Sensitive Detection Of Tetracycline Antibiotics Based On Molybdenum Disulfide Nanomaterials

One of the causes for undermining animal-derived food safety is excessive antibiotic residues in any edible parts of animal products,which include the original drugs and metabolite in animals.Tetracycline is a commonly used antibiotic,but the long-term intake of the foodstuffs with excessive tetracycline residues will increase the resistance of pathogenic bacteria,interfere with the normal flora in the human intestinal tract,and affect bone development.In order to prevent the harm of tetracycline,the establishment of tetracycline detection technology is essential for the food industry and public health.At present,microbial analysis,chromatography,immunoassay,UV-visible spectrophotometry,electrochemical analysis,and aptamer sensors have been applied in the detection of tetracycline,but these methods are limited by some defects,such as complicated extraction and purification processes,cumbersome operation and expensive cost.Therefore,it is very meaningful to develop a rapid detection method for tetracycline antibiotic residues in animal-derived foods.In this study,two sensitive and rapid detection methods of fluorescence and immunochromatography were established.The main results are as follows:1.Sensitive detection of tetracycline(TET)based on fluorescent molybdenum disulfide nanoplates(MoS₂NPs):Molybdenum disulfide nanoplates were synthesized through a"bottom-up"hydrothermal strategy to specifically detect tetracycline.Sodium molybdate and glutathione(GSH)were used as precursors to provide molybdenum and sulfur.The prepared MoS₂NPs emitted blue fluorescence in aqueous solution with excitation and emission peaks at 325 nm and 430 nm.Interestingly,the fluorescence of MoS₂NPs was quenched significantly by the synergistic effect of internal filtration effect and electron transfer after the addition of TET.Therefore,MoS₂NPs were used as detection probes to construct a“on-off”sensor for detecting TET.The fluorescence quenching behavior of MoS₂NPs by TET was also evaluated by the Stem-Volmer equation that indicated there is a dynamic quenching type.Under the optimal conditions,there was a good linear relationship between TET concentration(0.1-50?M)and fluorescence intensity,and the detection limit was calculated to be 0.032?M.Additionally,the sensor can be successfully applied in milk,milk powder and beef samples with the recovery of 89.11%-102.92%,indicating that this fluorescence sensor is suitable for rapid determination of TET.2.Construction and characterization of immunochromatographic assay based on MoS₂nanosheets for rapid detection of TET:The commcial bulk MoS₂was exfoliated into nanosheets and a simple differential-zone centrifugation strategy was applied to prepare uniform MoS₂nanosheets with different sizes and thicknesses(L-MoS₂,M-MoS₂and H-MoS₂).At the same time,labeling the nanosheets using conventional techniques without the complex cross-linking agents.Crucially,the MoS₂not only provide a suitable platform for immobilizing the biomolecules,but also further promote the performance of sensor by loading fewer antibodies.Through immunochromatographic reaction,a very small amount of MoS₂-Abs probes were fiercely competitive captured between target TET molecules and TET-BSA pre-coated on the T-line,leading to a more obviously naked-eye signal.Combining these merits,the proposed sensor showed supreme performance,exhibited exceptional sensitivity with a limit of detection(LOD)of 0.052 n M and outstanding specificity,and was perfectly applied to the detection of TET in milk,honey and beef samples.This work expands the considerable potential applications of the 2D materials in more platforms for immunochromatographic strips.