Covalent bonding of YIGSR and RGD to PEDOT/PSS/MWCNT-COOH composite material to improve the neural interface

Abstract

The development of coating materials for neural interfaces has been a pursued to improve the electrical, mechanical and biological performances. For these goals, a bioactive coating was developed in this work featuring a poly(3,4-ethylenedioxythiophene) (PEDOT)/carbon nanotube (CNT) composite and covalently bonded YIGSR and RGD. Its biological effect and electrical characteristics were assessed in vivo on microwire arrays (MWA). The coated electrodes exhibited a significantly higher charge storage capacity (CSC) and lower electrochemical impedance at 1 kHz which are desired to improve the stimulating and recording performances, respectively. Acute neural recording experiments revealed that coated MWA possess a higher signal/noise ratio capturing spikes undetected by uncoated electrodes. Moreover, coated MWA possessed more active sites and single units, and the noise floor of coated electrodes was lower than that of uncoated electrodes. There is little information in the literature concerning the chronic performance of bioactively modified neural interfaces in vivo. Therefore in this work, chronic in vivo tests were conducted and the PEDOT/PSS/MWCNT-polypeptide coated arrays exhibited excellent performances with the highest mean maximal amplitude from day 4 to day 12 during which the acute response severely compromised the performance of the electrodes. In brief, we developed a simple method of covalently bonding YIGSR and RGD to a PEDOT/PSS/MWCNT-COOH composite improving both the biocompatibility and electrical performance of the neural interface. Our findings suggest that YIGSR and RGD modified PEDOT/PSS/MWCNT is a promising bioactivated composite coating for neural recording and stimulating.

Self-supporting carbon nanotube films as flexible neural interfaces

“…This has been verified extensively with CNT/conducting polymer composites, i.e. PEDOT/PSS/MWCNT (CSC C = 8.6 mC cm −2 ) [65], in which CNTs were present as a conducting filler component. This charge accumulation was also noted here for self-supporting CNT films, for which the CSC C (29.95 ± 0.91 mC cm -2 ) was fourteen times higher relative to bare Pt foil electrodes (2.17 ± 0.10 mC cm -2 ),…”

Nano-Biomaterials for Retinal Regeneration

“…Iridium oxide–carbon nanotube hybrids (IrOx-CNT) were reported to have a high effective surface area and much higher charge storage capacities compared to pure iridium oxide [ 67 ]. Furthermore, the hybrid coatings formed by combining iridium oxide with reduced graphene oxide or graphene oxide exhibited 10% higher charge storage capacities than those of pure iridium oxide and iridium oxide–carbon nanotube hybrids, indicating superior electrochemical stability [ 52 , 68 , 69 , 70 , 71 ].…”

“…Grooved single-walled carbon nanotube/poly (3,4-ethylene dioxythiophene) composite films not only showed increased biocompatibility but also provided physical cues for neuronal cell proliferation and differentiation [ 72 ]. The inclusion of hydrogels and biomolecules to the hybrid coating further enhanced the number of active channels in an in vivo recording compared to a conventional coating [ 52 ]. Furthermore, the use of anti-inflammatory agents with hybrid nanomaterials not only decreased neuronal death/damage but also increased biocompatibility [ 101 , 102 ].…”

Micro/Nano Technologies for High-Density Retinal Implant

“…Hydrogels, biomolecules, etc. were often incorporated into the coating to further improve the biocompatibility, which was shown to benefit in vivo recording supported by more active channels and higher signal power than pure coating (Figure 12e) [131]. Anti-inflammatory drugs could also be incorporated in those composite coatings for alleviation [134].…”

“…( a ) TEM image of IrO x -CNT composite coating [127]; ( b ) Cyclic voltammetry (CV) curves of bare Pt, IrO x , and IrO x -CNT coated electrodes in PBS (pH = 7.4) at sweep rate of 20 mV⋅s −1 [127]; ( c ) SEM image of IrO x -GO composite coating [129]; ( d ) SEM image of SWNT-PPy composite coating [130]; ( e ) Influence of peptide bond on PEDOT/PSS/MWCNT composite coating [131]. Reproduced from the mentioned references with permission from the related journals.…”