Glucose sensitive poly (N-isopropylacrylamide) microgel based etalons.

Thermoresponsive microgels have been shown to be an excellent platform for designing sensor materials. Recently, poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgel based etalon materials have been described as direct sensing materials that can be designed to have a single, unique color. These color tunable materials show immense promise for sensing due to their spectral sensitivity and bright visual color. Here, we describe a proof-of-concept for etalon sensing of glucose. We found that aminophenylboronic acid (APBA)-functionalized pNIPAm-co-AAc microgels in an etalon respond to 3 mg/mL glucose concentrations by red shifting their reflectance peaks by 110 nm up to 150 nm. Additionally, APBA-functionalized pNIPAm-co-AAc microgels have a depressed volume phase transition temperature at 18-20 °C, which shifts to 24-26 °C after glucose binding. We also demonstrate that these materials show a marked visual color change, which is a first step towards developing direct read-out sensor devices.