1. A kanamycin homogeneous biosensing method based on nanogold aggregation is characterized by comprising the following steps:

(1) pretreatment of DNA strands

3 PV tubes were sampled and numbered #1, #2, #3, respectively, and 80 μ L tris (hydroxy acid) was added to the #1 PV tube at a concentration of 10 mM pH =7.4Methyl) aminomethane buffer solution containing 100 mM NaCl, 40 mM KCl, 10 mM MgCl₂；

Adding 10 mu L kanamycin aptamer solution S1 with the concentration of 10 mu M and 10 mu M Mg with the concentration of 10 mu L into a #1 PV tube²⁺The nucleic acid enzyme chain S2; the base sequence of the kanamycin aptamer S1 is 5'-ACGTAA CAT GGG GGT TGA GGC TAA GCC GAC TAG T-3', and the Mg²⁺The nucleotide sequence of the nucleic acid strand S2 is 5'-ACT AGT CAG CGA TCA CCC ATG TTA CGT AA-3';

adding 10 muL of hairpin probe H1 with the concentration of 40 muM into a #2 PV tube, wherein the base sequence of the hairpin probe H1 is 5' -SH- (CH)₂)₆-TTT TTT TTT TGG GTA GGG TCT TAC GTAT (rA) GGA CTA GTC AGC GAT CGG GAC CCT ACC-3', wherein rA in H1 denotes the adenosine ribonucleic acid at this position, the remainder being deoxyribonucleic acid;

adding 10 muL of hairpin probe H2 with the concentration of 40 muM into a #3 PV tube, wherein the base sequence of the hairpin probe H2 is 5' -GGT AGG GTC CCG CAC CCA TGT TAC GTAT (rA) GGA CTA GTG GTG CGG GTT GGG TTT TTT TTT T-SH- (CH)₂)₆ -3', wherein rA in H2 represents an adenosine ribonucleic acid at that position, the remainder being deoxyribonucleic acids;

the solution in #1 PV tube was heated to 95 deg.C^oC, slowly cooling for 2 h to room temperature after keeping for 5 min to obtain a stable hybrid double-stranded S1/S2 solution; then the solutions in the #2 and #3 PV tubes are heated to 95 DEG^oC, slowly cooling for 2H to room temperature after keeping for 5 min to respectively obtain a stable hairpin stem-loop structure H1 solution and a stable hairpin stem-loop structure H2 solution;

(2) preparation of functionalized gold nanoparticles

Collecting 2 PV tubes numbered #4 and #5, adding 1.0 mL gold nanoparticles with particle size of 13 nm into each PV tube, centrifuging to remove supernatant, dispersing again in 1.0 mL mixed solution containing 10 mM Tris (hydroxymethyl) aminomethane buffer solution with pH =7.4 and 0.01% Tween-20, and adding 0.1M K₂CO₃Adjusting to pH =8 of the solution;

adding into a #4 pipeAdding 10 mu L of the hairpin stem-loop structure H1 solution with the stable concentration of 40 mu M obtained in the step (1), adding 10 mu L of the hairpin stem-loop structure H2 solution with the stable concentration of 40 mu M obtained in the step (1) into #5 PV, slowly stirring and reacting the tubes #4 and #5 at room temperature for 12H, and then dropwise adding NaCl solution with the concentration of 1.0M into the tubes #4 and #5 PV respectively until the NaCl concentration in the PV tubes is 0.1M, wherein the time interval for adding the NaCl solution each time is more than 0.5H; then at 37^oThe vortex reaction is continued for 24H under the C condition to promote the formation of Au NP/H1 and Au NP/H2; finally, the collected Au NP/H1 and Au NP/H2 products were repeatedly washed by centrifugation three times with a tris (hydroxymethyl) aminomethane buffer solution having a concentration of 10 mM pH =7.4 and dispersed in 1 mL of a buffer solution containing 0.5% BSA, 100 mM NaCl, 40 mM KCl and 10 mM MgCl at 10000 rpm for 15 min to discard the supernatant₂10 mM tris (hydroxymethyl) aminomethane buffer pH =7.4, in 4^oC, storing for later use;

(3) homogeneous phase reaction determination of kanamycin content in standard solution

Taking 7 PV tubes, adding 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl into each PV tube₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then 10 muL of 1 muM hybrid double-stranded S1/S2 solution after annealing treatment in the step (1) is added into each PV tube, 50 muL of tris (hydroxymethyl) aminomethane buffer solution with kanamycin concentration gradient of 0, 0.0001 ng/mL, 0.001 ng/mL, 0.01 ng/mL, 0.1 ng/mL, 1 ng/mL and 10 mM pH =7.4 is added into each PV tube, and finally 50 muL of Au NP/H1 and 50 muL of Au NP/H2 are added into each PV tube at 37 muL^oC, after vortex mixing and reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer to establish a quantitative relation between the absorbance and the concentration of kanamycin;

(4) detection of kanamycin content in sample

50 μ L of the treated sample solution was added to 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then adding step (ii)Step (1), annealing the 10 muL of the 1 muM hybrid double-stranded S1/S2 solution, adding 50 muL of Au NP/H1 and 50 muL of Au NP/H2, and performing 37 u L annealing^oAnd C, after vortex mixing and reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer, and calculating the content of kanamycin in the sample solution according to the quantitative relation between the absorbance obtained in the step (2) and the concentration of kanamycin.

2. The use of the nanogold aggregation-based kanamycin homogeneous biosensing method as claimed in claim 1 in the detection of kanamycin content in a sample.

Background

Improper use of antibiotics often leads to the problem of residual contamination of antibiotics and also poses a great threat to social public safety. On the one hand, patients overuse antibiotics as a universal drug, resulting in the residual antibiotics and their metabolites in the body. When the drug accumulated in the body reaches a certain concentration, toxic and side effects such as anaphylaxis, hearing impairment and even antibiotic-resistant bacteria can be generated in patients. On the other hand, the antibiotic has the curative effect of promoting the growth of animals and preventing and controlling diseases in the animal husbandry, so that the demand and the consumption of the antibiotic in the animal husbandry are increased. However, related researches have shown that part of antibiotics and their metabolites remained in the animal body are discharged into the living environment due to low absorption rate of antibiotics by the organism, and then continue to circulate to the whole ecosystem through the food chain. When people use food containing antibiotic residues, the antibiotics gradually gather in the human body, thereby causing great threat to the life health of the people. For example, kanamycin is a kind of aminoglycoside high-efficiency broad-spectrum antibiotic, is mainly used for respiratory tract and urinary tract infection, septicemia, mastitis and the like caused by most gram-negative bacteria and part of drug-resistant staphylococcus aureus, and also has certain effects on chicken chronic respiratory disease, swine enzootic pneumonia, atrophic rhinitis, turtle red neck disease, famous and super-high-quality aquatic product disease and the like. However, the limit of the effective therapeutic amount of kanamycin is relatively close to the limit of toxic amount, and long-term and large-scale use of kanamycin can cause hearing loss, tinnitus, excitation and conduction block at nerve joints, and even can generate serious toxic and side effects such as nephrotoxic reaction, drug allergy and the like and drug resistance. Therefore, many countries including China and regions have strict restriction standards for antibiotic residues such as kanamycin in food and environmental media.

With the development of scientific research, the analysis and detection methods of antibiotics have made great progress. Among the conventional detection methods, there are many methods for quantitatively analyzing the concentration of antibiotic residues in the environment, and among them, separation analysis methods such as high performance liquid chromatography, liquid chromatography-mass spectrometry, etc. are most widely used in this field. However, these methods not only require expensive instruments and higher analysis cost, but also can be generally performed only in a laboratory, and it is difficult to meet the real-time and on-site detection requirements in practical applications. Compared with the prior art, the novel biosensing method developed based on the combination of the high-specificity aptamer recognition effect and various optical and electrochemical signal detection technologies has the advantages of high sensitivity, low sample consumption, low analysis cost, easy integration, miniaturization and intellectualization, and thus has good performance advantages and development prospects. Although many researches have been carried out in the research of various antibiotic photo-and electro-biosensing methods in recent years, most of them are established based on heterogeneous analysis mode, thus inevitably involving complicated operations such as multi-step washing and separation, and affecting the accuracy and repeatability of the method to some extent.

The development of various homogeneous colorimetric biosensing methods based on gold nanoparticle aggregation and color change thereof caused by high-specificity aptamer recognition of a target substance for convenient on-site detection of the target analyte in a complex matrix is receiving wide attention, but how to develop a suitable method to improve the analysis sensitivity of the methods and how to avoid background signal interference caused by complex nucleic acid design and coexistence of the nucleic acid design and various proteinases in homogeneous analysis systems is an important challenge facing the field at present. Therefore, the development of a new antibiotic biosensing method which is simple to operate and has excellent performances such as high sensitivity, good accuracy and low cost has very important significance for realizing the field rapid screening of antibiotic residues in complex media such as food or water.

Disclosure of Invention

The invention aims to solve the problems of complex operation, low analysis efficiency, high analysis cost, poor repeatability and the like of the existing detection methods such as chromatography, heterogeneous biosensing and the like of antibiotics such as kanamycin and the like, but the homogeneous colorimetric biosensing method constructed based on gold nanoparticle aggregation has low sensitivity and generally faces the challenges of complex nucleic acid design and background signal interference caused by coexistence of the gold nanoparticle and various proteinases, provides a simple novel gold nanoparticle aggregation system, and applies the system to the detection of antibiotics such as kanamycin and the like.

In order to realize the purpose, the invention is realized by the following technical scheme:

the invention relates to a kanamycin homogeneous biosensing method based on nanogold aggregation, which comprises the following steps:

(1) pretreatment of DNA strands

Taking 3 PV tubes and numbering #1, #2, #3 respectively, adding 80 μ L tris (hydroxymethyl) aminomethane buffer solution with the concentration of 10 mM and pH =7.4 into the #1 PV tube, wherein the buffer solution contains 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂；

Adding 10 mu L kanamycin aptamer solution S1 with the concentration of 10 mu M and 10 mu M Mg with the concentration of 10 mu L into a #1 PV tube²⁺The nucleic acid enzyme chain S2; the base sequence of the kanamycin aptamer S1 is 5'-ACGTAA CAT GGG GGT TGA GGC TAA GCC GAC TAG T-3', and the Mg²⁺The nucleotide sequence of the nucleic acid strand S2 is 5'-ACT AGT CAG CGA TCA CCC ATG TTA CGT AA-3';

adding 10 muL of hairpin probe H1 with the concentration of 40 muM into a #2 PV tube, wherein the base sequence of the hairpin probe H1 is 5' -SH- (CH)₂)₆-TTT TTT TTT TGG GTA GGG TCT TAC GTAT (rA) GGA CTA GTC AGC GAT CGG GAC CCT ACC-3', wherein rA in H1 denotes the adenosine ribonucleic acid at this position, the remainder being deoxyribonucleic acid;

adding 10 muL of hairpin probe H2 with the concentration of 40 muM into a #3 PV tube, wherein the base sequence of the hairpin probe H2 is 5' -GGT AGG GTC CCG CAC CCA TGT TAC GTAT (rA) GGA CTA GTG GTG CGG GTT GGG TTT TTT TTT T-SH- (CH)₂)₆ -3', wherein rA in H2 represents an adenosine ribonucleic acid at that position, the remainder being deoxyribonucleic acids;

the solution in #1 PV tube was heated to 95 deg.C^oC, slowly cooling for 2 h to room temperature after keeping for 5 min to obtain a stable hybrid double-stranded S1/S2 solution; then the solutions in the #2 and #3 PV tubes are heated to 95 DEG^oC, keeping for 5 min, slowly cooling for 2 h to room temperature to respectively obtain stable hairpin stem-loop structuresH1 solution and hairpin stem-loop structure H2 solution;

(2) preparation of functionalized gold nanoparticles

Collecting 2 PV tubes numbered #4 and #5, adding 1.0 mL gold nanoparticles (Au NPs) with particle diameter of 13 nm into each PV tube, centrifuging to remove supernatant, dispersing again in mixed solution containing 1.0 mL tris (hydroxymethyl) aminomethane buffer solution with concentration of 10 mM pH =7.4 and 0.01% Tween-20, and adding the mixed solution with concentration of 0.1M K₂CO₃Adjusting to pH =8 of the solution;

adding 10 mu L of the hairpin stem-loop structure H1 solution with the concentration of 40 mu M and stable obtained in the step (1) into a #4 tube, adding 10 mu L of the hairpin stem-loop structure H2 solution with the concentration of 40 mu M and stable obtained in the step (1) into a #5 PV, after the #4 tube and the #5 tube are slowly stirred and react for 12 hours at room temperature, dropwise adding NaCl solution with the concentration of 1.0M into the #4 PV tube and the #5 PV tube respectively until the NaCl concentration in the PV tube is 0.1M, wherein the time interval of adding the NaCl solution each time is more than 0.5 hour; then at 37^oThe vortex reaction is continued for 24H under the C condition to promote the formation of Au NP/H1 and Au NP/H2; finally, the collected Au NP/H1 and Au NP/H2 products were repeatedly washed by centrifugation three times with a tris (hydroxymethyl) aminomethane buffer solution having a concentration of 10 mM pH =7.4 and dispersed in 1 mL of a buffer solution containing 0.5% BSA, 100 mM NaCl, 40 mM KCl and 10 mM MgCl at 10000 rpm for 15 min to discard the supernatant₂10 mM tris (hydroxymethyl) aminomethane buffer pH =7.4, in 4^oC, storing for later use;

(3) homogeneous phase reaction determination of kanamycin content in standard solution

Taking 7 PV tubes, adding 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl into each PV tube₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then 10 muL of the 1 muM hybrid double-stranded S1/S2 solution after annealing treatment in the step (1) is added into each PV tube, and 50 muL of a tris (hydroxymethyl) aminomethane buffer solution with a concentration gradient of 0, 0.0001 ng/mL, 0.001 ng/mL, 0.01 ng/mL, 0.1 ng/mL, 1 ng/mL and 10 mM pH =7.4 containing kanamycin is added into each PV tube respectively,finally, 50 muL Au NP/H1 and 50 muL Au NP/H2 are added into each PV tube at 37^oC, after vortex mixing and reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer to establish a quantitative relation between the absorbance and the concentration of kanamycin;

(4) detection of kanamycin content in sample

50 μ L of the treated sample solution was added to 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then, 10 μ L of 1 μ M solution of the hybridized double strand S1/S2 annealed in the step (1) was added thereto, and 50 μ L of Au NP/H1 and 50 μ L of Au NP/H2 were added thereto at 37^oAnd C, after vortex mixing and reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer, and calculating the content of kanamycin in the sample solution according to the quantitative relation between the absorbance obtained in the step (2) and the concentration of kanamycin.

The invention also provides application of the kanamycin homogeneous biosensing method based on nanogold aggregation in detection of kanamycin content in a sample.

The working principle of the invention is as follows: by kanamycin (Kana) aptamer (S1) with Mg²⁺The double-stranded hybridization reaction of the functional nucleic acid structure (S2) of the nuclease can well inhibit the activity of the nuclease, and the Mg which can initiate the Cycle I reaction is released by utilizing the specific binding between the target kanamycin Kana and the aptamer (S1) of the kanamycin Kana²⁺Functional nucleic acid structure of nuclease (S2). Next, hairpin H1 was prepared from Mg by introducing two gold nanoparticles Au NP/H1 and Au NP/H2 modified with hairpins H1 and H2²⁺1/2 cleaved base sequence M1 of nuclease and G-quadruplex 1/2 base sequence modified on Au NP (Au NP/G1), and hairpin H2 is formed by Mg²⁺1/2 cleaved base sequence M2 of nuclease and G-quadruplex 1/2 base sequence modified on Au NP (Au NP/G2), and hairpins H1 and H2 are modified with one Mg in the ring region²⁺Recognition site (rA) for nucleases and methods for recognition of Mg²⁺Substrate sequence for nucleases. When released S2 specifically recognizes hair cut modified on Au NPsSandwiching H1 and H2, Mg²⁺Enzymatic reaction of nuclease will trigger release of G-quadruplex 1/2 base sequence in hairpin H1 and H2, and release of S2 chain to participate in next group reaction to realize circulation signal amplification, since G-quadruplex 1/2 base sequence can be at K⁺The G-quadruplex is formed by self-folding in the presence, so that two kinds of gold nanoparticles (Au NP/G1 and Au NP/G2) marked with the base sequence of the G-quadruplex 1/2 are converted from a dispersed state to an aggregated state, thereby causing the decrease of the absorbance signal of the gold nanoparticles and achieving the decreased S_aThe absorbance response. Further, Mg²⁺Enzymatic reaction of nucleases also initiated Mg in hairpins H1 and H2²⁺1/2 cleaved base sequence (M1, M2) of nuclease is released, and two pieces of 1/2 cleaved base sequences can be subjected to hybridization reaction to form a new composite Mg²⁺Nuclease secondary structure, thereby initiating a Cycle II reaction when Mg is complexed²⁺After nuclease action on hairpins H1 and H2 modified on Au NPs, Mg²⁺Enzymatic reaction of the nuclease will trigger release of the G-quadruplex 1/2 base sequence in hairpins H1 and H2, while complexing Mg²⁺Nuclease secondary structure is released to participate in the next group of reactions to realize cyclic signal amplification, at K⁺In the presence, the G-quadruplex 1/2 base sequence forms G-quadruplex by self folding to initiate gold nanoparticle aggregation, further reduce the absorbance signal of the gold nanoparticles and reach lower S_bThe absorbance response. Based on the Kana high specificity aptamer recognition, and Mg²⁺The quantitative relation between the absorbance signal of the homogeneous detection product and the concentration of the kanamycin analyte can be successfully established by constructing the gold nanoparticle aggregation reaction color development system through the double signal amplification effect caused by the nuclease catalysis shearing effect.

The aptamer adopted by the invention not only has the advantages of better stability, lower cost and the like compared with the traditional antibody, but also can well ensure the excellent selectivity of the method in the analysis of complex matrix by the specific recognition function between the aptamer and kanamycin analyte; mg released by triggering based on simple nucleic acid base design and Kana high-specificity aptamer recognition reaction²⁺Nuclease function in hairpin DNAThe nanogold aggregation reaction caused by the double three-dimensional catalytic shearing action on the surface of the Au NPs is solved, so that the higher analysis sensitivity of the method is effectively ensured, and the influences of complex operation and easy non-specific adsorption signal interference caused by the use of complex nano materials for signal amplification in the traditional method and the background signal interference caused by the coexistence of the complex nucleic acid design and various proteinases are well avoided; in addition, all biological recognition based on base design and nucleic acid and nuclease signal amplification reactions are carried out in one step in homogeneous solution, the operation is very convenient, the automation degree is high, the complicated multi-step operation and higher experimental technical requirements in the traditional heterogeneous analysis method are completely eliminated, the colorimetric signal detection is not only simple and intuitive, does not need expensive signal marks and large instruments, but also has good repeatability, so the method has very outstanding performance advantages compared with the traditional method, and has very good application value in the field and rapid detection fields of kanamycin residues in complex media such as food, water and the like.

The biosensing method constructed by the invention can be conveniently and simply used for high-selectivity detection of kanamycin content, has the excellent performances of high sensitivity, wide linear range, short detection time, low detection cost and the like, can realize quantitative response and accurate determination of kanamycin within the concentration range of 0.1 pg/mL-10 ng/mL, and well overcomes the defects of complex operation, high cost, long time, poor repeatability and the like of the traditional method.

The kanamycin homogeneous-phase biosensing method based on nanogold aggregation can also be used for detecting other antibiotics, and the detection of other antibiotics can be realized only by selecting corresponding aptamer according to the relevant properties of the antibiotics to be detected and designing a base series of corresponding DNA single strands.

Drawings

FIG. 1 is a schematic diagram of the detection principle of the present invention.

Detailed Description

Example 1

The kanamycin homogeneous biosensing method based on nanogold aggregation comprises the following steps:

(1) pretreatment of DNA strands

Taking 3 PV tubes and numbering #1, #2, #3 respectively, adding 80 μ L tris (hydroxymethyl) aminomethane buffer solution with the concentration of 10 mM and pH =7.4 into the #1 PV tube, wherein the buffer solution contains 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂；

Adding 10 mu L kanamycin aptamer solution S1 with the concentration of 10 mu M and 10 mu M Mg with the concentration of 10 mu L into a #1 PV tube²⁺The nucleic acid enzyme chain S2; the base sequence of the kanamycin aptamer S1 is 5'-ACGTAA CAT GGG GGT TGA GGC TAA GCC GAC TAG T-3', and the Mg²⁺The nucleotide sequence of the nucleic acid strand S2 is 5'-ACT AGT CAG CGA TCA CCC ATG TTA CGT AA-3';

adding 10 muL of hairpin probe H1 with the concentration of 40 muM into a #2 PV tube, wherein the base sequence of the hairpin probe H1 is 5' -SH- (CH)₂)₆-TTT TTT TTT TGG GTA GGG TCT TAC GTAT (rA) GGA CTA GTC AGC GAT CGG GAC CCT ACC-3', wherein rA in H1 denotes the adenosine ribonucleic acid at this position, the remainder being deoxyribonucleic acid;

adding 10 muL of hairpin probe H2 with the concentration of 40 muM into a #3 PV tube, wherein the base sequence of the hairpin probe H2 is 5' -GGT AGG GTC CCG CAC CCA TGT TAC GTAT (rA) GGA CTA GTG GTG CGG GTT GGG TTT TTT TTT T-SH- (CH)₂)₆ -3', wherein rA in H2 represents an adenosine ribonucleic acid at that position, the remainder being deoxyribonucleic acids;

the solution in #1 PV tube was heated to 95 deg.C^oC, slowly cooling for 2 h to room temperature after keeping for 5 min to obtain a stable hybrid double-stranded S1/S2 solution; then the solutions in the #2 and #3 PV tubes are heated to 95 DEG^oC, slowly cooling for 2H to room temperature after keeping for 5 min to respectively obtain a stable hairpin stem-loop structure H1 solution and a stable hairpin stem-loop structure H2 solution;

(2) preparation of functionalized gold nanoparticles

2 PV tubes were collected and numbered #4 and #5, respectively, 1.0 mL of gold nanoparticles (Au NPs) having a particle size of 13 nm was added to each PV tube, centrifuged to remove the supernatant, and redispersed in 1.0 mL of tris (hydroxymethyl) aminomethane buffer solution having a concentration of 10 mM pH =7.4Mixing the solution with 0.01% Tween-20, and adding 0.1M K₂CO₃Adjusting to pH =8 of the solution;

adding 10 mu L of the hairpin stem-loop structure H1 solution with the concentration of 40 mu M and stable obtained in the step (1) into a #4 tube, adding 10 mu L of the hairpin stem-loop structure H2 solution with the concentration of 40 mu M and stable obtained in the step (1) into a #5 PV, after the #4 tube and the #5 tube are slowly stirred and react for 12 hours at room temperature, dropwise adding NaCl solution with the concentration of 1.0M into the #4 PV tube and the #5 PV tube respectively until the NaCl concentration in the PV tube is 0.1M, wherein the time interval of adding the NaCl solution each time is more than 0.5 hour; then at 37^oThe vortex reaction is continued for 24H under the C condition to promote the formation of Au NP/H1 and Au NP/H2; finally, the collected Au NP/H1 and Au NP/H2 products were repeatedly washed by centrifugation three times with a tris (hydroxymethyl) aminomethane buffer solution having a concentration of 10 mM pH =7.4 and dispersed in 1 mL of a buffer solution containing 0.5% BSA, 100 mM NaCl, 40 mM KCl and 10 mM MgCl at 10000 rpm for 15 min to discard the supernatant₂10 mM tris (hydroxymethyl) aminomethane buffer pH =7.4, in 4^oC, storing for later use;

(3) homogeneous phase reaction determination of kanamycin content in standard solution

Taking 7 PV tubes, adding 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl into each PV tube₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then 10 muL of 1 muM hybrid double-stranded S1/S2 solution after annealing treatment in the step (1) is added into each PV tube, 50 muL of tris (hydroxymethyl) aminomethane buffer solution with kanamycin concentration gradient of 0, 0.0001 ng/mL, 0.001 ng/mL, 0.01 ng/mL, 0.1 ng/mL, 1 ng/mL and 10 mM pH =7.4 is added into each PV tube, and finally 50 muL of Au NP/H1 and 50 muL of Au NP/H2 are added into each PV tube at 37 muL^oAnd C, after carrying out vortex mixing reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer to establish a quantitative relation between the absorbance and the kanamycin concentration to obtain a working curve of the kanamycin standard solution, which is shown in the following table 1.

TABLE 1 kanamycin Standard solution working curves

Detection object	Linear range (ng/mL)	Coefficient of linear correlation	Detection limit (fg/mL)
				Kanamycin	0.0001~10	0.997	62

EXAMPLE 2 detection of kanamycin content in milk powder samples

Commercially available milk powder 1g was weighed and dissolved in 5 mL of tris (hydroxymethyl) aminomethane buffer solution containing 100 mM NaCl, 40 mM KCl and 10 mM MgCl at a concentration of 10 mM pH =7.4₂Taking 100 muL of the dissolved milk powder solution, adding 20% by mass of acetic acid into the dissolved milk powder solution, adjusting the pH to be =4.6, centrifuging the milk powder solution after 20 min to remove coagulated protein and fat in the sample, filtering the sample solution by using a 0.22 mu m filter membrane, and adjusting the pH of the sample solution to be =7.4 again;

50 μ L of the treated sample solution was added to 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then adding 10 mu L of 1 mu M hybridized double-stranded S1/S2 solution annealed in the step (1); then 50 muL of Au NP/H1 and 50 muL of Au NP/H2 solution were added to the solution at 37 muL^oC, after vortex mixing and reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer according to the factThe working curve obtained in example 1 was used to determine the kanamycin content of milk powder samples.

The detection result shows that no kanamycin residue is detected in the milk powder sample. Kanamycin standard solutions with different concentrations are continuously added into the milk powder samples to carry out a standard adding recovery experiment, and the experimental results are shown in the following table 2.

TABLE 2 addition of recovery test results for milk powder sample solutions

Serial number	Addition amount (ng/mL)	Average recovery (ng/mL)	RSD（%，n=5）	Average recovery (%)
					1	0.1	0.09421	3.6	94.2
2	0.01	0.01025	3.3	102.5
					3	0.001	0.00098	2.9	98.0

As can be seen from Table 2 above, the Relative Standard Deviation (RSD) of the test results of this example 2 is 2.9-3.6%, and the recovery rate of spiking is 94.2-102.5%, which shows that the analysis method of this example has higher accuracy and precision.

Example 3 detection of kanamycin content in Honey samples

Weighing commercially available honey 2 g, dissolving in 4 mL Tris (hydroxymethyl) aminomethane buffer solution with concentration of 10 mM pH =7.4, containing 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂(ii) a Then filtering the sample solution by using a filter membrane of 0.22 mu m; 50 μ L of the filtered sample solution was added to 40 μ L of 100 mM NaCl, 40 mM KCl and 10 mM MgCl₂10 mM tris (hydroxymethyl) aminomethane buffer solution pH = 7.4; then adding 10 mu L of 1 mu M hybridized double-stranded S1/S2 solution annealed in the step (1); then 50 muL of Au NP/H1 and 50 muL of Au NP/H2 solution were added to the solution at 37 muL^oAnd C, after vortex mixing and reaction for 120 min, measuring the absorbance value of the solution by using an ultraviolet-visible spectrophotometer, and detecting the content of kanamycin in the honey sample according to the working curve obtained in the embodiment 1.

The detection result shows that no kanamycin residue is detected in the honey sample. Kanamycin standard solutions with different concentrations are continuously added into the honey samples to carry out a standard adding recovery experiment, and the experiment results are shown in the following table 3.

TABLE 3 test results of spiking recovery of honey sample solutions

Serial number	Addition amount (ng/mL)	Average recovery (ng/mL)	RSD（%，n=5）	Average recovery (%)
					1	0.1	0.09794	3.1	97.9
2	0.01	0.00962	3.6	96.2
					3	0.001	0.001044	4.3	104.4

As can be seen from Table 3 above, the Relative Standard Deviation (RSD) of the test results of this example 3 is 3.1-4.3%, and the recovery rate of spiking is 96.2-104.4%, which shows that the analysis method of this example has higher accuracy and precision.