Hydrophilic Micro- and Macroelectrodes with Antibiofouling Properties for Biomedical Applications

Abstract

Implantable neural electrodes are generally used to record the electrical activity of neurons and to stimulate neurons in the nervous system. Biofouling triggered by inflammatory responses can dramatically affect the performance of neural electrodes, resulting in decreased signal sensitivity and consistency over time. Thus, long-term clinical applications require electrically conducting electrode materials with reduced dimensions, high flexibility, and antibiofouling properties that can reduce the degree of inflammatory reactions and increase the lifetime of neural electrodes. Carbon nanotubes (CNTs) are well known to form flexible assemblies such as CNT fibers. Herein, we report the covalent functionalization of predefined CNT fiber and film surfaces with hydrophilic, antibiofouling phosphorylcholine (PC) molecules. The electrochemical and spectroscopic characteristics, impedance properties, hydrophilicity, and in vitro antifouling nature of the functionalized CNT surfaces were evaluated. The hydrophilicity of the functionalized CNT films was demonstrated by a decrease in the static contact angle from 134.4°± 3.9°before to 15.7°± 1.5°after one and fully wetting after three functionalization cycles, respectively. In addition, the extent of protein absorption on the functionalized CNT films was significantly lower than that on the nonfunctionalized CNT film. Surprisingly, the faradic charge-transfer properties and impedance of the CNT assemblies were preserved after functionalization with PC molecules. These functionalized CNT assemblies are promising for the development of low-impedance neural electrodes with higher hydrophilicity and protein-fouling resistance to inhibit inflammatory responses.

A bio-inspired silkworm 3D cocoon-like hierarchical self-assembled structure from π-conjugated natural aromatic amino acids

“…56 This unique 3D structure and wettability property can find applications in areas requiring low protein-adsorption, such as in certain medical device coatings and antibiofouling applications. 57,58…”

“…56 This unique 3D structure and wettability property can find applications in areas requiring low protein-adsorption, such as in certain medical device coatings and antibiofouling applications. 57,58 The detailed biophysical characterization of the self-assembly of Fmoc-F and Fmoc-Y demonstrated the formation of cocoonlike structures by both Fmoc-F and Fmoc-Y on solvent casting from their solutions in ethanol, methanol, and acetone, which is independent of room conditions during drying. This type of hierarchical self-assembly of the 1D fibrils into cocoon-like structures is distinct from the simple 1D nanofibrils formed during the hydrogelation of the two Fmoc-functionalised amino acids.…”

Evaluation of Polymer-Coated Carbon Nanotube Flexible Microelectrodes for Biomedical Applications

“…CNT fibers are softer and more flexible than rigid metal- and silicon-based neural electrodes and have a bending stiffness that is orders of magnitude lower than those of silicon and carbon fiber electrodes [ 17 , 18 ]. Owing to their unique properties, CNTs can facilitate the generation of stable neural interfaces [ 8 , 13 , 19 , 20 , 21 ].…”