Detection Of Aflatoxin B1 By Electrochemical Biosensor Based On Metal-organic Coordination Polymer

Metal-organic jframeworks(MOFs)have the characteristics of large specific surface area,regular structure,controllability,and functionalizablity,which have attracted more and more researchers,attention.In recent years,the application of MOFs in the field of electrochemistry has been rapidly developed.The electrochemically active MOFs have been synthesized and used as biosensing media in the field of biochemistry,which has become one of the hot research topics.Electrochemical biosensors have the advantages of high-sensitive,high-specific and easy-operationable.They are widely used in food safety testing,biomedical analysis and environmental pollution monitoring,etc.Electrochemical biosensor is a new mode of sensor that combines electrochemical analysis methods with biotechnology.In general,researchers choose materials with good electrochemical activity for electrochemical analysis.Mycotoxins are pollutants that have strong carcinogenic effect.Aflatoxin B1(AFB1)is the most important and most toxic mycotoxin.It is most common in naturally contaminated food,and its toxicity and carcinogenicity are also strongest.It is the main cause of liver cancer.AFB1 is widely found in crops and their products and can be found in peanuts,com,cereals,coffee,beer and multiple condiments.The presences of AFB1 in foods have a great impact on peopled healthy lives.Therefore,it is important to construct a fast and sensitive method for detecting AFB1.The combination of AFB1 and specific aptamer has high specificity and affinity to design a highly sensitive electrochemical biosensor for the detection of AFB1.In this paper,copper metal salts and organic ligands were selected as reactants to synthesize electrochemically active Cu-MOFs as signal probes.An electrochemical biosensor was designed for the detection of AFB1 using the specific recognition of the aptamer and AFB1.The main contents are as follows:1.The electrochemical biosensor based on copper terephthalate(Cu-TPA)was used for the detection of aflatoxin B1.Firstly,gold nanoparticles(AuNPs)were loaded in Cu-TPA and then ligated to DNA1 to form Cu-TPA/AuNPs/S1 as a signal probe for electrochemical sensor.The DNA2(S2)was ligated to the gold electrode(GE),and the AFB1 aptamer(S3)was hybridized with S2 to form S3/S2/GE.The signal probe was attached to the electrode by hybridization of S3 and SI.Cu-TPA/AuNPs composites contain a large amount of Cu(?),which can obtain relatively stable and strong electrochemical signals.After adding a certain amount of AFB1,AFB1 and S3 combined to cause the signal probe to fall off and reduced the electrochemical signal.Electrochemical detection of AFB1 was achieved by changes in electrochemical signal values.The sensor has high sensitivity and low detection limit,and can also be used to detect AFB1 in beer samples.Under the optimized conditions,this electrochemical biosensor for detection AFB1 exhibited low detection limit of 4.2×10-6 ng/mL(signal/noise=3)and wide linear range of 10-5?10 ng/mL.The biosensor was also used to analyze AFB1 spiked beer sample,and the recovery was 95?106%.2.Next,a copper-terephthalate(Cu-BDC)with-NH2 was synthesized,and-NH2 was used to interact with AuNPs and then linked DNA as a signal probe.At the same time,the circular amplification function of Exonuclease ?(Exo ?)was used to construct the electrochemical biosensor for better detection of aflatoxin B1(AFB1).Hairpin DNA(S1)was immobilized on the electrode.AFB1 induced Exo ?hydrolyzed partially sequence of hairpin DNA,releasing single-stranded DNA into a new cycle.After multiple cycles,more capture sites were left on the electrode to connect the signal probes.The AuNPs were attached to Cu-BDC via-NH2 and then ligated to capture DNA as signal probe.The signal probes were attached to the electrode by complementary pairing of DNA bases to construct an electrochemical biosensor for AFB1 detection.Under the optimized condition,this electrochemical biosensor for detection AFB1 exhibited low detection linit of 6.7×10-7 ng/mL(signal/noise=3)and wide linear range of 10-6?1 ng/mL.The biosensor was also used to analyze AFB1 spiked beer sample,and the recovery was 96?103%.