Multi-unit rotary detection device and detection method for atrazine detection

Abstract

The invention relates to electrochemical detection, and discloses a multi-unit rotary detection device and a detection method for atrazine detection. The device comprises a base, a rotating disc is arranged on the base, a plurality of screen printing biosensors which are evenly arranged around a rotating shaft of the rotating disc are arranged on the upper end face of the rotating disc, and an atomization cleaning assembly for cleaning a working electrode area and a contactor making contact with an electrode lead are further installed on the base. The silk-screen printing biosensor can sequentially move to the lower portions of the atomization cleaning assembly and the contactor under the rotation effect of the rotating disc. According to the portable and flexible atrazine detection device and the corresponding detection method, a plurality of samples can be continuously and rapidly detected, the atrazine concentration in soil pore water can be rapidly obtained, and farmers are supported to make timely decisions between succeeding crop planting and soil remediation.

Description

TECHNICAL FIELD

[0001] The present application relates to electrochemical detection, and in particular to an electrochemical detection device and method for field pesticides. BACKGROUND

[0002] Herbicides play a crucial role in maintaining global agricultural productivity, with triazine compounds being among the most widely used. Among them, atrazine is widely used worldwide for selective control of broadleaf and grassy weeds, especially in corn, sorghum, and sugarcane cultivation. Its efficiency, cost-effectiveness, and broad-spectrum activity have contributed to its continued use in large-scale crop production globally. However, excessive and repeated use of atrazine can lead to its accumulation and long-term presence in the soil.

[0003] Research results show that in German agricultural soils, even after more than twenty years of banning the herbicide, atrazine content can still be detected, highlighting the potential of its environmental persistence and long-term ecological impact. Atrazine residues in the soil pose a significant threat to non-target organisms, especially sensitive rotation crops. In the widely adopted corn-soybean rotation system in some places, residual atrazine can adversely affect subsequent soybean crops and other sensitive species.

[0004] Studies have shown that atrazine dissolved in soil pore water is the effective part of crop absorption, so accurate and effective analysis of atrazine concentration in soil can avoid planting soybeans in fields with high residual atrazine, thereby avoiding pesticide phytotoxicity.

[0005] Current techniques for detecting atrazine mainly rely on expensive analytical equipment such as gas chromatography (GC) and high-performance liquid chromatography (HPLC) in laboratory environments. Although these traditional methods are sensitive, repeatable, and reliable, due to their inherent limitations, they are not suitable for certain use cases that require real-time and on-site detection. Therefore, there is an urgent need for sensitive and portable analytical equipment that can quickly detect atrazine concentrations in soil pore water to support farmers in making timely decisions between crop planting and soil remediation. SUMMARY

[0006] The present application provides a multi-unit rotary electrochemical detection device and a detection method thereof to solve the problem of how to quickly and conveniently detect the concentration of atrazine in soil pore water in the prior art.

[0007] To solve the above technical problems, the present application is solved by the following technical solutions: The application discloses a multi-unit rotary detection device for atrazine detection, which comprises a base, a rotating disc arranged on the base and capable of rotating, a plurality of screen printing biosensors arranged uniformly around the rotating shaft of the rotating disc and arranged on the upper end surface of the rotating disc, a working electrode area for carrying a target object to be detected and an electrode lead extended from the working electrode area and connected, an atomizing cleaning assembly for cleaning the working electrode area and a contactor in contact with the electrode lead, and the screen printing biosensors are capable of moving to the atomizing cleaning assembly and the lower part of the contactor in sequence under the action of the rotating disc.

[0008] Preferably, the base comprises a base body, a rotating disc mounting column extending upwardly is arranged in the middle of the base body, and the rotating disc is mounted on the rotating disc mounting column and is in clearance fit with the upper end surface of the base body.

[0009] Preferably, the upper end of the rotating disc mounting column is provided with an extension arm one and an extension arm two arranged along the radial direction of the rotating disc, the atomizing cleaning assembly is mounted on the extension arm one, the contactor is mounted on the extension arm two, and the atomizing cleaning assembly and the contactor can correspond to two different screen printing biosensors at the same time.

[0010] Preferably, the atomizing cleaning assembly comprises a liquid storage part and an atomizing sheet arranged at the lower end surface of the liquid storage part.

[0011] Preferably, the contactor comprises a contact mounting seat and a contact arranged at the contact mounting seat, and a spring for driving the contact to move towards the working electrode area is arranged at the contact.

[0012] Preferably, a power supply battery and an atomizing control module electrically connected with the atomizing sheet are arranged on the base body, the power supply battery is connected with the atomizing sheet through the atomizing control module, a control switch for controlling the opening and closing of the atomizing sheet is arranged on the atomizing control module, a wire hole is arranged in the middle of the rotating disc mounting column, and a wire electrically connected with the power supply battery is arranged in the wire hole.

[0013] Preferably, a loading hole for loading a nano probe is further arranged on the upper end surface of the rotating disc.

[0014] A detection method for atrazine detection is realized by a multi-unit rotary detection device, which comprises a screen printing biosensor, Pt@Pd nanoparticles as a peroxidase-like signal tag and a differential pulse voltammetry detection mode.

[0015] Preferably, the method comprises the following steps. Step S1, obtaining a pore water sample; Step S2, incubating the pore water sample with a nano probe to obtain a mixture A; Step S3, transferring the mixture A to the working electrode area of one screen printing biosensor to be detected; Step S4: Rotate the turntable so that the working electrode area of ​​the screen-printed biosensor to be tested, which carries mixture A, is opposite to the atomizing cleaning component. The atomizing cleaning component is loaded with phosphate-buffered saline solution. The atomizing cleaning component sprays the phosphate-buffered saline solution onto the surface of the working electrode area to elute unbound nanoprobes. Step S5: Continue rotating the turntable to remove the acid salt buffer solution from the surface of the working electrode area; Step S6: Add an electrochemical substrate solution containing hydroquinone and hydrogen peroxide to the surface of the working electrode area of ​​the screen-printed biosensor to be tested; Step S7: Rotate the turntable until it contacts the working electrode area of ​​the screen-printed biosensor to be tested with the contactor. Use the differential pulse voltammetry mode to measure and obtain the test result. The test is then complete.

[0016] Preferably, the nanoprobe in step S2 is prepared using the following steps: Step S21, Preparation of Pd@Pt nanoparticles: Potassium tetrachloroplatinate, sodium tetrachloropalladium, ascorbic acid and polyvinylpyrrolidone are mixed and ultrasonically treated in an ultrasonic cleaner to obtain Pd@Pt nanoparticles. Step S22: After centrifuging and washing, the Pd@Pt nanoparticles obtained in step S21 are dispersed in PBS buffer to obtain a Pd@Pt nanoparticle suspension. Step S23, Preparation of nanoprobes: Atrazine monoclonal antibody was added to Pd@Pt nanoparticle suspension to obtain composite liquid B; bovine serum albumin was injected into composite liquid B, and after centrifugation and washing, it was resuspended in phosphate buffer containing bovine serum albumin and sucrose to obtain nanoprobes.

[0017] This invention, by adopting the above technical solutions, has significant technical effects: This invention provides a portable and flexible atrazine detection device and corresponding detection method, which can continuously and rapidly detect multiple samples and quickly obtain the atrazine concentration in soil pore water, so as to support farmers in making timely decisions between crop planting and soil remediation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0019] Figure 2 yes Figure 1 Top view.

[0020] Figure 3 yes Figure 2 Cross-sectional view of the AA plane.

[0021] Figure 4 yes Figure 2Cross-sectional view of the middle BB plane.

[0022] Figure 5 These are morphological and microstructure diagrams of Pd@Pt nanoparticles in Example 3 of the present invention, where A is a scanning electron microscope image, B–D are transmission electron microscope images, and EF are elemental mapping images.

[0023] Figure 6 This is a Zeta potential diagram of the Pd@Pt nanoparticles and Ab-Pd@Pt nanoparticle composite in Example 4 of the present invention.

[0024] Figure 7 This is an electrochemical characterization diagram of the biosensor in Example 5 of the present invention, where A is a Nyquist plot, and in B, a represents naked SPE, b represents Au-SPE, c represents Ag-Au-SPE, and d represents Ag-BSA-Au-SPE in the presence of... CV curves in 0.1 MkCl aqueous solution, scan rate 100 mV / s.

[0025] Figure 8 This is a cyclic voltammogram of different redox media (3mM) obtained in PBS containing 2mM hydrogen peroxide using a SPE with Pd@Pt nanoparticles, as described in Example 6 of this invention. A represents hydroquinone, B represents thiophene acetate, C represents 3,3′,5,5′-tetramethylbenzidine, and blank represents measurements in PBS containing 2mM hydrogen peroxide at pH 7.4.

[0026] Figure 9 This is an optimization diagram of detection conditions in Example 7 of the present invention, where A represents the DPV response to 100 ng / mL atrazine and the DPV response without the target in a PBS solution containing 3 mM hydroquinone and 2 mM hydrogen peroxide, B represents the antigen concentration, C represents the incubation time between the nanoprobe and the target, and D represents the amount of Ab-labeled atrazine added at 0.1 ng / mL and 100 ng / mL, respectively.

[0027] Figure 10 This is a performance graph of the atrazine electrochemical biosensor in Example 8 of the present invention, where A is the DPV response curve (atrazine concentration from a to h: 0-250 ng / mL), and B is the linear relationship between current and the logarithm of atrazine concentration.

[0028] Figure 11 This is a schematic diagram of Example 9 of the present invention, where A represents the specificity at 100 ng / mL atrazine and other interfering proteins; and B represents the sensor repeatability study. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Example

[0030] This embodiment provides a multi-unit rotary detection device for atrazine detection, such as... Figures 1-4 As shown, it includes a base 1, on which a rotatable turntable 2 is provided. Multiple screen-printed biosensors 3 are evenly arranged around the rotation axis of the turntable 2 at the upper end surface of the turntable 2. In this embodiment, 6 screen-printed biosensors 3 are provided on the turntable.

[0031] The screen-printed biosensor 3 includes a working electrode area for carrying the target object to be detected and an electrode lead extending from and connected to the working electrode area. The base 1 is also equipped with an atomizing cleaning assembly 4 for cleaning the working electrode area and a contactor 5 that contacts the electrode lead. The screen-printed biosensor 3 can move sequentially to the lower part of the atomizing cleaning assembly 4 and the contactor 5 under the rotation of the turntable 2.

[0032] During operation, the operator can continuously drop the target object to be detected onto different sensors 3. By rotating them sequentially to the corresponding atomizing cleaning components 4 and the lower part of the contactor 5, continuous and rapid operation can be achieved, which can effectively improve the overall detection efficiency. Moreover, the overall device is small in size and portable, enabling on-site, low-cost, and easy-to-operate detection.

[0033] The screen-printed biosensor 3 includes a modified working electrode, a reference electrode, and a counter electrode. The areas where the working electrode, reference electrode, and counter electrode are located constitute the working electrode area. The working electrode, reference electrode, and counter electrode each extend and are connected to their respective electrode leads. The contactor 5 includes a contact mounting base 501 and a contact 502 disposed at the contact mounting base 501. A spring 503 is provided at the contact 502 to drive the contact 502 toward the working electrode area. When the screen-printed biosensor 3 moves to the lower part of the contactor 5, it can make contact with the contact 502 and maintain contact stability under the action of the spring 503. A multi-channel potentiostat is connected to the contact mounting base 501. When the contact 502 makes contact with the electrode leads, differential pulse voltammetry scanning detection of the target object on the working electrode area can be performed based on the multi-channel potentiostat.

[0034] Preferably, the base 1 includes a base body 101, with an upwardly extending turntable mounting post 102 in the middle of the base body 101. The turntable 2 is rotatably mounted on the turntable mounting post 102, and the lower end face of the turntable 2 is in clearance fit with the upper end face of the base body 101. In order to ensure the rotational stability of the turntable 2, a rotating bearing can also be provided between the turntable 2 and the turntable mounting post 102 so that it can rotate more smoothly and stably.

[0035] In this embodiment, the turntable 2 is also provided with a plurality of evenly arranged actuation grooves 201 on its side wall. When the operator rotates the turntable 2, he or she can rotate the turntable 2 by actuating the grooves 201 with his or her fingers, which makes the rotation of the turntable 2 more convenient.

[0036] In this embodiment, the upper end of the turntable mounting post 102 is provided with an extension arm 103 and an extension arm 104 arranged radially along the turntable 2 in the length direction. The atomizing cleaning component 4 is installed on the extension arm 103, and the contactor 5 is installed on the extension arm 104. The atomizing cleaning component 4 and the contactor 5 can correspond to two different screen-printed biosensors 3 at the same time.

[0037] The atomizing cleaning component 4 includes a liquid storage section 401 and an atomizing plate 402 disposed on the lower end face of the liquid storage section 401. The atomizing plate 402 is a microporous atomizing plate 402, which is connected to a PH2.0 port via a wire. The base body 101 is equipped with a power supply battery 105 and an atomizing control module 106 electrically connected to the atomizing plate 402. The power supply battery 105 is connected to the atomizing plate 402 through the atomizing control module 106. The atomizing control module 106 is equipped with a control switch 107 for controlling the opening and closing of the atomizing plate 402, and also has a PH2.0 port for insertion. The base body 101 has a battery mounting slot 110 at the bottom for mounting the battery 105. A battery mounting bracket is fixed in the battery mounting slot 110. A wire is connected to the battery mounting bracket to the power input port. The turntable mounting post 102 has a wire hole 108 in the middle that communicates with the battery mounting slot 110. The wire passes through the wire hole 108 and connects to the battery 105 and the atomization control module 106.

[0038] In this embodiment, the upper surface of the turntable 2 is also provided with a loading hole 109 for loading nanoprobes. The nanoprobes are loaded based on the device body, eliminating the need to set up test tubes to load the nanoprobes, which is more convenient. Example 2: Detection method for atrazine detection

[0039] This embodiment provides a detection method for atrazine detection, which can be implemented using the multi-unit rotary detection device in Embodiment 1. It is based on a high-sensitivity electrochemical detection mechanism involving Pt@Pd nanoparticles, specifically using a screen-printed biosensor 3, with Pt@Pd nanoparticles as a peroxidase-like signal tag for signal amplification mechanism, combined with electrochemical detection based on differential pulse voltammetry.

[0040] This embodiment includes the preparation of a screen-printed sensor for atrazine before specific detection. Specifically, a conventional screen-printed biosensor is first ultrasonically cleaned in ethanol and ultrapure water for 5 minutes each, repeated twice to ensure complete removal of surface contaminants. Subsequently, electrochemical cleaning is performed in 0.5M sulfuric acid at cyclic potentials between -0.2V and +1.5V (relative to Ag / AgCl) until a stable cyclic voltammogram (CV) is obtained, indicating that the electrode surface is clean and reproducible.

[0041] To deposit gold nanoparticles (AuNPs), 100 μL of 1% (w / v) solution was used. An aqueous solution was dropped onto the clean working electrode area of ​​the SPE. Electrochemical deposition was performed by 10 cycles of CV scanning between -0.4V and 0V to form a gold nanoparticle-modified electrode surface. After deposition, 10 μL of atrazine antigen solution was dropped onto the AuNP-modified working electrode and incubated at 4°C for 12 hours to allow for Au–S or Antigen immobilization was performed through interaction. To block non-specific binding sites, 10 μL of 1% (w / v) bovine serum albumin (BSA) solution was added and incubated at room temperature for 1 hour. Finally, unbound BSA was thoroughly washed away with phosphate-buffered saline (PBS) to complete electrode functionalization.

[0042] The specific testing steps are as follows: Step S1: Obtain a pore water sample; In this embodiment, pore water samples can be obtained by assembling simple tools on-site. Specifically: A pore water sampler was attached to a syringe with the needle removed. The pore water sampler was inserted into the soil to be tested. The syringe piston was pulled outward and kept in the corresponding position for more than 30 minutes. Pore water samples gradually appeared in the syringe. Step S2: Incubate 15 μL of pore water sample with the nanoprobe for a short incubation period of a few minutes to allow for competitive reactions, and obtain mixture A; The preparation of Pd@Pt nanoparticles and nanoprobes is as follows: (1) First, a mixed solution prepared by mixing 3.6 mL of 20 mM potassium tetrachloroplatinate, 0.4 mL of 20 mM sodium tetrachloropalladium, 4 mL of 100 mL of ascorbic acid and 20 mg of polyvinylpyrrolidone (PVP) was heated to 50 °C and sonicated in an ultrasonic cleaner for 4 hours. This synthesized Pd@Pt nanoparticles. Then, the nanoparticles were centrifuged at 12,000 rpm for 8 minutes, washed three times with acetone, and then washed three times with water. Finally, the Pd@Pt nanoparticles were dispersed in 5 mL of PBS (1 mM) to obtain a Pd@Pt nanoparticle suspension.

[0043] (2) Assembly of nanoparticle-labeled probes via electrostatic adsorption. First, 2 μL of 1 mg / mL atrazine monoclonal antibody was added to the Pd@Pt nanoparticle suspension, the pH was adjusted to 8.5, and the suspension was incubated at 4 °C for 4 hours. Then, 10.0% bovine serum albumin was injected into the composite liquid, and the nonspecific sites were incubated at room temperature for 30 minutes. Finally, the nanoparticles were centrifuged twice with 0.01 M (pH 7.4) phosphate buffer containing 2.0% bovine serum albumin and 3.0% sucrose, at 10,000 rpm for 10 minutes each time, and then resuspended in 200 μL of 0.01 M (pH 7.4) phosphate buffer to obtain the nanoparticle probes. The obtained nanoparticle probes were stored at 4 °C for future experiments.

[0044] Step S3: Transfer mixture A onto the working electrode area of ​​one of the screen-printed biosensors 3 to be tested; Step S4: Rotate turntable 2, first rotate 60° so that the working electrode area of ​​the screen-printed biosensor 3 to be tested, which carries mixture A, is opposite to the atomizing cleaning component 4. The atomizing cleaning component 4 is loaded with phosphate buffered saline. The atomizing cleaning component 4 sprays the phosphate buffered saline onto the surface of the working electrode area to remove unbound residues and impurities. Step S5: Continue to rotate the turntable 60° to remove the acid salt buffer solution from the surface of the working electrode area so that the washing solution is completely drained. Step S6: Add an electrochemical substrate solution containing 3 mM hydroquinone and 2 mM hydrogen peroxide to the surface of the working electrode area of ​​the screen-printed biosensor 3 to be detected, and react for 2 minutes; Step S7: Rotate the turntable 2 until the working electrode area of ​​the screen-printed biosensor 3 to be tested contacts the contactor 5, and use the differential pulse voltammetry mode to measure and obtain the detection result. The detection is then complete.

[0045] The DPV scan is performed from 0.1V to -0.45V (relative to the reference electrode), with a pulse amplitude of 50mV and a pulse width of 50ms.

[0046] This embodiment provides an apparatus and method for rapid quantitative detection of atrazine in soil pore water. The apparatus utilizes a 3D-printed rotatable platform to position a screen-printed biosensor 3 (SPE) for continuous analysis steps, thereby greatly simplifying the complex workflow of traditionally competitive immunosensor-based detection.

[0047] This (POC) device has a limit of detection (LOD) of 0.0116 ng / mL for atrazine, and its analytical performance has been validated with spiked samples, with recoveries ranging from 82.17% to 104.76%. The device's excellent performance is attributed to the peroxidase-like catalytic activity of the synthesized Pd@Pt nanoparticles, which act as efficient signal transducers. Furthermore, the integrated nebulizer plate ensures effective and uniform cleaning of unbound nanoprobes on each SPE, thereby improving measurement reproducibility. Example 3 Characterization of Pd@Pt nanoparticles and nanoprobes

[0048] The morphology and microstructure of the synthesized Pd@Pt nanoparticles were studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), such as... Figure 5 As shown in the image (AD), the nanoparticles possess a core-shell structure, with a deeper Pt core surrounded by a shallower Pd shell. The elemental mapping of Pd@Pt reveals the distribution of Pt and Pd. Figure 7 (A) The average particle size, measured from multiple TEM images, is approximately 40 nm. This nanoscale size contributes to enhanced surface reactivity, further supporting their function as effective catalytic probes, making Pd@Pt nanoparticles well-suited for signal amplification and biosensing platforms.

[0049] The Pt@Pd nanoparticle-antibody conjugate was characterized by zeta potential analysis. This binding depends on passive absorption via electrostatic interaction between the negatively charged nanoparticles and the positively charged antibody amino groups. Figure 6 As shown, the zeta potential of the Pt@Pd nanoparticles is -20.97 mV, indicating that the surface of the Pt@Pd nanoparticles is negatively charged before binding with the antibody. After binding with the atrazine antibody, the zeta potential increases to -7.16 mV. The change in zeta potential before and after binding confirms that the Pt@Pd nanoparticles have successfully bound to the antibody.

[0050] To further evaluate the peroxidase-like activity of the nanoprobe, it was added to a mixture containing TMB and... Upon immersion in the solution, a rapid color change of TMB was clearly observed within 1 minute. Correspondingly, the UV-vis spectrum showed a characteristic absorption peak at 652 nm, attributed to the oxidized TMBox species. This result confirms the excellent catalytic activity of the nanoprobe. Example 4 Electrochemical characterization of screen-printed biosensor SPE

[0051] The stepwise modification of screen-printed biosensors (SPEs) was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It contains 0.1 MkCl as a redox probe.

[0052] like Figure 7 As shown in A, the EIS Nyquist plot reflects the interfacial electron transfer resistance (R) at different modification stages. ct Curve b represents bare SPE. After electrodeposition of gold nanoparticles (AuNPs), the semicircle diameter further decreased, confirming enhanced electron transfer kinetics due to the high conductivity and large surface area of ​​AuNPs. However, sequential modification with atrazine antigen and bovine serum albumin (BSA) resulted in R... ct The gradual increase is attributed to the insulating properties of the immobilized proteins, which hinder electron transfer at the electrode-electrolyte interface.

[0053] Complementary CV analysis Figure 7 B) further confirms these observations. A pair of [something] appeared on the bare SPE. The coupling produces clear redox peaks (curve a). After AuNP deposition (curve b), the peak current increases significantly, reflecting the excellent electrocatalytic and conductive properties of the gold nanostructure. After immobilization of atrazine antigen (curve c), the redox peak current decreases significantly, indicating a reduction in surface conductivity due to the formation of a non-conductive protein layer. A further decrease in peak current is observed after blockade with bovine serum albumin (BSA) (curve d), consistent with the additional coverage of the electrode surface by insulating protein molecules.

[0054] These gradual electrochemical changes demonstrate the successful layer-by-layer assembly and surface functionalization of the SPE, confirming each stage of the sensor manufacturing process. Example 5 Evaluation of redox mediators used in electrochemical detection

[0055] Redox mediators play a crucial role in facilitating efficient electron transfer and amplifying electrochemical signals in sensing systems. To determine the most suitable redox mediator for our signal amplification strategy, we evaluated the electrochemical performance of three commonly used mediators: 3,3′,5,5′-tetramethylbenzidine, hydroquinone, and thiophene acetate (Thi). In the presence of Pt@Pd nanoparticles, their reduction peak currents were measured in PBS (pH 7.4) as an indicator of catalytic efficiency.

[0056] like Figure 8 As shown in A–C, in the absence of any redox mediator (blank), Electrochemical response in PBS (pH 7.4), in the presence of a single redox mediator. For example... Figure 8 In A, a distinct reduction peak was observed at -0.18 V, with a peak current of 12.0 μA for hydroquinone. Similarly, inFigure 8 In group B, thiolite exhibits a low peak reduction current of 8.78 μA at –0.20 V. Conversely, in Figure 8 The presence of 3,3′,5,5′-tetramethylbenzidine TMB in C leads to a reduction peak at approximately 0.20 V, with a peak current of only 6.80 μA. Among the three redox mediators tested, hydroquinone in nanoparticles and Hydroquinone exhibits the highest current response in its presence, while TMB shows the lowest. Therefore, hydroquinone was chosen as the optimal redox mediator for the signal amplification system. Example 6: Principle of Competitive Electrochemical Immunoassay

[0057] After adding the sample to the nanoprobe solution and incubating briefly, the target analyte specifically binds to the antibody-bound Pd@Pt nanoparticles (Ab–Pd@PtNPs). This binding prevents the Ab–Pd@PtNPs from being captured by the working electrode (SPE), where the corresponding hapten is immobilized. Therefore, in the subsequent PBS washing step, the unbound nanoprobes are removed, resulting in a reduction in the number of Pd@PtNPs remaining on the electrode surface. Thus, in Figure 9 In A, the electrochemical signal generated by the catalytic reaction of Pd@PtNPs with hydroquinone and hydrogen peroxide will decrease.

[0058] In this signal amplification strategy, Pd@PtNPs in In the presence of a catalyst, hydroquinone is oxidized to produce benzoquinone (BQ), which is then electrochemically reduced, producing a distinct reduction peak in the differential pulse voltammetry (DPV) curve. The peak current is directly proportional to the amount of Pd@PtNPs captured on the electrode, and therefore inversely proportional to the concentration of the target analyte in the sample. Thus, the combination of competitive immunoassay and electrochemical detection enables the quantitative determination of atrazine concentration. Subsequently, the analyte level is calculated from the calibration curve based on the DPV peak current. Example 7: Optimization of Detection Conditions

[0059] To develop sensitive, reproducible, and time-saving biosensing conditions, various operating parameters must be optimized, including the concentration of atrazine-modified antigen in the SPE, the incubation time of atrazine and Ab-Pt@PdNPs, and the amount of nanoprobes. Using 0.1 ng / mL and 100 ng / mL atrazine as models, the sensor optimization parameters were evaluated by comparing the corresponding current response and signal difference (ΔI) to achieve the best sensor performance.

[0060] The amount of atrazine antigen modified on the SPE affects the binding affinity with the antibody, thus influencing the current value. Therefore, we optimized the antigen concentration to improve sensitivity. Figure 9As shown in Figure B, increasing the concentration of atrazine antigen immobilized on the SPE surface from 5 to 15 μg / mL resulted in a significant enhancement of the current response at low atrazine concentrations (0.1 ng / mL). This enhancement is attributed to the increased surface coverage of the immobilized antigen, thereby enhancing competitive binding with free atrazine molecules in solution. Under these conditions, more Ab-Pt@Pd nanoprobes were captured by the surface-bound antigen and retained on the electrode, resulting in a stronger electrochemical signal. Conversely, at high atrazine concentrations (100 ng / mL), most nanoprobes preferentially bound to free atrazine in solution, resulting in fewer nanoprobes captured on the electrode and thus a smaller signal increase. The signal difference (ΔI) between low and high concentrations reached its maximum at 15 μg / mL, indicating that this is the optimal antigen loading for achieving the highest sensitivity. However, further increasing the antigen concentration to 20 and 25 μg / mL resulted in a sustained signal enhancement at high atrazine concentrations, but not at low concentrations, leading to a decrease in ΔI. This is attributed to the fact that the number of nanoprobes on the electrode surface had reached saturation, and the signal no longer increased at low analyte levels, while still allowing for effective probe capture at high atrazine concentrations. Therefore, 15 μg / mL was chosen as the optimal antigen concentration for sensor construction.

[0061] The incubation time between the nanoprobe and the target directly affects sensor performance, influencing the recognition between Ab-Pt@PdNP and atrazine. We optimized incubation times from 10 to 40 minutes to obtain the best performance. Figure 9 As shown in Figure C, the effect of incubation time between the Ab-Pt@Pd nanoprobe and atrazine in the range of 10 to 50 minutes was evaluated. The signal difference (ΔI) increased with increasing incubation time, reaching a maximum at 30 minutes, indicating that this duration provides sufficient time for effective antigen-antibody interaction and stable binding. However, extending the incubation time beyond 30 minutes did not further enhance ΔI and even resulted in a slight decrease. This reduction may be due to the different saturation kinetics at low and high atrazine concentrations: at low concentrations, the system may reach binding equilibrium earlier, while high concentrations continue to promote probe-antigen interaction over time. Therefore, the signal difference between the two concentrations becomes less significant at longer incubation times. Thus, 30 minutes was chosen as the optimal incubation time to maximize sensitivity and assay efficiency.

[0062] Equally important is optimizing the amount of nanoprobes. Too many nanoprobes increase background noise, thus reducing sensor sensitivity. Conversely, very low amounts result in signals so weak that the increase in Ab-Pd@Pt binding is undetectable in the control, or the difference in atrazine concentrations cannot be discerned. Figure 9As shown in Figure D, the signal difference (ΔI) increases with increasing volume of the Ab-labeled nanoprobe from 5 to 10 μL, indicating enhanced target recognition and improved signal output. However, further increases beyond 10 μL lead to a decrease in ΔI. This phenomenon can be attributed to the saturation of the nanoprobe on the electrode surface, particularly at low atrazine concentrations (0.1 ng / mL), where the weak competitive binding ability of the analyte limits probe displacement. Conversely, at high atrazine concentrations (100 ng / mL), the increased nanoprobe volume continues to enhance binding and signal output due to stronger competition. The largest difference in current response between low and high atrazine concentrations is observed at 10 μL, reflecting the optimal balance between signal generation and background interference. Therefore, 10 μL is chosen as the optimal nanoprobe volume to achieve high sensitivity while minimizing nonspecific signals. Example 8: Analytical performance of atrazine electrochemical biosensor

[0063] Under optimized conditions, the electrochemical performance of the biosensor for atrazine detection was evaluated using differential pulse voltammetry (DPV). Figure 10 As shown in Figure A, the reduction peak current gradually decreased with increasing atrazine concentration, consistent with the competitive immunoassay format. A good linear relationship was observed between the reduction peak current and the logarithm of the atrazine concentration in the range of 0.1 to 250 ng / mL, as shown in Figure A. Figure 10 As shown in B in the figure. The corresponding linear regression equation is I(μA) = 11.52046 – 3.23017logC, with a correlation coefficient of R² = 0.994, indicating excellent linearity. The limit of detection (LOD) was calculated to be 0.0116 ng / mL (S / N = 3), indicating that the developed biosensor has high sensitivity.

[0064] Compared to some traditional immunoassay-based methods and other electrochemical detection methods, the proposed device exhibits a superior sensitivity range. This high sensitivity is primarily attributed to the excellent biocompatibility and intrinsic peroxidase-like catalytic activity of the Pt@Pd nanoparticles, which facilitates efficient signal generation in the presence of hydrogen peroxide and hydroquinone. Furthermore, the incorporation of Pt@Pd nanoparticles significantly enhances the conductivity of the nanoprobe. This improved conductivity results in a greater difference in current signal between low and high analyte concentrations. At lower analyte concentrations, more Ab–Pt@PdNPs are immobilized on the working electrode surface due to the competitive immunoassay mechanism. The higher nanoparticle density not only accelerates the catalytic reaction—generating a stronger electrochemical signal—but also reduces the electrode surface resistance, further amplifying the signal difference. This dual contribution to signal enhancement forms the basis for the device's high sensitivity and excellent analytical performance. Example 9: Selectivity and Reproducibility of the Detection Device

[0065] To evaluate the specificity of the proposed electrochemical device for atrazine detection, six herbicides—promethazine, glyphosate, diuron, thidiazuron, nicosulfuron, and bensulfuron-methyl—were tested. Each herbicide was detected at a concentration of 100 ng / mL and compared with atrazine at the same concentration. Figure 11 As shown in Figure A, the change in current response from non-target herbicides is minimal, indicating that the interference is negligible. In contrast, a significant decrease in current was observed in the presence of atrazine at the same concentration, demonstrating the excellent selectivity of this biosensor. This high specificity is attributed to the strong and selective binding affinity of the immobilized atrazine antibody, further validating the anti-interference capability of the developed sensing platform.

[0066] The reproducibility of the biosensor was also evaluated by fabricating six identical devices and measuring the current response to 100 ng / mL atrazine. Figure 11 As shown in B, the current signals are consistent, and the resulting standard deviation (SD) is 0.133 (n=6), which confirms the good reproducibility and reliability of the sensor manufacturing and testing process. Example 10: Evaluation of the applicability of the device in pore water sample analysis

[0067] To evaluate the accuracy and practicality of the developed electrochemical device, uncontaminated soil was first extracted using the aforementioned portable extraction tool to obtain pore water samples. These samples were then added to known concentrations of atrazine (10, 50, and 100 ng / mL) to simulate environmental pollution scenarios. Each concentration level was analyzed at three time points using the device, and the results are summarized in Table 1, which shows the recovery rates of atrazine in soil pore water samples determined by this device (n=3).

[0068] Recovery rates ranged from 82.17% to 104.76%, and relative standard deviations (RSDs) ranged from 2.15% to 6.42%, indicating reasonable reproducibility and quantitative reliability. These results confirm that the device exhibits negligible matrix interference and maintains high analytical accuracy in complex environmental matrices. The results demonstrate that our device can detect soil pore water and can well simulate the detection of atrazine in the field.

[0069]

[0070] It is readily understood that those skilled in the art can combine, split, or reorganize the embodiments provided in this application to obtain other embodiments, none of which exceed the protection scope of this application.

[0071] In summary, the above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the present invention.

Claims

1. A multi-unit rotary detection device for atrazine detection, comprising a base (1), characterized in that: The base (1) is provided with a rotating turntable (2). Multiple screen-printed biosensors (3) are evenly arranged around the rotation axis of the turntable (2) at the upper end face of the turntable (2). The screen-printed biosensor (3) includes a working electrode area for carrying the target object to be detected and an electrode lead extending from and connected to the working electrode area. The base (1) is also equipped with an atomizing cleaning assembly (4) for cleaning the working electrode area and a contactor (5) that contacts the electrode lead. The screen-printed biosensor (3) can move sequentially to the lower part of the atomizing cleaning assembly (4) and the contactor (5) under the rotation of the turntable (2).

2. The multi-unit rotary detection device for atrazine detection according to claim 1, characterized in that: The base (1) includes a base body (101), and a turntable mounting post (102) extending upward is provided in the middle of the base body (101). The turntable (2) is rotatably mounted on the turntable mounting post (102) and the lower end face of the turntable (2) is in clearance fit with the upper end face of the base body (101).

3. The multi-unit rotary detection device for atrazine detection according to claim 2, characterized in that: The upper end of the turntable mounting post (102) is provided with an extension arm one (103) and an extension arm two (104) arranged radially along the turntable (2) in the length direction. The atomizing cleaning assembly (4) is installed on the extension arm one (103), and the contactor (5) is installed on the extension arm two (104). The atomizing cleaning assembly (4) and the contactor (5) can correspond to two different screen-printed biosensors (3) at the same time.

4. The multi-unit rotary detection device for atrazine detection according to claim 3, characterized in that: The atomizing cleaning assembly (4) includes a liquid storage section (401) and an atomizing plate (402) disposed on the lower end face of the liquid storage section (401).

5. The multi-unit rotary detection device for atrazine detection according to claim 1, characterized in that: The contactor (5) includes a contact mounting base (501) and a contact (502) disposed at the contact mounting base (501), and a spring (503) is provided at the contact (502) for driving the contact (502) to move toward the working electrode area.

6. The multi-unit rotary detection device for atrazine detection according to claim 4, characterized in that: The base body (101) is provided with a power supply battery (105) and an atomization control module (106) electrically connected to the atomizing plate (402). The power supply battery (105) is connected to the atomizing plate (402) through the atomization control module (106). The atomization control module (106) is provided with a control switch (107) for controlling the opening and closing of the atomizing plate (402). The turntable mounting column (102) is provided with a wire hole (108) in the middle. A wire electrically connected to the power supply battery (105) is connected in the wire hole (108).

7. The multi-unit rotary detection device for atrazine detection according to claim 1, characterized in that: The upper surface of the turntable (2) is also provided with loading holes (109) for loading nanoprobes.

8. A detection method for atrazine, characterized in that, It is implemented using the multi-unit rotary detection device described in any one of claims 1-7.

9. The detection method for atrazine detection according to claim 8, characterized in that, Includes the following steps: Step S1: Obtain a pore water sample; Step S2: Incubate the pore water sample with the nanoprobe to obtain mixture A; Step S3: Transfer mixture A to the working electrode area of ​​one of the screen-printed biosensors (3) to be tested; Step S4: Rotate the turntable (2) so that the working electrode area of ​​the screen-printed biosensor (3) carrying mixture A is opposite to the atomizing cleaning assembly (4). The atomizing cleaning assembly (4) is filled with phosphate buffered saline solution. The atomizing cleaning assembly (4) sprays the phosphate buffered saline solution onto the surface of the working electrode area. Step S5: Continue rotating the turntable (2) to remove the acid salt buffer solution from the surface of the working electrode area; Step S6: Add an electrochemical substrate solution containing hydroquinone and hydrogen peroxide to the surface of the working electrode area of ​​the screen-printed biosensor (3) to be detected; Step S7: Rotate the turntable (2) until the working electrode area of ​​the screen-printed biosensor (3) to be tested contacts the contactor (5), and use the differential pulse voltammetry mode to measure and obtain the detection result. The detection is then completed.

10. The detection method for atrazine detection according to claim 9, characterized in that, The nanoprobe in step S2 is prepared using the following steps: Step S21, Preparation of Pd@Pt nanoparticles: Potassium tetrachloroplatinate, sodium tetrachloropalladium, ascorbic acid and polyvinylpyrrolidone are mixed and ultrasonically treated in an ultrasonic cleaner to obtain Pd@Pt nanoparticles. Step S22: After centrifuging and washing, the Pd@Pt nanoparticles obtained in step S21 are dispersed in PBS buffer to obtain a Pd@Pt nanoparticle suspension. Step S23, Preparation of nanoprobes: Atrazine monoclonal antibody was added to Pd@Pt nanoparticle suspension to obtain composite liquid B; bovine serum albumin was added to composite liquid B, and after centrifugation and washing, it was resuspended in phosphate buffer containing bovine serum albumin and sucrose to obtain nanoprobes.

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