Foundation (EPSCoR) Research Infrastructure Improvement Award (#OIA-2119237). We want to thank Eva Rose M. Balog, and her research group, for providing our ELP.