Polymer Hydrogel Carbon Nanotubes Neuron Probe

In this paper, gold electrode was modified with polyethylene glycol diacrylate/single-walled carbon nanotubes (PEGDA/SWNTs) hydrogel coating. Electrochemical properties of the hydrogel-modified electrode as well as mechanisms of the drug release from PEGDA/SWNTs hydrogel coating were investigated.The gold substrate was chemically modified by covalent binding. The fabrication was performed in in-situ layer-by-layer assembly method. First the surface of the cleaned and activated gold substrate was chemically modified with cysteamine, followed by Michael addition between PEGDA and cysteamine to introduce pendant vinyl surface functionalities on the surface of gold electrode. The self-assembly of cysteamine and Michael addition were demonstrated by contact angle, X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV).After acid treatment, the shortened SWNTs were dispersed in PEGDA hydrogel precursor mixture by ultrasonication. The mixture was spread evenly onto the molecular-modified gold electrode with a microsyringe, followed by ultraviolet irradiation for photopolymerization. The electrochemical properties of the resulted hydrogel-modified electrode were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that SWNTs enhanced the conductivity of the hydrogel coating. Furthermore, adhesive strength of the hydrogel coating on the hydrogel-modified electrode made by covalent binding and dip-coating was carried out separately. The results showed that covalent binding had a better adhesive strength compared to dip-coating.For doping drug into three-dimensional network structure, dexamethasone was dissolved in PEGDA hydrogel precursor mixture, and the mixture was photopolymerized under ultraviolet irradiation. The physical and chemical properties of the hydrogel coating as well as the mechanisms of the drug release from the hydrogel were investigated. It was found that SWNTs had some sorption on dexamethasone, prolonged the release period of dexamethasone from hydrogel.