Electrochemical Aptasensor For Thrombin Using Co-catalysis Of Hemin/G-quadruplex DNAzyme And Octahrdral Cu₂O-Au Nanocomposites For Signal Amplification

In this work,novel octahedral Cu₂O-Au nanocomposites were synthesized and first applied in an electrochemical aptasensor to detect thrombin?TB?with the aid of a DNAzyme for signal amplification.The octahedral Cu₂O-Au nanocomposites have not only simultaneously served as signal amplifying molecules but have also been utilized as an ideal loading platform to immobilize a large number of electroactive substances and recognition probes.Gold nanoparticles?Au NPs?were grown directly on the surface of the octahedral Cu₂O nanocrystals,and the Cu₂O-Au nanocomposites obtained had the advantages of large surface areas and excellent biocompatibilities.The hemin/G-quadruplex,which was formed by intercalating hemin into the amino terminated thrombin binding aptamer?NH₂-TBA?,and the electroactive toluidine blue?Tb?were immobilized onto the Cu₂O-Au nanocomposite surfaces through a stable Au-N bond.AuNPs,Cu₂O and hemin/G-quadruplex co-catalyse the H₂O₂ in the working buffer to promote the electron transfer of Tb as a multiple signal amplification strategy in order to improve the performance of the electrochemical aptasensor.Under optimal conditions,the designed aptasensor exhibited sensitive detection of TB from 100 fM to 20 nM with a lower detection limit of 23fM.This proposed aptasensor exhibited good sensitivity,high specificity and acceptable reproducibility and could be widely applied in bioassay analysis.