An electromagnetic eddy current assisted core-shell sers magnetic separation detection device

Abstract

The application discloses a kind of electromagnetic eddy current auxiliary core-shell SERS magnetic separation detection devices, including control system, electromagnetic device and SERS detection system;Control system includes computer and is used for controlling the power control switch of electromagnetic device;Electromagnetic device includes four electromagnets equally distributed on substrate;Each electromagnet has independent power control switch;Control system controls the on-off of each power control switch, realizes to the current direction and current size in first electromagnet, second electric electromagnet, third electromagnet and fourth electromagnet are controlled;SERS detection system includes laser, SERS probe, SERS processor and SERS computer;Laser emits laser, and SERS probe fixed in the central of substrate detects sample, SERS processor pre-processes the information fed back to SERS probe, and the signal after this pre-processing is transmitted to SERS computer, and then the signal is finally handled and output by SERS computer.

Description

Technical Field

[0001] This invention relates to the fields of nanomaterials and food science, and in particular to an electromagnetic eddy current-assisted core-shell SERS magnetic separation and detection device. Background Technology

[0002] Strengthening scientific research on hazardous substance monitoring technologies in food safety and improving the accuracy and efficiency of food safety testing are key to maintaining food safety and protecting consumers' health.

[0003] Traditional detection methods suffer from drawbacks such as complex pretreatment, long processing cycles, and complex sample preparation. Surface-enhanced Raman spectroscopy, as an ultrasensitive and rapid detection technology, possesses unique molecular structural fingerprints, which can significantly amplify Raman signals and even achieve ultrasensitive detection of single molecules. Compared with other detection technologies, it has outstanding advantages in non-destructive testing, no need for sample pretreatment, and providing high spatial resolution, thus having broad development prospects.

[0004] Among the factors affecting the SERS detection effect, the design of the SERS substrate is the main factor. In the process of synthesizing the SERS substrate, impurity particles are usually washed away and separated by centrifugation, which involves complex preparation steps, multiple centrifugation times, and long time.

[0005] In recent years, magnetic nanoparticles (MNPs) have shown great application potential. Firstly, MNPs are easy to synthesize and have controllable sizes, exhibiting good dispersibility, uniformity, magnetic response properties, and biocompatibility. Secondly, the surface of MNPs is easily modified, for example, with functional linking groups, surface charges, and various recognition elements (such as antibodies and aptamers), enabling specific binding or recognition of target molecules. Thirdly, they are easy to separate; MNPs can be rapidly enriched under the influence of a magnet, significantly reducing analysis time. Furthermore, magnetic MNPs can be combined with many noble metal nanomaterials to prepare magnetic SERS substrate composites for SERS signal enhancement. These composites can align in an ordered manner under an applied magnetic field, thus increasing "hot spots" and further enhancing the SERS signal.

[0006] However, magnetic SERS substrates still require the use of magnets to deposit and enrich the substrate during the detection process, followed by discarding the supernatant before detection. This process may result in uneven deposition, leading to inaccurate SERS detection results. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide an electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device. This invention controls the magnetic force distribution near the SERS probe to be uniform, resulting in a uniform distribution of the magnetic SERS substrate near the probe. Furthermore, it eliminates the need for magnet deposition to separate the supernatant, making operation more convenient, reducing experimental time, and enabling the magnetic SERS substrate to be applied to a wider range of scenarios.

[0008] This invention is achieved through the following technical solution:

[0009] An electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device includes a control system, an electromagnetic device, and a SERS detection system;

[0010] The control system includes a computer 1-1 and a power control switch 1-2 for controlling the electromagnetic device;

[0011] The electromagnetic device includes a first electromagnet 2-1, a second electromagnet 2-2, a third electromagnet 2-3, and a fourth electromagnet 2-4, which are evenly distributed on the inner substrate of the base shell 2-6.

[0012] The first electromagnet 2-1, the second electromagnet 2-2, the third electromagnet 2-3 and the fourth electromagnet 2-4 each have an independent power control switch 1-2;

[0013] The control system controls the on / off state of each power control switch 1-2, thereby controlling the direction and magnitude of the current in the first electromagnet 2-1, the second electromagnet 2-2, the third electromagnet 2-3, and the fourth electromagnet 2-4.

[0014] The control system also controls the order in which the first electromagnet 2-1, the second electromagnet 2-2, the third electromagnet 2-3, and the fourth electromagnet 2-4 are switched on and off by controlling the switching on and off of each power control switch 1-2.

[0015] The SERS detection system includes a laser 3-1, a SERS probe 3-2, a SERS processor 3-3, and a computer. The laser 3-1 emits a laser beam, which is used to detect the sample by the SERS probe 3-2, which is fixed in the center of the base shell 2-6. The SERS processor 3-3 preprocesses the information fed back by the SERS probe and transmits the preprocessed signal to the computer, which then performs the final processing and output of the signal.

[0016] Before the SERS processor 3-3 preprocesses the information fed back from the SERS probe, it is necessary to measure the SERS spectrum of the standard solution of the target analyte in advance to obtain the linear regression equation of the logarithmic concentration of the standard solution of the target analyte and the SERS intensity of the characteristic peak. Substituting the SERS intensity of the characteristic peak at the time of measurement into the equation, the concentration of the target analyte can be obtained.

[0017] After the first electromagnet 2-1, the second electromagnet 2-2, the third electromagnet 2-3, and the fourth electromagnet 2-4 are connected to the power supply, they respond in a cyclical manner in the following order:

[0018] S1: First electromagnet 2-1on, second electromagnet 2-2on, third electromagnet 2-3on, fourth electromagnet 2-4on;

[0019] S2: First electromagnet 2-1on, second electromagnet 2-2on-, third electromagnet 2-3off, fourth electromagnet 2-4off;

[0020] S3: First electromagnet 2-1off, second electromagnet 2-2on, third electromagnet 2-3on-, fourth electromagnet 2-4off;

[0021] S4: First electromagnet 2-1off, second electromagnet 2-2off, third electromagnet 2-3on, fourth electromagnet 2-4on-;

[0022] S5: First electromagnet 2-1on-, second electromagnet 2-2off, third electromagnet 2-3off, fourth electromagnet 2-4on;

[0023] The process continues in the order of S1-S5. Due to the change in current, the magnetic force of each electromagnet changes. The magnetic force changes in order from large to small, which eventually causes the magnetic particles in the cuvette to swing around the SERS probe 3-2 evenly, realizing the magnetic separation of the core and shell SERS and completing the detection at the same time.

[0024] In S1-S5, on indicates startup, off indicates shutdown, and on- indicates reduced current.

[0025] The base shell 2-6 is made of non-magnetic material. The base shell 2-6 is fixed to the support component or connecting component by the clamping sleeve 3-4.

[0026] The control system is a computer.

[0027] Compared with the prior art, the present invention has the following advantages and effects:

[0028] This invention controls the on / off state of each power control switch 1-2 through a control system, thereby controlling the direction and magnitude of the current in the first electromagnet 2-1, the second electromagnet 2-2, the third electromagnet 2-3, and the fourth electromagnet 2-4. The control system also controls the sequential on / off state of the first electromagnet 2-1, the second electromagnet 2-2, the third electromagnet 2-3, and the fourth electromagnet 2-4 by controlling the on / off state of each power control switch 1-2. As described above, this invention cleverly achieves uniform magnetic force distribution near the SERS probe through control, resulting in a uniform distribution of the magnetic SERS substrate near the probe. Furthermore, it eliminates the need for magnet deposition to separate the supernatant, making operation more convenient, reducing experimental time, and enabling the magnetic SERS substrate to be applied to a wider range of scenarios. Attached Figure Description

[0029] Figure 1 This is an overall schematic diagram of the electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device according to the present invention.

[0030] Figure 2 This is a schematic diagram of the device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection according to the present invention.

[0031] Figure 3 This is a top view of the device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection according to the present invention.

[0032] Figure 4 This is a partially enlarged view (front view) of the electromagnetic eddy current SERS detection probe of the present invention.

[0033] Figure 5 The SERS spectra (A) for detecting different concentrations of AFB1 in this invention and at 1467 cm⁻¹ -1 Linear regression curve of SERS intensity versus AFB1 log concentration at location (B). Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0035] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0036] (1) Synthesis of MNP@Ag-PEI

[0037] First, MNPs (ZnFe2O4) were prepared using an EG / EDG dual-thermal solvent method. Then, a layer of positively charged polyethyleneimine (PEI) was adsorbed onto the (negatively charged) surface of the MNPs, followed by the attachment of negatively charged AuNPs to the MNP@PEI surface. Using the AuNPs as seed sites, a silver shell was then modified onto the surface using a silver-ammonia reaction to form MNP@Ag. The thickness and shape of the silver shell were controlled by adjusting the amount of AgNO3 added. Different volumes (50, 100, 200, 300, and 400 μL) of PEI (5 mg / mL) were mixed with 400 μL of the prepared MNP@Ag and sonicated for 30 minutes to form MNP@Ag-PEI microspheres. After rinsing five times with ultrapure water, the final volume of the obtained MNP@Ag-PEI microspheres was adjusted to 400 μL with ultrapure water.

[0038] (2) Detection of actual samples

[0039] For AFB1 detection in actual samples, three uncontaminated nuts (peanuts, walnuts, and almonds) were first selected as pretreatment samples. The three samples were then ground into powder and weighed to 5g each. Next, 100μL of AFB1 solution (100μg / mL) was added to each of the three powders (5g) and allowed to stand for 30 minutes. Each nut powder was then dissolved in a mixture of methanol and ultrapure water (Vmethanol:Vwater = 4:1, total volume 9.9mL), followed by vigorous sonication for 30 minutes to aid extraction. After centrifugation at 12000rpm for 30 minutes, 15mg GBC and 400mg PSA were added sequentially to 3mL of the supernatant, followed by shaking (1200rpm) for 10 minutes to remove excess pigments, organic acids, and fats. Finally, the supernatant was centrifuged at 8000rpm for 5 minutes and filtered using a 0.22μm micromembrane sterile syringe filter. After incubation for the same period, measurements were performed using an electromagnetic eddy current-assisted core-shell SERS magnetic separation device. The solution was transferred to a cuvette, which was then placed on a cuvette holder. The SERS spectral acquisition system was turned on, and SERS spectra were measured using a laser confocal Raman microscope under a 785 nm laser.

[0040] When the computer starts up (1-1), the first electromagnet (2-1), the second electromagnet (2-2), the third electromagnet (2-3), and the fourth electromagnet (2-4) are connected to the power supply and respond in the following cyclical order:

[0041] S1: First electromagnet 2-1on, second electromagnet 2-2on, third electromagnet 2-3on, fourth electromagnet 2-4on;

[0042] S2: First electromagnet 2-1on, second electromagnet 2-2on-, third electromagnet 2-3off, fourth electromagnet 2-4off;

[0043] S3: First electromagnet 2-1off, second electromagnet 2-2on, third electromagnet 2-3on-, fourth electromagnet 2-4off;

[0044] S4: First electromagnet 2-1off, second electromagnet 2-2off, third electromagnet 2-3on, fourth electromagnet 2-4on-;

[0045] S5: First electromagnet 2-1on-, second electromagnet 2-2off, third electromagnet 2-3off, fourth electromagnet 2-4on;

[0046] The process continues in the order of S1-S5. Due to the change in current, the magnetic force of each electromagnet changes. The magnetic force changes in order from large to small, which eventually causes the magnetic particles in the cuvette to swing around the SERS probe 3-2 evenly, realizing the magnetic separation of the core and shell SERS and completing the detection at the same time.

[0047] The laser of the SERS detection system emits a laser of a fixed wavelength. After the SERS probe irradiates the sample, the signal is processed by the SERS spectrometer and transmitted to the computer to complete the acquisition and output of the SERS spectrum, thus completing the magnetic separation detection of the core-shell SERS of AFB1.

[0048] Based on optimized detection conditions, a standard curve was determined by introducing a series of AFB1 standard solutions of different concentrations.

[0049] Figure 5 (A) is the SERS spectrum of different concentrations of AFB1 detected by an electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device. (B) is the SERS spectrum at 1467 cm⁻¹. -1 The linear relationship between the SERS intensity at a given location and the logarithmic concentration of the AFB1 standard solution was determined by the linear regression equation y = -1038.15x + 3416.54, with a correlation coefficient R0. 2 The linear range was 0.001–1000 ng / mL, with a value of 0.9980. Based on this, the LOD and LOQ were calculated to be 0.45 pg / mL and 1.499 pg / mL, respectively.

[0050] The results of the determination of real samples are shown in Table 1. The recovery rate of the SERS method was 95.2%-108.6%, and the RSD value of the method did not exceed 9.7%, which confirmed the accuracy of the substrate detection.

[0051] Finally, the traditional ELISA method was used as a reference, and the detection results were compared with those of the electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device. As shown in Table 1, the recovery rate obtained by the ELISA method was 92.1%-108.9%, and the RSD value was 1.4%-8.0%. Therefore, the SERS detection results are comparable to those of the ELISA method, indicating the great potential of this electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device for detecting AFB1 in real food samples.

[0052] (3) Statistical analysis

[0053] All SERS spectra were measured under the following conditions: 785 nm excitation laser source, 100 mV power, 10 s acquisition time, and five recordings. The mean ± standard deviation was used as the SERS intensity. All other experimental measurements were performed in triplicate, and the final results were expressed as mean ± standard deviation. All data were analyzed and processed using Excel 2016 and Origin 2019b software (OriginLabCo., MA, USA).

[0054] Finally, the limit of detection (LOD) and limit of quantitation (LOQ) are calculated using the following formulas:

[0055] Y LOD =3S0+Y0(1);

[0056] LOQ = 3.33LOD(2);

[0057] Where S0 represents the standard deviation of SERS in the blank sample, and Y0 represents the average SERS of the blank sample.

[0058] Table 1 shows the detection of spiked AFB1 in nut samples (peanuts, walnuts, and almonds) using the established electromagnetic eddy current-assisted core-shell SERS magnetic separation detection device and the conventional ELISA method.

[0059]

[0060] As described above, the present invention can be implemented well.

[0061] The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection, comprising a control system, an electromagnetic device, and a SERS detection system; characterized in that: The control system includes a computer (1-1) and a power control switch (1-2) for controlling the electromagnetic device; The electromagnetic device includes a first electromagnet (2-1), a second electromagnet (2-2), a third electromagnet (2-3), and a fourth electromagnet (2-4) evenly distributed on the substrate inside the base shell (2-6); The first electromagnet (2-1), the second electromagnet (2-2), the third electromagnet (2-3), and the fourth electromagnet (2-4) each have an independent power control switch (1-2); The control system controls the on / off state of each power control switch (1-2) to control the direction and magnitude of the current in the first electromagnet (2-1), the second electromagnet (2-2), the third electromagnet (2-3), and the fourth electromagnet (2-4); The control system also controls the order in which the first electromagnet (2-1), the second electromagnet (2-2), the third electromagnet (2-3), and the fourth electromagnet (2-4) are switched on and off by controlling the switching on and off of each power control switch (1-2). The SERS detection system includes a laser (3-1), a SERS probe (3-2), a SERS processor (3-3), and a computer. The laser (3-1) emits a laser beam, which is used to detect the sample by the SERS probe (3-2) fixed in the center of the base shell (2-6). The SERS processor (3-3) preprocesses the information fed back by the SERS probe and transmits the preprocessed signal to the computer, which then performs the final processing and output of the signal.

2. The device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection according to claim 1, characterized in that: Before the SERS processor (3-3) preprocesses the information fed back by the SERS probe, it is necessary to measure the SERS spectrum of the standard solution of the target analyte in advance to obtain the linear regression equation of the logarithmic concentration of the standard solution of the target analyte and the SERS intensity of the characteristic peak. Substituting the SERS intensity of the characteristic peak at the time of measurement into the equation, the concentration of the target analyte can be obtained.

3. The device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection according to claim 1, characterized in that: After the first electromagnet (2-1), the second electromagnet (2-2), the third electromagnet (2-3), and the fourth electromagnet (2-4) are connected to the power supply, they respond cyclically in the following order: S1: First electromagnet (2-1) on, second electromagnet (2-2) on, third electromagnet (2-3) on, fourth electromagnet (2-4) on; S2: First electromagnet (2-1) on, second electromagnet (2-2) on-, third electromagnet (2-3) off, fourth electromagnet (2-4) off; S3: First electromagnet (2-1) off, second electromagnet (2-2) on, third electromagnet (2-3) on-, fourth electromagnet (2-4) off; S4: First electromagnet (2-1) off, second electromagnet (2-2) off, third electromagnet 2-3 on, fourth electromagnet (2-4) on-; S5: First electromagnet (2-1) on-, second electromagnet (2-2) off, third electromagnet (2-3) off, fourth electromagnet (2-4) on; The process continues in the order of S1-S5. Due to the change in current, the magnetic force of each electromagnet changes. The magnetic force changes in order from large to small, which eventually causes the magnetic particles in the cuvette to swing around the SERS probe (3-2) evenly, realizing core-shell SERS magnetic separation and completing the detection at the same time. In S1-S5, on indicates startup, off indicates shutdown, and on- indicates reduced current.

4. The device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection according to claim 1, characterized in that: The base shell (2-6) is made of non-magnetic material.

5. The device for electromagnetic eddy current-assisted core-shell SERS magnetic separation detection according to claim 1, characterized in that: The control system is a computer.

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