Study On The Sensing Detection Of Ampicillin And Kanamycin By Electrochemical Aptasensor

Recent years,with a growing international concern on the antibiotic residual event,developing all various of new detection technologies for achieving the fast monitoring of residual pollution locations has been a big problem related to people's physical and mental health,which can not be ignored.Among these new developed technologies,the electrochemical aptamer-based sensor based on the conformation change of redox-modified DNA shows a lot of good advantages helpful for achieving the practical application.Therefore,this technology has been one of the future important development directions for the monitoring of pesticide and veterinary drug residues.In this paper,employing the DNA-based aptamer as the molecular recognition element and kanamycin A(KMY-A)and ampicillin(AMP)as the model targets,two electrochemical sensors were designed and fabricated based on one-probe or two-probe system,respectively.The key parameters affecting the sensing efficiency were optimized;two electrochemical signal-out methods,alternate current voltammetry(ACV)and cyclic voltammetry(CV),were applied for confirming the happening of sensing process;some basic performance parameters,sensitivity,selectivity and sensing speed etc.,were systematically investigated.Two corresponding works are addressed as follows:1.A one-probe sensor(S-2)based on 3MB-labelled signaling probe was fabricated for the determination of KMY-A.Three key parameters,the probe coverage,the ion strength of working media and the ACV measuring frequency,were optimized.When used for the analysis of target KMY-A,the proposed sensor showed a 443.6±24.8 of SE% at the adding concentration of 2.0 mM.Within the range of 0.01-10.0 m?,a good linear relationship was confirmed between the detection signal and the KMY-A concentration with limit of detection of 3.3 nM.When used for the investigation of selectivity,the proposed sensor showed good discrimination ability with the discriminating coefficients of-0.0011~0.019.In addition,this sensor system also showed a very fast sensing speed with only needing the response time of ~15 s.When used in detecting of2 practical samples,50% milk and 50% tap water,the sensor method performs good with the SE% of 217.7±16.8% and 306.6±28.2%.Furthermore,the relative standard deviation(RSD)of parallel determination(n=10)is 1.8%,which shows a good fabrication stability.Compared with S-1,the comprehensive sensing performance was effectively improved.2.A single-brace duplex structure aptasensor(S-4)based on the signaling mechanism of displacement reaction was fabricated for the determination of AMP.Three key parameters,the bracing duplex length,the temperature of duplex formation and the ACV measuring frequency,were optimized.When used for the analysis of target AMP,the proposed sensor showed 70.29±4.8% of SE% at the adding concentration of 1.0 mM.Within the range of 0.0002-10.0 mM,a good linear relationship was confirmed between the detection signal and the AMP concentration with limit of detection of ~30 nM.When used for the investigation of selectivity,the proposed sensor showed good discrimination ability with the discriminating coefficients of 0.12 ~ 0.23.In addition,this sensor system also showed a very fast sensing speed with only needing the response time of ~80 s.When used in detecting of 4 practical samples,50% saliva,50% urine,50% milk,and 50% tap water,the sensor method performs good with the SE% of62.21±6.2%,55.03±3.6%,31.12±3.3% and 28.25±4.4%.Furthermore,the relative standard deviation(RSD)of parallel determination(n=10)is 3.4%,which shows a good fabrication stability.Compared with S-3,the background signal was decreased greatly and the comprehensive sensing performance was effectively improved.