阅读说明：本技术 一种副溶血性弧菌检测方法 (Vibrio parahaemolyticus detection method ) 是由 蒋晨豪 李昱权 孙雨玘 叶海芬 陈佳琪 宁景苑 张建锋 易晓梅 惠国华 于 2020-12-23 设计创作，主要内容包括：本发明公开了一种副溶血性弧菌检测方法。它包括以下步骤：S1：配置不同浓度的副溶血性弧菌悬浮液,检测每个浓度的副溶血性弧菌悬浮液对应的特征值Y,将这些值进行拟合得到浓度计算公式：Y＝0.2+0.1×LgX,X为副溶血性弧菌的浓度；S2：取待测副溶血性弧菌悬浮液,检测其对应的特征值Y,根据浓度计算公式：Y＝0.2+0.1×LgX,计算出待测副溶血性弧菌悬浮液的浓度。本发明能够准确检测出副溶血性弧菌浓度,操作简单。(The invention discloses a vibrio parahemolyticus detection method. It comprises the following steps: s1: preparing vibrio parahaemolyticus suspension liquid with different concentrations, detecting characteristic values Y corresponding to the vibrio parahaemolyticus suspension liquid with each concentration, and fitting the values to obtain a concentration calculation formula: y is 0.2+0.1 × LgX, and X is the concentration of vibrio parahaemolyticus; s2: taking the vibrio parahaemolyticus suspension to be detected, detecting the corresponding characteristic value Y, and calculating according to a concentration calculation formula: and Y is 0.2+0.1 multiplied by LgX, and the concentration of the vibrio parahaemolyticus suspension to be detected is calculated. The invention can accurately detect the concentration of the vibrio parahemolyticus and has simple operation.)

1. A vibrio parahemolyticus detection method is characterized by comprising the following steps:

s1: preparing vibrio parahaemolyticus suspension liquid with different concentrations, detecting characteristic values Y corresponding to the vibrio parahaemolyticus suspension liquid with each concentration, and fitting the values to obtain a concentration calculation formula: y is 0.2+0.1 × LgX, and X is the concentration of vibrio parahaemolyticus;

s2: taking the vibrio parahaemolyticus suspension to be detected, detecting the corresponding characteristic value Y, and calculating according to a concentration calculation formula: and Y is 0.2+0.1 multiplied by LgX, and the concentration of the vibrio parahaemolyticus suspension to be detected is calculated.

2. The method for detecting Vibrio parahaemolyticus according to claim 1, wherein the method for detecting the characteristic value Y corresponding to a concentration of Vibrio parahaemolyticus suspension comprises the steps of:

m1: forming a first electrochemical sensor array by using a first working electrode, a first counter electrode and a first reference electrode, forming a second electrochemical sensor array by using a second working electrode, a second counter electrode and a second reference electrode, wherein the vibrio parahaemolyticus antigen is not cultured on the first working electrode, and the vibrio parahaemolyticus antigen is cultured on the second working electrode;

m2: the vibrio parahaemolyticus suspension with the concentration is detected for m times by the same method, and the detection steps of each detection are as follows:

dripping 2.5 μ l of Vibrio parahaemolyticus suspension with the concentration on the unused first working electrode and the unused second working electrode, standing for 30 minutes, respectively inserting the first electrochemical sensor array and the second electrochemical sensor array into two same buffer solutions, and sequentially switching n different scanning rates from small to large by adopting a cyclic voltammetry method for detection to obtain n reduction peak current differences delta Ip_i1、ΔIp_i2…ΔIp_in，ΔIp_in＝Ip1_in-Ip2_in，ΔIp_inFor the reduction peak current difference at the nth scan rate in the ith test, Ip1_inThe reduction peak current value corresponding to the first electrochemical sensor array at the nth scanning rate in the ith detection is Ip2_inThe reduction peak current value corresponding to the second electrochemical sensor array at the nth scanning speed in the ith detection is more than or equal to 1 and less than or equal to m;

m3: constructing a feature matrix D according to the detection data of m times of detection,

m4: performing secondary spline interpolation on each row of data of the feature matrix D to obtain m curves x (t) corresponding to each row of data, performing the same data processing on the m curves x (t) to obtain m feature values F, wherein the data processing on each curve x (t) comprises the following steps:

bringing x (t) into a nonlinear oriented saturated resonance modelIn, the flat feedback cascade steady state potential function:

the detection signal loading component of (t) cos (kt + η) + x (t),

wherein t is an interpolation variable, k is a real parameter, η is a real parameter, nois (t) is colored noise with uneven power spectral density function, P is a real parameter, Q is a real parameter, a, b, c are real numbers, delta is a flat delay parameter,

adjusting the value of t, and enabling the nonlinear directional saturated resonance model to be t-t_rAnd (3) when the point position reaches resonance, calculating a characteristic value F of a resonance state:

m5: and averaging the m characteristic values F to obtain an average value which is the value of the characteristic value Y.

3. The method of claim 2, wherein the n different scanning rates comprise 50mV/s, 100mV/s, 200mV/s, 300mV/s, 400mV/s, and 500 mV/s.

4. The method for detecting Vibrio parahaemolyticus according to claim 2, wherein the buffer solution is prepared by the following method: 0.5mmol/l of H₂O₂The solution is mixed evenly with 1.0mol/l Thi/HaC-NaAc solution according to the volume ratio of 1: 2.

5. The method for detecting Vibrio parahaemolyticus of claim 2, wherein the first working electrode and the second working electrode are both copper film electrodes, the first counter electrode and the second counter electrode are both Pt electrodes, and the first reference electrode and the second reference electrode are both Ag/AgCl electrodes.

6. The method for detecting Vibrio parahaemolyticus according to claim 2, wherein the Vibrio parahaemolyticus antigen is incubated on the second working electrode by:

n1: mixing silver paste SL and sodium alginate SA according to the mass ratio of 1: 3 to prepare 10ml of sol water solution, then carrying out ultrasonic dispersion for 15min, and weighing 5mg of graphene oxide GO and 1mg of amino-functionalized organic metal framework material NH₂dissolving-CuBTC in the sol water solution, and performing ultrasonic oscillation for 25min to obtain GO/NH₂The mixture of-CuBTC/SL/SA was taken at 1.5. mu.L of GO/NH₂Dropping the mixed solution of-CuBTC/SL/SA on the surface of the second working electrode, drying for 5h at room temperature, and forming a layer of GO/NH on the second working electrode₂-a film of CuBTC/SL/SA;

n2: diluting the vibrio parahaemolyticus polyclonal antibody solution by 300 times by using PBS buffer solution, then modifying 4 mu l of the diluted vibrio parahaemolyticus polyclonal antibody solution on the dried second working electrode, and standing and drying the modified vibrio parahaemolyticus polyclonal antibody solution in a drying dish;

n3: dripping 3.5 μ l of vibrio parahaemolyticus antigen solution on the second working electrode, culturing at 30 deg.C for 25min, washing off uncombined vibrio parahaemolyticus antigen on the second working electrode with distilled water, and air drying.

7. The method for detecting Vibrio parahaemolyticus according to claim 6, wherein the Vibrio parahaemolyticus antigen solution is prepared by the following method: the concentration is 2 x 10⁸cfu/ml～2×10⁹Inactivating cfu/ml vibrio parahaemolyticus with 8% -12% formalin at 25-39 deg.C, centrifuging to remove formalin after inactivation, coating flat plate for aseptic test, precipitating with equal volume of aseptic normal saline after determining sterilityAnd re-suspending to obtain the vibrio parahaemolyticus antigen solution.

8. The method for detecting Vibrio parahaemolyticus according to claim 6, wherein the Vibrio parahaemolyticus polyclonal antibody solution is prepared by the following method:

after the rabbits are raised for 2 weeks, 15ml of blood is collected from the ear veins, and serum is taken out to be used as a negative serum sample; immunizing rabbit with vibrio parahaemolyticus antigen, performing second immunization at intervals of 3 days, performing booster immunization at intervals of 6 days, performing carotid artery one-time blood sampling at 4 days after booster immunization, standing at room temperature for 45min, transferring to 4 deg.C overnight, and centrifuging at 4 deg.C and 5000rpm for 45min the next day to obtain antiserum for storage;

fixing 1.5ml affinity chromatographic column on a protein purifier, washing out protective agent solution by deionized water, balancing the column by PBS buffer solution, loading 1.5ml antiserum sample on the column, eluting impurities by PBS buffer solution, and finally eluting vibrio parahaemolyticus polyclonal antibody by citric acid buffer solution to obtain vibrio parahaemolyticus polyclonal antibody solution.

Technical Field

The invention relates to the technical field of bacteria detection, in particular to a vibrio parahemolyticus detection method.

Background

Food-borne diseases refer to a general term for diseases which are caused by food contaminated by pathogenic bacteria entering human bodies by means of ingestion and causing human body infection or poisoning, and threaten human health and life safety. Although the development of modern science and technology reaches a certain level, food-borne diseases still seriously harm the health of people no matter in developed or developing countries, and the frequent food safety events in recent years also indicate that the food-borne diseases are not effectively controlled, so that the development of a novel detection technology for accurately detecting the food-borne pathogenic bacteria is very important, and the detection technology has important significance for preventing and controlling the food-borne diseases and guaranteeing the health of people.

Vibrio parahaemolyticus can cause diseases such as neonatal meningitis, septicemia, necrotizing enteroconjunctivitis and the like, and poses serious threats to human health and life safety, so that the research on the method for accurately detecting the Vibrio parahaemolyticus is of great significance. The existing vibrio parahaemolyticus detection method generally adopts a chemical detection method, and has the defects of complex operation and poor repeatability.

Disclosure of Invention

In order to solve the technical problems, the invention provides a vibrio parahemolyticus detection method which can accurately detect the concentration of vibrio parahemolyticus and is simple to operate.

In order to solve the problems, the invention adopts the following technical scheme:

the invention relates to a vibrio parahemolyticus detection method, which comprises the following steps:

s1: preparing vibrio parahaemolyticus suspension liquid with different concentrations, detecting characteristic values Y corresponding to the vibrio parahaemolyticus suspension liquid with each concentration, and fitting the values to obtain a concentration calculation formula: y is 0.2+0.1 × LgX, and X is the concentration of vibrio parahaemolyticus;

s2: taking the vibrio parahaemolyticus suspension to be detected, detecting the corresponding characteristic value Y, and calculating according to a concentration calculation formula: and Y is 0.2+0.1 multiplied by LgX, and the concentration of the vibrio parahaemolyticus suspension to be detected is calculated.

Preferably, the method for detecting the characteristic value Y corresponding to the vibrio parahaemolyticus suspension at a certain concentration comprises the following steps:

m1: forming a first electrochemical sensor array by using a first working electrode, a first counter electrode and a first reference electrode, forming a second electrochemical sensor array by using a second working electrode, a second counter electrode and a second reference electrode, wherein the vibrio parahaemolyticus antigen is not cultured on the first working electrode, and the vibrio parahaemolyticus antigen is cultured on the second working electrode;

m2: the vibrio parahaemolyticus suspension with the concentration is detected for m times by the same method, and the detection steps of each detection are as follows:

dripping 2.5 μ l of Vibrio parahaemolyticus suspension with the concentration on the unused first working electrode and the unused second working electrode, standing for 30 minutes, respectively inserting the first electrochemical sensor array and the second electrochemical sensor array into two same buffer solutions, and sequentially switching n different scanning rates from small to large by adopting a cyclic voltammetry method for detection to obtain n reduction peak current differences delta Ip_i1、ΔIp_i2…ΔIp_in，ΔIp_in＝Ip1_in-Ip2_in，ΔIp_inFor the reduction peak current difference at the nth scan rate in the ith test, Ip1_inThe reduction peak current value corresponding to the first electrochemical sensor array at the nth scanning rate in the ith detection is Ip2_inThe reduction peak current value corresponding to the second electrochemical sensor array at the nth scanning speed in the ith detection is more than or equal to 1 and less than or equal to m;

m3: constructing a feature matrix D according to the detection data of m times of detection,

m4: performing secondary spline interpolation on each row of data of the feature matrix D to obtain m curves x (t) corresponding to each row of data, performing the same data processing on the m curves x (t) to obtain m feature values F, wherein the data processing on each curve x (t) comprises the following steps:

bringing x (t) into a nonlinear oriented saturated resonance modelIn (1),

flat feedback cascade steady state potential function:

the detection signal loading component of (t) cos (kt + η) + x (t),

wherein t is an interpolation variable, x (t) is a curve obtained by performing quadratic spline interpolation on a reduction peak current difference value obtained at a specific scanning speed, k is a real parameter, eta is a real parameter, nois (t) is colored noise with uneven power spectral density function, P is a real parameter, Q is a real parameter, a, b and c are real numbers, and delta is a flat delay parameter,

adjusting the value of t, and enabling the nonlinear directional saturated resonance model to be t-t_rAnd (3) when the point position reaches resonance, calculating a characteristic value F of a resonance state:

m5: and averaging the m characteristic values F to obtain an average value which is the value of the characteristic value Y.

In the process of detecting the vibrio parahaemolyticus suspension for m times, a first working electrode and a second working electrode which are not used are adopted for each detection.

Preferably, the n different scan rates comprise 50mV/s, 100mV/s, 200mV/s, 300mV/s, 400mV/s, 500 mV/s.

Preferably, the buffer solution is prepared by the following method: 0.5mmol/l of H₂O₂The solution is mixed evenly with 1.0mol/l Thi/HaC-NaAc solution according to the volume ratio of 1: 2.

Preferably, the first working electrode and the second working electrode are both copper film electrodes, the first counter electrode and the second counter electrode are both Pt electrodes, and the first reference electrode and the second reference electrode are both Ag/AgC1 electrodes.

Preferably, the method for culturing the vibrio parahaemolyticus antigen on the second working electrode is as follows:

n1: mixing silver paste SL and sodium alginate SA according to the mass ratio of 1: 3 to prepare 10ml of sol water solution, then carrying out ultrasonic dispersion for 15min, and weighing 5mg of graphene oxide GO and 1mg of amino-functionalized organic metal framework material NH₂dissolving-CuBTC in the sol water solution, and performing ultrasonic oscillation for 25min to obtain GO/NH₂The mixture of-CuBTC/SL/SA was taken at 1.5. mu.L of GO/NH₂Dropping the mixed solution of-CuBTC/SL/SA on the surface of the second working electrode, drying for 5h at room temperature, and forming a layer of GO/NH on the second working electrode₂-a film of CuBTC/SL/SA;

n2: diluting the vibrio parahaemolyticus polyclonal antibody solution by 300 times by using PBS buffer solution, then modifying 4 mu l of the diluted vibrio parahaemolyticus polyclonal antibody solution on the dried second working electrode, and standing and drying the modified vibrio parahaemolyticus polyclonal antibody solution in a drying dish;

n3: dripping 3.5 μ l of vibrio parahaemolyticus antigen solution on the second working electrode, culturing at 30 deg.C for 25min, washing off uncombined vibrio parahaemolyticus antigen on the second working electrode with distilled water, and air drying.

Selecting graphene oxide GO and amino functionalized organic metal framework material NH₂-CuBTC is used as a second working electrode modification material, sodium alginate SA and silver paste SL are used as dispersing agents to enable graphene oxide GO and amino functionalized organic metal framework material NH₂-CuBTC is dispersed to be stably fixed on the surface of the second working electrode, and NH is utilized₂Enriching the concentration of the analyte with CuBTC, then fixing the vibrio parahaemolyticus antibody on the modified second working electrode, incubating the vibrio parahaemolyticus antigen on the prepared second working electrode, and using the circulating membraneThe reduction peak current value is detected by ring voltammetry (CV).

Preferably, the preparation method of the vibrio parahaemolyticus antigen solution is as follows: the concentration is 2 x 10⁸cfu/ml～2×10⁹Inactivating cfu/ml vibrio parahaemolyticus with 8% -12% formalin at 25-39 ℃, centrifuging to remove the formalin after inactivation, coating a flat plate for aseptic inspection, and resuspending a precipitate with equal volume of sterile physiological saline after determining the sterility, thereby obtaining the vibrio parahaemolyticus antigen solution.

Preferably, the preparation method of the vibrio parahaemolyticus polyclonal antibody solution is as follows:

after the rabbits are raised for 2 weeks, 15ml of blood is collected from the ear veins, and serum is taken out to be used as a negative serum sample; immunizing rabbit with vibrio parahaemolyticus antigen, performing second immunization at intervals of 3 days, performing booster immunization at intervals of 6 days, performing carotid artery one-time blood sampling at 4 days after booster immunization, standing at room temperature for 45min, transferring to 4 deg.C overnight, and centrifuging at 4 deg.C and 5000rpm for 45min the next day to obtain antiserum for storage;

fixing 1.5ml affinity chromatographic column on a protein purifier, washing out protective agent solution by deionized water, balancing the column by PBS buffer solution, loading 1.5ml antiserum sample on the column, eluting impurities by PBS buffer solution, and finally eluting vibrio parahaemolyticus polyclonal antibody by citric acid buffer solution to obtain vibrio parahaemolyticus polyclonal antibody solution.

The invention has the beneficial effects that: can accurately detect the concentration of the vibrio parahaemolyticus, and is simple to operate.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

Example (b): the method for detecting vibrio parahemolyticus of the present embodiment, as shown in fig. 1, includes the following steps:

s1: preparing vibrio parahaemolyticus suspension liquid with different concentrations, detecting characteristic values Y corresponding to the vibrio parahaemolyticus suspension liquid with each concentration, and fitting the values to obtain a concentration calculation formula: y is 0.2+0.1 × LgX, and X is the concentration of vibrio parahaemolyticus;

s2: taking the vibrio parahaemolyticus suspension to be detected, detecting the corresponding characteristic value Y, and calculating according to a concentration calculation formula: and Y is 0.2+0.1 multiplied by LgX, and the concentration of the vibrio parahaemolyticus suspension to be detected is calculated.

In the scheme, a rectangular coordinate system is established by taking the concentration of the vibrio parahemolyticus suspension as an x axis and the characteristic value Y as a Y axis, corresponding points are marked in the rectangular coordinate system by the concentration of each vibrio parahemolyticus suspension and the corresponding characteristic value Y, and the points are fitted to obtain a concentration calculation formula: y is 0.2+0.1 × LgX.

The method for detecting the characteristic value Y corresponding to the vibrio parahaemolyticus suspension with a certain concentration comprises the following steps of:

m1: forming a first electrochemical sensor array by using a first working electrode, a first counter electrode and a first reference electrode, forming a second electrochemical sensor array by using a second working electrode, a second counter electrode and a second reference electrode, wherein the vibrio parahaemolyticus antigen is not cultured on the first working electrode, and the vibrio parahaemolyticus antigen is cultured on the second working electrode;

m2: the vibrio parahaemolyticus suspension with the concentration is detected for m times by the same method, and the detection steps of each detection are as follows:

dripping 2.5 μ l of Vibrio parahaemolyticus suspension with the concentration on the unused first working electrode and the unused second working electrode, standing for 30 minutes, respectively inserting the first electrochemical sensor array and the second electrochemical sensor array into two same buffer solutions, and sequentially switching n different scanning rates from small to large by adopting a cyclic voltammetry method for detection to obtain n reduction peak current differences delta Ip_i1、ΔIp_i2…ΔIp_in，ΔIp_in＝Ip1_in-Ip2_in，ΔIp_inFor the reduction peak current difference at the nth scan rate in the ith test, Ip1_inThe reduction peak current value corresponding to the first electrochemical sensor array at the nth scanning rate in the ith detection is Ip2_inFor the second electrochemistry at the nth scan rate in the ith detectionI is more than or equal to 1 and less than or equal to m corresponding to the reduction peak current value of the sensor array;

m3: constructing a feature matrix D according to the detection data of m times of detection,

m4: performing secondary spline interpolation on each row of data of the feature matrix D to obtain m curves x (t) corresponding to each row of data, performing the same data processing on the m curves x (t) to obtain m feature values F, wherein the data processing on each curve x (t) comprises the following steps:

bringing x (t) into a nonlinear oriented saturated resonance modelIn (1),

flat feedback cascade steady state potential function:

the detection signal loading component of (t) cos (kt + η) + x (t),

wherein t is an interpolation variable, x (t) is a curve obtained by performing quadratic spline interpolation on a reduction peak current difference value obtained at a specific scanning speed, k is a real parameter, eta is a real parameter, nois (t) is colored noise with uneven power spectral density function, P is a real parameter, Q is a real parameter, a, b and c are real numbers, and delta is a flat delay parameter,

adjusting the value of t, and enabling the nonlinear directional saturated resonance model to be t-t_rAnd (3) when the point position reaches resonance, calculating a characteristic value F of a resonance state:

m5: and averaging the m characteristic values F to obtain an average value which is the value of the characteristic value Y.

In the process of detecting the vibrio parahaemolyticus suspension for m times, a first working electrode and a second working electrode which are not used are adopted for each detection.

The n different scan rates include 50mV/s, 100mV/s, 200mV/s, 300mV/s, 400mV/s, and 500 mV/s.

The preparation method of the buffer solution comprises the following steps: 0.5mmol/l of H₂O₂The solution is mixed evenly with 1.0mol/l Thi/HaC-NaAc solution according to the volume ratio of 1: 2.

The first working electrode and the second working electrode are both copper film electrodes, the first counter electrode and the second counter electrode are both Pt electrodes, and the first reference electrode and the second reference electrode are both Ag/AgC1 electrodes.

The method for culturing the vibrio parahaemolyticus antigen on the second working electrode comprises the following steps:

n1: mixing silver paste SL and sodium alginate SA according to the mass ratio of 1: 3 to prepare 10ml of sol water solution, then carrying out ultrasonic dispersion for 15min, and weighing 5mg of graphene oxide GO and 1mg of amino-functionalized organic metal framework material NH₂dissolving-CuBTC in the sol water solution, and performing ultrasonic oscillation for 25min to obtain GO/NH₂The mixture of-CuBTC/SL/SA was taken at 1.5. mu.L of GO/NH₂Dropping the mixed solution of-CuBTC/SL/SA on the surface of the second working electrode, drying for 5h at room temperature, and forming a layer of GO/NH on the second working electrode₂-a film of CuBTC/SL/SA;

n2: diluting the vibrio parahaemolyticus polyclonal antibody solution by 300 times by using PBS buffer solution, then modifying 4 mu l of the diluted vibrio parahaemolyticus polyclonal antibody solution on the dried second working electrode, and standing and drying the modified vibrio parahaemolyticus polyclonal antibody solution in a drying dish;

n3: dripping 3.5 μ l of vibrio parahaemolyticus antigen solution on the second working electrode, culturing at 30 deg.C for 25min, washing off uncombined vibrio parahaemolyticus antigen on the second working electrode with distilled water, and air drying.

Selecting graphene oxide GO and amino functionalized organic metal framework material NH₂-CuBTC is used as a second working electrode modification material, sodium alginate SA and silver paste SL are used as dispersing agents to enable graphene oxide GO and amino functionalized organic metal framework material NH₂-CuBTC is dispersed to be stably fixed on the surface of the second working electrode, and NH is utilized₂Concentration of-CuBTC-enriched analyteThen fixing the vibrio parahaemolyticus antibody on the modified second working electrode, incubating vibrio parahaemolyticus antigen on the prepared second working electrode, and detecting the reduction peak current value by using Cyclic Voltammetry (CV).

The preparation method of the vibrio parahaemolyticus antigen solution comprises the following steps: the concentration is 2 x 10⁸cfu/ml～2×10⁹Inactivating cfu/ml vibrio parahaemolyticus with 8% -12% formalin at 25-39 ℃, centrifuging to remove the formalin after inactivation, coating a flat plate for aseptic inspection, and resuspending a precipitate with equal volume of sterile physiological saline after determining the sterility, thereby obtaining the vibrio parahaemolyticus antigen solution.

The preparation method of the vibrio parahaemolyticus polyclonal antibody solution comprises the following steps:

after the rabbits are raised for 2 weeks, 15ml of blood is collected from the ear veins, and serum is taken out to be used as a negative serum sample; immunizing rabbit with vibrio parahaemolyticus antigen, performing second immunization at intervals of 3 days, performing booster immunization at intervals of 6 days, performing carotid artery one-time blood sampling at 4 days after booster immunization, standing at room temperature for 45min, transferring to 4 deg.C overnight, and centrifuging at 4 deg.C and 5000rpm for 45min the next day to obtain antiserum for storage;

fixing 1.5ml affinity chromatographic column on a protein purifier, washing out protective agent solution by deionized water, balancing the column by PBS buffer solution, loading 1.5ml antiserum sample on the column, eluting impurities by PBS buffer solution, and finally eluting vibrio parahaemolyticus polyclonal antibody by citric acid buffer solution to obtain vibrio parahaemolyticus polyclonal antibody solution.