Preparation And Properties Of Three Novel Electrochemical Sensors

Due to the advantages of simple instrument,easy operation and rapid detection,electrochemical sensors have been applied for various analytes determination in many fields.Three-dimensional?3D?nickel foam has many advantages,such as low cost,good conductivitty and large specific surface area.It can be used as a base electrode for the fabrication of electrochemical sensors to sensitively detecttarget molecules.Single-signal detection based on traditional electrochemical sensors is sensitive to internal or external conditions.To a certain extent,single-signal detection would affect the accuracy and reliability of the sensor.The use of dual signal to build ratiometric?the ratio of the two current signals at different potentials as a detection signal?electrochemical sensors has received attention.For ratiometric based electrochemical sensing,the ratio of two current signals at different potentials is employed as the detected signal.One current signal is used as a specific recognition signal for the analyte,while the other is used as a reference signal with constant response.Thus,the ratio of these two signals can provide a built-in correction for the above mentioned factors and achieve more accurate and reliable analysis.Based on the above considerations,the following work has been carried out.1.Goldnanoparticles?AuNPs?andhydroquinonewereelectrodepositedand electropolymerized on a three-dimensional nickel foam to fabricated a simple and effective electrochemical sensor for depominedetection.The performance of the sensor was characterized by scanning electron microscopy,electrochemical impedance spectroscopy and cyclic voltammetry.The effect factors of electrodeposition time of AuNPs,polymerization pH,cycles of polymerization and rate of polymerization were optimized for the sensor preparation.Under optimal conditions,the sensor was sensitive to dopamine detection with a linear range of 1.0×10^-7-1.0×10^-55 mol/L with a detection limit of 4.19×10^-88 mol/L.The sensor was used in the actual sample of dopamine detection and the results are satisfactory.2.A ratiometricstrategybasedelectrochemicalsensorwasdevelopedby electropolymerization of thionine?THI?and?-cyclodextrin??-CD?composites film on glassy carbon electrode surface for imidacloprid?IMI?detection.THI played a role of an inner reference element to provide a built-in correction.And the modified?-CD showed good selective enrichment for IMI to improve the sensitivity and anti-interference ability of the sensor.The current ratio between IMI and THI was calculated as the detected signal for IMI sensing.Compared with common single-signal sensing,the proposed ratiometric strategy showed a higher linear range and a lower limit of detection of 4.0×10^-8-1.0×10^-55 mol/L and 1.7×10^-88 mol/L,respectively,for IMI detection.On the other hand,the ratiometric strategy endowed the sensor with good accuracy,reproducibility,and stability.The sensor also was used for IMI determination in real samples with satisfactory results.The simple,effective,and reliable way reported here can be further used to prepare ratiometric strategy based electrochemical sensors for other compounds selective and sensitive detection with good accuracy and stability.3.Boric acid-functionalized carbon quantum dots?C-dots?were prepared through a one-step hydrothermal method,which were modified onto the surface of pTHI/GCE to construct a novel ratiometric electrochemical sensor.Compared with only C-dots modified electrode,THI played the role of inner reference element,providing a built-in correction,which made the sensor have higher accuracy and stability for NADH detection.The conditions for sensor preparation,such as carbon quantum dot immersion time,carbon quantum dot concentration,polymerization rate,and polymerization cycles,were optimized..Under the optimal conditions,the sensor showed the sensitive detection for NADH with a linear range of 5.0×10^-7-1.0×10^-44 mol/L and a detection limit of 1.5×10^-77 mol/L.The boric acid-functionalized C-dots showed good anti-interference ability for NADH detection.The sensor also can be used in the actual sample NADH determination with satisfactory results.