Application Of DNA Nucleic Acid Aptamer/Co₃O₄ Nanozyme In The Detection Of Kanamycin

Kanamycin(KAN)is often used extensively as a growth hormone analog and as an antibacterial agent.However,abusive doses can easily lead to antibiotic residues in food,which can trigger a range of toxic effects in humans.Traditional detection methods are effective in detecting KAN,but they are time-consuming,costly,and cumbersome to perform.The application of DNA nucleic acid aptamers in combination with nanozymes is a promising strategy with the advantages of low cost,good stability,and a wide range of applications.Based on this,a chemiluminescent and colorimetric aptasensor was constructed for the rapid quantitative detection of KAN using Co3O4 nanoparticles(Co3O4 NPs)nanozyme activity and DNA nucleic acid aptamer of the high specificity,and the main researches arc as follows:(1)A DNA aptamer/Co3O4 NPs nanozyme catalyzing the luminol-H2O2 reaction was used to amplify the chemiluminescence signal by exploiting the chemiluminescent properties of luminol oxidation by H2O2.The specific binding of KAN to the aptamer leads to the formation of steric hindrance block within the solution and the inhibition of the nanozyme activity,resulting in a reduction in signal intensity.The degree of signal reduction is only related to the KAN concentration.Under optimal test conditions,there was good linearity between KAN concentration and signal intensity in the range of 0.05 μM-8 μM,with a minimum detection limit of 50 nM.The detection systcm performed well in the presence of competing antibiotics and was virtually unaffected.The method was also suitable for the detection of KAN in milk samples with sample recoveries of 97.6%-99.4%.The chemiluminescent sensor has the advantages of being cost-effective,specific,and sensitive,requiring no external light source and no modification of the nucleic acid aptamer,and has potential applications in food detection.(2)A simple and sensitive colorimetric assay for KAN detection using DNA aptamers to enhance the peroxidase-like nanozyme activity of Co3O4 NPs,which possess the peroxidase-like activity and catalyze the oxidative color change of 3,3’,5,5’tetramethylbenzidine(TMB)in the presence of H2O2,has been proposed for the first time.Interestingly,the specific DNA aptamer of KAN can modulate the catalytic activity of the Co3O4 NPs nanozyme by enhancing the affinity between TMB and Co3O4 NPs.In the presence of KAN,the aptamer desorbs from the surface of Co3O4 NPs,leading to a decrease in the catalytic capacity of Co3O4 NPs.The color change of the solution can be judged by the naked eye and monitored by a microplate reader.Under optimal test conditions,the analytical system signal was log-linear with KAN concentration in the range of 0.1 μM-30μM,with a minimum detection limit of 44.2 nM and actual sample recoveries of 97.2%99.5%.The sensor showed good selectivity for KAN even in the presence of other competing antibiotics.The results of this colorimetric sensor are visible to the naked eye,simple to operate,and highly sensitive,and will have promising applications in animal husbandry and agricultural products.These two new optical biosensors will provide new ideas for the future detection of KAN in food and provide a common platform for the detection of other targets in biological samples.