Silver nanoparticle microdisk array chip and construction method and application thereof

Abstract

The application discloses a silver nanoparticle microdisk array chip and a construction method and application thereof. A PDMS needle tip array with dopamine ink attached is contacted with an HDMS-ITO substrate through micro-contact printing technology, dopamine ink is transferred to the HDMS-ITO substrate, a dopamine ink droplet array with uniform size and arrangement is obtained, then the PDA array of micron size is realized by using the property that dopamine can be oxidized and polymerized in an alkaline ammonia atmosphere, the arrayed PDA is soaked in an AgNO3 solution, and the AgNPs microdisk array chip with specific growth on the PDA array and uniform size is obtained by incubation at room temperature without adding a reducing agent. The chip is applied to electrochemical detection of urea, has a low detection limit and a wide detection range, and can be extended to a series of other small molecule analysis and detection.

Description

Technical Field

[0001] This invention belongs to the field of silver nanomaterials technology, specifically relating to a silver nanoparticle microdisk array chip, its construction method, and its application in the electrochemical detection of urea. Background Technology

[0002] Urea is a major nitrogenous metabolic product in the human body. Its metabolic process involves urea produced in the liver flowing through body fluids, then being filtered by the glomeruli in the kidneys and excreted in urine. Studies have shown that patients with liver disease, kidney dysfunction, or uremia produce large amounts of urea that cannot be excreted normally, leading to elevated urea levels in the blood and saliva. Clinically, urea levels are used as one of the indicators of kidney function or uremia.

[0003] Silver nanoparticles (AgNPs) have a large specific surface area, active catalytic properties, and unique plasmon resonance light scattering characteristics. Their synthesis and assembly on substrates have shown good development prospects in many fields, especially in the construction of electrochemical sensors for molecular detection. However, some current technologies for fabricating nanomaterial arrays on substrates have some drawbacks. For example, the method of fabricating AgNP array structures based on inkjet printing technology requires the prior synthesis of AgNPs, which is a complicated process. At the same time, due to the limitations of the number and size of the nozzles in inkjet printing technology, its printing throughput and resolution are usually not high [1]. In addition, the above technologies require expensive instruments and equipment and trained professional technicians, which limits the large-scale application of this technology. Although screen printing technology is suitable for large-scale nanoarray fabrication, its printing accuracy is low [2]. Therefore, it is of great significance to develop a simple, low-cost, and large-scale nanoparticle array fabrication method.

[0004] [1] Kim, K.; Jung, M.; Kim, B.; Kim, J.; Shin, K.; Kwon, O.-S.; Jeon, S., Low-voltage, high-sensitivity and high-reliability bimodal sensor array with fully inkjet-printed flexible conducting electrode for low powerconsumption electronic skin. Nano Energy 2017, 41 , 301-307.

[0005] [2] Sun, J.; Sun, R.; Jia, P.; Ma, M.; Song, Y., Fabricating flexible conductive structures by printing techniques and printable conductive materials.

[0006] Journal of Materials Chemistry C 2022, 10 (25), 9441-9464. Summary of the Invention

[0007] To address the technical problems existing in the construction of existing silver nanoparticle arrays, the present invention aims to provide a silver nanoparticle microdisk array chip, its construction method, and its application. Based on microcontact printing (μCP) technology, a polydopamine (PDA) array is prepared, and then an in-situ silver nanoparticle (AgNPs) microdisk electrode array is constructed. This method features high printing throughput, a simple process, short printing time, and no need for complex instruments or equipment. The AgNPs microdisk array exhibits uniform size and, when applied to the electrochemical detection of urea, demonstrates a low detection limit and a wide detection range.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0009] A method for constructing a silver nanoparticle microdisk array chip includes the following steps:

[0010] (1) Dopamine hydrochloride, glycerol and ascorbic acid were mixed to obtain dopamine ink; indium tin oxide (ITO) glass was modified with hexamethyldisilazane (HMDS) to obtain HMDS-ITO substrate;

[0011] (2) Spray dopamine ink onto the PDMS tip array to spread the dopamine ink evenly on the PDMS tip array. Then, make parallel contact between the PDMS tip array and the HMDS-ITO substrate to obtain a uniformly sized dopamine droplet array on the HMDS-ITO substrate.

[0012] (3) The HMDS-ITO substrate carrying dopamine droplet array is placed in an ammonia atmosphere for treatment, and then the residual droplets are removed by water washing, so that polydopamine array can be obtained on the HMDS-ITO substrate.

[0013] (4) The HMDS-ITO substrate carrying the polydopamine array is placed in AgNO3 solution to obtain the silver nanoparticle microdisk array chip.

[0014] In this invention, dopamine hydrochloride, glycerol, and ascorbic acid are first mixed to obtain dopamine ink. Glycerol promotes the adhesion of the dopamine ink to the substrate, while ascorbic acid prevents the oxidation of the dopamine ink during storage. Then, the dopamine ink is sprayed onto a PDMS tip array and brought into contact with an HMDS-ITO substrate, resulting in a uniformly sized array of dopamine droplets on the HMDS-ITO substrate. The dopamine droplet array is then placed in ammonia gas, and the dopamine undergoes oxidative polymerization to obtain a polydopamine array. Finally, the polydopamine surface contains abundant catechol groups, which release electrons when oxidized to quinone groups, inducing Ag... + The reduction reaction occurs when the polydopamine array is immersed in an Ag ion solution, which reduces the Ag ions into silver nanoparticles and fixes them on the surface of the PDA array, ultimately resulting in a uniform AgNPs microdisk array chip.

[0015] Further, in step (1), the concentration of dopamine hydrochloride in the dopamine ink is 5~10 mg / mL, the mass fraction of glycerol is 5~15wt%, and the concentration of ascorbic acid is 1~5 mg / mL.

[0016] Further, in step (1), the modification process specifically involves: ultrasonically cleaning the indium tin oxide (ITO) glass sequentially in acetone, ethanol, and water, drying it with nitrogen, and then placing the ITO glass in a petri dish containing a hexamethyldisilazane (HMDS) solution at 60-80°C for 4-8 hours. The modification of the ITO glass with HMDS prevents the diffusion of the printed dopamine droplet array during the polymerization process, thus obtaining a uniform PDA array of the desired size.

[0017] Furthermore, in step (2), the PDMS tip array is first placed in an oxygen plasma cleaner and treated at 80-100 W for 30-60 s. In this invention, placing the PDMS tip array in an oxygen plasma cleaner first can increase its hydrophilicity.

[0018] Furthermore, in step (3), the treatment temperature under an ammonia atmosphere is 40~50℃ and the time is 8~12 h.

[0019] The present invention also provides a silver nanoparticle microdisk array chip obtained by the above construction method.

[0020] This invention proposes a method for fabricating polydopamine (PDA) arrays based on microcontact printing (μCP) technology, thereby constructing in-situ silver nanoparticle (AgNPs) microdisk electrode array chips. Polydimethylsiloxane (PDMS) tip arrays are elastic stamps containing thousands of pyramid-shaped tips. Through microcontact printing, the PDMS tip arrays, coated with dopamine ink, are simply brought into contact with an HMDS-ITO substrate, transferring the ink onto the substrate to obtain a neatly arranged, uniformly sized array of dopamine ink droplets. This method offers high printing throughput, a simple process, and short printing time. Furthermore, it eliminates the need for complex equipment, reducing manufacturing costs. Then, utilizing the oxidative polymerization property of dopamine in an alkaline ammonia atmosphere, micron-sized PDA arrays can be fabricated. The arrayed PDAs are immersed in AgNO3 solution and incubated at room temperature without the addition of a reducing agent, resulting in uniformly sized AgNPs microdisk array chips specifically grown on the PDA array.

[0021] The present invention also provides an application of the above-mentioned silver nanoparticle microdisk array chip, which is used for the electrochemical detection of urea.

[0022] The advantages of this invention are:

[0023] 1. This invention develops a method for preparing PDA arrays and achieving in-situ synthesis of AgNPs microdisk array chips based on μCP technology. μCP technology has high printing throughput, simple process, short printing time, and no need for expensive instruments and equipment, thus reducing production costs. The PDA oxidation polymerization under an ammonia atmosphere requires a short time and is less likely to damage the printing tips. Without the addition of additional reducing agents, the AgNPs deposited in situ using PDA material are uniform in size and specifically distributed on the PDA film.

[0024] 2. The AgNPs microdisk array chip of the present invention is used for the electrochemical detection of urea, with a detection limit of 0.1 mM and a fitting curve range of 0.5 mM-100 mM, exhibiting both a low detection limit and a wide detection range. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the preparation process of the silver nanoparticle microdisk array in Example 1.

[0026] Figure 2 This is an optical microscope image of the dopamine droplet array from Example 1.

[0027] Figure 3 The images show optical microscope (A), scanning electron microscope (B), and atomic force microscope (C) images of the PDA array in Example 1.

[0028] Figure 4The images show the Raman spectra of the PDA array (PDA-HMDS-ITO), HMDS-ITO substrate, and ITO glass in Example 1.

[0029] Figure 5 The XPS spectrum of the PDA array in Example 1 is shown in (A), where (B) is the C1s spectrum, (C) is the N1s spectrum, and (D) is the O1s spectrum.

[0030] Figure 6 The images show scanning electron microscope (A) and atomic force microscope (B) images of the PDA array of Example 1 after incubation in AgNO3 solution.

[0031] Figure 7 The image shows the XPS spectrum (left) of the PDA array and AgNPs microdisk array chip (AgNPs-PDA) in Example 1, and the enlarged image shows the Ag3d spectrum (right) of the AgNPs microdisk array chip.

[0032] Figure 8 Optical microscope image (A) of the PDA array on the ITO substrate in Comparative Example 1 and optical microscope image (B) of the PDA array on the HMDS-ITO substrate in Example 1.

[0033] Figure 9 Cyclic voltammetry (CV) plots of AgNPs microdisk array chip in NaOH solution (AgNPs-PDA array-NaOH) and urea-containing NaOH solution (AgNPs-PDA array-urea NaOH).

[0034] Figure 10 The CV curves (A) of the AgNPs microdisk array chip in response to different concentrations of urea and the corresponding peak current versus urea concentration calibration graph (B). Detailed Implementation

[0035] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention. These embodiments are merely illustrative, and the invention is not limited to them.

[0036] Example 1

[0037] (1) Prepare an ethanol solution containing 10 wt% glycerol, 3 mg / mL ascorbic acid and 8 mg / mL dopamine hydrochloride, and denote it as dopamine ink;

[0038] (2) Place the PDMS needle array in an oxygen plasma cleaner and process it for 30 seconds at a power of 100 W;

[0039] (3) Place the indium tin oxide (ITO) glass in acetone, ethanol and water in sequence for ultrasonic cleaning for 3 minutes, dry it with nitrogen, place the ITO glass in a petri dish containing hexamethyldisilazane (HMDS) solution, and treat it in an oven at 80°C for 6 hours. This is called HMDS-ITO substrate.

[0040] (4) Spray dopamine ink onto the PDMS tip array, wait 10 seconds at room temperature to allow the dopamine ink to spread evenly on the PDMS tip array, place the HMDS-ITO substrate on the table, hold the ink-covered PDMS tip array in your hand, and make parallel contact between the PDMS tip array and the HMDS-ITO substrate for 3 seconds. Remove the PDMS tip array to obtain a uniformly sized dopamine droplet array on the HMDS-ITO substrate.

[0041] (5) The HMDS-ITO substrate carrying the dopamine droplet array is placed in an ammonia atmosphere and treated at 40°C for 10 hours. Then, the residual droplets on the PDA array are washed away with water to obtain the polydopamine array (PDA array) on the HMDS-ITO substrate.

[0042] (6) The HMDS-ITO substrate carrying the polydopamine array was immersed in AgNO3 solution and incubated at room temperature for 20 hours. Then it was rinsed with water and sonicated in water for 5 minutes. After being dried with nitrogen, the AgNPs micro disk array chip was obtained.

[0043] Figure 2 The optical microscopic image shows a patterned dopamine droplet array, indicating the fabrication of a uniformly sized and neatly arranged dot array. The dots in the array have a size of 8 μm and a spacing of 100 μm, consistent with the spacing between adjacent tips in a PDMS tip array.

[0044] Dopamine self-polymerized under ammonia atmosphere to obtain a uniformly distributed PDA array, as shown in the optical microscope and scanning electron microscope images respectively. Figure 3 A and Figure 3 As shown in Figure B, the dot size of the PDA array is observed to be the same as that of the original dopamine droplets. The morphology of individual PDA dots was characterized using atomic force microscopy. Figure 3 C), it was found that the PDA was in the form of a thin film with a smooth surface, a height of 121.7 nm, and a size of 8 μm, which was consistent with optical microscopy ( Figure 3 A) and scanning electron microscope ( Figure 3 B) is consistent with the characterization.

[0045] To determine the chemical structure of the prepared PDA film, Raman analysis was performed on the PDA array. Figure 4 (Solid line), two strong broad peaks appeared. 1342 cm -1 The peak at that location corresponds to an aromatic group.ν (CN) extension and indole ring extension, while another appears at 1579 cm. -1 The peak at that location can be attributed to the deformation of catechol. In ITO glass (… Figure 4 (dotted lines) and HMDS-ITO substrate ( Figure 4 On the (stretched line), only one characteristic peak was observed (possibly due to SiO4 stretching). These results indicate that PDAs were successfully prepared on HMDS-ITO substrates based on μCP technology, and HMDS modification does not introduce other chemical impurities into the substrate in the Raman scanning region.

[0046] To better analyze the functional group structure of the obtained PDA thin film, X-ray photoelectron spectroscopy (XPS) was performed. Figure 5 A), and for high-resolution spectra ( Figure 5 B, 5C, and 5D were analyzed in detail. C1s spectra (…) Figure 5 B) It can be fitted to three peaks, namely CH x / CC (284.6 eV), CN / CO (286.2 eV), and C=O (288.5 eV), where the C=O peak can be partially attributed to the quinone structure of PDA. N1s spectrum ( Figure 5 The fitted peaks for C) are R-NH2 (401.8 eV), R-NH-R (400.0 eV), and C=NR (398.6 eV). The high content of R−NH−R indicates that it is formed by the self-polymerization of 5,6−dihydroxyindole from the primary amine of dopamine. The O1s spectrum ( Figure 5 D) can be divided into two parts: OC (532.0 eV) comes from the C-OH structure of catechol in PDA, while O=C (530.0 eV) mainly comes from the 5,6-indolequinone and dopamine catechol structures. XPS analysis further confirmed the formation of PDA on the substrate and the presence of catechol functional groups in PDA.

[0047] To observe the morphology of the PDA film after incubation in AgNO3 solution, it was characterized by SEM (Sequencing and Microscopy). Figure 6 A). The magnified image shows that the PDA film contains closely packed nanoparticles with a diameter of 20 nm, and there is no obvious non-specific adsorption of AgNPs around the film. Additionally, Figure 6 B shows the atomic force microscopy characterization of the PDA film after incubation with AgNO3. (Compared with an atomic force microscopy image of a single PDA film.) Figure 3 B) In contrast, the changes in the height and surface morphology of the PDA film after AgNO3 incubation further indicate that uniform nanoparticles were successfully deposited on the PDA surface.

[0048] like Figure 7As shown, the chemical composition and elemental changes before and after AgNO3 incubation were investigated using XPS. It was observed that after incubation in AgNO3 solution, a strong signal peak of 370.0 eV appeared on the XPS spectrum (light gray curve) of the PDA array. High-resolution XPS ( Figure 7 The spectrum (right) shows two peaks with binding energies of 374.4 eV and 368.4 eV, which are attributed to Ag3d. 3 / 2 and Ag3d 5 / 2 The three-dimensional bimodal splitting of Ag to 6 eV confirms the presence of zero-valent silver on the PDA array surface. Combined with the morphological characterization of the PDA array after AgNO3 incubation, it can be confirmed that AgNPs were successfully deposited on the PDA film.

[0049] Comparative Example 1

[0050] (1) Prepare an ethanol solution containing 10 wt% glycerol, 3 mg / mL ascorbic acid and 8 mg / mL dopamine hydrochloride, and denote it as dopamine ink;

[0051] (2) Place the PDMS needle array in an oxygen plasma cleaner and process it for 30 seconds at a power of 100 W;

[0052] (3) Place the indium tin oxide (ITO) glass in acetone, ethanol and water in sequence for ultrasonic cleaning for 3 minutes, and dry it with nitrogen gas. This is then recorded as the ITO substrate.

[0053] (4) Spray dopamine ink onto the PDMS tip array, wait 10 seconds at room temperature to allow the dopamine ink to spread evenly on the PDMS tip array, place the ITO substrate on the table, hold the ink-covered PDMS tip array in your hand, and make parallel contact between the PDMS tip array and the ITO substrate for 3 seconds. Remove the PDMS tip array to obtain a dopamine droplet array on the ITO substrate.

[0054] (5) Place the ITO substrate carrying the dopamine droplet array in an ammonia atmosphere and treat it at 40°C for 10 hours. Then wash away the residual droplets on the PDA array with water to obtain the polydopamine array on the ITO substrate.

[0055] Figure 8 A shows an optical microscope image of a polydopamine array obtained by printing dopamine droplets on an ITO substrate and polymerizing them under an ammonia atmosphere. It can be seen that under the same printing and polymerization conditions, due to the lack of any modification, the PDAs on the ITO substrate are of uneven size and the PDA array pattern is incomplete. This is contrasted with the complete and uniformly sized PDA array obtained on an HMDS-ITO substrate. Figure 8(B) It can be seen that the modification of HMDS prevents the diffusion of dopamine droplet arrays during the polymerization process, and at the same time makes PDA less likely to fall off during water washing.

[0056] Application Example 1

[0057] AgNPs microdisk array chip for electrochemical detection of urea:

[0058] Electrochemical response of this silver nanoparticle microdisk array (AgNPs-PDA array) to urea was investigated using colorimetry (CV). The CV curve of the AgNPs-PDA array in NaOH solution showed several distinct redox peaks. Figure 9 The peak around 0.3 V during the forward scan corresponds to the electrochemical formation of AgOH and monovalent Ag species. The subsequent current surge around 0.75 V corresponds to the further electrochemical oxidation of Ag, forming a denser oxide layer. The cathode peak at 0.08 V during the reverse scan corresponds to the electrochemical reduction of silver oxide. After adding urea to the NaOH solution, a new oxidation peak appears at 0.65 V in the CV curve. This is because the electrochemical oxidation of urea by Ag oxide generates current. The specific equation for the electrochemical catalytic oxidation of urea is shown below:

[0059] Oxidation reaction: Ag(OH)₂ + 2OH⁻ - → AgO(OH)2 + H2O + 2e -

[0060] AgO(OH)2 + CO(NH2)2 + H2O → Ag(OH)2 + CO2 + N2

[0061] Reduction reaction: 2H₂O + 2e⁻ - → H2 + 2OH -

[0062] Overall reaction: CO(NH2)2 + H2O → CO2 + N2 + H2

[0063] The performance of an AgNPs microdisk array chip in electrochemical detection of urea was investigated by performing CV scans in urea solutions of different concentrations. Figure 10 As shown in Figure A, when the urea concentration increases from 0.5 mM to 100 mM, the peak current intensity at approximately 0.65 V gradually increases. A fitting graph is constructed with urea concentration as the ordinate and the peak current at approximately 0.65 V as the abscissa. Figure 10(B) It can be found that the correlation coefficient of the fitting curve between urea concentration and peak current is 0.999. Based on a signal-to-noise ratio of 3:1, the detection limit of this chip for the electrochemical detection of urea is 0.1 mM, and the fitting curve ranges from 0.5 mM to 100 mM. This method demonstrates a low detection limit and a wide detection range for the electrochemical detection of urea.

Claims

1. An application of a silver nanoparticle microdisk array chip, characterized in that, Using a silver nanoparticle microdisk array chip for the electrochemical detection of urea; The method for constructing the silver nanoparticle microdisk array chip is as follows: (1) Dopamine hydrochloride, glycerol and ascorbic acid were mixed to obtain dopamine ink; indium tin oxide glass was modified with hexamethyldisilazane to obtain HMDS-ITO substrate; The modification process is as follows: Indium tin oxide glass is ultrasonically cleaned in acetone, ethanol and water in sequence, dried with nitrogen, and then placed in a petri dish containing hexamethyldisilazane solution and placed at 60~80℃ for 4~8 hours. The concentration of dopamine hydrochloride in the dopamine ink is 5-10 mg / mL, the mass fraction of glycerol is 5-15 wt%, and the concentration of ascorbic acid is 1-5 mg / mL. (2) Spray dopamine ink onto the PDMS tip array to spread the dopamine ink evenly on the PDMS tip array. Then, make parallel contact between the PDMS tip array and the HMDS-ITO substrate to obtain a uniformly sized dopamine droplet array on the HMDS-ITO substrate. The PDMS tip array was first placed in an oxygen plasma cleaner and treated at 80~100 W for 30~60 s; (3) The HMDS-ITO substrate carrying dopamine droplet array is placed in an ammonia atmosphere for treatment, and then the residual droplets are removed by water washing, so that polydopamine array can be obtained on the HMDS-ITO substrate. The treatment temperature under an ammonia atmosphere is 40~50℃, and the time is 8~12 h; (4) The HMDS-ITO substrate carrying the polydopamine array is placed in AgNO3 solution to obtain the silver nanoparticle microdisk array chip.

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