Research And Application Of Biosensors For Tetracycline Specific Recognition Based On Aptamers And Nanomaterials

Tetracycline is a broad-spectrum antibiotic.If the dosage is too large or abused,it will cause residues in food and different degrees of harm to human health.Therefore,it is of great practical significance to establish a rapid and sensitive method for the detection of tetracycline residues in food products.In this paper,tetracycline worked as template,a novel method for tetracycline residues detection was developed,which was based on high affinity aptamers and novel nanomaterials.The main research contents are as follows:1.Study on the preparation of aptasensor based on nano antimony doped tin oxide and chitosan compositeNano antimony doped tin oxide possesses high conductivity,preparation of nano tin oxide-chitosan composite membrane by excellent film forming and adsorption properties of chitosan,the study found that the composite membrane had good adsorption and stability,and its rich amino and porous structure was conducive to the effective immobilization of aptamer.Combined with the advantages of interdigitated array microelectrodes,it can enlarge the impedance change and reduce the interference effect of non target analyte.The results showed that the biosensor had the characteristics of large linear range of 1×10-1~1×106 μg/L with a detection limit of 3.0 μg/L.2.Study on the preparation of ratiometric aptasensor based on ferrocene/carbon nanofibers-gold nanoparticlesFerrocene and nanofibers had good conductivity and large specific surface area,which can effectively improve the performance of the electrode.The aptamer was effectively immobilized by the "Au-S" bond using gold nanoparticles,the ratiometric aptasensor was fabricated by two aptasensors and their detection results were calculated by ratio,improving the accuracy of aptasensor and reducing the differences between batches.Tetracycline was used to test and the results showed that there was a good linear correlation in the range of 10-2~106 μg/L with a detection limit of 0.33 μg/L.3.Study on the preparation of aptasensor based on enzyme assisted target circulation and ordered mesoporous carbon-gold nanoparticlesFor exonuclease III,specific recognition sequence of DNA double chain was not strictly required.Exonuclease III was selected for auxiliary target signal amplification cycle in this experiment.Combined with the application of enzyme and nanomaterials,the signal was amplified two times,so that the sensitivity for detection was improved and the detection limit was 3.0 μg/L.When the sample was diluted 3 times,the samples were directly determined.The results showed that the pretreatment method could realize the rapid detection of tetracycline residues in milk samples.In contrast to the above three kinds of aptasensors,the results showed that nanocomposites had a good synergistic effect for electrode modification,aptamers could be effectively fixed by means of self assembled films,through the comparison of sample pretreatment.It was found that the pretreatment method of direct dilution of milk samples combined with the portability of screen-printed carbon electrodes could effectively realize the rapid detection of tetracycline residues in milk.