Several Metal Nanomaterials Synthesized By Carbon Dots As The Reductant And Their Application In Electrochemical Sensing

As a new fluorescent carbon nanomaterial,carbon nanodots(C-dots)have many oxygen containing groups such as carboxyl,hydroxyl on the surface compared with semiconductor quantum dots,and hence it is easy for surface functionalization.And carbon nanodots exhibit excellent properties such as good biocompatibility,water solubility and stability,low biological toxicity and good reducibility.C-dots were used as the reductant and stabilizer for synthesis of noble metal-C-dots nanocomponents.The nanomaterial creates a nano-hybrid material with the integrated properties of the two components.Human immunoglobulin G(HIgG)plays a vital role in recognizing some diseases,H2O2 is an important byproduct in various biological processes,nitrite(NO2-)is one of the widespread inorganic pollutants existing in foods,environment and physiological systems.Hence,the development of some accurate,sensitive,rapid and simple analytical methods for the above mentioned objects is very significant in science study.In this thesis,after the review of the progress of the carbon and metal nanomaterials,some noble metal carbon nanocomposites were prepared based on carbon dots as the reductant,and used the nanocomposites to construct three electrochemical sensors for the analysis of H2O2 and nitrite(NO2-)and human immunoglobulin G,The main contents are listed as follows:L Ag/C NC were prepared based on C-dots by chemical deposition method,the Ag/C NC were immobilized on glassy carbon electrode(GCE)to fabricated an electrochemical biosensor for analysis of H2O2 and nitrite(NO2-).The fabricated sensors displayed linear response in the H2O2 and nitrite concentration from 5 μM-11.05 mM and 4 μM-2 mM,with a detection limit of 5 μM-11.05 mM and 4 μM-2 mM(S/N),respectively.The developed biosensor was successfully applied for analysis of nitrite in real sample,the recovery is good,and these results are satisfactory.2.A double signal electrochemical Human immunoglobulin G immunosensor was proposed based on PDA-rGO-AuNPs and Ag/C nanocomposite.Firstly,Ag/C NC were prepared,Ag/C NC acting as a signal label and antibodies carrier,could not only give electrochemical signal directly from Ag/C NC but also catalyze the reduction of H2O2 to oxidize HQ for detection of HIgG.The measured peak current was proportional to the HIgG concentration from O.lto 100 ng mL’1.3.A novel signal amplified immunosensor was constructed based on in situ producing of AA as an electroactive substance using ALP and Ag-Au bimetallic nanoparticles as the catalytic amplifier and bioconjugate label for sensitive detection of HIgG.For fabrication of the immunosensor,MWCNTs-AuNPs was firstly modified on GCE as the immobilization matrix for capturing of Ab1 with the good electronic conductivity and larger surface area of MWCNTs,as well as the good properties of AuNPs.Ag-Au bimetallic was employed for immobilizing ALP and Ab2 to form ALP-Ab2-Ag-Au bimetallic bioconjugate as the signal probe.The changing peak current was proportional to the HIgG concentration from 0.005-100 ng mL-1,with a detection limit of 0.0009 ng mL-1(S/N).The developed biosensor was successfully applied for analysis of HIgG in human serum samples,these results are satisfactory.