Modified Electrodes and Electrochemical Systems Switchable by Temperature Changes

Abstract

This article is an overview of extensive research efforts in the area of temperature‐controlled electrochemical systems. Electrochemical reactions, including electrocatalytic and bioelectrocatalytic processes, have been reversibly activated and inhibited by temperature changes. This was achieved by modification of electrode surfaces with thermo‐sensitive polymers (e.g., poly(N‐isopropylacrylamide), PNIPAM) which are reversibly switched by temperature changes between two different structures: swollen expanded coil conformation and shrunken collapsed globule state. While the swollen hydrophilic state allows penetration of redox species to the electrode conducting support and activates electrochemical reactions, the collapsed hydrophobic state isolates the electrode surface and inhibits electrochemical processes. Electrodes modified with the thermo‐switchable polymers have been additionally functionalized with photo‐switchable molecules (e.g., spiropyran derivatives) to achieve double‐controlled electrochemical reactions switchable by temperature changes and light signals. Incorporation of metallic nanoparticles or graphene species in the temperature‐sensitive polymer films resulted in sophisticated features and multi‐signal controlled behavior of the nano‐composite systems.

Bioelectrocatalytic Electrodes Modified with PQQ‐Glucose Dehydrogenase‐Calmodulin Chimera Switchable by Peptide Signals: Pathway to Generic Bioelectronic Systems Controlled by Biomolecular Inputs

“…Signal‐controlled (bio)electrochemical systems with switchable/tunable activity are essential for assembling bioelectronic, (particularly implantable bioelectronic) systems with adaptable behavior in biological environment. The majority of signal‐controlled electrochemical systems has been based on electrodes chemically modified with stimuli‐responsive materials (usually polymers) sharply changing their properties upon receiving external signals in the form of light irradiation, magnetic field application, temperature change, pH variation, etc. These changes result in activation/inhibition of electrochemical processes at the modified electrode surfaces, predominantly affecting electronic communication between biological molecules (usually enzymes, frequently involving electron‐transfer mediators) and the conducting support, thus switching bioelectrocatalytic processes ON and OFF.…”

Electroactive, Mediating and Thermosensitive Microgel Useful for Covalent Entrapment of Enzymes and Formation of Sensing Layer in Biosensors

“…Materials consisting of microgels are usually characterized by low viscosity and very high surface area. This fact is very useful in such potential applications of microgels as controlled drug delivery systems [1][2][3] and catalysis [4]. This phenomenon is a reversible response of the polymer network -or a reversible change in its volume to an external stimuli, such as change in temperature, pH, ionic strength and magnetic/electric field [1][2][3][4][5][6].…”

“…A very interesting property of these materials is their ability to undergo the volume phase transition phenomenon. This phenomenon is a reversible response of the polymer network -or a reversible change in its volume to an external stimuli, such as change in temperature, pH, ionic strength and magnetic/electric field [1][2][3][4][5][6]. Importantly, the volume change in a microgel is much quicker than that in a regular-size hydrogel.…”

“…Importantly, the volume change in a microgel is much quicker than that in a regular-size hydrogel. This fact is very useful in such potential applications of microgels as controlled drug delivery systems [1][2][3] and catalysis [4].…”

Modified Electrodes and Electrochemical Systems Switchable by Light Signals

“…In the most sophisticated systems, the activity of switchable electrodes was controlled by complex multi‐enzyme systems, being reversibly activated‐inactivated by various patterns of different biochemicals added to solutions , thus mimicking biological regulative and adaptive properties. The present review article continues a series of papers addressing various signal‐controlled electrochemical systems, including those sensitive to temperature changes , magnetic field application and pH variation . The present article overviews various electrochemical systems, including modified electrodes, with switchable features controlled by optical signals and based on photoisomerizable molecules.…”