Application Of Coinage Metal Nanoparticles In Electrochemical Biosensors

Currently,coinage metal nanoparticles(including gold,silver and copper nanoparticles)have attracted wide attention because of their large specific surface area,high catalytic activity and surface properties.These nanoparticles can be adjusted according to the requirements of practical applications.Gold nanoparticles can be functionalized by the electroactive molecules,and plenty of electrochemical probes can be immobilized due to the large specific surface area.Silver and copper have good electrochemical redox activity,and the formation of multiple copper/silver nanoparticles will provide amplified electrochemical signals,so copper/silver nanoparticles can be used as electrochemical probe molecules.(?)An electrochemical approach has been developed for the sensitive and accurate determination of SA in human serum samples.In this method,the high conductivity gold nanodendrites modified carbon cloth was used as the base electrode to amplify the signal.Furthermore,the high affinity of nucleic acid aptamer was used to realize the high specificity recognition of sialic acid,which improved the selectivity of sialic acid determination.The electrochemical signal of thionine was introduced and the secondary signal was amplified by boric acid-diol reaction combined with thionine/gold nanoparticles/4-mercaptophenylboric acid composite.The prepared nucleic acid aptamer electrochemical sensor showed high sensitivity,good selectivity and long-term stability in the determination of sialic acid.The sensor has been applied to the determination of sialic acid in real serum samples with a detection limit of 60 nmol·L^-1.(?)In order to solve these problems and improve the analytical performance,we constructed a double-signal amplified electrochemical sensor for ultrasensitive detection of A?oligomer.In this study,A?oligomer sensor with copper nanoparticles as electrochemical signal probe was constructed,using gold nanoparticles modified vertical graphene/carbon cloth film as substrate electrode.Copper nanoparticles synthesized in situ using poly(thymine)-templated were used as electrochemical signal probes.The prion protein was immobilized on the surface of the substrate electrode by Au-S bond as the receptor of A?oligomer,and the nucleic acid aptamer-T30-copper nanocluster conjugate recognized A?oligomer by nucleic acid aptamer.Copper nanoparticles were introduced as electrochemical signal probes.The experimental results show that the electrochemical biosensor constructed by this method has high sensitivity,low detection limit,high specificity and good stability,and is feasible in the detection of human serum samples.It is of great significance for the early diagnosis and treatment of Alzheimer's disease.(?)An electrochemical biosensor detection method for ultra-sensitive detection of recombinant human PrP^Cprotein was established,using gold nanoparticles modified glassy carbon electrode as the substrate electrode and DNA-silver nanoparticles(AgNPs)synthesized in situ by cytopyridine-rich sequence DNA template as the electrochemical signal probe.The surface area and conductivity of the glassy carbon electrode were increased by gold-plated nanoparticle film by electrodeposition.Then,the mercapto modified PrP^Cspecific aptamer was fixed on the surface of the electrode by Au-S bond.After the aptamer selectively recognizes PrP^C,the aptamer without recognizing PrP^Cforms double-stranded DNA with its complementary strand.Furthermore,the feature of double-stranded specific endonuclides only cutting double-stranded DNA was used to remove the aptligand single strand that did not react with PrP^C.Furthermore,DNA-AgNPs synthesized in situ with C-rich sequences of DNA template were used as the signal probe to realize the ultra-sensitive monitoring of PrP^C.