Electrochemical immunosensor with aptamer-based enzymatic amplification.

An electrochemical immunosensor is reported by using aptamer-based enzymatic amplification with immunoglobulin E (IgE) as the model analyte. In this method, the IgE antibody is covalently immobilized as the capture probe on the gold electrode via a self-assembled monolayer of cysteamine. After the target is captured, the biotinylated anti-IgE aptamer is used as the detection probe. The specific interaction of streptavidin-conjugated alkaline phosphatase to the surface-bound biotinylated detection probe mediates a catalytic reaction of ascorbic acid 2-phosphate substrate to produce a reducing agent ascorbic acid. Then silver ions in the solution can be reduced, leading to the deposition of metallic silver on the electrode surface. The amount of deposited silver, which is determined by the amount of IgE target bound on the electrode surface, can be quantified using the stripping voltammetry. The results obtained demonstrated that the electrochemical immunosensor possesses high specificity and a wide dynamic range with a low detection limit that possibly arises from the combination of the highly specific aptamer and the highly sensitive stripping determination of enzymatically deposited silver.

[Effect of tongxinluo ultramicro-pulverization on myocardial post-reperfusion no-reflow in mini-swine model of acute myocardial infarction].

OBJECTIVE: To assess the effect of Tongxinluo (TXL) ultramicro-pulverization in preventing and treating post-reperfusion no-reflow in mini-swine model of acute myocardial infarction. METHODS: Forty mini-swines were randomly divided into 5 groups, the control group, the three (low-, middle- and high-dose) TXL groups and the sham-operation group, with 8 in each group. After pigs in the three TXL groups were administered with TXL in a dose of 0.05g/kg, 0.2g/kg and 0.5g/kg once a day for 3 days respectively, they were made into acute myocardial ischemia/reperfusion model by ligating left anterior descending coronary artery for 3h followed with 1h of untying. Hemodynamic examination and myocardial contrast echocardiography (MCE) were conducted before and after ligation, and after reperfusion, finally, pathological analysis was done. RESULTS: Post-reperfusion ventricular function injury was significantly improved in the three TXL groups, as compared with the control group, the no-reflow area determined by hemodynamic and MCE decreased from 78.5 +/- 4.4% and 82.3 +/- 1.9% in control to 43.4 +/- 3.2% and 44.6 +/- 3.3% (low-dose), 25.2 +/- 2.4% and 25.7 +/- 4.0% (middle-dose), 24.0 +/- 1.9% and 24.9 +/- 4.2% (high-dose), respectively (P < 0.05 or P < 0.01), and the myocardial infracted area was reduced from 98.5 +/- 1.4% to 89.8 +/- 4.6%, 80.2 +/- 3.1% and 79.9 +/- 3.1%, respectively (P < 0.05, P < 0.01). CONCLUSION: TXL ultramicro-pulverization can effectively prevent and treat no-reflow after myocardial acute infarction following reperfusion, and reduce the infracted area.