Study On Construction And Performance Of Aptasensor Based On Nanoconjugates

Aptasensors are a new class of biosensors that use aptamers as identification elements.They have the characteristics of high sensitivity,good selectivity,and low detection cost.They have broad application prospects in the fields of environmental monitoring and medical diagnostics.In recent years,combining the unique properties of nanomaterials with aptasensors to construct aptasensors based on nanoconjugates has become one of the hotspots in biosensor research.In this dissertation,three kinds of aptasensors based on nanoconjugates were constructed with different nanomaterials and detection principles,and their performances were studied through the detection of targets.The main contents were described as follows:Firstly,a dopamine(DA)electrochemical aptasensor based on nanoconjugates was constructed.Aptamer and gold nanoparticles-invertase-complementary DNA nanoconjugates were used as capture probe and detection probe,respectively.In the absence of dopamine,the detection probe was captured on 96-well plate by the aptamer through complementary base pairing.When it was in presence,DA interacted with its aptamer with a stronger affinity forcing the detection probe away from the 96-well plate to catalytic sucrose into glucose,thus indirect detection of dopamine concentration was performed by measuring glucose concentration with a glucose meter.Under optimized experimental conditions,the linear detection range of the aptasensor for dopamine was 0.45~10mmol/L,the detection limit was 0.45mmol/L,and the correlation coefficient was 0.997.Secondly,an aflatoxin B1(AFB1)electrochemical aptasensor based on nanoconjugates was constructed.By using AFB1 monoclonal antibody as capture probe and gold nanoparticles-invertase-aptamer nanoconjugates as detection probe,a sandwich-type aptasensor was constructed based on the sandwich-type structure which was formed after the addition of target AFB1.The more targets were added,the more detection probes were fixed,and the smaller the number of detection probes in the supernatant.According to the amount of glucose in the supernatant after addition of sucrose,AFB1 concentration was detected in combination with a glucose meter.Under the optimized experimental conditions,the linear detection range of the aptasensor for AFB1 was 0.5~5ng/mL,the detection limit was 0.5ng/mL,and the correlation coefficient was 0.99.Finally,a dopamine fluorescent aptasensor based on nanoconjugates was constructed.By using carbon quantum dots(CQDs)as fluorescent groups and gold nanoparticles(AuNPs)as quenching groups,a DA fluorescent aptasensor was built based on the fluorescence resonance energy transfer.In the absence of DA,CQDs were adsorbed on the aptamer-AuNPs through the electrostatic force between CQDs and aptamer,and the fluorescence is quenched.When it was added,DA specifically combined with its aptamer,making the CQDs break away from AuNPs,which lead to the recovery of fluorescence.The photoluminescence intensity was linearly as a function of the target DA concentration,so DA concentration could be detected with a fluorescence spectrophotometer.Under optimized experimental conditions,the linear detection ranges of dopamine in buffer and actual samples were 0.5~250?mol/L and 0.8~100?mol/L,and the detection limits were 0.01?mol/L and 0.5?mol/L,respectively.The correlation coefficients were 0.991 and 0.973,respectively.The results showed that the three aptasensors based on nanoconjugates had good detection performance and achieved specific and sensitive detection for their targets.They not only have application potential in the field of food safety testing,but also broaden the application platform for nanomaterials.