A glucose micro-biosensor was employed as detector in capillary electrophoresis (CE) for determining the concentration of glucose in human serum. The micro-biosensor was based on the immobilization of the SWNTs-glucose oxidase-chitosan biocomposite at a platinized Au electrode by electrodeposition. The influencing factors including separation voltage, detection potential, pH value, and the concentration of the buffer were studied. Suitable conditions were obtained for the determination of glucose: running buffer, 25 mM PBS (pH 8.0); separation field strength, 250 V cm(-1); detection potential, 0.80 V vs. saturated calomel electrode. Under optimized detection conditions, glucose responded linearly from the range of 5 μM to 1 mM with a correlation coefficient of 0.9986 for the injection voltage of 5.0 kV and injection time of 10 s. The concentration limit of detection of the method was 1 μM (S/N = 3). The micro-biosensor exhibited good stability and durability in the analytical procedures. The relative standard deviation of the migration time and peak current were 1.7% and 2.6%, respectively. Glucose in human serum from two healthy individuals and two diabetics was successfully determined, giving a good prospect for a new clinical diagnostic instrument.
A new composite electrode of multiwall carbon nanotubes (MWNTs) and 1-dodecyl-3-methylimidazolium hexafluorophosphate (DDMIMPF 6 ) was fabricated to determine rutin. This electrode showed very attractive electrochemical performances compared to other kinds of ionic liquid modified electrodes and notably improved sensitivity and stability. Electrochemical behavior of rutin at the composite electrode had been investigated in pH 2.09 Britton-Robinson buffer solution by cyclic voltammetry and square wave voltammetry. The experimental results suggested that the composite electrode exhibited an electrocatalytic activity toward the redox of rutin. The electrochemical parameters of rutin were calculated with the results of the charge transfer coefficient (α) and the standard rate constant (k s ) as 0.48 and 2.09 s −1 . Under the selected conditions, the reduction peak current was linearly dependent on the concentration of rutin in the range of 0.03-1.5 μM, with a detection limit of 0.01 μM (S/N03). The relative standard deviation for six times successive determination of 1 μM rutin was 1.6 %. The method was successfully applied to the determination of rutin in tablets and urine samples without the influence of the coexisting substances. In addition, the MWNTs/DDMIMPF 6 composite electrode exhibits a distinct advantage of simple preparation, surface renewal, good reproducibility, and stability.
Acupuncture help alleviate depression-like behaviors, but the neural mechanisms behind such antidepressive impacts are still unknown. Abnormalities in the perineuronal net (PNN) have been documented in multiple psychiatric disorders. The modulation and neural mechanism of PNNs in the antidepressant process of electroacupuncture (EA) at Baihui (GV20) and Yintang (GV29) points were investigated in this work. A rat depression model was induced by chronic unpredicted mild stress (CUMS). Acupuncture was performed on model rats in the EA group at GV20 and GV29 acupoints every other day for 30 min each time. The uoxetine (FLX) group of model rats were gavaged with 10 mg/kg uoxetine each day. Immunohistochemistry and western blot assays were used to evaluate the density and components of PNNs, the protein expression levels of the main synthase of GABA, GAD67, and of the synaptic proteins GLuA1, and PSD95 in the pre-limbic (PrL) and sub-limbic (IL) of mPFC. We found that four weeks of CUMS could decrease the levels of PNN component proteins aggrecan and brevican and GAD67.Electroacupuncture exhibited signi cant anti-depressive effects on depressive rats by altering the levels of PNNs. Speci cally, aggrecan and brevican are involved in the anti-depression mechanism of electroacupuncture. After electroacupuncture treatment, the decreased expression of GAD67, GLuA1 and PSD95 in the mPFC induced by CUMS for four weeks was also reversed. This indicates that the mechanism of acupuncture's antidepressant effect may be based on reversing the stress-induced decline in PNN expression, the functional impairment of GABA neurons, and the regulation of excitatory synaptic expression.
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