Bimetal nanoparticle composite graphene portable electrochemical sensor prepared based on step-by-step laser induction method

Abstract

The invention discloses a bimetallic nanoparticle composite graphene portable electrochemical sensor prepared based on a step-by-step laser induction method, and belongs to the field of electrochemical sensing. Sulfamethoxazole (SMX) and trimethoprim (TMP) are selected as research objects, polyimide (PI) is taken as a substrate material, alloy nanoparticles of nickel and copper are introduced into laser induced graphene (LIG) through a two-step laser method, a NiCuNPs / LIG electrode material is prepared, and the electrochemical sensing technology is combined, so that the electrochemical sensing performance of the electrochemical sensor is improved. The laser-induced graphene electrochemical sensor which has excellent sensitivity and excellent selectivity and is used for detecting sulfamethoxazole and trimethoprim is constructed. According to the present invention, the portable analysis detection of the sulfamethoxazole content and the trimethoprim content is achieved, and the novel method for detecting the interaction between the sulfonamide antibiotics and the electrochemical sensor by using the portable element provides the reliable technical support for the detection of the sulfonamide antibiotics under the instant analysis environmental condition, such as the field, the emergency or the special scene.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical sensing, and particularly relates to a preparation method and application of a portable electrochemical sensor based on bimetallic nanoparticles composite graphene prepared by a stepwise laser-induced method. Background Art

[0002] Antibiotic pollution has become a global environmental concern. Due to the widespread use of antibiotics in the medical and agricultural fields, these compounds enter the natural environment through wastewater discharge, farmland infiltration and other channels, leading to the imbalance of the ecosystem and the increase of antibiotic resistance. In particular, sulfonamide (sulfamethoxazole (SMX) and trimethoprim (TMP)) antibiotics pose a potential threat to the environment and public health due to their wide application and persistence in the environment.

[0003] To effectively address the issue of antibiotic pollution, it is crucial to develop simple and rapid detection methods for timely identification of toxic pollutants in food and taking corresponding measures. Currently, the detection of most chemical and biological pollutants relies on centralized laboratories, which not only have limited sample throughput, but also involve complex processes, high costs, multiple analysis steps, sensitive reagents and expensive equipment, and are not portable. Therefore, there is an urgent need for a more efficient method that can perform remote screening at food production and processing sites lacking resources or professional equipment. Such easy-to-use, low-cost and on-site deployable technology will significantly improve the management and control level of environmental safety.

[0004] Currently, "point-of-care testing" has gradually become a new direction for environmental detection. Point-of-care testing refers to sampling and analysis on-site, without complex sample pretreatment, submission for inspection and equipment testing steps, and can quickly obtain results, which is of great significance for the early detection and real-time monitoring of environmental pollution. However, portable sensors for point-of-care testing still face many challenges. Traditional electrodes have problems such as high cost, large volume and fragility. Therefore, new portable sensors with advantages such as thin, flexible and low cost have become a research hotspot and are expected to provide better protection for human health. Existing biosensors still need to be further improved in terms of sensitivity, selectivity and stability.

[0005] As an emerging sensing technology, electrochemical sensors are considered an ideal choice for detecting antibiotics due to their rapid reaction, low cost, high sensitivity, low power consumption, and good selectivity. Portable electrochemical sensing strategies are emerging sensing platforms in recent years. They provide reliable, simple, and rapid results, are easy to carry, and have the ability to detect on-site. Portable electrochemical sensors only require a small amount of consumables and solvents during use, the sample pretreatment and preparation are simple, and they are cost-effective. In addition, it can achieve automated detection, has an intuitive user interface, is easy to operate, and can also be connected to digital ports and Bluetooth to analyze a larger number of samples in a shorter time at a lower cost. In recent years, the portable electrochemical sensor market has shown a steady growth trend, with continuous technological innovation and upgrading, and the application fields are constantly expanding. In the future, with the continuous progress of technology, portable electrochemical sensors will develop towards higher sensitivity and selectivity, wider application fields, and the direction of intelligence and networking.

[0006] Currently, the detection methods for sulfamethoxazole (SMX) and trimethoprim (TMP) are mainly laboratory techniques such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). However, these methods generally have problems such as complex operation, long time consumption, and expensive equipment, and it is difficult to meet the needs of on-site real-time monitoring. Therefore, it is of great significance to develop a rapid, low-cost, portable, and highly sensitive antibiotic detection method. The present invention is based on constructing a portable electrochemical sensor to achieve the effective monitoring of sulfamethoxazole (SMX) and trimethoprim (TMP). Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing a small electrochemical sensor by using polyimide (PI) as the electrode substrate, generating graphene loaded with nickel-copper nanoparticles through two-step laser induction as the electrode material, and combining it with a portable electrochemical workstation for the rapid and portable detection and analysis of sulfamethoxazole and trimethoprim.

[0008] The purpose of the present invention is mainly achieved by the following technical means:

[0009] In the present invention, using polyimide (PI) as the substrate material, generating graphene loaded with nickel-copper nanoparticles through two-step laser induction as the electrode material, combining electrochemical sensing technology, and combining a portable three-electrode with a small electrochemical workstation. The specific steps for preparing the portable electrochemical sensor in the present invention are as follows:

[0010] 1) Before laser induction, polyimide (PI) is ultrasonically cleaned with anhydrous ethanol and deionized water for 3 minutes respectively and then dried for standby.

[0011] 2) Use a computer to draw the pattern of the three-electrode system and import the pattern into CO 2In the laser, a portable electrode is constructed by laser-induced generation of nickel and copper nanoparticle-doped graphene twice, denoted as NiCuNPs / LIG.

[0012] 3) Stick polyimide insulating tape on the wire area of the electrode surface to isolate the sensing area and the detection area.

[0013] 4) Drop 2 μL of Ag / AgCl ink (purchased from ALS, Japan, product number 011464) at the position of the reference electrode, and dry it under an infrared lamp to serve as the reference electrode.

[0014] In step 2), the customized pattern is pre-drawn by CorelLASER 2013.02 software, CO 2 The laser power of the laser engraving system is set to 9.0 W, the laser scanning speed is fixed at 120 mm / s, and the laser is set to the focused state. When preparing the NiCuNPs / LIG three-electrode, the laser parameters have a significant impact on the physical and chemical properties of graphene. In this invention, the laser power is optimized. Among them, the laser power varies between 7.0 W and 9.0 W. As the laser power increases, the conductivity of the laser-induced graphene electrode (LIG) gradually increases. When the laser processing parameter is 9.0 W, the electrochemical performance is the best. When the laser power further increases, the generated LIG is easy to fall off. Finally, 9.0 W is selected as the optimal laser power. Under the optimal laser parameters, the generated NiCuNPs / LIG three-electrode has holes of different sizes, showing a quite dense hierarchical porous structure and a three-dimensional graphene skeleton in three dimensions ( Figure 1 ).

[0015] In step 2), the total concentration of the mixed aqueous solution of NiCl 2 and CuCl 2 is 100 mmol / L. Different ratios of the bimetallic aqueous solution have a great influence on the performance of the laser-induced graphene sensor. The ratio of the bimetallic aqueous solution directly affects the morphology of Ni-Cu bimetallic nanoparticles on the graphene surface during the laser-induced process, and then significantly changes the electrochemical performance of the sensor. During the experiment, the molar ratio of the Ni and Cu bimetallic aqueous solutions was optimized, and different Ni and Cu molar ratios (100:0, 87:13, 75:25, 62:38, 50:50, 38:62, 25:75, 13:87, 0:100) were compared. Differential pulse voltammetry (DPV) was used for measurement. The results show that at a molar ratio of 87:13, the peak current value of the differential pulse voltammetry (DPV) response is the highest, as Figure 3As shown, the charge transfer resistance (Rct) value of the NiCuNPs-modified electrode decreased significantly, which proves that the presence of NiCuNPs reduces the electron transfer resistance and effectively promotes the conductivity of the nanomaterials, consistent with the results of cyclic voltammetry (CV).

[0016] The specific steps for preparing the sulfamethoxazole (SMX) and trimethoprim (TMP) electrochemical sensors in this invention are as follows:

[0017] 1) Before laser induction, polyimide (PI) was ultrasonically cleaned with absolute ethanol and deionized water for 3 minutes respectively and then dried for standby.

[0018] 2) The three-electrode pattern was drawn by computer and the pattern was imported into the CO 2 laser, and LIG was induced on the polyimide (PI) film by using the CO 2 laser. The laser power was set at 9.0 W, the laser scanning speed was 120 mm / s, the laser was adjusted to the focusing mode, and the laser-induced graphene electrode (LIG) was generated by one-step laser induction. Then, the electrode surface was rinsed with ultrapure water and dried with nitrogen to stabilize the LIG electrode.

[0019] 3) 5 μL of the mixed aqueous solution with a total concentration of 100 mmol / L of NiCl 2 and CuCl 2 was pipetted and dropped at the working electrode position. The molar ratio of NiCl 2 and CuCl 2 was 87:13. Under the same conditions of one-time laser, the CO 2 laser was used to perform secondary laser induction at the same position on the polyimide (PI) film to generate the graphene electrode material (NiCuNPs / LIG) with NiCuNPs uniformly embedded in LIG.

[0020] 4) The wire area of the three-electrode pattern was encapsulated with polyimide insulating tape. Then, 2 μL of Ag / AgCl ink (purchased from ALS, Japan, product number 011464) was dropped and coated on the surface of the reference electrode of NiCuNPs / LIG and dried under an infrared lamp with a rated power of 800 W for 5 minutes to serve as the reference electrode.

[0021] Simultaneous specific recognition and detection of sulfamethoxazole and trimethoprim based on the portable electrochemical sensor:

[0022] 1) The modified electrode was immersed in the KCl solution containing K 3 [Fe(CN) 6 , and then electrochemical voltammetry scanning and alternating current impedance method measurement were performed on each modified electrode. After scanning, the corresponding cyclic voltammogram (CV) and alternating current impedance (EIS) diagrams could be obtained.

[0023] 2) Immerse the prepared electrochemical sensor into standard solutions of sulfamethoxazole and trimethoprim at a certain concentration, and measure using differential pulse voltammetry (DPV). Plot the concentration against the DPV response value.

[0024] 3) Select K + , Na + , Mg 2+ , Cl - and SO 4 2- as coexisting substances in the detection environment of sulfamethoxazole and trimethoprim to determine the selectivity of the portable electrochemical sensor.

[0025] Advantages of the present invention: This method creatively develops a step-by-step, low-cost and scalable method to in-situ prepare a shape-controllable hybrid electrode (NiCuNPs / LIG) with NiNPs and CuNPs uniformly embedded in LIG. Utilizing the high electrocatalytic activity of uniformly embedded NiCuNPs and the three-dimensional porous structure of LIG with excellent conductivity, the proposed portable (NiCuNPs / LIG) electrochemical sensor has excellent sensing performance for sulfamethoxazole and trimethoprim, and this method has not been reported. In summary, a concept of a portable electrochemical sensor for sulfonamide antibiotics NiCuNPs / LIG prepared by a simple, efficient and step-by-step laser direct writing process is designed, which can provide inspiration for constructing LIG electrodes embedded with various shape-controllable heterogeneous nanomaterials for high-performance sensors, highlighting the potential application prospects of portability. The laser-induced surface modification method proposed in this study, based on the characteristics of laser-induced non-contact and computer control, may be an attractive candidate method for mass-producing sensors.

[0026] Compared with other technologies for detecting sulfamethoxazole and trimethoprim, this method has a wider detection range for the two antibiotics, a low detection limit, and can detect two substances coexisting in the environment simultaneously, with good practical performance. This method realizes the effective and real-time detection and analysis of the content of sulfonamide antibiotics using portable components, and has broad development prospects in point-of-care testing. Description of the Drawings

[0027] Figure 1 is a high-resolution SEM image of a laser-induced nickel-copper nanoparticle-doped graphene electrode (NiCuNPs / LIG).

[0028] Figure 2 is a cyclic voltammetry (CV) diagram of a laser-induced graphene electrode before and after modification with nickel-copper nanoparticles in a KCl solution containing K 3 [Fe(CN) 6 .

[0029] Figure 3are impedance (EIS) diagrams of the laser-induced graphene electrode before and after modification with nickel-copper nanoparticles in a KCl solution containing K 3 [Fe(CN) 6 .

[0030] Figure 4 is a linear relationship diagram between the DPV response value of the electrochemical sensor (NiCuNPs / LIG) and the concentration of sulfamethoxazole.

[0031] Figure 5 is a linear relationship diagram between the DPV response value of the electrochemical sensor (NiCuNPs / LIG) and the concentration of trimethoprim. Detailed implementation mode

[0032] Example 1

[0033] A portable electrochemical sensor, including a working electrode, with polyimide as the substrate and nickel and copper metal nanoparticles as the modified electrode material, and producing nickel and copper-doped laser-induced graphene as the electrode material through two-step laser induction.

[0034] For the portable electrochemical sensor described above, the working electrode is a nickel and copper nanoparticle-doped laser-induced graphene electrode, with polyimide as the substrate material. The nickel and copper nanoparticles can provide more active sites for binding analytes, improving the sensitivity and selectivity of the sensor. There has been no report on a portable electrochemical sensor that produces nickel and copper nanoparticle-doped graphene through two-step laser induction so far.

[0035] For the portable electrochemical sensor described above, the nickel and copper nanoparticles are co-formed with the graphene material through two-step laser induction, creatively developing a two-step, low-cost and scalable method to in-situ prepare a shape-controllable hybrid electrode (NiCuNPs / LIG) with NiNPs and CuNPs uniformly embedded in LIG. This not only simplifies the steps of graphene doping but also utilizes the high electrocatalytic activity of uniformly embedded NiCuNPs and the three-dimensional porous structure of LIG with excellent conductivity to increase the reaction sites on the surface of the modified electrode and improve the sensitivity of the sensor. In short, the laser-induced surface modification technology proposed in this study, with its advantages of non-contact processing and precise computer control, provides a new idea for the preparation of heterogeneous nanomaterial / LIG composite electrodes with controllable morphology, and such electrodes show good application potential in the field of high-performance sensors. This technology is expected to become an ideal choice for mass production of sensors, especially in the application of portable devices with broad prospects.

[0036] The specific steps for preparing the sulfamethoxazole and trimethoprim electrochemical sensors in the present invention are as follows:

[0037] 1) Before laser induction, the polyimide (PI) film was ultrasonically cleaned with absolute ethanol and deionized water for 3 minutes respectively, and then dried for standby.

[0038] 2) The three - electrode pattern was drawn by computer and the pattern was imported into the CO 2 laser. Using the CO 2 laser to induce LIG on the polyimide (PI) film. The laser power was set at 9.0 w, the laser scanning speed was 120 mm / s, the laser was adjusted to the focusing mode, and the laser - induced graphene electrode (LIG) was generated by one - step laser induction. After that, the electrode surface was rinsed with ultrapure water and dried with nitrogen to stabilize the LIG electrode.

[0039] 3) Use a pipette to transfer 5 μL of the mixed aqueous solution with a total concentration of 100 mmol / L of NiCl 2 and CuCl 2 and drop it on the working electrode position. The molar ratio of NiCl 2 and CuCl 2 is 87:13. Under the same conditions of one - time laser, use the CO 2 laser to perform secondary laser induction at the same position on the polyimide (PI) film to generate a graphene electrode material (NiCuNPs / LIG) with NiCuNPs uniformly embedded in LIG.

[0040] 4) Use polyimide insulating tape to encapsulate the wire area of the three - electrode pattern to isolate the sensing area and the reaction area.

[0041] 5) Take 2 μL of Ag / AgCl ink and apply it on the surface of the reference electrode of NiCuNPs / LIG, and dry it under an infrared lamp with a rated power of 800 W for 5 min to obtain a self - contained three - electrode system.

[0042] Example 2

[0043] Based on the portable electrochemical sensor prepared in Example 1 for detection:

[0044] 1) Immerse the portable electrochemical sensor into 10 mL of 0.1 mol / L KCl solution containing 5 mmol / L K 3 [Fe(CN) 6 , and then perform electrochemical cyclic voltammetry scanning, differential pulse voltammetry scanning and alternating current impedance measurement on the electrochemical sensor. After scanning, the corresponding cyclic voltammetry (CV) diagram, differential pulse voltammetry (DPV) diagram and alternating current impedance (EIS) diagram can be obtained;

[0045] 2) Immerse the prepared electrochemical sensor into standard solutions containing sulfamethoxazole and trimethoprim with different concentration gradients (0.1, 0.5, 1, 5, 10, 20, 40, 60, 80, 100, 200, 300, 400, and 500 μmol / L), and measure using differential pulse voltammetry (DPV). Plot the concentration against the DPV response value;

[0046] 3) Select K + , Na + , Mg 2+ , Cl - and SO 4 2- as co-existing substances in the detection environment of sulfamethoxazole and trimethoprim to determine the selectivity of the portable electrochemical sensor.

[0047] As shown in the appendix Figure 4 , the peak current response Ipa and the concentration of sulfamethoxazole show a good linear relationship in the range of 100 μmol / L - 500 μmol / L. The linear equation is I pa (μA) = 0.0119x (μmol / L) + 6.007, and the correlation coefficient (R 2 ) is 0.993. The detection limit (LOD) of this method is calculated to be 0.01 μmol / L (S / N = 3). As shown in the appendix Figure 5 , the peak current response I pa and the concentration of trimethoprim show a good linear relationship in the range of 100 μmol / L - 500 μmol / L. The linear equation is: I pa (μA) = 0.0571x (μmol / L) + 0.379, and the correlation coefficient (R 2 ) is 0.997. The detection limit (LOD) of this method is calculated to be 0.005 μmol / L (S / N = 3). It shows that the portable electrochemical sensor constructed by the present invention can achieve quantitative detection of sulfamethoxazole and trimethoprim. Compared with the previously reported detection methods, the present invention has a wider detection range and a lower detection limit. This is because the NiCuNPs / LIG modified electrode has better electrochemical performance.

[0048] To study the selectivity of the sensor, some inorganic ions commonly found in drugs or foods were selected as interfering substances. 1 mmol / L (50 times the concentration of sulfamethoxazole and trimethoprim) of inorganic substances NaCl, KCl, MgSO 4It has little impact on the detection of 20 μmol / L sulfamethoxazole and trimethoprim (relative error less than 5%). Under the conditions of 100 μmol / L sulfamethoxazole and trimethoprim, the reproducibility and parallelism were investigated by DPV. The same sensor was continuously tested 10 times, and the calculated average RSD values were 3.75% and 4.24% (n = 10) respectively. The average RSD values of different sensors were 1.80% and 2.66% (n = 5) respectively. The prepared NiCuNPs / LIG sensor was stored in a vacuum bag. After one week, the current responses of the electrode to sulfamethoxazole and trimethoprim remained above 95%. In summary, this method has good repeatability, parallelism and stability.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bimetallic nanoparticle composite graphene portable electrochemical sensor prepared by a step-by-step laser induction method, characterized in that: The working electrode is a laser-induced graphene electrode, which uses polyimide as a flexible substrate material, and the polyimide is converted into graphene through the first step of laser induction; the nickel-copper nanoparticles are modified electrode materials, which are introduced into the graphene electrode through the second step of laser induction, comprising the following steps: 1) Before laser induction, polyimide (PI) was ultrasonically cleaned with anhydrous ethanol and deionized water respectively and then wiped dry for use; 2) Drawing a three-electrode pattern on a computer, importing the pattern into a CO2 laser, and inducing graphene LIG on polyimide (PI) using a CO2 laser; setting the laser power to 9.0w, the laser scanning speed to 120mm / s, and adjusting the laser to a focusing mode, a laser-induced graphene electrode (LIG) is generated in one step, and then the electrode surface is rinsed with ultrapure water and blown dry with nitrogen to stabilize the LIG electrode; 3) Use a pipette to take 5 μL of a mixed aqueous solution of NiCl2 and CuCl2 with a total concentration of 100 mmol / L and drop it on the working electrode position. The molar ratio of NiCl2 to CuCl2 is 87:

13. Under the same conditions as the primary laser, a secondary laser induction is performed on the same position of polyimide (PI) using a CO2 laser to generate a graphene electrode material (NiCuNPs / LIG) with NiCuNPs uniformly embedded in LIG. 4) The wire area of ​​the three-electrode pattern was encapsulated with polyimide insulating tape, and then 2 μL Ag / AgCl ink was applied to the reference electrode surface of NiCuNPs / LIG, and then dried under an infrared lamp with a rated power of 800 W for 5 min to obtain the three-electrode system itself.

2. According to the preparation method of claim 1, a bimetallic nanoparticle composite graphene portable electrochemical sensor prepared by a step-by-step laser induction method is obtained.

3. The method for detecting sulfamethoxazole and trimethoprim using the portable electrochemical sensor according to claim 2, characterized in that: The following steps are involved: 1) The portable electrochemical sensor is immersed in the detection solution, and then the electrochemical sensor is subjected to electrochemical cyclic voltammetry scanning, differential pulse voltammetry scanning and electrochemical impedance spectroscopy measurement. After scanning, the corresponding cyclic voltammetry (CV) graph, differential pulse voltammetry (DPV) graph and electrochemical impedance spectroscopy (EIS) graph can be obtained; 2) immersing the portable electrochemical sensor in standard solutions containing sulfamethoxazole and trimethoprim with different concentration gradients, measuring by differential pulse voltammetry (DPV), and plotting the solubility versus DPV response value; 3) Select K + 、Na + Mg 2+ , Cl - and SO4 2- The selectivity of the portable electrochemical sensor was determined as the detection environmental coexistence of sulfamethoxazole and trimethoprim.

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