| Kanamycin as a commonly used aminoglycoside antibiotic,can not only treat a variety of infectious diseases,but also promote the growth of livestock and poultry,which widely used in agriculture and animal husbandry.However,its abuse will lead to excessive residues in animal-derived foods such as milk and meat,and enter the human body through the biological circulation system,which will seriously affect human health.The traditional detection method is highly sensitive,due to the expensive instrument and complicated pretreatment,it cannot meet the requirements of rapid and on-site detection.Therefore,it is important to develop an accurate and sensitive method to detect kanamycin residues rapidly.Electrochemiluminescence(ECL)aptasensor is constructed by using aptamer as molecular recognition element combined with electrochemiluminescence technology.It is widely used in the safety detection of agricultural products due to its advantages of simple operation,high sensitivity and fast response.Luminol,as a common luminescent substance,has the advantages of cheap,non-toxic and high luminescent efficiency.Different immobilization forms of luminol have certain influences on the performance and application of sensors.Therefore,in order to achieve sensitive and rapid detection of kanamycin,the performance of ECL aptasensors constructed by different immobilization forms of luminol was studied in this paper.The main contents were as follows:(1)An ultrasensitive ECL aptasensor for detection of kanamycin was constructed by self-assembly method using the chemiluminescence properties of luminol-hydrogen peroxide(H2O2)in alkaline solution.Silver nanoparticles(AgNPs)acted as effective catalyzer to accelerate H2O2 decomposition to produce various reactive oxygen species for signal amplification,thus increased the ECL intensity of luminol.The ECL aptasensor displayed a wide linear range from 0.5 to 100 ng/mL with limit of detection of 0.06 ng/mL.(2)In order to simplify the construction of the aptasensor and enhance the immobilization effect of aptamer on the electrode,a dual-signal-amplified ECL aptasensor based on multi-walled carbon nanotubes@titanium dioxide/thionine(MWCNTs@TiO2/Thi)was proposed by placing luminol in the test solution.The MWCNTs@TiO2 with large specific surface area and favorable biocompatibility could accelerate electron transfer and enable high loading of luminol to enhance the ECL response.Thi could further enhance conductivity through π-π stacking force to accelerate the electron transmission.The ECL aptasensor showed a wide linear range from 1.0×10-1 to 1.0×105 ng/mL with a limit of detection of 0.049 ng/mL.(3)In order to enhance the sensitivity of aptasensor,a sandwich ECL aptasensor for kanamycin detection was constructed by using luminol functionalized aptamer as a signal probe.The sensor served polyethyleneimine-molybdenum disulfide-multi-walled carbon nanotubes(PEI-MoS2-MWCNTS)as the substrate,which provided a large number of binding sites for Aptl coupling.Luminol functionalized aptamer(Apt2-Ag-luminol-PAMAM)was used as a signal probe to construct a sandwich aptasensor by the specific combination of kanamycin and aptamer.Ag-luminol-PAMAM composites could generate stable ECL signals,and PEI-MoS2-MWCNTs composite could accelerate the electron transfer rate and further improve the sensitivity of aptasensor.The prepared aptasensor showed a good linear relationship in the range from 1.0×10-3 to 1.0×103 ng/mL with limit of detection of 0.21 pg/mL.The above researches provide new methods for the detection of small molecule pollutants by ECL aptasensor sensing technology,and provide new ideas for the field of agricultural product safety detection. |
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