ИСТИНА

Microgels are crosslinked polymeric particles consisting of a porous network swollen by a solvent with the ability to undergo often a volume phase transition with respect to environmental changes. Introduction of charges into the microgel network leads to a possible interaction of the polyelectrolyte microgel with oppositely charged counterions based on electrostatic attraction (host-guest interplay). In case of redox-active counterions, the charge of these guest molecules can be changed by electrochemical means. Hence, we address thermoresponsive cationic microgels and their influence on the electrochemistry of hexacyanoferrates. Further, we investigate the influence of the counterion guests on the swelling of the microgel hosts. The combination of hydrodynamic voltammetry and electrochemical impedance spectroscopy allowed a distinction between the electron pathways. In addition, the data strongly suggest the selective uptake of ferricyanide and an encapsulation of the guest molecules inside the microgel network at elevated temperatures. By that, the size of the cationic microgel can be reversibly modulated by electrochemical switching leading to a redox-responsive microgel system. Further, adsorption of these microgels onto conductive substrates allow their use as optimized hosts of oppositely charged enzymes with a high loading capacity in the well hydrated interior microgel environment. This opens the way toward microgel-based biosensors: the enzymes catalyze the transformation of non-electroactive substrates to electroactive products, which can be detected amperometrically. Electrochemical techniques provide even further information on the location of the enzymes within these microgel-based films.