Electroactive bio-epoxy incorporated chitosan-oligoaniline as an advanced hydrogel coating for neural interfaces

Neural electrodes have opened new horizon in neuroscience which discover the new aspect of neural and brain behavior. Neural electrodes are usually fabricated using metals. Metals cause chronic inflammation in long term due to mechanical mismatch with soft tissue. In this regards, hydrogel based coating has been proposed to regulate the modulus. Electroactive hydrogel coating because of the similar modulus with brain, proper biocompatibility and low impedance can be used as proper coating for neural interface. In this work, the electroactive epoxidized chitosan was firstly synthesized and studied for electroactivity using cyclic voltammetry and UV-vis. Cyclic voltammetry diagram exhibited two redox peak between 0.38 and 0.8 related to oxidation/reduction transient; In addition, UV-vis spectra exhibited pi-pi(star) transition and benzenoid to quinoid excitonic transition around 330 nm and 620 nm, respectively. Swelling ratio of the electroactive epoxidized chitosan was decreased 150% compared to electroactive one (500%). The hydrophobic oligoaniline decreased the swelling ratio and hindered the water molecule diffusion within the hydrogel structure. Hence, the degradation rate was decreased by enhancing the oligoaniline content. Electroactive coating showed the lower impedance compared to isolated one. Moreover, the electroactive substrate exhibited more cell proliferation because of its conductive nature which enhanced the PC12 cells activity. This study introduced the novel hydrogel based on electroactive coating, which can be potentially used as a neural electrode coating and pave a way for architecting new coating for biomedical devices.