Construction Of Electrochemical Aptamer Sensing Platform Based On Enzyme-functionalized Porous Carbon Materials And Its Application In The Detection Of Antigenic Protein

The development of a highly sensitive and specific biosensor to detect tumor markers plays an important role in the early diagnosis and treatment of cancer.Electrochemical aptasensors have been widely concerned and applied in many fields because of their high selectivity,high sensitivity,fast response,and simple operation.Since the concentration of various tumor marker proteins is very low,various signal amplification strategies have been developed in the process of biochemical signal transduction to electrical signal.These include the use of nanomaterials,enzymes,amplification technology and other excellent properties and functions to build electrochemical aptasensors,which greatly improve the sensitivity of the sensor.Zeolitic imidazolate frameworks（ZIFs）derived porous carbon materials contribute to enzyme-catalyzed reactions due to their porosity and large specific surface area,which is more conducive to improving the electron transport rate.In addition,using a substrate with low electrochemical background signal and catalyzing the redox reaction by an enzyme can further amplify the electrical signal and improve the detection sensitivity of the sensor.In this paper,an electrochemical aptasensing platform is constructed based on the ZIF-derived porous carbon materials functionalized by enzymes.The main research contents are as follows:Aptamer and bifunctional enzyme co-functionalized MOF-derived porous carbon for low-background electrochemical Aptasensing.In this paper,a novel sandwich-type electrochemical aptasensor for low background electrochemical sensing was developed by coupling the tyrosinase-triggered electrochemical-chemical redox cycle with nanoscale porous carbon.Aptasensors are used to detect prostate specific antigens（PSA）,the most typical tumor marker for early diagnosis and subsequent treatment of prostate cancer.ZIF-8carbonization is prepared to porous carbon,and after carboxylation,ZIF-8-derived nanoporous carbon（NCZIF）is covalently functionalized with tyrosinase and aptamers by carboxyl groups on its surface.With the aid of phenol and NADH,the aptasensor can detect0.01 ng m L-1 PSA,with a linear relationship in the concentration range of 0.01 ng m L-1 to 50 ng m L-1.The actual sample experimental results show that the aptamer sensor achieves low background electrochemical sensing of PSA in human serum.Stimulus-responsive dual-channel highly specific biosensor based on ZIF-8 derived porous carbon materials.The aptamer chain（Apt-1）of PSA is hybridized with the complementary chain（c DNA1）to form a double-stranded ds DNA,followed by a covalent modification with alkaline phosphatase（ALP）to form a recognition probe on the surface of the carboxylated carbon material.At the same time,the surface of the carboxylated magnetic beads modifies the aptamer chain（Apt-2）.When a target molecule appears,nanoenzymes and magnetic beads work together to identify the target molecule,forming a sandwich structure.At the same time,the sandwich structure releases the complementary chain c DNA1,which separates c DNA1 from the sandwich structure by magnetic separation.The released c DNA1 triggers the NCZIF that encapsulates the pyrophosphoric acid（PPI）,releasing the PPI as a signaling molecule into the channel.Under the catalysis of ALP,PPI reacts with molybdenum in the acid bottom solution to produce an electrochemical signal to achieve highly specific electrochemical biosensing detection of PSA.Under the auxiliary catalysis of carbonized ZIF,the aptamer sensor has high sensitivity and selectivity for the detection of PSA,with a linear range from 10 fg m L-1 to 100 ng m L-1 and a detection limit of 8.8×10-6 ng mL^-1.