In Vivo Electrochemical Measurement of Glucose Variation in the Brain of Early Diabetic Mice

Diabetes is a chronic disease caused by a decrease in insulin level or insulin resistance. Diabetes also has detrimental effects on the brain, which can lead to the injury of the blood-brain barrier and influence the glucose transport. In this study, we use in vivo electrochemical measurement to explore the glucose variation in the brain of early diabetic mice. The glucose level in mice brain is measured using a carbon fiber microelectrode modified with the osmium-derivatized polymer and glucose oxidase. The electrode shows an excellent electrochemical performance, antibiofouling ability, and high stability, which can work stably in the mice brain for 2 h. By monitoring the glucose level in the brain of normal and diabetic mice after injection of concentrated glucose solution into the abdominal cavity, it is found that the variation of cerebral glucose decreases by ∼2 fold for diabetic mice. It is proposed that diabetes can downregulate the activity of glucose transporter in the brain and finally inhibit the brain glucose uptake.

Electrodeposition of Cobalt Oxides on Carbon Nanotubes for Sensitive Bromhexine Sensing

We develop an electrochemical sensor for the determination of bromhexine hydrochloride (BHC), a widely use mucolytic drug. The sensor is prepared by electrodeposition of cobalt oxides (CoO_x) on a glassy carbon electrode modified with carboxylated single-walled carbon nanotubes (SWCNT). A synergistic effect between CoO_x and SWCNT is observed, leading to a significant improvement in the BHC electrooxidation current. Based on cyclic voltammetry studies at varying scan rates, we conclude that the electrochemical oxidation of BHC is under mixed diffusion–adsorption control. The proposed sensor allows the amperometric determination of BHC in a linear range of 10–500 µM with a low applied voltage of 0.75 V. The designed sensor provides reproducible measurements, is not affected by common interfering substances, and shows excellent performance for the analysis of BHC in pharmaceutical preparations.