Eight Electrochemical Sensors With High Performance Based On Several Functional Nanomaterials

Nano materials and nano composite materials is getting more and more attention in environment,food,disease detection and other fields,and they also provide new opportunities for the research of electrochemical sensors because of their controllable morphology,composition,structure and size,specific surface area,excellent electrical conductivity,prominent catalytic characteristics,etc.In this paper,eight novel nanocomposites were prepared,and three kinds of enzyme-free electrochemical sensors and five aptamer-based electrochemical biosensors were constructed.The relationship between the types,compositions,sizes,and electrocatalytic properties of the composites and the response performance of the sensors was studied.In addition,the relationship between the signal amplification technologies as well as the double signal output modes and the response performance of the high performance sensor was also studied.Based on these nanomaterials,the new electrochemical sensing methods for detecting H₂O₂?c Tn I?PAT and OTA were established respectively.This research can enrich the electrical analysis methods.In addition,it can provide reference for the detection of food contaminants and disease biomarkers.This dissertation has been divided to three chapters;The main contributions of the author are mainly written in the following two aspects:1.Au NPs/MnO₂,Cu-TCPP MOF/Cu_5.4O NPs,and NHC@Ag USNPs nano-composites were prepared.Three kinds of enzyme-free electrochemical sensors for the detection of H₂O₂ were constructed based on the prepared nano-composites.This novel electrochemical sensing methods for detecting H₂O₂ were established.The morphology,composition,structure and size of the composite were investigated by TEM,SEM,XRD and XPS.The results showed that the synthesized Au NPs/Mn O₂ had a spherical and porous flowerlike structure.The Au NPs with a diameter of about 10 nm were uniformly dispersed on the surface of Mn O₂.Cu-TCPP MOF/Cu_5.4O NPs is a two-dimensional nanocomposite,and Cu_5.4O NPs(4.0 nm)are uniformly distributed on the surface of Cu-TCPP MOF.The prepared NHC@Ag NPs have a spherical structure of Ag NPs with a particle size about 2.5nm.And they are uniformly dispersed without aggregation.The electrochemical results showed that the catalytic reduction current of Au NPs/Mn O₂ nanocomposite was linear to H₂O₂ in the range of 2.5-1.4×10³?mol·L^-1 and 1.4×10³-13.9×10³?mol·L^-1,and the detection limit was 0.3?mol·L^-1.The linear range of H₂O₂ catalyzed by Cu-TCPP MOF/Cu_5.4O NPs nanocomposites was 0.1-0.6×10³?mol·L^-1 and 0.6×10³-20.6×10³?mol·L^-1,and the detection limit was 0.03?mol·L^-1.The linear range of NHC@Ag USNPs for catalysis of H₂O₂ was 0.1-0.1×10³?mol·L^-1,0.1×10³-0.6×10³?mol·L^-1 and 0.6×10³-20×10³?mol·L^-1.The detection limit was 0.02?mol·L^-1.Compared with the three electrochemical sensing methods of H₂O₂,the catalytic performance of Cu-TCPMOF/Cu_5.4O NPs nanocomposite increased rapidly with the decrease of the particle size of the nano-catalyst.Therefore,the catalytic performance of Cu-TCPMOF/Cu_5.4O NPS nanocomposite for H₂O₂ has a wider linear range than Au NPs/Mn O₂,and the detection limit is reduced by 10 times.The Ag NPs with the smallest particle size shows more excellent electrocatalytic performance.Compared with similar sensing methods,this method has the widest linear range and the lowest detection limit.2.NGE,MoS₂,Cu-TCPPMOF nanosheets,and two kinds of gold nano-materials were prepared.Three electrochemical biosensors based on layered nano-materials and dual-signal biosensors based on different spherical gold nanoparticles were constructed.Thus,new methods for detecting food contaminants and disease markers were established.The above nanomaterials were characterized by SEM,TEM,XRD and XPS.The results showed that NGE,MoS₂ and Cu-TCPP MOF are three kinds of layered materials.Both NGE and Cu-TCPP MOF are micron in size with more wrinkles and larger specific surface area.Both the traditional gold nanomaterials and NHC@Au NPs are spherical nanomaterials,while the NHC@Au NPs has smaller size and more specific surface area than the traditional gold nanomaterials.The thermal stability results showed that NHC@Au NPs was more stable than traditional gold nanoparticles,which maked it suitable for application in vivo.The electrochemical performance results showed that the five methods had good specificity.For three electrochemical biosensors based on layered nanomaterials,the relationship between signal amplification technology and the new highly sensitive electrochemical biosensors was studied.It was found that the linear range of the electrochemical biosensor based on MoS₂nanosheet aptamer was 10×10^-6-1?mol·L^-1,and the detection limit was 3.3×10^-6?mol·L^-1.The linear range of the unlabeled aptamer electrochemical biosensor based on NGE was2.5×10^-7-2.5×10^-2?mol·L^-1,and the detection limit is 1.8×10^-7?mol·L^-1.The linear range of the aptamer electrochemical biosensor based on Cu-TCPP MOF nanosheets were 2.5×10^-7-2.5×10^-1?mol·L^-1and 2.5×10^-1-25?mol·L^-1,the detection limits was 0.8×10^-7?mol·L^-1.Compared with the detection performance of the aptamer electrochemical biosensor based on MoS₂ nanosheet without signal amplification measure,the detection performance of the aptamer electrochemical biosensor based on NGE/Cu-TCPP MOF with signal amplification measure has been improved.Compared with the same type of OTA biosensors,the linear range of the aptamer electrochemical biosensors based on Cu-TCPP MOF can be extended by one order of magnitude,and the final detection limit can be reduced by 18 times.The results showed that the two kinds of biosensors with two kinds of signals,which improves the accuracy of the output signal of the biosensor.The aptasensor based on traditional gold nanoparticles outputs two kinds of fluorescence and electrochemical signals,while electrochemical aptasensor with dual-signals based on water-soluble gold nanoparticles outputs two kinds of electrochemical signals.This work not only improves the sensitivity of the electrochemical biosensor,but also improves the accuracy of the electrochemical biosensor so that the performance of the electrochemical biosensor has been improved.