September 30, 2022

Responsive polymers are used in drug delivery, switchable biocompatible coatings, and advanced bio-interfaces in bioanalytical devices. Thermo-responsive polymers, where changing the temperature stimulates changes in the polymer properties, are the most common in biomedical applications. All thermo-responsive polymers have a lower critical solution temperature (LCST). Above or below this temperature determines the state of the polymer.

Many different external parameters affect the response speeds of the collapsing and swelling states in thermos-responsive polymers. With a plasmonic heating technique that optically excites localized surface plasmon (LSP) modes on the surface of Au nanoparticles, the temperature of the polymer hydrogel layer can be precisely controlled with respect to the ambient bulk temperature. By testing different bulk temperatures, longer heating beam pulses, and a variety of temperature change increases, researchers realized response times as low as 1.5 ms for the collapsing state and single digit milliseconds for the swelling state of the polymer hydrogel. With the investigated complex and different response times of thermo-responsive polymer networks, advances can be made in biomedical and miniature actuator applications.

The effect of the ambient bulk temperature on the sample was critical to the speed and timing of the thermo-response. To control this temperature, researchers used Wavelength Electronics’ LFI-3751 temperature controller to operate a Peltier device attached to the flow cell and substrate with the nanoparticle and polymer hydrogel layer. The high performance LFI-3751 temperature controller ensured constant and stable temperature of the polymer networks. By controlling this temperature and carefully increasing or decreasing above or below the LCST, researchers found the effects on ambient bulk temperature paired with plasmonic heating on thermo-responsive polymer networks.
The complete case study is available as CS-TC06.

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