Noble metal sensitized invasive porous bioelectrodes: advanced medical device for enhanced neuronal activity and chronic alcohol treatment

Abstract

Invasive bioelectrodes are widely used as an effective treatment for several acute and chronic diseases. In earlier work using high surface area invasive porous bioelectrodes evaluated in an animal model of alcoholism withdrawal, we demonstrated significantly improved electrophysiological and behavioral responses. In this study, we further modify the surface of these invasive porous bioelectrodes with noble metal (Ag, Au, Pt) nanoparticles. Compared to both conventional and porous bioelectrodes, noble metal sensitized invasive porous bioelectrodes show markedly increased low threshold (LT) and wide dynamic range (WDR) neuronal activity. In particular, Pt-sensitized invasive porous bioelectrodes show the highest WDR neuronal activity only upon insertion. In addition, Ag-sensitized invasive porous bioelectrodes, whose surface area is about 37 times greater than that of conventional bioelectrodes, show improved electrochemical properties with higher LT and WDR neuronal activity when stimulated. In an animal model of chronic alcoholism, using normal and alcohol-treated Sprague-Dawley (SD) rats evaluated with the elevated plus maze (EPM) test, the Ag-sensitized invasive porous bioelectrodes show about 20% higher open arms time. These results suggest that these noble metal-sensitized invasive bioelectrodes may offer improved therapeutic outcomes for the treatment of chronic alcoholism, and given these enhanced electrophysiological properties, for other conditions as well.

Fig. 1. Schematic illustration of whole experimental procedures.

Fig. 2. FE-SEM surface images of: (a) invasive conventional bioelectrode (ICB), (b) invasive porous bioelectrode (IPB), (c) Ag-IPB, (d) Au-IPB and (e) Pt-IPB. The insert shows close up views of the bioelectrode tips. (f) Box plot showing median size values of electrodeposited nanoparticles.

Fig. 3. (a) Charge transfer resistance (R_CT) vs. electrodeposition time for x-IPB of various electrodeposition times. (b) Fitted Nyquist plots corresponding to electrochemical impedance spectra (EIS) for ICB, IPB and x-IPB (2.0 V, 75 s electrodeposition).

Fig. 4. Comparison of neuronal response activity. Changes of LT and WDR neuronal response (a) without bioelectrode stimulation, and (b) with bioelectrode stimulation in each group. Horizontal line: 100% of activity induced by VFFs stimulation.

Fig. 5. Comparison of percentages of open arms time compared to the entire time during withdrawal from chronic alcohol treatment in each group.