Biomimetic sensor based on hemin/carbon nanotubes/chitosan modified microelectrode for nitric oxide measurement in the brain

摘要

A novel biomimetic microsensor for measuring nitric oxide (NO) in the brain in vivo was developed. The sensor consists of hemin and functionalized multi-wall carbon nanotubes covalently attached to chitosan via the carbodiimide crosslinker EDC followed by chitosan electrodeposition on the surface of carbon fiber microelectrodes. Cyclic voltammetry supported direct electron transfer from the Fe~(III)/Fe~(II) couple of hemin to the carbon surface at -0.370V and -0.305V vs. Ag/AgCl for cathodic and anodic peaks, respectively. Square wave voltammetry revealed a NO reduction peak at -0.762V vs. Ag/AgCl that increased linearly with NO concentration between 0.25 and 1μM. The average sensitivity of the microsensors was 1.72nA/μM and the limit of detection was 25nM. Oxygen and hydrogen peroxide reduction peaks were observed at -0.269V and -0.332V vs. Ag/AgCl, respectively and no response was observed for other relevant interferents, namely ascorbate, nitrite and dopamine. The microsensor was successfully applied to the measurement of exogenously applied NO in the rat brain in vivo.