| Microbial contamination is an important factor leading to food safety problems.When eating contaminated food by microorganisms,pathogenic bacteria will multiply and metabolize in human tissues,producing toxic chemicals and threatening human health.Adenosine triphosphate（ATP）is commonly used as an indicator to detect microbial contamination.Therefore,it is of great significance to establish a high sensitivity and accuracy ATP detect method for food safety and production environment monitoring.In this study,aptasensor is constructed from the preparation of nanocomposite materials with excellent performance and nucleic acid amplification strategy,it is used to quickly,sensitively and accurately detect ATP.The main research contents are as follows:1.A hierarchically porous Zr-MOF labeled electrochemical biosensor for the detection of ATP was constructed using polyethylenimine-reduced graphene oxide/Gold nanowire nanocomposite（PEI-r GO/Au NWs）and exonuclease I（Exo I）assisted target recycling strategy.PEI-r GO/Au NWs nanocomposite not only favor the immobilization of C-DNA but also facilitate the electron transfer and elevate the electrode surface area.In addition,hierarchically porous Zr-MOFs,high stability and large mesoporous property,could load more signal molecules.In the presence of ATP,ATP aptamer was released from the C-DNA,thus introducing signal label onto the electrode surface.Meanwhile,Exo I selectively digested the aptamer which bound with ATP,the released ATP participated new binding with the rest aptamer.Therefore,a significant increase in MB current intensity was observed.Under optimal conditions,the proposed aptasensor showed excellent performance with a linear range of 1×10-6～1×10μM and a detection limit of 3.76×10-8μM by differential pulse voltammetry.In addition,the proposed biosensor showed an outstanding performance with reproducibility,stability and anti-interference ability,and was applied to the determination of ATP in real samples,recovery rate is 84.98%～112.33%.2.In order to improve the high storage condition and lack of stability of protease,aptazyme was introduced to replace protease assisted signal amplification strategy.Herein,aptazymes based significant catalyzed signal amplification strategy,an electrochemical aptasensor was constructed for ATP detection using polyethyleneimine functionalized molybdenum disulfide（PEI-Mo S2）/Au@Pt Pd nanobipyramids（Mo S2/Au@Pt Pd NBPs）as modified material.Among them,Mo S2/Au@Pt Pd NBPs has a large specific surface area and good electrical conductivity,and can carry substantial DNA strand and amplify the redox signal of methylene blue（MB）.Additionally,a novel kind of nitrogen-rich COF is prepared using melamine and cyanuric acid（MCA）.We synthesize MCA and the Co-based metal organic framework（Co-MOF）as the signal label.Due to theπ-πstacked interactions of Co-MOF@MCA can expand the load efficiency and surface concentration of the signal label,the signal response was an order of magnitude higher than that of Co-MOF or MCA as the signal label.Target ATP changes the conformation of the aptazyme and be activated.With the assistance of metal ions,the signal label is circularly cleaved,causing an amplification of the signal.Under optimal conditions,the aptasensor can detect ATP in 1×10-5～1×102μM,the low limit of detection of 7.37×10-10μM,the recoveries for beer samples were100～110%.Therefore,the novel aptasensor has an extensive application prospect in quality supervision and food safety.3.Aptazyme triggering depends on the action of metal particles.In this chapter,an aptasensor based on Ag Pd NPs/Co Se2 and snowflake-like Au@Pt Cu Ni nanomaterials were constructed using an enzyme-free signal amplification strategy for sensitive detection of ATP.Ag Pd NPs/Co Se2 nanocomposites modified the surface of electrode to obtain a larger specific surface area and higher electrical conductivity,improving the detection performance of gold electrode.The snowflake-like Au@Pt Cu Ni as signal material can connect a large number of signal molecules and nucleic acid chains through covalent bonding.At the same time,the highly specific aptamer is used as the recognition progenitor and combined with CHA signal amplification strategy to achieve effective signal amplification.Under the optimal conditions,the electrochemical signal response showed good linear correlation with the logarithm of ATP concentration in the range of 1×10-5～1×10μM,and the detection limit was 1.03×10-15μM.The aptasensor exhibited good analytical performance and was successfully applied to the detection of beer samples with the recoveries of 91.6～116.0%.It shows its potential application in the field of food analysis. |
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