Manipulation of Surface Hydration States by Tuning the Oligo(Ethylene Glycol) Moieties on PEDOT to Achieve Platelet‐Resistant Bioelectrode Applications

Abstract

These electrodes are generally used for electrostimulation or electrophysiological recording. [2] To improve the signal transmission of these electrodes, electrode materials and their surface properties are key. To improve biocompatibility in relation to mechanical matching between tissues and electrodes, researchers are focusing on conducting polymers because of their stable electrochemical properties, soft nature, and strong biocompatibility. [3] The commercially available poly(3,4-ethylenedioxythiophene):poly( styrene sulfonate) (PEDOT:PSS) is among the most successful conducting polymers and is widely used because of its superior stability and ease of processing. [4] PEDOT exhibits mixed electronic and ionic conducting properties because it has a conjugated structure and is permeable to ions when immersed in electrolyte solutions, which improves charge injections at electrode surfaces and reduces electrochemical impedance when PEDOT is used to coat metallic electrodes. Many biomedical applications based on PEDOT and PEDOT:PSS have been demonstrated, including biosensors, [5] microelectrode arrays, [6] organic electrochemical transistors, [7] tissue engineering, [8] and brain-machine interfaces. [9] Biocompatibility and long-term stability remain major challenges for the application of PEDOT-coated implanted electrodes. The uncontrolled nonspecific binding and conformational change of proteins on PEDOT-coated electrodes can trigger foreign body reactions, leading to the malfunction and reduced lifetime of implanted electrodes. [10] Studies have presented modified PEDOT, mainly through the incorporation of peptides or growth factors during electropolymerization to improve the biocompatibility and long-term performance of PEDOT-coated electrodes. [11] Chemical modification through covalent bonding with functional groups on PEDOT coating has also been used to modify the PEDOT surface. In this process, EDOT monomers with functional groups are first designed and chemically synthesized. After electropolymerization to form PEDOT coating with these functional groups, surface modification can be further progressed through bioconjugation reactions with target biomolecules. [12] More recent studies have revealed that the incorporation of zwitterionic Poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have demonstrated potential in the development of bioelectrodes because of their superior conductivity. However, developing reliable implanted bioelectrodes requires improvements in biocompatibility and the prevention of nonspecific adhesion. In this study, a six ethylene glycol (EG)-functionalized EDOTs with three different EG lengths (tri-EG, tetra-EG, and hexa-EG) and two types of end groups, hydroxyl (−OH) and methoxy (−OCH 3 ) is synthesized and systematically investigated. By coating them on gold electrodes using electropolymerization, the surface and electrochemical properties of these functionalized PEDOT-coated electrodes are investigated. Although PEDOT with −OH groups on the surface is more hydrophili...

High-Conductivity, Low-Impedance, and High-Biological-Adaptability Ionic Conductive Hydrogels for Ear-EEG Acquisition

“…In summary, the prepared PHM hydrogels showed optimal performance: high conductivity and low impedance compared with recently reported hydrogel bioelectrodes, ,− as depicted in Figure S3. In addition, the PHM hydrogel bioelectrode exhibited excellent biocompatibility, which is often ignored in studies on bioelectrodes.…”

Design of biomaterials through direct ring-opening metathesis polymerisation of functionalised cyclic alkenes

“…94 The hydration state and biocompatibility of these polymers can be tuned by controlling the side chain spacing 94,114,139–141 and changing the chemical structure of the side chains. 142–167…”

Engineering Superaerophobic Electrodes Using Hydrophilic PEDOT and Colloidal Lithography for Enhanced Bubble Release and Efficient Hydrogen Evolution Reaction

“…25 The electrochemical and surface properties of PEDOT can be tuned by introducing different functional groups. 26,27 As previously discussed, the surface properties of electrodes play a crucial role in HER performance. Therefore, the functional groups of EDOT derivatives bearing hydroxymethyl (EDOT-OH) and sulfonate (EDOT-SuNa) were applied to modify the electrode surface.…”

“…Poly­(3,4-ethylenedioxythiophene) (PEDOT) exhibits excellent electronic properties and stability and has been promising material for electrochemical applications including sensors, solar cells, fuel cells, and supercapacitors . The electrochemical and surface properties of PEDOT can be tuned by introducing different functional groups. , As previously discussed, the surface properties of electrodes play a crucial role in HER performance. Therefore, the functional groups of EDOT derivatives bearing hydroxymethyl (EDOT-OH) and sulfonate (EDOT-SuNa) were applied to modify the electrode surface.…”