Disclosure of Invention
The invention aims to provide a preparation method of a DA monoclonal antibody immunoaffinity column, the prepared immunoaffinity column has the characteristics of high performance and strong recognition by screening out an antibody with specificity to DA toxin, can be applied to analysis and determination of DA toxin in different marine organisms, effectively solves the problem of unsatisfactory purification of a sample in pretreatment, reduces sample matrix interference, shortens analysis time, improves method recovery rate, and fills the blank of the immunoaffinity technology in the field of DA toxin detection.
The invention also provides an application of the DA monoclonal antibody immunoaffinity column.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a preparation method of a DA monoclonal antibody immunoaffinity column, which comprises the following steps:
(1) synthetic immunogens
10mg of bovine serum albumin, 2mL of 0.05M sodium acetate buffer solution with pH7.4, 1mg of domoic acid and 60 mu L of formaldehyde solution with the mass concentration of 37% are sequentially added into a small flask, mixed uniformly, stirred at 37 ℃ for 48 hours, dialyzed with 0.1M PBS buffer solution with pH7.3 at 4 ℃ for 3 days, and changed every day for 2 times to obtain immunogen DA-BSA.
(2) Synthetic assay antigen
10mg of chicken egg white albumin, 2mL of 0.05M sodium acetate buffer solution with pH7.4, 1mg of domoic acid and 60 mu L of formaldehyde solution with the mass concentration of 37% are sequentially added into a small flask, mixed uniformly, stirred at 37 ℃ for 48 hours, dialyzed by 0.1M PBS buffer solution with pH7.3 at 4 ℃ for 3 days, and changed every day for 2 times to obtain the original DA-OVA for detection.
(3) Monoclonal antibody preparation and purification
Taking 5 female Balb/c mice with the age of 6-8 weeks, injecting DA-BSA (Dada-bovine serum albumin) 20 mu g/mouse subcutaneously at the back, starting to strengthen the immunity after immunizing for 4 weeks, and strengthening the immunity for 1 time every 2 weeks; in the primary immunization, emulsifying immunogen DA-BSA and an isovolume Freund's complete adjuvant, and emulsifying immunogen DA-BSA and an isovolume Freund's incomplete adjuvant in the boosting immunization, wherein the immunization dose and the immunization mode are unchanged;
after 10 days of 2-time boosting immunization, taking tail venous blood of mice for detection, coating a detection source DA-OVA, detecting the titer of serum by using an indirect competitive ELISA method, selecting a BALB/c mouse with the highest titer for preparing hybridoma, boosting the abdominal cavity of the mouse once 3 days before fusion, taking the spleen cell of the BALB/c mouse with the highest titer to fuse with a myeloma cell Sp2/0, and screening to obtain the hybridoma;
BALB/c mice were intraperitoneally injected with 0.5mL liquid paraffin for sensitization, and 8 days later, mice were intraperitoneally injected with 1X 107And (3) extracting ascites from the abdominal cavity of the mouse by using a syringe after 10 days, extracting the ascites for 1 time every 1 day, centrifuging, collecting supernate, purifying the supernate by adopting a saturated ammonium sulfate method, and further purifying by adopting a protein affinity chromatography to obtain the DA monoclonal antibody.
(4) Affinity column preparation
Weighing 0.5g of CNBr activated sepharose 4B dry powder, swelling the sepharose 4B dry powder by using 100mL of 1M HCl solution, and washing; then washing with 100mL of coupling buffer solution to obtain gel;
taking 1.5mL of the swelled gel, adding 1.5mL of 10mg/mL DA monoclonal antibody, carrying out oscillation coupling reaction at room temperature for 2h, carrying out suction filtration, washing the gel with 30mL of coupling buffer solution, carrying out suction filtration, adding 10mL of blocking buffer solution, carrying out oscillation reaction at room temperature for 2h, carrying out suction filtration, washing the gel with 100mL of 0.01M PBS buffer solution with pH7.3, transferring the gel into a 5mL column tube, adding 0.01M PBS solution with the mass concentration of 0.05% of thimerosal and 0.05% of bovine serum albumin respectively and storing the gel at 2-8 ℃.
Preferably, in step (4), the formulation of the coupling buffer is: 0.1 mol. L-1 NaHCO3,0.5 mol·L-1 NaCl,pH8.3。
Preferably, in step (4), the formulation of the blocking buffer is: 0.1 mol. L-1 Tris-HCl,pH 8.0。
An application of DA monoclonal antibody immunoaffinity column in determination of chondroacronic acid toxin is disclosed.
Therefore, the invention has the following beneficial effects: the DA toxin immunoaffinity column with high performance and strong recognition is prepared by screening out the antibody with specificity to the DA toxin, and the obtained DA toxin immunoaffinity column can be applied to analysis and determination of the DA toxin in different marine organisms, so that the problem of unsatisfactory sample purification in pretreatment is effectively solved, the interference of a sample matrix is reduced, the analysis time is shortened, the recovery rate of the method is improved, and the blank of the immunoaffinity technology in the field of DA toxin detection is filled.
Detailed Description
The invention is further described below by means of specific embodiments.
In the present invention, all percentages are by weight unless otherwise specified, all equipment and materials are commercially available or commonly used in the industry, and the methods in the following examples are conventional in the art unless otherwise specified.
Instrument and reagent
ACQUITY ultra high performance liquid chromatography-tandem Mass spectrometer Xevo TQ-S (Waters, USA); MS2 vortex mixer (IKA, germany); nitrogen blow dryer (organo matio corporation, usa); centrifuge5810 high speed Centrifuge (Eppendorf, germany); 12 channel solid phase extraction device (supelco, usa).
Domoic Acid (DA) standard (purity ≥ 98.0%, canadian national research council); acetonitrile, methanol (chromatographically pure, Merck, germany); ammonium acetate, formic acid (Sigma, usa); disodium hydrogen phosphate dodecahydrate, sodium dihydrogen phosphate dihydrate, sodium chloride, and ammonia water (Shanghai national drug group); the experimental water is ultrapure water.
(II) preparation of PBS buffer solution
2.18g of sodium dihydrogen phosphate dihydrate, 12.90g of disodium hydrogen phosphate dodecahydrate and 8.50g of sodium chloride are weighed respectively, dissolved by water and fixed to 1000 mL.
(III) 25. mu.g/mL Domoic Acid (DA) standard solution
Accurately transferring a proper amount of domoic acid standard solution, diluting with methanol to a constant volume of 50mL, and storing at-20 ℃ in the dark for 3 months.
Examples
(a) Synthetic immunogens
Adding 10mg of bovine serum albumin, 2mL of 0.05M sodium acetate buffer solution with pH of 7.4, 1mg of domoic acid and 60 mu L of formaldehyde solution with the mass concentration of 37% into a small flask in sequence, mixing uniformly, stirring at 37 ℃ for 48h, dialyzing with 0.1M PBS buffer solution with pH of 7.3 at 4 ℃ for 3 days, and changing the solution 2 times every day to obtain immunogen DA-BSA;
(b) synthetic assay antigen
Sequentially adding 10mg of chicken egg white albumin, 2mL of 0.05M sodium acetate buffer solution with pH7.4, 1mg of domoic acid and 60 mu L of formaldehyde solution with the mass concentration of 37 percent into a small flask, uniformly mixing, stirring at 37 ℃ for 48h, dialyzing by using 0.1M PBS buffer solution with pH7.3 at 4 ℃ for 3 days, and changing the solution 2 times every day to obtain the original DA-OVA for detection;
(c) monoclonal antibody preparation and purification
Taking 5 female Balb/c mice with the age of 6-8 weeks, injecting DA-BSA (Dada-bovine serum albumin) 20 mu g/mouse subcutaneously at the back, starting to strengthen the immunity after immunizing for 4 weeks, and strengthening the immunity for 1 time every 2 weeks; in the primary immunization, emulsifying immunogen DA-BSA and an isovolume Freund's complete adjuvant, and emulsifying immunogen DA-BSA and an isovolume Freund's incomplete adjuvant in the boosting immunization, wherein the immunization dose and the immunization mode are unchanged;
after 10 days of 2-time boosting immunization, taking tail venous blood of mice for detection, coating a detection source DA-OVA, detecting the titer of serum by using an indirect competitive ELISA method, selecting a BALB/c mouse with the highest titer for preparing hybridoma, boosting the abdominal cavity of the mouse once 3 days before fusion, taking the spleen cell of the BALB/c mouse with the highest titer to fuse with a myeloma cell Sp2/0, and screening to obtain the hybridoma;
BALB/c mice were intraperitoneally injected with 0.5mL liquid paraffin for sensitization, and 8 days later, mice were intraperitoneally injected with 1X 107Extracting ascites from the abdominal cavity of the mouse by using an injector after 10 days, then extracting the ascites for 1 time every 1 day, centrifuging, collecting supernate, purifying the supernate by adopting a saturated ammonium sulfate method, and further purifying by using a protein affinity chromatography to obtain a DA monoclonal antibody;
(d) affinity column preparation
Weighing 0.5g of CNBr activated sepharose 4B dry powder, swelling the sepharose 4B dry powder by using 100mL of 1M HCl solution, and washing; then washing with 100mL of coupling buffer solution to obtain gel, wherein the formula of the coupling buffer solution is as follows: 0.1 mol. L-1 NaHCO3,0.5 mol·L-1NaCl,pH8.3;
Taking 1.5mL of the swelled gel, adding 1.5mL of 10mg/mL DA monoclonal antibody, oscillating at room temperature for coupling reaction for 2h, filtering, and washing the gel with 30mL of coupling buffer solution, wherein the formula of the coupling buffer solution is as follows: 0.1 mol. L-1 NaHCO3,0.5 mol·L-1NaCl, pH8.3, suction filtration, and the addition of 10mL of blocking buffer, the formulation of the blocking buffer is: 0.1 mol. L-1Tris-HCl, pH8.0, room temperature oscillation reaction for 2h, suction filtration, then 100mL PBS buffer solution of 0.01M, pH7.3 to wash the gel, and transfer to 5mL column tube, add PBS solution of 0.01M, pH7.3 containing the mass concentration of 0.05% thimerosal, 0.05% bovine serum albumin, respectively, store at 2-8 ℃.
The application method of the DA monoclonal antibody immunoaffinity column obtained by the invention in determination of chondroacronic acid toxins comprises the following steps:
(1) sample pretreatment: accurately weighing 2.00g of a fully homogenized sample into a 50mL centrifuge tube with a plug, adding 8mL of 75% methanol aqueous solution in volume concentration, carrying out vortex oscillation for 2min, carrying out ultrasonic extraction for 10min, centrifuging at 7000r/min for 5min, and transferring the supernatant into another 50mL centrifuge tube to obtain a primary extract; adding 8mL of 75% methanol aqueous solution into the residual residue, and repeatedly extracting once to obtain a secondary extracting solution; mixing the primary extract and the secondary extract, and diluting to a constant volume of 20mL to obtain an extract; transferring 1mL of the extracting solution into another 50mL of centrifugal tube, and adding 5mL of PBS buffer solution for dilution to obtain a sample solution to be purified;
(2) purifying the immunoaffinity column: taking a DA monoclonal antibody immunoaffinity column, removing an affinity column plug after the DA monoclonal antibody immunoaffinity column is recovered to room temperature, discharging a preservation solution in the column, and then loading a sample solution; after the sample loading is finished, eluting the affinity column by using 6mL of methanol water solution with volume concentration of 50%, squeezing out residual liquid in the column, discarding all effluent liquid, eluting by using 3mL of methanol solution containing ammonia water with mass concentration of 2%, drying the collected eluent by using nitrogen at 50 ℃, dissolving by using 1mL of initial mobile phase with constant volume, filtering by using a 0.22 mu m filter membrane, and then supplying liquid chromatography-mass spectrometry for analysis;
the liquid chromatography conditions were: a chromatographic column: ACQUITY UPLC BEH C18A column (2.1 mm x 50 mm, 1.7 μm); the sample injection volume is 2 mu L; the temperature of the sample chamber is 10 ℃; the column temperature is 40 ℃; the flow rate is 0.2 mL/min; mobile phase a was acetonitrile and B was a 2mmol/L ammonium acetate solution containing 0.1% formic acid, gradient elution: 0-1.0 min, 90% A; 1.0-3.0 min, 90-10% A; 3.0-4.0 min, 10% A; 4.0-4.1 min, 10% -90% A; 4.1-5.5 min, 90% A;
the mass spectrum conditions are as follows: electrospray ion source, positive ion scanning (ESI-); the detection mode is as follows: multiple Reaction monitoring mode (MRM); capillary voltage: 3.0 kV; ion source temperature: 150 ℃; desolventizing gas temperature: 600 ℃; taper hole gas flow: 150L/h; desolventizing agent gas flow: 1000L/h; taper hole voltage: 12V; collision energy: 16 eV; analyte qualitative ion pair:m/z 312.2 >248.2; analyte quantification ion pair:m/z 312.2 > 266.2。
59 parts of 5 varieties of coastal cities, namely mussels, ark shells, scallops and oysters are analyzed and detected by the method, and the obtained detection results are shown in table 1. The DA detection rate is 10%, the detection rate comprises 5 batches of scallops and 1 batch of oysters, the scallop detection rate is highest, and the DA pollution level is different from 0.9 to 11.8 mug/g; the oyster detection rate is 7%, and the DA content is 0.07 mug/g.
TABLE 1 contamination level of DA in Positive samples
Variety of (IV) C
| DA concentration (μ g/g)
|
Scallop
| 11.8
|
Scallop
| 14.9
|
Scallop
| 0.7
|
Scallop
| 9.3
|
Scallop
| 0.9
|
Oyster shell
| 0.07 |
Therefore, the DA monoclonal antibody immunoaffinity column obtained by the invention has the characteristics of high performance and strong identification, and can completely meet the analysis and determination requirements of DA toxin in marine organisms.
The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.