Modified carbon dots for potential flexible electrode applications

Muscle atrophy due to peripheral nerve injuries remains a challenge to which typical exercise and protein supplement intervention are not beneficial. Electrically stimulating the denervated muscles using implantable electrodes is emerging as a promising potential strategy to prevent muscle atrophy during the nerve regeneration period. So far, conventional implantable electrodes utilized metals for their high conductivity and corrosion resistance. Recent studies replaced metals with flexible conductive polymers to evade the mechanical mismatch of biological tissues with the rigid metals. However, conductive polymers are also restricted by their cost and hazardous nature. Therefore, there is still a need for novel conductive, flexible, low cost, and safe implantable electrodes for potential prevention of muscle atrophy in peripheral nerve injury patients. This work reports the development of a novel low cost, conductive, and flexible implantable electrode composed of the biocompatible polydimethylsiloxane (base) and boronic-acid modified carbon dots (filler). In this study, electrical properties and electrochemical stability of the electrodes were evaluated using electrochemical impedance spectroscopy and cyclic voltammetry. Electrodes prepared in this work with low boronic-acid carbon dot (BA-CDs) percentages possessed impedances as low as 123 Ω with a conductivity of
$1.04\times 10^{-3}$
S/cm, and were electrochemically stable and capable of storing charge. The obtained electrical properties are comparable to those of other PDMS-based electrodes as well as other implantable electrode materials despite using only 10% of the BA-CDs. Furthermore, the developed electrodes had an elasticity (0.0108 MPa) compatible with that of biological tissues.