| Biological molecules such as hydrogen peroxide（H2O2）and ascorbic acid（AA）,dopamine（DA）,uric acid（UA）closely related to human vital movement,play a very important role in human metabolism.Therefore,the development of a sensitive and rapid method for detection of these biomolecules is of great significance both in clinical diagnosis and neurochemistry.Traditional methods,such as chromatography,fluorescence and so on,can also detect these biomolecules,but long time consuming and complicated operation made them limited in application.Due to the electroactivity themselves of these biomolecules,electrochemical sensor is a very attractive choice in analytical chemistry for biomolecules analysis based on the change of the current signals.However,these biomolecules can not be recognized sensitively and selectively at bare glassy carbon electrode owing to its poor catalytic activity.In order to improve the sensitivity and accuracy of the electrode,surface microstructure that can recognize these biomolecules rapidly and specifically must be introduced on the bare electrode.MoS2,as a typical layered semiconductor compound of transition metal,has a special physicochemical properties when compared to conventional nanomaterials,which made it an extensive application in material engineering,photoelectrochemical catalysis,and biosensing.This dissertation is devoted to the construction of nanohybrid sensing interface by MoS2 nanocomposites for rapid and sensitive detection of these biomolecules.The morphology and crystal structure of the nanocomposites were characterized by SEM,TEM,XRD and EDS.Meanwhile,the electrochemical performance of the biosensors were thoroughly investigated by cyclic voltammetry（CV）,differential pulse voltammetry（DPV）and chronoamperometry（i-t）.The main work is described as follows:（1）MoS2 nanoflowers were obtained from one step hydrothermal reaction of sodium molybdate dihydrate and L-cysteine under the condition of 200℃for 36 hours.The prepared MoS2 nanoflowers were dropped on the surface of the glassy carbon electrode（GCE）by a drop coating method,and Au/Pt bimetallic nanoparticles were deposited uniformly on the surface of the nanomaterial by one-step electrodeposition to construct a MoS2-Au/Pt@GCE electrochemical sensor for the detection of H2O2.The concentration of H2O2 vs the reduction current showed a good linear relationship in the range of 10μM to 19.07 mM with the detection limits of 0.39μM（S/N=3）,and the sensitivity was 142.68μA mM-1 cm-2 under the optimized operating conditions.The prepared MoS2-Au/Pt@GCE electrochemical sensor has a good application in the actual serum samples.（2）The porous and three-dimensional MoS2/rGO nanocomposites were synthesized by hydrothermal method and a high sensitive MoS2/rGO@GCE sensor was constructed for the detection of H2O2.Under the optimized conditions,the linear range of H2O2 was2μM to 23.18 mM with the detection limit of 0.19μM（S/N=3）,and the sensitivity was101.70μA mM-1 cm-2.Compared with other hydrogen peroxide sensors reported in the literature,the MoS2/rGO@GCE sensor exhibited a wide linear range and high sensitivity.（3）MoS2/rGO/Au@GCE electrochemical sensor was constructed to detect ascorbic acid,dopamine and uric acid individually and simultaneously.CV and DPV were carried out to study the electrochemical behavior of MoS2/rGO/Au@GCE.The linear ranges of AA,DA and UA were 2.0–5400.0μM（AA）,0.3-198.3μM（DA）and 5.0–2215.0μM（UA）with the detection limits of 0.93μM（AA）,0.11μM（DA）and 0.74μM（UA）（S/N=3）for individually,respectively.The linear ranges of AA,DA and UA were 5.0-3305.0μM（AA）,0.3-204.3μM（DA）and 5.0-315.0μM（UA）for simultaneously whih the detection limits of 1.46μM,0.15μM and 0.29μM（S/N=3）,respectively.The developed electrochemical sensor has a good recovery in the actual serum samples,which provides a new method for the rapid and accurate detection of ascorbic acid,dopamine and uric acid in real samples. |
