Molecularly imprinted sensor for detecting linoleic acid as well as preparation method and application of molecularly imprinted sensor
A molecularly imprinted sensor, prepared by doping graphene oxide with palladium nanoparticles and using a cobalt ferrite composite material, solves the problem of complexity and high cost in the detection of linoleic acid in existing technologies, achieving rapid and accurate detection results, and is suitable for food safety testing.
Patent Information
- Application Number
- CN202511102551.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-07
- Publication Date
- 2025-11-21
AI Technical Summary
Existing methods for detecting linoleic acid require complex pretreatment steps and expensive equipment, which limits their practical application in the pork supply chain, and they lack highly sensitive and selective detection methods.
A molecularly imprinted polymer material was prepared by copolymerizing palladium nanoparticle-doped graphene oxide and cobalt ferrite composite material with linoleic acid as template molecules. This material was then coated onto the electrode surface to form a molecularly imprinted sensor, which was detected by differential pulse voltammetry.
It enables rapid, accurate, highly sensitive, and highly selective detection of linoleic acid, simplifies the preparation process, reduces costs, and is suitable for food safety testing.
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Figure CN120992709A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of analytical detection, in particular to a molecular imprinting sensor for detecting linoleic acid and a preparation method and application thereof. BACKGROUND
[0002] Linoleic acid (LA) is an unsaturated fatty acid, and its intake in human body is crucial for preventing coronary heart disease, thrombosis, inflammation and obesity. In addition, LA can be used as a marker for detecting pork quality due to its easy oxidation, which produces by-products and leads to rancidity. Therefore, it is important to establish a reliable method for detecting LA.
[0003] Various methods for detecting LA have been developed, such as colorimetric method, gas chromatography and spectroscopy, which can achieve accurate detection of LA. However, these methods require complex pretreatment steps, professional technicians and expensive equipment, which limits their practical use in pork supply chain. In contrast, electrochemical sensors are attracting attention due to their rapid response, simple operation and low cost.
[0004] Therefore, it is a technical problem to be solved in the art to develop an electrochemical sensor for detecting linoleic acid. SUMMARY
[0005] In order to solve the above technical problems, the present application provides a preparation method of a molecular imprinting sensor for detecting linoleic acid, comprising: dispersing palladium nanoparticles (PdNPs)-graphene oxide (GO) and cobalt ferrite (CoFe2O4) in a solvent to obtain a composite material solution, then adding a functional monomer, a template molecule, a crosslinking agent and an initiator for copolymerization reaction, and eluting the template molecule to obtain a molecular imprinting polymer material, and coating the molecular imprinting polymer material (MIP / PdNPs-GO / CoFe2O4) on the surface of an electrode to obtain the molecular imprinting sensor; the functional monomer is 4-vinylpyridine (4-VP), and the template molecule is linoleic acid.
[0006] The palladium nanoparticle-doped graphene oxide has a large specific surface area and good electron transfer capacity, and has good electrochemical catalytic activity, which can promote the oxidation or reduction reaction of the electrical signal probe, and can significantly improve the response signal intensity of the sensor to the target substance LA. In addition, the doping of palladium nanoparticles can stabilize the structure of graphene oxide and prevent its aggregation, thereby improving the stability and repeatability of the sensor. CoFe2O4 has stable chemical properties, which can ensure the long-term reliability and stability of the sensor, and reduce the performance fluctuations and damage caused by environmental factors. LA as a template molecule interacts with 4-VP functional monomer to form a molecularly imprinted polymer with specific recognition ability for LA. After the template molecule is eluted, the MIP / PdNPs-GO / CoFe2O4 material forms a highly matched binding site for the target molecule, which can efficiently recognize and bind LA, and the homogeneous molecularly imprinted polymer material can improve the sensitivity of target substance detection.
[0007] In some embodiments, palladium nanoparticles (PdNPs)-graphene oxide (GO) and cobalt ferrite (CoFe2O4) are dispersed in a solvent to prepare a composite solution, and the solution is purged with N2 for more than 30 minutes.
[0008] In some embodiments, the electrode is a screen-printed electrode (SPE).
[0009] In some embodiments, the solvent is acetonitrile; and / or, the cross-linking agent is EGDMA; and / or, the initiator is AIBN.
[0010] In some embodiments, the copolymerization reaction conditions include refluxing at 50-80°C, preferably at 70°C.
[0011] In some embodiments, the refluxing time is 6-18h, preferably 12h.
[0012] In some embodiments, the reagent for eluting the template molecule is a mixture of methanol and acetic acid; preferably in a volume ratio of 1:1.
[0013] In some embodiments, in the composite solution, the concentration of palladium nanoparticle-graphene oxide is 0.3-0.8 mg / mL; the concentration of cobalt ferrite is 0.1-0.5 mg / mL, preferably 0.25-0.3 mg / mL; and / or, in the copolymerization reaction system, the concentration of the template molecule is 1-5 mM, preferably 2 mM; the concentration of the functional monomer is 3-9 mM, preferably 6 mM; and / or, the concentration of the coated molecularly imprinted polymer material is 1-8 mg / mL, preferably 5 mg / mL.
[0014] In some embodiments, the electrode is removed from surface impurities before use.
[0015] Preferably, the method for removing surface impurities comprises: placing the electrode in 0.01-0.1 M phosphate buffer (pH=7.2-7.4), preferably 0.01 M phosphate buffer, and activating by constant potential method (preferably 1.7 V).
[0016] Preferably, the activation time is 180 s to 300 s (more preferably 180 s).
[0017] Further, the present application provides a molecular imprinting sensor for detecting linoleic acid prepared by the preparation method of any one of the above embodiments.
[0018] Further, the present application provides the use of the molecular imprinting sensor in detecting the content of linoleic acid in a sample.
[0019] In some embodiments, the sample includes but is not limited to plant samples, animal samples (such as pork, etc.), processed products or biomedical samples.
[0020] In some embodiments, the form of the sample includes but is not limited to solid, liquid or powder.
[0021] Further, the present application provides a method for detecting the content of linoleic acid, comprising: connecting the molecular imprinting sensor to an electrochemical workstation, and detecting the content of linoleic acid in a sample by differential pulse voltammetry.
[0022] Preferably, the detection conditions of the differential pulse voltammetry include: potential -0.2-0.6 V, potential increment 0.004 V, amplitude 0.05 V, pulse width 0.05 s, pulse period 0.5 s, and sampling width 0.02 s.
[0023] In the specific implementation process, the content of linoleic acid can be obtained by establishing a standard curve.
[0024] In the specific implementation process, the pretreatment method for meat samples includes: stirring the meat sample and placing it in an ethanol solution for vigorous shaking, then centrifuging to obtain the supernatant, diluting the supernatant with (preferably 0.01 M) PBS buffer solution (preferably 10-fold dilution) for detection.
[0025] Compared with the prior art, the present application has the following beneficial effects: This invention provides a molecularly imprinted sensor for detecting linoleic acid (LA). This sensor can rapidly and accurately detect LA content in samples such as pork, achieving high sensitivity and selectivity for LA detection. The molecularly imprinted sensor of this invention has a simple preparation method and low manufacturing cost, and has broad application prospects in the field of food safety testing. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the fabrication process of the molecularly imprinted sensor in Example 1.
[0027] Figure 2 These are the detection performance test curves for different molecularly imprinted sensors. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. In the embodiments provided in this specification, where specific techniques or conditions are not specified, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. The PdNPs-GO and CoFe2O4 nanomaterials in the following embodiments were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.
[0029] Example 1 This embodiment provides a molecularly imprinted sensor for detecting linoleic acid, and its preparation process is illustrated in the schematic diagram below. Figure 1 As shown, the preparation method is as follows: (1) The SPE electrode was placed in 0.01M phosphate buffer (pH=7.2~7.4) and activated for 180 s using a constant potential method (1.7 V) to remove impurities from the electrode surface.
[0030] (2) Disperse 10 mg PdNPs-GO and 8 mg CoFe2O4 in 30 mL acetonitrile (ACN) and purge with N2 for 30 minutes.
[0031] (3) Add 2 mM LA and 6 mM 4-VP to the above solution, followed by 270 μL EGDMA and 20 mg AIBN.
[0032] (4) The mixture was refluxed at 70°C for 12 h, and then the precipitate was collected by centrifugation. The collected precipitate was washed with a methanol / acetic acid mixture (1:1, v / v) for 30 min, and then dried at 60°C under vacuum overnight to obtain the molecularly imprinted polymeric material (MIP / PdNPs-GO / CoFe2O4).
[0033] (5) A 5 mg / mL dispersion of the molecularly imprinted polymeric material was prepared, 5 μL of which was dropped onto the surface of the working electrode and dried to obtain a molecularly imprinted sensor, which was named MIP / PdNPs-GO / CoFe2O4 / SPE or MIP(4-VP) / PdNPs-GO / CoFe2O4 / SPE.
[0034] Example 2 The detection performance of the molecularly imprinted sensor prepared in Example 1 was tested in this example, and the steps were as follows: A series of LA-phosphate buffer solutions (pH=7.2-7.4) with concentrations of 1 nM, 10 nM, 100 nM, 1 μM, 10 μM, 100 μM, 1 mM and 10 mM were prepared, respectively. The molecularly imprinted sensor of Example 1 was connected to an electrochemical workstation (BIOSYP P20), and the detection was performed by differential pulse voltammetry (potential-0.2~0.6V, potential increment 0.004 V, amplitude 0.05 V, pulse width 0.05 s, pulse period 0.5 s, sampling width 0.02 s). After the standard solution was incubated on the electrode for 2 min, it was carefully removed, and then a mixed solution of 5 mM [Fe(CN)6] 3- / 4- and 1 M KCl was added dropwise. As the concentration of the LA solution increased, the molecularly imprinted polymer cavities were occupied, which hindered the redox of the electrical signal probe, and the DPV peak value gradually decreased. The peak current of the oxidation peak obtained in the blank solution was taken as I0, and the peak current obtained in the standard LA solution with different concentrations was taken as I x (x=1, 2, 3…), respectively. The ΔI x was calculated by the formula ΔI=I0-I x , respectively. Thus, a relationship curve between the logarithm of the LA concentration and ΔI was obtained, as shown in Figure 2 , and the linear detection range was 1 nM-10 mM.
[0035] Example 3 The accuracy of the molecularly imprinted sensor prepared in Example 1 was detected in this example. Specifically, the LA content in a pork sample was detected, and the steps were as follows: (1) 2.5 g of pork sample was stirred and crushed and placed in 10 mL of ethanol solution and shaken vigorously; (2) The above solution was placed in a centrifuge and centrifuged at a speed of 6000 r / min for 2 min; (3) The supernatant was taken and diluted 10 times with 0.01M PBS buffer solution, and then connected to an electrochemical workstation using the molecular imprinting sensor prepared in Example 1, and then tested by differential pulse voltammetry.
[0036] At the same time, the same pork sample was tested by gas chromatography (GC) as a control, and the conditions of gas chromatography were as follows: (1) Capillary column: polydicyclopentylsiloxane strong polarity stationary phase, column length 100 m, inner diameter 0.25 mm, film thickness 0.2 μm; (2) Injector temperature: 270 ℃; (3) Detector temperature: 280 ℃; (4) Programmed temperature: initial temperature 100 ℃, duration 13 min; 100 ℃-180 ℃, temperature rise rate 10 ℃ / min, hold for 6 min; 180 ℃-200 ℃, temperature rise rate 1 ℃ / min, hold for 20 min; 200 ℃-230 ℃, temperature rise rate 4 ℃ / min, hold for 10.5 min.
[0037] (5) Carrier gas: nitrogen.
[0038] (6) Split ratio: 100:1.
[0039] (7) Injection volume: 1.0 μL.
[0040] (8) The detection conditions should meet the requirements of at least 2000 / m of theoretical plate number (n) and at least 1.25 of resolution (R).
[0041] The same pork sample was tested for 6 times, and the results are shown in Table 1. The results show that the RSD of the detection results of Example 1 is 11.43%, the results have good consistency and are close to the detection concentration of gas chromatography, indicating that the detection results of the molecular imprinting sensor of Example 1 are accurate and reliable.
[0042] Table 1 Test results of LA in pork samples
[0043] Comparative Example 1 This comparative example provides a molecular imprinting sensor for detecting linoleic acid, and the only difference in the preparation method is that 4-VP is replaced with an equal amount of methacrylic acid (MAA), and the prepared molecular imprinting sensor is named MIP(MAA) / PdNPs-GO / CoFe2O4 / SPE.
[0044] The detection performance was tested according to the method of Example 2, and the results are shown inFigure 2 As shown in the figure, the detection range of the molecular imprinting sensor is 10 nM-1 mM, and the detection effect is not as good as that of Example 1.
[0045] Comparative Example 2 This comparative example provides a molecular imprinting sensor for detecting linoleic acid, and the preparation method is only different from that of Example 1 in that PdNPs-GO is replaced with an equal amount of PdNPs-CNT, and the prepared molecular imprinting sensor is named MIP(4-VP) / PdNPs-CNT / CoFe2O4 / SPE.
[0046] The detection performance is tested according to the method of Example 2, and the results are shown in the figure. Figure 2 As shown in the figure, the detection range of the molecular imprinting sensor is 100 nM-10 mM, and the detection effect is not as good as that of Example 1.
[0047] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for preparing a molecularly imprinted sensor for detecting linoleic acid, characterized by, The application relates to a molecular imprinting sensor and a use thereof. The palladium nanoparticle-graphene oxide and cobalt ferrite are dispersed in a solvent to prepare a composite solution, then a functional monomer, a template molecule, a crosslinking agent and an initiator are added to carry out a copolymerization reaction, the template molecule is eluted to prepare a molecular imprinting polymer material, and the molecular imprinting polymer material is coated on the surface of an electrode to prepare the molecular imprinting sensor; the functional monomer is 4-vinylpyridine, and the template molecule is linoleic acid.
2. The production method according to claim 1, characterized by, The electrode is a screen-printed electrode.
3. The production method according to claim 1, characterized by, The solvent is acetonitrile; the crosslinking agent is EGDMA; and the initiator is AIBN.
4. The preparation method according to claim 1, characterized in that, The copolymerization reaction is carried out under reflux at 50-80 DEG C.
5. The production method according to claim 4, characterized by, The reflux time is 6-18 hours.
6. The method of claim 1, wherein, The eluent of the template molecule is a mixture of methanol and acetic acid.
7. The preparation method according to claim 1, characterized in that, In the composite solution, the concentration of the palladium nanoparticle-graphene oxide is 0.3-0.8 mg / mL, and the concentration of the cobalt ferrite is 0.1-0.5 mg / mL. In the copolymerization reaction system, the concentration of the template molecule is 1-5 mM, and the concentration of the functional monomer is 3-9 mM. The concentration of the coated molecular imprinting polymer material is 1-8 mg / mL.
8. A molecularly imprinted sensor for detecting linoleic acid, characterized by, The molecular imprinting sensor is prepared by the preparation method in any one of claims 1-7.
9. The use of the molecular imprinting sensor in claim 8 in detecting the content of linoleic acid in a sample.
10. A method of detecting linoleic acid content, characterized by, The application relates to a molecular imprinting sensor and a use thereof. After the molecular imprinting sensor in claim 8 is connected to an electrochemical workstation, the content of linoleic acid in a sample is detected by a differential pulse voltammetry method.