| CPC G01N 33/12 (2013.01) [G01N 33/54366 (2013.01); G01N 2430/00 (2013.01)] | 7 Claims |
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1. A flexible paper-based sensor for detecting tetracycline residues in meat products, wherein the flexible paper-based sensor is prepared through steps of:
(1) dissolving yttrium chloride hexahydrate, ytterbium chloride hexahydrate and erbium chloride hexahydrate in a first solvent, followed by addition of oleic acid and 1-octadecene, a first reaction under heating and stirring, and cooling to obtain a first mixture, wherein the first solvent is methanol;
dissolving ammonium fluoride and sodium hydroxide in a second solvent to produce a solution, wherein the second solvent is methanol; mixing the solution with the first mixture followed by a second reaction under heating and stirring, injection of nitrogen gas, a third reaction under heating and stirring in a nitrogen atmosphere, and cooling to obtain a second mixture; and subjecting the second mixture to washing, centrifugation and drying to obtain an upconversion fluorescent nanomaterial; and
mixing the upconversion fluorescent nanomaterial with chloroform, toluene and a polyacrylic acid aqueous solution followed by a fourth reaction under stirring, centrifugation and drying to obtain a carboxylated upconversion nanomaterial;
(2) adding a 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride aqueous solution and a N-hydroxysulfosuccinimide aqueous solution to the carboxylated upconversion nanomaterial to obtain an incubation system; incubating the incubation system under shaking, followed by addition of a solution of a complementary chain of a tetracycline aptamer under shaking to obtain a UCNPs-cDNA signal probe;
(3) dissolving 2-aminoterephthalic acid and Fe(NO3)3·9H2O in N, N-dimethylformamide under stirring, followed by a fifth reaction in a reactor, centrifugal washing and drying to obtain NH2-MIL-53(Fe);
dissolving NH2-MIL-53(Fe) and CuCl2 in deionized water followed by a sixth reaction under stirring to obtain NH2-MIL-53(Fe)@Cu2+;
adding a glutaraldehyde solution and a phosphate-buffered saline (PBS) to NH2-MIL-53(Fe)@Cu2+ followed by shaking in the dark, and centrifugation to collect a precipitate; and
adding the tetracycline aptamer to the precipitate followed by shaking overnight and centrifugation to obtain an Apt-MIL-53(Fe)@Cu2+ capture probe;
(4) mixing the UCNPs-cDNA signal probe with the Apt-MIL-53(Fe)@Cu2+ capture probe to obtain a detection probe; and
(5) dropwise adding the detection probe onto a central area of a paper-based substrate to obtain the flexible paper-based sensor;
wherein in step (1), a ratio of the yttrium chloride hexahydrate to the ytterbium chloride hexahydrate to the erbium chloride hexahydrate to the first solvent to oleic acid to 1-octadecene is (220-250) mg:(70-80) mg:(5-10) mg:(6-10) mL:(6-10) mL:(15-20) mL;
a ratio of ammonium fluoride to sodium hydroxide to the second solvent is (0.1-0.2) g:(0.1-0.15) g: 10 mL;
a ratio of the upconversion fluorescent nanomaterial to chloroform to toluene to the polyacrylic acid aqueous solution is 25 mg: 2 mL: 3 mL: 10 mL; and
the first reaction is carried out at 160-170° C. under stirring at 300-500 rpm for 25-40 min; the second reaction is carried out at 50-70° C. under stirring at 300-500 rpm for 70-100 min; and the third reaction is carried out at 290-300° C. under stirring at 300-500 rpm for 60-90 min.
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