Optical Devices Constructed from Ferrocene-Modified Microgels for H₂O₂ Sensing

Ferrocene-modified poly( N -isopropylacrylamide)-based microgels were synthesized, characterized, and used to construct optical devices (etalons). The response of the microgels and etalons to H 2 O 2 was investigated, and we show that both the microgel diameter and the optical properties of the etalons depend on the solution concentration of H 2 O 2 from 0.6 to 35 mM. This behavior is a direct result of the oxidation of ferrocene, which influences the microgel diameter. This was also demonstrated by electrochemical-mediated oxidation/reduction of ferrocene using cyclic voltammetry. We go on to show that these materials could be used to monitor H 2 O 2 that is generated from enzymatic reactions. Specifically, we show that the H 2 O 2 generated from the oxidation of glucose catalyzed by glucose oxidase could be quantified. Finally, the devices can be reused multiple times via a regeneration process. This investigation illustrates the versatility of the etalon system to detect species of broad relevance and how they could potentially be used to quantify products of biological reactions.