Electrochemically Driven, Electrode‐Addressable Formation of Functionalized Polydopamine Films for Neural Interfaces

Abstract

An array of chemically functionalized electrodes is a versatile platform for investigation/manipulation of the electroactive cellular functions that are realized in the network fashion, as well as for multiplexed detection of analytes. For example, multielectrodes have been used intensively for both perturbation of many cellular systems with electrical stimulations and measurements of electrical signals from them at the spatiotemporal resolution in the applications, such as chipbased sensors [1] and prosthetic devices, [2] along with fundamental studies of electrophysiology. [3] In particular, nerve cells are a representative example for electrically excitable cells, the functions of which are achieved by the tightly polarized electrical communications between neurons, and multielectrodes have been the core part of neuron-material interfaces. [2,4] In vitro neuron-multielectrode interfaces have generally been formed by coating all of the electrode surfaces with one kind of neuron-adhesive molecules, such as poly(amino acid)s or peptides. [5] Although this coating approach has been successful in collective studies of neuronal connectivity and activities, [6] it would be desirable for sophisticated control and manipulation of neurons to develop methods for coating and functionalizing each electrode independently. The electrode addressability would allow us to locate or manipulate neurons or synapses with directionality control, because the electrodes are asymmetrically functionalized, not to mention being beneficial in multiplexed detection of targets. The differently functionalized electrodes on a substrate also could be utilized to investigate the responses of neurons at the single-cell level at a time.Electrochemically driven reactions on self-assembled monolayers have been used for electrode-selective functionalizations, [7] but this approach requires a specific electrode material, depending on the self-assembling molecules, and cumbersome synthetic procedures. As an alternative, conducting polymers have been adopted for coating of neural electrodes. [8] Although they can be electrochemically deposited onto the electrodes with relative ease, while retaining electrical properties of the electrodes for neural interfaces in the reliable manner, direct functionalization is not possible owing to the lack of functionalizable groups in their structures. [9] In this work, we report the electrochemically driven formation of polydopamine (pDA) films that are substrateindependent, simple to functionalize, and site-addressable.We have previously reported that the substrate-independent, bulk-coated pDA film did not impede the functions of the electrodes, suggesting one of the optimal materials for neural interfaces. [10] The facile functionalization of pDA films by codeposition was also demonstrated in the bulk coating. [11] Because the polymerization of dopamine is thought to occur through oxidative coupling of 1,2-dihydroxybenzene (catechol), we reasoned that the electrochemical method [12] could be utilized to deposi...

Poly(norepinephrine): Ultrasmooth Material‐Independent Surface Chemistry and Nanodepot for Nitric Oxide

“…), [3,[5][6][7][8][9] ceramics, [9,10] carbon materials [graphene, carbon nanotubes (CNTs), and peptide nanowires], [7,11,12] and living cells. [13] The applications for catecholamines have also become widespread for biomaterials (neural interfaces, [14] biocompatible surface modifications, [4,5] antibacterial surface preparation, [15] biomineralization, [16] and single-cell encapsulation, [13] ), sensors/ catalysts, [12,17] microfluidics, [18] mass spectrometry, [9] ultrafiltration membrane preparation, [19] corrosion resistance, [8] and energy storage devices including lithium ion batteries [20] and capacitors. [21] Despite the extensive use of pDA as a coating, the resulting uncontrollable surface morphology after functionalization is still a significant problem associated with pDA surface chemistry.…”

Novel platinum black electroplating technique improving mechanical stability

“…Polydopamine is known for its adhesive characteristic which strengthen the adhesion between different materials [13,17]. In this study, the polydopamine layers which were placed among platinum black structures might work as a reinforcing agent of platinum black structure.…”

“…Polydopamine is famous for its strong adhesion to universal materials [13]. It has been utilized in various applications such as biosensors, nanoparticle fabrication and cell patterning [14][15][16][17]. Recently, area specific polydopamine layer deposition was demonstrated through electrochemical deposition [18].…”

Porous Carbons – Hyperbranched Polymers – Polymer Solvation

“…A related investigation of hybrid electrode surfaces covered with polymer-grafted gold particles could be achieved using electrochemical AFM [558]. The electropolymerization of dopamine leads to conjugated polydopamine films, which can serve on electrodes as neural interfaces [559]. In some cases, the molecular design allowed the preparation of water sensors [549].…”