Investigation Of Ordered Assembly Of New Carbon Nanomaterials For Electrochemical Sensing Applications

Electrochemical sensors,with advantages of high sensitivity,low detection limit,portable equipment,low-cost,and ease of miniaturization,have attracted considerable interests of many chemical analysts.In recent years,with the rapid development of nanoscience,nanomaterials were extensively used for the construction of electrochemical biosensors.Based on the excellent physical and chemical properties of carbon-based materials,graphene and carbon nanotubes were promising for electrochemical sensing applications.This dissertation focuses on the preparation,characteration and sensing applications of carbon nanomaterials-based biosensors,which are summarized as follows.In the first section,the fundamental conceptions,preparation and functionalization methods of graphene and carbon nanotubes were summarized.The sensing applications of carbon material-based electrochemical sensors were briefly reviewed.In the second section,a convenient,rapid,and low-cost method for direct electroanalysis of antioxidants was realized at choline?Ch?functionalized monolayer supported graphene interface.The graphene was uniformly assembled on Ch monolayer with a suitable distribution state.The resulting graphene/Ch film exhibited remarkable electrocatalytic activities towards the oxidation of tert-butylhydroquinone?TBHQ?and butylated hydroxyanisole?BHA?due to the advantages of high electrode activity,large effective surface area,and fast electron transfer kinetics.The peak separation between TBHQ and BHA was achieved to be 0.238 V,which was large enough for their potential recognition and simultaneous detection.Under the optimum conditions,the linear ranges were 0.40-120?M and 0.60–200?M,and the detection limits were 0.14??and 0.19?M for TBHQ and BHA,respectively.Moreover,the practical application ability of the proposed system was confirmed by detection of TBHQ and BHA in commercial edible oil samples,which makes the system promising for applications in the assessment of food safety and public health.In the third section,Au nanoparticles?AuNPs?were compactly deposited on graphene modified glassy carbon electrode?GCE?for the construction of electrochemical sensors.The physicochemical properties of the AuNPs/GR/GCE were characterized by field emission scanning electron microscope?FE-SEM?and cyclic voltammetry?CV?.The results revealed that the AuNPs/GR film with favourable morphology can effectively catalyze the oxidation reactions of several antioxidants.As a consequence,the oxidation currents of TBHQ and BHA increased markedly,and the peak potentials shifted negatively due to the promotion of electrode reaction kinetics.The constructed sensor exhibited good performances of wide linear range,low detection limit,and excellent stability for the determination of antioxidants.In the fourth section,an efficient electrochemical biosensor was developed for the assay of adenosine triphosphate?ATP?based on the assembly of multiwalled carbon nanotubes?MWNTs?on choline?Ch?functionalized monolayer modified GCE.Ch can be covalently immobilized onto the surface of GCE through oxygen atom.The Ch monolayer could provide a positively charged surface with–N⁺?CH₃?₃ polar head groups,which was favorable for the construction of negatively charged MWNTs.Consequently,the MWNTs/Ch film exhibited remarkable electrocatalytic activities towards the oxidation of ATP.In comparison with the traditional methods to detect ATP,the advantages involved in this work were shown to be rapid,straight forward,cost-effective and easily operated,which make the system promising for potential applications in biochemistry and molecular biology.