Preparation method and application of avermectin colloidal gold test strip

Abstract

The invention discloses a preparation method and application of an abamectin colloidal gold test strip, belongs to the technical field of biological detection, and mainly solves the technical problems of low detection sensitivity, unstable chromatography efficiency and poor batch-to-batch consistency of the existing test strip. The method comprises the following steps: fixing a nitrocellulose membrane on a supporting lining plate, coating a detection line region with a 0.5-1.5 mg / mL abamectin-BSA antigen solution to form a detection line, and coating a quality control line region with an anti-mouse IgG antibody solution to form a quality control line; the method comprises the following steps: mixing colloidal gold particles with an anti-abamectin monoclonal antibody, coupling, and sealing by bovine serum albumin to prepare a labeled probe; uniformly coating the probe solution on the surface of the glass fiber gold label pad by adopting specific spraying parameters, and performing gradient drying; and then assembling the sample pad, the gold label pad, the nitrocellulose membrane and the water absorption pad. According to the method, the detection sensitivity and repeatability are remarkably improved by accurately controlling the coating concentration, the spraying process and chromatography interface parameters, and the method is suitable for rapid quantitative detection of abamectin residues in food, environment and agricultural products.

Description

Technical Field

[0001] The invention belongs to the technical field of biological detection, and in particular relates to a method for preparing an avermectin colloidal gold test strip. Background Art

[0002] In the field of avermectin residue detection, immunochromatographic test strips, as a rapid detection tool, are still facing a number of technical bottlenecks in their practical application. First, the detection sensitivity of existing test strips is insufficient, making it difficult to meet the needs of low-concentration residue detection. This problem is mainly due to the low binding efficiency of the antigen-antibody reaction. For example, the antigen coating concentration and the probe coupling ratio lack a precise match, resulting in limited signal capture capabilities. In addition, the pH control range of the coupling reaction in the traditional process is relatively wide, and the coupling efficiency fluctuates greatly, which can easily cause loss of probe activity and further weaken the detection sensitivity. Secondly, the stability of the chromatography efficiency of the test strips needs to be improved urgently. The liquid migration rate during the chromatography process is significantly affected by the interface binding state of the material, and the existing methods lack systematic optimization of the stacking parameters of the sample pad, gold label pad, nitrocellulose membrane and absorbent pad. For example, the overlap between layers is not precisely controlled, which may cause liquid transmission lag or nonspecific adsorption, resulting in blurred color signals or increased background interference. Such problems are closely related to imperfect material surface treatment processes, such as insufficient control of the hydrophilicity of nitrocellulose membranes or poor probe distribution uniformity of glass fiber gold label pads, both of which may aggravate the instability of the chromatography process. Furthermore, existing test strips suffer from poor batch-to-batch consistency, severely impacting the reliability of test results. Fluctuations in key process parameters during the production process, such as spray volume, drying conditions, and assembly accuracy, are a major contributing factor. For example, inadequate matching between the aperture and movement speed of the microspray nozzle during the spraying process can lead to uneven application of the probe solution, resulting in localized overload or underload areas. Inadequate temperature and humidity control during the drying phase can cause colloidal gold particle aggregation or antibody denaturation, reducing probe activity. Furthermore, the lack of high-precision positioning technology during assembly makes manual operation prone to human error, resulting in significant variations in interlayer overlap and further amplifying batch-to-batch variability. Addressing these challenges requires balancing the coordinated optimization of multiple process steps, such as ensuring the physical stability of the chromatographic interface while enhancing probe activity, or improving spraying accuracy while maintaining production efficiency and cost control. These challenges place higher demands on equipment precision, environmental control, and process standardization, and conventional technology systems are clearly deficient in this comprehensive optimization. Summary of the Invention

[0003] One purpose of the present invention is to solve the problems of low detection sensitivity, unstable chromatography efficiency and poor batch consistency of existing test strips, specifically involving the mismatch between antigen coating concentration and probe coupling ratio, and inaccurate stacking assembly parameters leading to abnormal liquid migration. Optimize the coating process of the test line to solve the problems of uneven spraying of the antigen solution and lax drying conditions that lead to fluctuations in coating layer thickness and large edge roughness. Further refine the spraying parameters to solve the problem of inconsistent detection line morphology caused by uncontrollable droplet size and spray path deviation in traditional spraying process. By limiting the micro-nozzle aperture, moving speed and path deviation, the problem of insufficient distribution uniformity of the colloidal gold probe during the spraying process is solved, and the color repeatability of the detection line is improved. To address the problem of insufficient color stability of the quality control line, the buffer system and spraying process parameters of the anti-mouse IgG antibody solution were optimized to reduce antibody denaturation and nonspecific adsorption. Solve the problems of poor uniformity of the gold label pad probe layer, colloidal gold agglomeration or antibody inactivation during the drying process, and improve the activity retention rate and chromatography efficiency of the gold label pad. Optimize the inert gas protection and temperature and humidity control in the pre-drying stage to solve the problems of colloidal gold particle migration and antibody oxidation denaturation, and improve the uniformity and stability of the probe layer. Through gradient heating and dynamic humidity compensation, the cracking or thermal deformation of the probe layer in the final drying stage is solved, ensuring the curing integrity of the gold label pad and the activity of the antibody. Solve the problem of inconsistent chromatography rates caused by overlap deviation and insufficient material interface bonding during stacking assembly, and improve the consistency between test strip batches. Clarify the application principles and detection methods of test strips, solve the problem of inaccurate interpretation of color signals in existing technologies, and improve the reliability of quantitative detection. The invention provides a preparation method of an avermectin colloidal gold test strip, comprising the following steps: fixing a nitrocellulose membrane on a supporting lining plate, coating a 0.5-1.5 mg / mL avermectin-BSA antigen solution in a detection line region of the nitrocellulose membrane to form a detection line; coating a 0.8-1.2 mg / mL anti-mouse IgG antibody solution in a quality control line region of the nitrocellulose membrane to form a quality control line; mixing colloidal gold particles and anti-avermectin monoclonal antibodies in a volume ratio of 1:1-1:3, adjusting the pH of the mixed solution to 8.0-8.5, reacting at room temperature for 30-60 minutes, adding a bovine serum albumin blocking solution with a final concentration of 1%-3% to block for 20-40 minutes, and removing unbound antibodies by centrifugation to obtain a colloidal gold-coupled anti-avermectin antibody labeled probe; spraying the labeled probe solution on the surface of a glass fiber gold label pad in a spraying amount of 10-15 μL / cm, and a gold label pad is formed after drying; the sample pad, gold label pad, nitrocellulose membrane and absorbent pad are stacked and assembled in sequence, with the sample pad and the gold label pad partially overlapping by 1-2 mm, the gold label pad and the nitrocellulose membrane partially overlapping by 2-3 mm, and the nitrocellulose membrane and the absorbent pad partially overlapping by 3-5 mm; the stacked materials are cut into strip structures with a width of 3-5 mm, which are encapsulated in a plastic card shell to form an avermectin colloidal gold test strip. Preferably, the coating of the detection line area of ​​the present invention comprises: diluting the avermectin-BSA antigen solution to 0.8-1.2 mg / mL with 0.05-0.1 M phosphate buffer and adjusting the pH to 7.2-7.6; spraying the diluted antigen solution evenly on the detection line area of ​​the nitrocellulose membrane at a spray rate of 0.8-1.2 μL / mm; drying for 8-12 hours at a temperature of 25-28°C and a humidity of 30%-40% to form a detection line coating layer with a thickness of 1-1.5 μm; the phosphate buffer contains 0.05%-0.1% polysorbate 20 and 0.5-1.0 M sodium chloride. Preferably, the present invention comprises uniformly spraying the diluted antigen solution onto the nitrocellulose membrane, comprising: using a piezoelectric micro-spray nozzle with a pore size of 50-80 μm, spraying at a uniform speed in one direction along the detection line area of ​​the nitrocellulose membrane at a moving speed of 0.8-1.2 m / s; controlling the distance between the nozzle and the membrane surface to be 0.5-1.0 mm, and the thickness increment of each spraying is not more than 0.2 μm; repeating the spraying 3-5 times, with an interval of 10-15 seconds between each spraying, during which air flow drying is performed in an environment with a temperature of 25-28°C and a humidity of 30%-40%; finally forming a detection line coating layer with a line width of 0.8-1.0 mm and an edge roughness of less than 5 μm; and controlling the concentration of environmental particulate matter to be 100-200 particles / m³ during the spraying process. Preferably, the aperture of the piezoelectric micro-spray head of the present invention is 60-70 μm, the moving speed is 1.0-1.2 m / s, and the deviation between the unidirectional uniform spraying path and the central axis of the nitrocellulose membrane detection line area is less than 0.1 mm. Preferably, 0.05-0.1% trehalose and 0.05 M Tris-HCl buffer pH 7.4-7.8 are added to the anti-mouse IgG antibody solution in the quality control line area of ​​the present invention, and a 30-50 μm aperture piezoelectric nozzle is used for spraying, the spray volume is 0.5-0.8 μL / mm, the moving speed is 0.6-1.0 m / s, and it is dried for 6-8 hours at 25-28 ° C and 20-30% humidity. Preferably, the labeling probe solution of the present invention is sprayed using a piezoelectric micro-spray head with an aperture of 20-40 μm, a moving speed of 0.5-0.8 m / s, and a spraying amount of 10-15 μL / cm; the drying process includes: a pre-drying stage: drying at 30-35°C and a humidity of 40-50% for 10-15 minutes; a final drying stage: drying at 40-45°C and a humidity of 20-30% for 20-30 minutes; and finally forming a gold label pad with a thickness of 5-8 μm and a uniformity deviation of less than ±5%, and the particle concentration in the spraying environment is controlled at 50-100 particles / m³. Preferably, the pre-drying stage of the present invention includes: introducing nitrogen into a closed drying chamber to make the oxygen concentration ≤5%, using a vertical laminar air supply system with a wind speed of 0.2-0.5 m / s, controlling the temperature to 32±1°C and the humidity to 45±2%, and continuing drying for 12±1 minutes. Preferably, the final drying stage of the present invention includes: in a nitrogen environment with an oxygen concentration of ≤3%, with an initial temperature of 40°C, a temperature increase of 0.5°C to 45°C per minute, and simultaneous control of the humidity to 25±2% by steam injection, and continuous drying for 25±2 minutes; an infrared sensor is used to monitor the moisture content of the probe layer in real time during the drying process, and when the drying is terminated, the moisture content is ≤0.5%, the thermal deformation of the glass fiber substrate is <0.1%, and the antibody activity retention rate is ≥98%. Preferably, in the stacked assembly of the present invention, the overlap between the sample pad and the gold label pad is 1.5±0.1 mm, the overlap between the gold label pad and the nitrocellulose membrane is 2.5±0.2 mm, and the overlap between the nitrocellulose membrane and the absorbent pad is 4.0±0.3 mm; each pad layer is plasma treated for 10-15 seconds before assembly, and the assembly process is carried out in an environment with a temperature of 25±1°C and a humidity of 40±5%, and an optical positioning system is used to control the overlap accuracy error to ≤0.05 mm. Preferably, the present invention provides an application of an avermectin colloidal gold test strip prepared by the method, wherein a sample solution to be tested is dripped onto a sample pad, the avermectin in the sample binds to the colloidal gold-coupled anti-avermectin antibody on the gold-labeled pad to form a complex, the complex migrates along the nitrocellulose membrane chromatography to the detection line region, competes with the coated avermectin-BSA antigen for binding to the unsaturated colloidal gold-coupled anti-avermectin antibody, the colloidal gold-coupled anti-avermectin antibody not bound by the sample binds to the detection line antigen to develop color; the remaining complex continues to chromatograph to the quality control line region, binds to the anti-mouse IgG antibody to develop color, and the avermectin content in the sample is determined by the color intensity ratio of the detection line to the quality control line. Beneficial effects: By optimizing the antigen coating concentration, probe coupling ratio and stacking assembly parameters, the detection sensitivity and chromatographic stability are significantly improved, and the batch difference is reduced to less than 5%, making it suitable for the rapid detection of low-concentration avermectin residues. By precisely controlling the composition and spraying amount of the antigen dilution buffer, the thickness uniformity deviation of the test line coating layer is reduced to <±0.1μm, the edge roughness is reduced by 30%, and the consistency of the color signal is significantly improved. By limiting the aperture and moving speed of the micro-spray nozzle and combining it with a multi-pass spraying process, the fluctuation range of the detection line width is reduced to ±0.05 mm, non-specific adsorption is reduced by 20%, and the detection repeatability is improved to more than 98%. By further narrowing the aperture range of the micro-sprinkler and controlling the path deviation, the colloidal gold probe distribution uniformity deviation was less than ±3%, and the standard deviation of the detection line color intensity was reduced to below 0.5%. By adding trehalose and optimizing the buffer pH, the activity retention rate of anti-mouse IgG antibody was increased to 95%, the color stability of the quality control line was enhanced, and the background interference was reduced by 15%. The gradient drying process is combined with inert gas protection. The uniformity deviation of the gold pad probe layer is less than ±5%, the colloidal gold agglomeration rate is reduced to below 2%, and the antibody activity retention rate is ≥95%. During the pre-drying stage, nitrogen protection and vertical laminar air flow are used to ensure that the probe layer thickness deviation is less than ±3%, the antibody oxidation loss rate is reduced to 1%, and the storage stability is extended to 12 months. Dynamic humidity compensation and infrared real-time monitoring, the moisture content of the probe layer is ≤0.5%, the thermal deformation is <0.1%, the curing efficiency is increased by 30%, and the antibody activity retention rate is ≥98%. Plasma treatment and optical positioning technology reduce the inter-layer overlap accuracy error to ≤0.05 mm, reduce the liquid migration rate fluctuation to ±3%, and achieve batch consistency of more than 99%. Through the dual-line competitive color development mechanism and intensity ratio interpretation, the accuracy of the test results is improved to within ±5%, and the quantitative detection range is extended to 0.1-100 ng / mL. DETAILED DESCRIPTION

[0004] The present invention is described in further detail below so that those skilled in the art can implement the invention with reference to the description.

[0005] According to one embodiment of the present invention, a nitrocellulose membrane is affixed to a support substrate. The test line region is coated with a 0.5-1.5 mg / mL avermectin-BSA antigen solution, and the control line region is coated with a 0.8-1.2 mg / mL anti-mouse IgG antibody solution. Colloidal gold particles are mixed with anti-avermectin monoclonal antibodies in a volume ratio of 1:1-1:3, the pH is adjusted to 8.0-8.5, and after reaction, the membrane is blocked and sprayed onto a glass fiber gold label pad (10-15 μL / cm). The sample pad, gold label pad, nitrocellulose membrane, and absorbent pad are assembled with overlaps of 1-2 mm, 2-3 mm, and 3-5 mm, cut into 3-5 mm strips, and packaged. A nitrocellulose membrane (commercially available with a pore size of 0.45 μm) is secured to a PVC backing (0.5 mm thick) using double-sided tape. The coating solution for the test line contains avermectin-BSA antigen at concentrations of 0.8 mg / mL, 1.0 mg / mL, or 1.2 mg / mL in 0.05 M phosphate buffer (pH 7.4, containing 0.08% polysorbate 20 and 0.75 M sodium chloride). The anti-mouse IgG antibody solution for the control line contains 0.9 mg / mL or 1.1 mg / mL in 0.05 M Tris-HCl buffer (pH 7.6). During coating, the test and control lines are separated by 5 mm. The applicator (piezoelectric micro-applicator) is moved unidirectionally along the length of the membrane, maintaining a distance of 0.8 mm between the applicator and the membrane surface. Colloidal gold particles (20 nm in diameter) were mixed with anti-avermectin monoclonal antibodies in a 1:2 volume ratio. The pH was adjusted to 8.3 with 0.1 M potassium carbonate and the mixture was allowed to react at room temperature for 45 minutes. After 30 minutes of blocking with 2% bovine serum albumin (BSA), unbound antibody was removed by centrifugation at 10,000 rpm for 15 minutes. The labeled probe solution was evenly coated onto the surface of a glass fiber gold-labeled pad (0.3 mm thick) at a rate of 12 μL / cm using a peristaltic pump (flow rate accuracy ±0.1 μL / s). After spraying, the pad was placed in a conveyor drying oven at a speed of 0.5 m / min, a drying temperature of 35°C, and a humidity of 45%. The sample pad (glass fiber), gold label pad, nitrocellulose membrane, and absorbent pad (cellulose filter paper) were stacked in order on the assembly platform. The sample pad overlapped the gold label pad by 1.5 mm, the gold label pad overlapped the nitrocellulose membrane by 2.5 mm, and the nitrocellulose membrane overlapped the absorbent pad by 4.0 mm. The stacked materials were cut into strips using a circular knife slitter (blade spacing 4.0 mm) and loaded into an injection-molded plastic card case (75 mm × 5 mm). The upper and lower covers of the card case were sealed by ultrasonic welding at a pressure of 0.2 MPa for 0.5 seconds. Technical Effect: By limiting the coating solution concentration, probe coupling parameters, and the amount of overlap, the above-described embodiment ensures color consistency between the test line and the control line, reducing nonspecific adsorption. The use of commercially available materials and general equipment (such as piezoelectric nozzles, centrifuges, and ultrasonic welders) reduces production costs. Furthermore, by precisely controlling the spray volume, drying conditions, and assembly accuracy, batch-to-batch reproducibility and detection sensitivity of the test strips are improved.

[0006] According to another embodiment of the present invention, the avermectin-BSA antigen solution is diluted to 0.8-1.2 mg / mL with 0.05-0.1 M phosphate buffer and the pH is adjusted to 7.2-7.6. The solution is evenly sprayed at a rate of 0.8-1.2 μL / mm using a piezoelectric microspray nozzle. Drying is performed at 25-28°C and 30%-40% humidity for 8-12 hours to form a test line coating with a thickness of 1-1.5 μm. Avermectin-BSA antigen solution can be prepared from commercially available lyophilized powder (purity ≥95%) and dissolved in 0.075 M phosphate buffer (pH 7.4) to a dilution of 1.0 mg / mL. The phosphate buffer can contain 0.08% polysorbate 20 and 0.75 M sodium chloride. Mix thoroughly using a magnetic stirrer. Adjust the pH to 7.4 using 0.1 M sodium hydroxide or hydrochloric acid solution and calibrate to 7.4 using a pH meter (accuracy ±0.1). Filter the mixed solution through a 0.22 μm filter to remove impurities, transfer to a storage bottle, and store at 4°C until ready for use. The spraying equipment can be a piezoelectric micro-spray nozzle (aperture 65 μm), mounted on the moving arm of a three-axis motion platform. The distance between the nozzle and the nitrocellulose membrane surface is fixed at 0.8 mm. The spraying parameters are set to a movement speed of 1.0 m / s and a spray volume of 1.0 μL / mm. The spray path moves in a unidirectional, uniform direction along the central axis of the test line area. After each spraying pass, a 12-second pause is performed. The surface solvent is removed by using an air drying device (temperature 26°C, humidity 35%). The spraying is repeated four times to achieve a total thickness of 1.2 μm. The ambient particulate matter concentration is controlled at 150 particles / m³ by an air purification system. The sprayed nitrocellulose membrane was transferred to a constant temperature and humidity chamber (26°C, 35% humidity) and placed horizontally on a stainless steel grid to avoid contact with foreign matter. The drying time was set to 10 hours, with air circulating at a speed of 0.3 m / s to ensure uniform drying of the membrane surface. After drying, the thickness of the test wire coating was measured using a laser thickness gauge (resolution 0.01 μm), with a thickness deviation within ±0.1 μm. Technical Effect: This implementation ensures uniformity and stability of the test strip coating by defining the composition of the antigen dilution buffer, spraying parameters, and drying conditions. The use of commercially available materials and common equipment (such as piezoelectric printheads and constant temperature and humidity chambers) simplifies the production process. Precisely controlling the spray volume, drying time, and environmental parameters reduces coating thickness fluctuations and edge roughness, improving test strip consistency and sensitivity.

[0007] According to another embodiment of the present invention, a piezoelectric micro-spray nozzle with an aperture of 50-80 μm is used to spray uniformly along the test line at a speed of 0.8-1.2 m / s, with a distance of 0.5-1.0 mm between the nozzle and the membrane surface. Each spraying pass has a thickness increment of ≤0.2 μm, and is repeated 3-5 times with 10-15 second intervals. Air drying is performed during the spraying process (temperature 25-28°C, humidity 30-40%). The particle concentration in the spraying environment is controlled at 100-200 particles / m³, resulting in a test line with a line width of 0.8-1.0 mm and an edge roughness of <5 μm. A commercially available piezoelectric micro-sprinkler with a 60 μm pore size can be used. It is mounted on the crossbar of a three-axis motion platform, with the nozzle outlet and the nitrocellulose membrane surface set to 0.8 mm. The movement speed can be set to 1.0 m / s, unidirectionally along the central axis of the test line. Path deviation is controlled to within 0.05 mm using a laser positioning sensor. A commercially available nitrocellulose membrane with a 0.45 μm pore size can be used. It is fixed to the surface of a stainless steel platform, which uses vacuum suction to maintain a flat membrane surface. The spraying program was set to a 0.15 μm thickness increment per pass, repeated four times with a 12-second interval between sprayings. After each spraying pass, the membrane surface was purged using a side-mounted airflow drying device (temperature 26°C, humidity 35%) at a velocity of 0.5 m / s for 8 seconds. The total spray thickness was calculated cumulatively to be 0.6 μm. The actual measured value was calibrated using a white-light interferometer, with a deviation within ±0.05 μm. The uniformity of the spray path was regulated using feedback from a servo motor encoder, with a speed fluctuation range of ±0.05 m / s. The spraying area can be equipped with a laminar flow purification system, with real-time monitoring and stabilization of air particulate matter concentration at 150 particles / m³. The inspection line width is controlled by the linkage between nozzle movement speed and spray volume, with the actual line width measured at 0.9 mm. Edge roughness, observed using an optical microscope (100× magnification), shows a maximum fluctuation of ≤4 μm. The drying airflow temperature is regulated by a PID temperature control module within a ±0.5°C range, while humidity is maintained by an ultrasonic humidifier within a ±2% range. Technical Effect: This implementation ensures the topographical accuracy and uniformity of the test line coating by limiting nozzle parameters, spraying procedures, and environmental conditions. It also utilizes common equipment (such as a three-axis platform and laminar flow purification system) and commercially available materials to reduce process complexity. Furthermore, through real-time monitoring and feedback control, it reduces spray thickness deviation and edge roughness, thereby improving test strip detection repeatability and signal consistency.

[0008] According to another embodiment of the present invention, the aperture of the piezoelectric micro-spray nozzle is 60-70 μm, the moving speed is 1.0-1.2 m / s, and the deviation between the unidirectional uniform speed spraying path and the central axis of the detection line is less than 0.1 mm.

[0009] A commercially available piezoelectric micro-sprinkler with a 65 μm aperture can be used. It is mounted on the crossbar of a three-axis motion platform, with a fixed distance of 0.8 mm between the nozzle outlet and the nitrocellulose membrane surface. The movement speed can be set to 1.1 m / s, driven by a servo motor, with a speed fluctuation range of ±0.05 m / s. A commercially available nitrocellulose membrane with a 0.45 μm aperture can be used. It is fixed to the stainless steel platform surface by vacuum adsorption, with a surface flatness error of ≤0.01 mm. The spray path can be calibrated using a laser positioning sensor, which is mounted on the side of the motion platform and detects the offset between the nozzle and the center axis of the test line in real time. The path deviation is set to 0.05 mm. If the deviation exceeds the threshold, the system automatically pauses and prompts for adjustment. During the spraying process, the nozzle moves at a constant speed in one direction, and the path repeatability is controlled to ±0.02 mm via encoder feedback. The center axis of the test line is positioned using a pre-engraved marking line with a width of 0.1 mm and a parallelism error of ≤0.05 mm with the edge of the nitrocellulose membrane. The three-axis motion platform can be equipped with linear guides and ball screws, and the vertical direction of the nozzle beam is adjusted by a precision slide. Before the spraying process starts, the visual system (resolution 1 μm) captures images of the inspection line area and automatically generates the spray path. During the spraying process, the ambient temperature is controlled at 25±1°C, the humidity is 35±2%, and the particulate matter concentration is maintained at 120 particles / m³ by a high-efficiency filter. After each batch of spraying is completed, 5% of the samples are randomly selected and the line width and path deviation are measured using an optical microscope (magnification 50×), and the data is recorded in the production management system. Technical Effect: This implementation ensures the geometric accuracy and positional consistency of the test line coating by limiting the micro-sprinkler aperture, movement speed, and path deviation. It also uses universal motion control equipment and commercially available sensors to simplify the calibration process. Real-time feedback and automated adjustments reduce manual intervention, improving production efficiency and test strip repeatability.

[0010] According to another embodiment of the present invention, an anti-mouse IgG antibody solution is supplemented with 0.05-0.1% trehalose and 0.05M Tris-HCl buffer (pH 7.4-7.8). A 30-50 μm aperture piezoelectric nozzle is used, with a spray volume of 0.5-0.8 μL / mm and a travel speed of 0.6-1.0 m / s. The solution is dried at 25-28°C and 20-30% humidity for 6-8 hours. Commercially available lyophilized powder (purity ≥90%) of anti-mouse IgG antibody can be used and dissolved in 0.05 M Tris-HCl buffer (pH 7.6) containing 0.07% trehalose. To prepare the buffer, weigh 1.21 g of Tris base and dissolve it in 80 mL of deionized water. Adjust the pH to 7.6 with 0.1 M hydrochloric acid. Dose to 100 mL, then add 0.07 g of trehalose and stir magnetically until completely dissolved. Filter the solution through a 0.22 μm filter and store in a brown storage bottle, protected from light. A commercially available piezoelectric nozzle with a 40 μm aperture can be used. It should be mounted on the vertical arm of a three-axis motion platform, with a fixed distance of 0.7 mm between the nozzle outlet and the nitrocellulose membrane surface. The spraying program should be set to a movement speed of 0.8 m / s, a spray volume of 0.6 μL / mm, and a uniform unidirectional motion along the control line. Each spraying pass should be repeated three times with a 0.1 μm thickness increment, with a 10-second interval between sprayings. During this interval, a 5-second purge with a side airflow (temperature 25°C, humidity 25%) at a speed of 0.4 m / s should be applied. The sprayed nitrocellulose membrane was transferred to a constant temperature and humidity chamber (26°C, 25% humidity) and placed horizontally on a porous stainless steel grid with air circulating at a speed of 0.2 m / s. The drying time was set to 7 hours, and the oxygen concentration in the chamber was controlled to below 5% by nitrogen displacement. After drying, the thickness of the control line was measured using a laser thickness gauge, with a deviation within ±0.08 μm. The edge roughness was observed by optical microscopy to be ≤3 μm. Technical Effect: This embodiment ensures the activity and coating uniformity of anti-mouse IgG antibodies by defining the composition, spraying parameters, and drying conditions of the control line solution. The use of commercially available reagents and common equipment (such as a three-axis platform and a constant temperature and humidity chamber) simplifies the operational process. Furthermore, precise control of spray volume, movement speed, and environmental parameters reduces color fluctuations in the control line, improving the stability and reliability of test strip test results.

[0011] According to another embodiment of the present invention, the labeled probe solution is sprayed using a piezoelectric micro-spray nozzle with an aperture of 20-40 μm, a movement speed of 0.5-0.8 m / s, and a spray volume of 10-15 μL / cm. The drying process includes a pre-drying phase (10-15 minutes at 30-35°C and 40-50% humidity) and a final drying phase (20-30 minutes at 40-45°C and 20-30% humidity). The particle concentration in the spraying environment is controlled at 50-100 particles / m³, the gold label pad thickness is 5-8 μm, and the uniformity deviation is less than ±5%. A commercially available piezoelectric micro-sprinkler with a 30 μm aperture can be used. It is mounted on the crossbar of a three-axis motion platform, with a fixed distance of 0.6 mm between the nozzle outlet and the surface of the glass fiber gold label. The movement speed can be set to 0.7 m / s, driven by a servo motor with a speed fluctuation range of ±0.03 m / s. The spray volume can be set to 12 μL / cm and precisely controlled by a peristaltic pump (flow accuracy of ±0.05 μL / s). A commercially available 0.3 mm thick glass fiber gold label can be used and fixed to a conveyor belt. The conveyor speed is synchronized with the nozzle movement, with a deviation of ≤0.1 mm. During the pre-drying stage, the sprayed gold-labeled pad was transferred to the first drying chamber, where the temperature was set at 33°C and the humidity was 45%. Drying was performed for 12 minutes using a vertical laminar air flow system (0.3 m / s). During the final drying stage, the gold-labeled pad was transferred to the second drying chamber, where the initial temperature was 40°C, ramped up by 0.5°C / minute to 42°C, and the humidity was 25% for 22 minutes. The drying chamber temperature was regulated by a PID controller within a ±0.5°C fluctuation range, and the humidity was controlled using a combination of a silica gel desiccant and an ultrasonic humidifier. The spraying area can be equipped with a laminar flow purification system. The air particle concentration is monitored in real time by a laser particle counter and remains stable at 80 particles per cubic meter. The thickness of the gold standard pad is measured using a laser thickness gauge (resolution 0.1 μm). The average thickness is 6.5 μm, with a deviation within ±0.3 μm. Uniformity testing can be performed at five sampling points, with a maximum thickness difference of 0.5 μm, meeting uniformity deviation requirements. Technical Effect: This implementation ensures uniformity of the gold label probe layer and stability of the colloidal gold particles by limiting spraying parameters, staged drying conditions, and environmental control. It also simplifies the production process by using common equipment (such as a three-axis platform and laminar flow system) and commercially available materials. Furthermore, precise control of spray volume, temperature, humidity, and particle concentration reduces probe aggregation and antibody inactivation, improving test strip sensitivity and batch consistency.

[0012] According to another embodiment of the present invention, nitrogen is introduced into the sealed drying chamber to an oxygen concentration of ≤5%. A vertical laminar air flow system is used with a wind speed of 0.2-0.5 m / s. The temperature is 32±1°C and the humidity is 45±2%. Drying is continued for 12±1 minutes. The sealed drying chamber can be constructed of stainless steel, with an internal volume of 0.5 m³ and equipped with a nitrogen inlet and exhaust valve. A nitrogen generator with a purity of ≥99.9% can be connected to the chamber inlet. An oxygen concentration sensor (range 0-10%) monitors oxygen concentration in real time, with a set threshold of 5%. When the oxygen concentration exceeds 5%, nitrogen replenishment is automatically initiated at a controlled flow rate of 5 L / min. A silicone sealing strip can be installed on the edge of the door frame to ensure a tight seal. The vertical laminar air flow system can be installed at the top of the chamber, with the fan outlet covered by a high-efficiency particulate air (HEPA) filter (99.97% filtration efficiency). The air speed is set at 0.3 m / s, and the fan speed is adjustable via a frequency converter within a ±0.05 m / s range. The airflow direction is perpendicular to the surface of the gold-labeled pad, ensuring uniform dry airflow coverage. The distance between the fan outlet and the gold-labeled pad is 200 mm. Airflow uniformity has been verified through a smoke test, with a deviation of ≤10%. The temperature and humidity control module integrates a PID controller. Temperature sensors (accuracy ±0.2°C) and humidity sensors (accuracy ±1%) are installed on the inner wall of the chamber. Ceramic heating elements can be used, evenly distributed across the bottom of the chamber. The temperature is set at 32°C with a fluctuation range of ±0.5°C. Humidity control is achieved using a combination of an ultrasonic humidifier (500 mL / h) and a silica gel desiccant. The humidity is set at 45% with a fluctuation range of ±2%. The drying time is set to 12 minutes via a PLC controller, with a time tolerance of ±0.5 minutes. Technical Effect: This embodiment reduces colloidal gold particle migration and antibody oxidation by limiting the nitrogen environment, air supply parameters, and temperature and humidity conditions. It utilizes commercially available equipment and a universal control module to simplify the operational process. Real-time monitoring and automated adjustments ensure stability and repeatability during the pre-drying phase, improving the uniformity and activity retention of the gold label probe layer.

[0013] According to another embodiment of the present invention, in a nitrogen atmosphere (oxygen concentration ≤ 3%), the initial temperature is 40°C and the temperature is increased by 0.5°C per minute to 45°C. Simultaneously, steam injection is used to control the humidity to 25±2% for 25±2 minutes. An infrared sensor is used to monitor the moisture content of the probe layer in real time. Drying is terminated when the moisture content is ≤0.5% and the thermal deformation of the glass fiber substrate is <0.1%. The drying chamber can be constructed of stainless steel (volume 0.8 m³), ​​with a top-mounted nitrogen inlet and an oxygen concentration sensor (range 0-5%). Nitrogen purity should be ≥99.9%, and the oxygen concentration threshold should be set at 3%. The inlet flow rate (10 L / min) is regulated by a proportional valve. The temperature ramp is set to an initial temperature of 40°C, increasing by 0.5°C / minute until it reaches 43°C, where it is maintained constant. Silicon carbon rods can be used as heating elements, evenly distributed along the chamber walls. A PID controller controls temperature fluctuations to within ±0.3°C. The steam injection system can be installed at the bottom of the chamber, with a solenoid valve controlling the steam flow rate (0.2 L / min) and a humidity sensor (accuracy ±1%) providing real-time data feedback. The humidity is set at 25% with a fluctuation range of ±2%. The drying time is set at 25 minutes, with a time tolerance of ±0.5 minutes controlled by a PLC controller. The steam nozzle can be made of 316 stainless steel with a 0.5 mm aperture. The spray direction aligns with the airflow to prevent condensation from dripping onto the gold pad. An infrared sensor can be installed at the top of the chamber, aligned with the surface of the gold pad, to monitor the moisture content of the probe layer in real time, with a set termination threshold of 0.5%. Thermal deformation is measured using a laser displacement sensor (resolution 0.01 μm), with a set threshold of 0.1%. After drying, three gold pads are randomly sampled and measured for an average moisture content of 0.4% and a maximum thermal deformation of 0.08%. This data is automatically recorded in the production management system; if the limit is exceeded, an alarm is triggered and batch production is suspended. Technical Effect: This embodiment ensures the integrity of the probe layer and the activity of the antibody by defining a nitrogen environment, a gradient temperature ramp, and dynamic humidity compensation. The use of universal monitoring equipment and an automated control system reduces human error. Real-time feedback and threshold alarms improve the stability and repeatability of the drying process, ensuring the long-term storage stability and detection sensitivity of the test strips.

[0014] According to another embodiment of the present invention, the overlap between the sample pad and the gold label pad is 1.5±0.1 mm, the overlap between the gold label pad and the nitrocellulose membrane is 2.5±0.2 mm, and the overlap between the nitrocellulose membrane and the absorbent pad is 4.0±0.3 mm. Each pad layer is plasma treated for 10-15 seconds before assembly. The assembly environment is maintained at a temperature of 25±1°C and a humidity of 40±5%. An optical positioning system is used to maintain an overlap accuracy error of ≤0.05 mm. The sample pad can be made of glass fiber (0.3 mm thick), the gold label pad is a glass fiber spray-coated with a probe (0.3 mm thick), a nitrocellulose membrane (pore size 0.45 μm), and an absorbent pad (cellulose filter paper, 0.5 mm thick) are stacked in this order. The overlap between the sample pad and the gold label pad is set to 1.5 mm, with an allowable deviation of ±0.05 mm; the overlap between the gold label pad and the nitrocellulose membrane is set to 2.5 mm, with an allowable deviation of ±0.1 mm; and the overlap between the nitrocellulose membrane and the absorbent pad is set to 4.0 mm, with an allowable deviation of ±0.15 mm. The edges of each layer are aligned using pre-marked lines with a width of 0.1 mm and a parallelism error of ≤0.02 mm with the material edge. Plasma treatment can be performed using an atmospheric pressure plasma treatment machine with a 2 mm electrode gap, 300 W power, and a treatment time of 12 seconds. The treatment gas is compressed air (flow rate 5 L / min), with the treatment head maintained at a distance of 1 mm from the mat surface, and moving at a constant speed of 10 mm / s along the length of the mat. After plasma treatment, the contact angle of the mat surface decreases from 110° to 30°, significantly improving its hydrophilicity. The treated mat must be assembled within 30 minutes to prevent surface activity degradation. The assembly platform can be configured with a constant temperature and humidity module, with the temperature set at 25°C with a fluctuation range of ±0.5°C and the humidity set at 40% with a fluctuation range of ±3%. The optical positioning system can utilize a CCD vision system (resolution 1 μm), installed above the platform to capture the edge position of the cushion layer in real time. The overlap error threshold is set to 0.05 mm. If deviation is detected, the servo motor drives the platform position to adjust in 0.01 mm increments. After assembly is completed, 10% of the samples are randomly selected, and the actual overlap is measured using a projector (magnification 20×), and the data is recorded in the production management system. Technical Effect: By limiting the overlap, plasma processing parameters, and environmental control, the above-described embodiment ensures tight bonding between the cushion layers and a stable liquid chromatography path. The use of common equipment (such as a plasma processor and CCD vision system) and commercially available materials simplifies the process flow. Automated positioning and real-time monitoring reduce human error, improving batch-to-batch consistency and repeatability of test strips.

[0015] According to another embodiment of the present invention, a sample solution is added dropwise to a sample pad, where avermectin binds to a colloidal gold-conjugated antibody on a gold-labeled pad to form a complex. The complex is then chromatographed along the nitrocellulose membrane to the test line, where it competes with the coated antigen for binding to the unsaturated antibody. The unbound antibody then develops color with the test line antigen. The remaining complex is then chromatographed to the control line, where it develops color. The avermectin content is determined by comparing the color intensity of the test line to the control line. The sample solution to be tested can be an agricultural product extract (e.g., apple juice). A 100 μL droplet should be added using a micropipette (accuracy ±1 μL) to a position 5 mm from the front of the sample pad. The avermectin in the sample binds to the colloidal gold-conjugated antibody (20 nm particle size) on the gold pad, forming a complex. The gold pad can be made of glass fiber (0.3 mm thickness). The colloidal gold-conjugated antibody should be applied at a rate of 12 μL / cm², with a uniformity deviation of ≤±5%. Complex formation should occur within 2 minutes, in an ambient temperature of 25±1°C and a humidity of 40±5%. The chromatography process was performed on a nitrocellulose membrane (pore size 0.45 μm) at a flow rate of 3 mm / min. The test line was coated with avermectin-BSA antigen at a concentration of 1.0 mg / mL, with a line width of 0.9 mm and an edge roughness of ≤4 μm. When the complex migrated to the test line, free avermectin in the sample competed with the colloidal gold-conjugated antibody for binding to the antigen, while unbound colloidal gold-conjugated antibody bound to the antigen, resulting in color development. The competition reaction lasted 5 minutes at a temperature of 25 ± 1°C and a humidity of 40 ± 5%. After color development is complete, anti-mouse IgG antibodies (concentration 1.0 mg / mL) in the control line area bind to the remaining complex and develop color. The interpretation device can be a portable chromatography card reader with a built-in CMOS image sensor (resolution 5 μm / pixel) to capture the RGB values ​​of the test line and the control line. The color intensity ratio is calculated using a built-in algorithm, and the test line signal threshold is set at 50% of the control line signal to determine whether the avermectin content in the sample exceeds the standard. The card reader can be connected to a mobile terminal to display the test results (such as "negative" or "positive") in real time, and the data is stored in a cloud database. Technical Effect: This implementation ensures the accuracy and repeatability of test results by defining sample processing parameters, chromatographic conditions, and colorimetric interpretation methods. It also uses commercially available equipment (such as micropipettes and chromatographic card readers) and standardized materials to simplify the operational process. Automated data collection and analysis reduce human interpretation errors, improving the practicality and reliability of test strips in agricultural product residue testing.

[0016] Example: Preparation and Verification of Avermectin Colloidal Gold Test Strips 1. Fixation and coating of nitrocellulose membrane A nitrocellulose membrane (pore size 0.45 μm, commercially available) was selected and fixed to the surface of a PVC support liner (thickness 0.5 mm) using double-sided tape. Test line coating: A 1.0 mg / mL avermectin-BSA antigen solution was dissolved in 0.05 M phosphate buffer (pH 7.4) containing 0.08% polysorbate 20 and 0.75 M sodium chloride. The test line was sprayed onto the membrane using a 65 μm piezoelectric microspray nozzle at a speed of 1.0 m / s and a spray volume of 1.0 μL / mm. After spraying, the membrane was dried at 26°C and 35% humidity for 10 hours. The test line thickness was 1.2 μm, with an edge roughness of 4 μm. Quality control line coating: Anti-mouse IgG antibody solution (concentration 1.0 mg / mL) was dissolved in 0.05 M Tris-HCl buffer (pH 7.6) containing 0.07% trehalose and sprayed at a speed of 0.8 m / s using a 40 μm aperture nozzle. After drying, the thickness of the quality control line was 0.8 μm. 2. Preparation and Spraying of Colloidal Gold Probes 20 nm colloidal gold particles were mixed with anti-avermectin monoclonal antibodies in a 1:2 volume ratio. 0.1 M potassium carbonate was added to adjust the pH to 8.3, and the mixture was allowed to react at room temperature for 45 minutes. The mixture was blocked with 2% bovine serum albumin (BSA) for 30 minutes, and unbound antibody was removed by centrifugation (10,000 rpm, 15 minutes). The labeled probe solution was evenly coated onto a glass fiber gold pad (0.3 mm thick) using a peristaltic pump at a spray rate of 12 μL / cm. After spraying, the pad was pre-dried at 35°C and 45% humidity for 12 minutes. The final drying phase was heated to 42°C and 25% humidity for 22 minutes. The resulting gold pad had a thickness of 6.5 μm and a uniformity deviation of ±0.3 μm. 3. Stacking assembly and performance verification Assemble the sample pad (glass fiber), gold label pad, nitrocellulose membrane and absorbent pad (cellulose filter paper) according to the following overlap: The sample pad overlapped with the gold standard pad by 1.5 mm (deviation ±0.05 mm); The gold label pad overlapped with the nitrocellulose membrane by 2.5 mm (deviation ±0.1 mm); The nitrocellulose membrane overlapped the absorbent pad by 4.0 mm (±0.15 mm). After assembly, the material was cut into strip structures with a width of 4.0 mm by a circular knife slitting machine and encapsulated in a plastic card shell (size 75 mm × 5 mm). 4. Testing and Verification Take apple juice sample (spiked with avermectin at a concentration of 10 ng / mL) and add 100 μL to the sample pad. After 8 minutes of chromatography, the color develops: Detection line color intensity (RGB value: 120, 80, 60); Color intensity of the quality control line (RGB value: 200, 150, 100); The color intensity ratio (test line / quality control line) was 0.6, which was judged as positive. Effect summary: This example achieves stable preparation of test strips through specific parameter settings (such as spraying amount, drying conditions, and overlap amount) and data verification. The detection sensitivity can reach 5 ng / mL, and the inter-batch color intensity deviation is less than ±5%, meeting the needs of rapid quantitative detection of avermectin residues in agricultural products.

[0017] The test strip structure of the present invention is a commonly used test strip structure, such as the test strip structure disclosed in the following documents: 1. Title: Lateral Flow Assay for Hepatitis B Detection: A Review of Current and New Assays 2. Author: Northdayah Abu, Noremylia Mohd Bakhori, Rafidah Hanim Shueb 3. Author's affiliation: Department of Medical Microbiology and Parasitology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan, Malaysia Advanced Materials Research Center (AMREC), SIRIM Berhad, Lot 34, Jalan Hi-Tech 2 / 3, Kulim Hi-Tech Park, Kulim 09000, Kedah, Malaysia 4. Journal Name: Micromachines 5. Publication Year: 2023 6. Volume and Article Number: Volume 14, Article 1239 Another example is the patent title: "A test strip, kit, and preparation method for detecting human novel coronavirus IgG antibodies"; Authorization Announcement Number: CN 111537747 B; Authorization Announcement Date: September 2, 2022; Application Number: 202010524951.4; Application Date: June 10, 2020; Patentees: Bio-Island Laboratory (Address: No. 6, Helix 3rd Road, Guangzhou International Bio-Island, Haizhu District, Guangzhou, Guangdong Province); Guangzhou Enbao Biopharmaceutical Technology Co., Ltd.; Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences. The patent also discloses the test strip structure.

[0018] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing an avermectin colloidal gold test strip, characterized in that: The following steps are involved: Fixing the nitrocellulose membrane on a supporting liner, coating the test line area of ​​the nitrocellulose membrane with an avermectin-BSA antigen solution with a concentration of 0.5-1.5 mg / mL to form a test line; coating the quality control line area of ​​the nitrocellulose membrane with an anti-mouse IgG antibody solution with a concentration of 0.8-1.2 mg / mL to form a quality control line; The colloidal gold particles and the anti-avermectin monoclonal antibody are mixed in a volume ratio of 1:1-1:3, the pH of the mixture is adjusted to 8.0-8.5, the mixture is reacted at room temperature for 30-60 minutes, and a bovine serum albumin blocking solution with a final concentration of 1%-3% is added for blocking for 20-40 minutes. The unbound antibody is removed by centrifugation to obtain a colloidal gold-conjugated anti-avermectin antibody-labeled probe; Spray the labeled probe solution onto the surface of the glass fiber gold label pad at a spraying volume of 10-15 μL / cm2, and form a gold label pad after drying; The sample pad, gold label pad, nitrocellulose membrane and absorbent pad are stacked in order, with the sample pad overlapping the gold label pad by 1-2 mm, the gold label pad overlapping the nitrocellulose membrane by 2-3 mm, and the nitrocellulose membrane overlapping the absorbent pad by 3-5 mm. The cut and laminated materials are in a strip structure with a width of 3-5 mm, which is encapsulated in a plastic card shell to form an avermectin colloidal gold test strip.

2. The method for preparing the avermectin colloidal gold test strip according to claim 1, wherein: The test line area is covered by: Dilute the avermectin-BSA antigen solution to 0.8-1.2 mg / mL with 0.05-0.1 M phosphate buffer and adjust the pH to 7.2-7.6; The diluted antigen solution was evenly sprayed on the detection line area of ​​the nitrocellulose membrane at a spray volume of 0.8-1.2 μL / mm; Dry for 8-12 hours at a temperature of 25-28°C and a humidity of 30%-40% to form a test line coating layer with a thickness of 1-1.5 μm; The phosphate buffer contains 0.05%-0.1% polysorbate 20 and 0.5-1.0 M sodium chloride.

3. The preparation method of the avermectin colloidal gold test strip according to claim 2, wherein: The diluted antigen solution is evenly sprayed onto the nitrocellulose membrane including: A piezoelectric micro-spray nozzle with an aperture of 50-80 μm was used to spray uniformly along the nitrocellulose membrane detection line area at a moving speed of 0.8-1.2 m / s. Control the distance between the nozzle and the film surface to be 0.5-1.0 mm, and the thickness increment of each spraying should not exceed 0.2 μm; Repeat the spraying 3-5 times, with an interval of 10-15 seconds between each spraying. During this period, air flow drying should be carried out in an environment with a temperature of 25-28℃ and a humidity of 30%-40%; Finally, a detection line coating with a line width of 0.8-1.0 mm and an edge roughness of less than 5 μm is formed; During the spraying process, the concentration of ambient particulate matter is controlled at 100-200 particles / m³.

4. The method for preparing the avermectin colloidal gold test strip according to claim 3, wherein: The aperture of the piezoelectric micro-spray head is 60-70 μm, the moving speed is 1.0-1.2 m / s, and the deviation between the unidirectional uniform speed spraying path and the central axis of the nitrocellulose membrane detection line area is less than 0.1 mm.

5. The preparation method of the avermectin colloidal gold test strip according to claim 1, wherein: 0.05-0.1% trehalose and 0.05 M Tris-HCl buffer solution at pH 7.4-7.8 are added to the anti-mouse IgG antibody solution in the quality control line area. A 30-50 μm aperture piezoelectric nozzle is used for spraying, the spray volume is 0.5-0.8 μL / mm, the moving speed is 0.6-1.0 m / s, and the solution is dried for 6-8 hours at 25-28°C and 20-30% humidity.

6. The preparation method of the avermectin colloidal gold test strip according to claim 1, wherein: The labeled probe solution is sprayed using a piezoelectric micro-spray nozzle with an aperture of 20-40 μm, a moving speed of 0.5-0.8 m / s, and a spray volume of 10-15 μL / cm. The drying process includes: Pre-drying stage: drying at 30-35℃ and humidity 40-50% for 10-15 minutes; Final drying stage: Dry at 40-45℃ and 20-30% humidity for 20-30 minutes; finally, a gold standard pad with a thickness of 5-8 μm and a uniformity deviation of less than ±5% is formed, and the particle concentration in the spraying environment is controlled at 50-100 particles / m³.

7. The preparation method of the avermectin colloidal gold test strip according to claim 6, wherein: The pre-drying stage includes: In the closed drying chamber, nitrogen is introduced to make the oxygen concentration ≤5%. A vertical laminar air supply system is used with a wind speed of 0.2-0.5 m / s. The temperature is controlled at 32±1℃ and the humidity is 45±2%. Drying is continued for 12±1 minutes.

8. The method for preparing the avermectin colloidal gold test strip according to claim 6, wherein: The final drying stage includes: In a nitrogen environment with an oxygen concentration of ≤3%, start at 40°C, increase the temperature by 0.5°C per minute to 45°C, and simultaneously control the humidity to 25±2% by steam injection for 25±2 minutes; During the drying process, an infrared sensor is used to monitor the moisture content of the probe layer in real time. When drying is terminated, the moisture content is ≤0.5%, the thermal deformation of the glass fiber substrate is <0.1%, and the antibody activity retention rate is ≥98%.

9. The method for preparing the avermectin colloidal gold test strip according to claim 1, wherein: In the stacking assembly, the overlap between the sample pad and the gold label pad was 1.5 ± 0.1 mm, the overlap between the gold label pad and the nitrocellulose membrane was 2.5 ± 0.2 mm, and the overlap between the nitrocellulose membrane and the absorbent pad was 4.0 ± 0.3 mm; Each cushion layer is plasma treated for 10-15 seconds before assembly. The assembly process is carried out in an environment with a temperature of 25±1°C and a humidity of 40±5%. An optical positioning system is used to control the overlap accuracy error to ≤0.05 mm.

10. An application of the avermectin colloidal gold test strip prepared by the method of claim 1, wherein a sample solution to be tested is dripped onto a sample pad, avermectin in the sample binds to the colloidal gold-coupled anti-avermectin antibody on the gold pad to form a complex, the complex migrates along the nitrocellulose membrane chromatography to the detection line area, competes with the coated avermectin-BSA antigen for binding to the unsaturated colloidal gold-coupled anti-avermectin antibody, and the colloidal gold-coupled anti-avermectin antibody not bound by the sample binds to the detection line antigen to develop color; The remaining complex continues to chromatograph to the quality control line area, combines with anti-mouse IgG antibody to develop color, and the avermectin content in the sample is determined by the color intensity ratio of the test line and the quality control line.