| Electrochemical sensor uses the principle of electrochemical analysis and experimental technology to generate the electrical signal related to the concentration of the target in the analysis process,so as to achieve the qualitative analysis and quantitative detection of the target molecules.In recent years,electrochemical sensors have shown great application potential in the field of biological analysis due to their low cost,simple operation,high sensitivity and good selectivity.Because of the small size of nanomaterials,they have outstanding electrochemical properties such as high catalytic activity,large specific surface area and good conductivity,which can effectively improve the detection sensitivity,selectivity,and stability of electrochemical sensors.Therefore,in this paper,three different electrochemical sensing platforms are constructed using nanomaterials and used to detect ?-glucosidase and its inhibitors,quercetin(QR)in food and pharmaceuticals,and hydrogen peroxide(H2O2)released by living cells under external stimulation.The main research content of this dissertation is divided into three parts as following:(1)We utilized an integrated electrochemical probe which consist of two redox groups instead of two redox molecules,and combining with merits of enlarging the electroactive surface area and promoting the electron transfer of carbon nanohorns modified electrode,a new ratiometric electrochemical sensor for the assay of ?-glucosidase and its inhibitors was fabricated.Under the optimal conditions,the ratiometric signal enabled the detection of ?-glucosidase in a range of 0.001-0.016 U/mL with a detection limit of 0.00056 U/mL.Furthermore,two ?-glucosidase inhibitors,acarbose and mulberry bark,were used to assess the feasibility of screening potential anti-diabetic medicine,and the IC50 values of 0.55 mM and 3.38 mg/mL were obtained respectively.(2)QR is one of the most important nutrients in the human diet and has many biological activities.Therefore,it is necessary to develop an effective and reliable analysis method to detect QR.In this part,the three-dimensional highly porous gold film(hp-Au)modified gold electrode(Au)was prepared by a facile self-templating method,it was found that hp-Au possess high surface-to-volume ratio and excellent conductivity.Combining with the multiple merits of hp-Au,the hp-Au/Au showed an excellent detection performance towards QR compared with bare electrode and gold nanoparticles modified gold electrode,the detection limit was 3.9 nM in a wide concentration range from 20 nM to 100 ?M.Meantime hp-Au/Au also showed good selectivity,stability and reproducibility.Moreover,the practical application of this sensor was verified by detecting QR in drink or food and medicine samples(3)H2O2 is a major metabolite of oxygen in living organisms and its concentration level is related to various diseases,so it is of great significance to monitor the H2O2 released from living cells under external stimulation,which imposes stricter requirements on the sensitivity of detection technology.In this work,we have found that carbon black(CB)could preserve bimetallic PdCu alloy's nanostructure,meanwhile improve the dispersion of nanoparticles,provided high conductivity and large specific surface area,thus the PdCu/CB nanohybrid exhibited enhanced electroanalytical performance of H2O2.Under the optimal conditions,the PdCu/CB nanohybrid modified electrode showed a low detection limit of 54 nM with a wide detection range from 0.4 ?M to 5.0 mM.Finally,the application of PdCu/CB/GCE in real-time monitoring H2O2 released from Raw 264.7 cells was achieved. |
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