Preparation Of Nanocomposites Via Thiol-Click Chemistry And Its Electrochemical Applications

Electrochemical analysis is an important branch of instrumental analysis,which is measured by the electrical response of a chemical system or samples to be established on the basis of the analysis method and measured by some physical quantities such as current,conductance,potential,or power,etc.to determine the electrochemical properties and content of the obtained material.Thiol-click reaction is one of click reaction by free radicals or ion mechanism making the S-H bond and double bond or triple bond for crosslinking reaction.Since it has good stereoselectivity,mild reaction conditions,convenient operation,less side effects,higher yield and the advantages of less pollution to the environment,which became a popular method of synthesis of functional nanomaterials.Besides,conducting polymers（CPs）including Polyaniline,Polypyrrole and Polythiophene have excellent characteristics of polymer,excellent performance of semiconductor material,low price,less environmental pollution,simple synthesis,extremely easy to modify with carrier material,which is considered to be highly valuable polymer.It is worthy to point out that CPs can be easily thiolated through nucleophilic substitution reactions of thiols with the CPs at their oxidation state,which can be regard as extension of thiol-click reaction.This dissertation based on thiol-CPs click reaction to prepare a series of nanocomposite for methanol electro-oxidation and highly sensitive electrochemical immune detection of phytohormone IAA,main research results are as follows:1.In this work,polyaniline/electrochemically reduced graphene oxide（PANI/ERGO）was firstly prepared by one step of electrochemical oxidation and reduction method.Following that,2,5-dimercapto-1,3,4-thiadiazole（DMcT）was covalently bound on PANI bone by using electro-assisted thiol-ene click reaction to introduce a large number of surface functional groups（such as S and N）,which can anchor and grow PtNPs（platinum nanoparticles）on the thiolated polyaniline（TPANI）/ERGO through electrodeposition.Scan electron microscopy（SEM）reveals that PtNPs was highly and uniformly dispersed on the TPANI/ERGO.In addition,Cyclic voltammetry（CV）shows that PtNPs/TPANI/ERGO possess a higher electrochemical surface area and electrocatalytic performance towards methanol electro-oxidation compared to PtNPs/PANI/ERGO.2.In this work,Carbon nanotubes（CNTs）were functionalized with thiolated polymer and then employed as a novel supporter for platinum nanoparticles（PtNPs）.The functionalization was carried out via microwave-assisted thiol-ene reaction of2,5-dimercapto-1,3,4-thiadiazole（DMcT）with oxidized polyaniline in the presence of CNTs,endowing lots of surface functional groups（such as S and N）on the CNTs.PtNPs was deposited on the thiolated polyaniline functionalized CNTs（TPANI-CNTs）to achieve PtNPs/TPANI-CNTs nanohybrid.PtNPs in size of 3-6 nm highly dispersed on the TPANI-CNTs according to the transmission electron microscopy（TEM）characterization.Cyclic voltammetry（CV）studies showed that the PtNPs/TPANI-CNTs nanohybrid had a higher electrocatalytic performance and stability toward methanol oxidation compared to PtNPs supported on the conventional polyaniline functionalized CNTs（PANI-CNTs）or pristine CNTs.3.An electrochemical immunosensor with dual signal amplification for ultrasensitive detection of indole-3-acetic acid（IAA）based on highly dispersed Au-thiolated polymeric was reported in this work,which firstly involves in thiolated composite of2,5-dimercapto-1,3,4-thiadiazole（DMcT）,polyaniline（PANI）and carbon nanotubes（CNTs）to achieve highly dispersed Au Nanoparticles via microwave-assisted method,and the thiolated composite was served as signal amplification to immobilize antibody on the glassy carbon electrodes（GCE）.Secondly,gold nanoparticles（AuNPs）functionalized with HRP labeled IgG（AuNPs/HRP-IgG）was used as signal amplification probe,where HRP-IgG could be immobilized on the N-glycosylation site from 4-aminophenylboronic acid through specific binding.Finally,the immunological binding between anti-IAA/Au/TPANI-CNTs and IAA made electron transfer of potassium ferricyanide blocked to achieve ultrasensitive detection of IAA by differential pulse voltammetry（DPV）.The fabricated electrochemical immunosensor not only exhibited an optimal line arrange from 1×10^-1212 to 1×10^-8g/ml with the limit of detection of 6.7×10^-13g/ml（S/N=3）,but also possessed good selectivity,reproducibility and stability for detection of IAA.