A monitoring system and method for high-throughput imaging of single nanoscale electrochemical reactions

Abstract

The application discloses a kind of to the monitoring system and method of high-throughput imaging of single nanometer individual electrochemical reaction, laser incidence angle in optical imaging module in the present application is above total internal reflection angle, so that laser is irradiated on working electrode by imaging magnification device to generate evanescent field;Light barrier is used to block reflected light and pass through scattered light, and the dynamic reaction process of nanometer individual is recorded by image acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical signal acquisition device optical

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical imaging, and in particular to a monitoring system and method for high-throughput imaging of single-nanoparticle electrochemical reactions. BACKGROUND

[0002] Understanding the electrochemical behavior of nanomaterials at the single-particle level is crucial for advancing the fields of catalysis, biosensing, and energy applications. However, the electron transfer processes between nanomaterials and electrode surfaces, as well as their complex interactions, pose significant challenges for studying their mechanisms. For example, single nanoparticle impact electrochemical (SNIE) measurements show multiple current peaks during a single collision, indicating the presence of multiple modes of motion and electrochemical activity. While some theoretical models and machine learning methods have been developed to interpret these complex current patterns, a fundamental challenge faced by these methods is the lack of imaging capabilities and spatial resolution, which prevents direct observation and correlation of the electrochemical behavior and motion of nanoparticles.

[0003] Imaging techniques offer some solutions to this challenge, but there are still some shortcomings:

[0004] (1) Electrochemical scanning probe microscopy (SPM) can image the electrochemical properties of nanoscale samples with high spatial resolution, but due to its slow scanning speed, it is difficult to perform large-scale and high-throughput detection.

[0005] (2) Optical techniques such as dark-field microscopy (DFM) provide sufficient spatial and temporal resolution by detecting the scattered light of nanoscale objects, which is very useful for tracking their electrochemical reactions. However, due to the six-fold decay of scattering intensity with particle diameter, the sensitivity for smaller nanoparticles is significantly reduced.

[0006] CN108226095 A discloses an electrochemical impedance spectroscopy measurement device and method for single nanoparticles, which includes a monochromatic laser adjustment module for introducing monochromatic laser into dark-field imaging and adjusting the range of the single wavelength; a particle excitation module connected to the monochromatic laser adjustment module for exciting the scattering resonance of single nanoparticles of noble metals with localized plasmon resonance, including a plano-convex lens and an electrochemical cell; a voltage application module connected to the particle excitation module for applying a periodic modulation voltage to the electrochemical cell; a particle scattering intensity detection module connected to the voltage application module and the particle excitation module, including a lock-in amplifier and a photomultiplier tube; this invention introduces monochromatic laser into dark-field imaging, and equips the photomultiplier tube with a lock-in amplifier in the detector, which allows the direct detection of the scattering intensity value changes of single nanoparticles under voltage modulation, and obtains the electrochemical impedance spectrum of single nanoparticles.

[0007] CN111122552A discloses a method for monitoring cell copper ion secretion by single particle electrochemical luminescence imaging technology; an electrochemical luminescence microscopic imaging system is constructed, which can be used for observing the electrochemical luminescence of single nanoparticles, realizing the spatial resolution of single nanoparticles; at the same time, a graphitic carbon nitride nanosheet is used to construct an electrochemical luminescence microscopic imaging sensor, which can monitor the copper ions in the local micro area of the electrode; by monitoring the electrochemical luminescence intensity change of single graphitic carbon nitride nanosheet around the single cell, the content of cell copper ion secretion is reflected in real time.

[0008] For nanomaterials with dynamic reactions and complex structures, it is more challenging to accurately analyze their electrochemical processes and movements because they have multiple reaction sites and more complex movements. SUMMARY

[0009] The present application aims at the problem that the electrochemical behavior of complex nanometer individuals is difficult to characterize, and provides a high-throughput and high-precision real-time monitoring system for single nanometer individuals. The system realizes real-time monitoring of the electrochemical behavior and micro-movement of single nanometer individuals on the electrode surface based on the principle of total internal reflection interference scattering, and provides technical support for the mechanism research of complex electrochemical reactions at the nanoscale.

[0010] To achieve the above purpose, the technical scheme adopted by the present application is:

[0011] A monitoring system for high-throughput imaging of single nanometer individual electrochemical reaction, comprising an electrochemical module, an optical imaging module and a control module;

[0012] The electrochemical module comprises an electrochemical workstation and an electrochemical cell, and the working electrode, reference electrode and counter electrode in the electrochemical cell are connected with the electrochemical workstation; the working electrode is a conductive thin film glass sheet;

[0013] The optical imaging module comprises a light source, a lens, a spectroscope, an imaging magnification device, a light shield and an image acquisition device;

[0014] The light source emits laser light, and the laser incidence angle is adjusted to be above the total internal reflection angle, so that the laser light passes through the imaging magnification device to irradiate on the working electrode to generate an evanescent field; the light shield is arranged at the back focal plane of the imaging magnification device, and is used to block the reflected light and pass the scattered light, and the optical signal is collected by the image acquisition device;

[0015] The control module is used for collecting the data signals of the image acquisition device and the electrochemical workstation, and controlling the working parameters of the image acquisition device and the electrochemical workstation.

[0016] The system in the application generates evanescent field on the surface of the working electrode, only illuminates the nanometer individual close to the electrode surface, reduces the scattering interference of impurities in the solution, and records the dynamic reaction process of the nanometer individual (including nanoparticles and nanowires) with high space-time resolution. s and the scattering light E b generated by the roughness of the electrode surface Through this, the imaging contrast and sensitivity are enhanced through the principle of interference between the two. Finally, according to the light signal (image) collected by the image acquisition device, the change of the intensity of the nanometer individual in each frame image with time is analyzed, the reaction rate of the individual is calculated, and the corresponding current signal is derived according to the relationship between the image intensity and the particle size, so as to characterize the dynamic behavior of the nanometer individual in the electrochemical reaction.

[0017] The principle is based on the interference of E s and E b The formula (3) is:

[0018]

[0019] Where I is the optical signal intensity of a single nanometer individual collected by the image acquisition device, is the phase difference between the two scattering fields, is the interference scattering term, which contributes most to the signal and plays a leading role.

[0020] The light shield includes a support frame and a blocking piece fixed in the frame, the blocking piece is used to block the reflected light, and a scattering light passage is provided between the blocking piece and the support frame; the blocking piece is made of low light transmission material, such as metal plate (anodized aluminum, etc.), plastic plate (polyethylene, polypropylene, polyvinyl chloride, etc.), wood plate, etc.; the material of the blocking piece must have low light transmission, and its surface is difficult to scatter and reflect.

[0021] The preparation method of the light shield includes numerical control machining, and the shape of the light shield and the blocking piece is not limited to the shape in the patent. Any shape that can be adapted to the microscope and can selectively block reflected light and allow scattered light to pass through can be used.

[0022] The reference electrode is one or more of commonly used reference electrodes such as silver / silver chloride and saturated calomel electrode, the counter electrode is one or more of electrodes such as platinum wire and carbon electrode, the working electrode is a glass sheet coated with ITO film or a glass sheet with other conductive coating (such as gold, platinum, etc.), and the three-electrode system can apply precise voltage to excite and control the electrochemical reaction of a single nanometer individual.

[0023] The light source is a laser or other monochromatic light source.

[0024] The depth of the evanescent field is within 300 nm; the illumination area is above 200 μm x 200 μm, realizing total internal reflection illumination of a large field of view, and hundreds of nanoparticles can be monitored simultaneously.

[0025] The image acquisition device is one or more of a high-frame-rate CMOS camera and a CCD camera, ensuring that the motion trajectory of the nanoparticles during the reaction and the change in the intensity of the interference scattering can be accurately recorded.

[0026] The application also provides a monitoring method for high-throughput imaging of the electrochemical reaction of single nanoparticles, which is performed by using the monitoring system and comprises the following steps:

[0027] In step S1, nanoparticles are deposited on a working electrode, and a reaction solution is added to an electrochemical cell;

[0028] In step S2, the incident angle of the light source is adjusted so that the light source generates an evanescent field on the working electrode after passing through the imaging magnification device; a light shield is arranged at the focal plane of the imaging magnification device to block the reflected light in the electrochemical cell from passing through the scattered light; the optical signal of the nanoparticles is collected by the image acquisition device; and the electrochemical workstation is started to apply a potential to the three electrodes, so that the nanoparticles react.

[0029] In step S3, the electrochemical signal of a single nanoparticle is calculated according to the optical signal collected by the image acquisition device, and the dynamic behavior of the nanoparticles in the electrochemical reaction is monitored.

[0030] The nanoparticles include nanoparticles or nanowires, such as silver nanoparticles (AgNPs) or nanowires (AgNWs), or nanoparticles modified by chemical functional groups.

[0031] When the nanoparticles are nanoparticles, the calculation of the optical signal of a single nanoparticle in step S3 is performed according to formula (1), the optical intensity I of a single nanoparticle collected by the image acquisition device is used to calculate the current i of a single nanoparticle at different times t:

[0032]

[0033] where ρ x is the density of the nanoparticles x, m x is the mass of a single x nanoparticle, and k is a constant of 2.6.

[0034] When the nanoparticles are nanowires, the calculation of the optical signal of a single nanoparticle in step S3 is performed according to formula (2), the optical intensity I of a single nanowire collected by the image acquisition device is used to calculate the current i of a single nanowire at different times t:

[0035]

[0036] When the nano individual is a nanowire, the collected optical intensity can be the optical intensity of the entire nanowire or the optical intensity of any position on the nanowire, and the corresponding obtained current is the current of the entire nanowire or any position on the nanowire.

[0037] The collected optical signal includes the interference scattering intensity signal of the nano individual changing with time and the motion signal of the spatial position of the nano individual changing with time, and the optical signal is the collected optical image. Therefore, the specific application of the monitoring method of the present application includes:

[0038] (1) Nanoparticle dynamic electrochemical reaction monitoring: the motion rate of the nano individual is calculated through optical imaging, which is used to track the motion of a single nanoparticle on the electrode surface at high resolution. At the same time, the current generated in the electrochemical reaction process is analyzed through the interference scattering intensity, and the motion and the current are correlated.

[0039] (2) Heterogeneous nanomaterial behavior characterization: used to analyze the heterogeneous behavior of nanomaterials of different sizes, shapes or surface modifications in the electrochemical reaction process, and reveal the reaction characteristic differences caused by the motion mode, adhesion strength and electrochemical activity differences of different particles.

[0040] (3) Nanowire dissolution reaction monitoring: used to track the reaction process of one-dimensional nanomaterials (such as nanowires) on the electrode surface, analyze the dissolution mode and mechanism, and the influence of the interaction between nanowires on the reaction.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] The nanometer individual electrochemical imaging system of the present application has high resolution, high throughput and real-time imaging capability, which can significantly improve the sensitivity and efficiency of nanoparticle electrochemical reaction analysis. Moreover, the micro-motion of the nanoparticle can be tracked and analyzed at the same time as the reaction, revealing the complex interaction between the nanoparticle and the electrode interface. Finally, the relationship between the electrochemical reaction and the micro-motion is established, providing a powerful tool for dynamic measurement of electrochemical behavior. This method can be applied to the reactivity research of nanomaterials in the fields of catalysis, energy storage and biosensing, and can be further expanded to more complex nanostructures and two-dimensional material systems.

[0043] The system and method of the present application are suitable for monitoring the electrochemical reaction behavior of single nanoparticles and nanowires on the electrode surface, and can be used in the following fields:

[0044] (1) Catalyst performance research: analyzing the change of the electrochemically active area of the nanoparticle in the catalytic process to provide data support for the improvement of the catalyst activity;

[0045] (2) Electrochemical property evaluation of battery materials: the study of the dissolution, corrosion and deposition behavior of nanoparticles in battery materials helps to improve the stability and performance of battery materials;

[0046] (3) Analysis of the mechanism of the interaction between nanomaterials and surfaces: by tracking the movement path and dissolution rate of nanoparticles, the kinetic behavior of their adhesion to surfaces is studied in depth, providing basic data for the optimization of the application of nanomaterials in the fields of energy and sensing. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 Fig. 1A is a schematic diagram of the device system structure of the present application; Figure 1 Fig. 1B is a schematic diagram of the structure of the light shield 23 in the system; Figure 1 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm.

[0048] Wherein 11 is an electrochemical workstation, 12 is an electrochemical cell, 13 is a working electrode, 21 is a light source, 22 is an imaging magnification device, 23 is a light shield, 24 is an image acquisition device, 31 is a control module; 1 is a blocking piece, 2 is a scattered light path, and 3 is a support frame.

[0049] Figure 2 Fig. 1A is a schematic diagram of the device system structure of the present application; Figure 2 Fig. 1B is a schematic diagram of the structure of the light shield 23 in the system; Figure 2 Fig. 1A is a schematic diagram of the device system structure of the present application; Figure 2 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm. Figure 2 Fig. 1B is a schematic diagram of the structure of the light shield 23 in the system; Figure 2 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm. Figure 2 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm. Figure 2 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm. Figure 2 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm.

[0050] Figure 3 Fig. 1A is a schematic diagram of the device system structure of the present application; Figure 3 Fig. 1B is a schematic diagram of the structure of the light shield 23 in the system; Figure 3 Fig. 1C is an optical field image collected by the image acquisition device in Example 1, in which each bright spot is a 30 nm AgNP, and the scale is 20 μm. Figure 3Figure B shows the optical intensity change of AgNP-NH2 from approaching to contacting ITO until the reaction is completed; Figure 3 D in the middle is the position image of AgNP-NH2 at each moment of tracking; Figure 3 The E in the middle is Figure 3 C is the current-time (it) image calculated by formula (1); Figure 3 F is Figure 3 The relationship between the AgNP-NH2 movement rate and current (vi) in middle B; Figure 3 G is the movement rate (v) of unmodified AgNP, AgNP functionalized with streptavidin (AgNP-SA) and AgNP-NH2, and the peak current (i p ), current peak width (i w ) and current peak area (i A ) comparison statistics.

[0051] Figure 4 A is an optical imaging image of a uniformly reacted silver nanowire (AgNW) in Example 3 at different times; Figure 4 Middle B is Figure 4 Three different parts of AgNW in A (in Figure 4 1-3) marked in A), and the intensity change diagram of the entire AgNW during the reaction process; Figure 4 C is composed of Figure 4 Figure B shows the current-time (it) diagram of different parts of the AgNW obtained by transformation using formula (2).

[0052] Figure 5 A is an optical image of an AgNW in Example 3 in which one end reacts before the other end; Figure 5 Middle B is Figure 5 Current-time (it) diagram of different parts of the AgNW during the reaction process of A; Figure 5 Middle C is an optical image of an AgNW whose two ends react before the center; Figure 5 D is Figure 5 Current-time (it) diagram at different locations during the reaction of AgNW in C.

[0053] Figure 6 This is an optical imaging diagram of an AgNW in motion accompanied by reaction in Example 3 and a schematic diagram of the reaction principle.

[0054] Figure 7 A in the middle is the optical imaging image of AgNWs where five reactions and interactions occur together; Figure 7 Middle B is Figure 7 Current-time (it) diagram of the five AgNWs during the reaction process in Figure A. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. Those skilled in the art can modify or replace equivalently based on the technical solutions of the present application without departing from the spirit and scope of the present application, which should be covered in the protection scope of the present application.

[0056] As shown in Figure 1 A system for high-throughput imaging of electrochemical reactions of single nanoparticles or nanowires, comprising an electrochemical module, an optical imaging module and a control module;

[0057] The electrochemical module comprises an electrochemical workstation 11 and an electrochemical cell 12, and a working electrode 13, a silver / silver chloride reference electrode and a platinum wire counter electrode in the electrochemical cell 12 are connected with the electrochemical workstation 11; the working electrode 13 is an ITO glass sheet, which is arranged at the bottom of the electrochemical cell 12;

[0058] The optical imaging module comprises a light source 21, a lens, a beam splitter, an imaging magnification device 22, a light shield 23 and an image acquisition device 24; the light source 21 emits laser light, and the incident angle is adjusted by adjusting the position of the light source relative to the lens, so that the laser light passes through the imaging magnification device (objective lens) 22 to generate an evanescent field on the working electrode 13, and the field of view of the evanescent field can reach 200 μm×200 μm.

[0059] The structure diagram of the light shield 23 is shown in Figure 1 B, which is arranged at the back focal plane of the imaging magnification device 22, and is used to block the reflected light in the electrochemical cell 12, while allowing most of the scattered light to pass through, so that the scattered light signal is collected by the image acquisition device 24;

[0060] The light source is a laser or other monochromatic light source, and the light intensity is 5 mW; the image acquisition device 24 is a high-frame-rate CMOS camera, which has a frame rate of at least 100 frames / s, and the positioning accuracy of the centroid positioning of the nanoparticles reaches 2.4 nm;

[0061] The control module 31 is used to collect the data signals of the image acquisition device 24 and the electrochemical workstation 11, and control the working parameters of the image acquisition device and the electrochemical workstation.

[0062] The method for preparing the light shield is as follows: in the graphing software, the Figure 1The drawing paper shown in the middle B is made by numerical control machining. The material of the blocking piece is anodized aluminum, and the shape of the blocking piece is not limited to the shape in the specific embodiment of the application. Any shape that can be adapted to a microscope and can selectively block reflected light and allow scattered light to pass through can be used. The material of the blocking piece is not limited to anodized aluminum. Any material that can effectively block light can be used.

[0063] During the experiment, the optical images of the nanoparticles or nanowires are collected by the image acquisition device 24 to obtain an image sequence of the electrochemical reaction process. The electrochemical signal (current) is obtained by measuring and analyzing the scattering intensity of each nanoparticle or nanowire through the FIJI software, and quantitatively converting the optical signal into a current signal through formula (1) or formula (2). The nanoparticle movement signal (i.e. the change of position) is obtained by locating the center of mass of each frame of image through the TrackMate plug-in in the FIJI software, thereby obtaining the velocity information.

[0064] Example 1

[0065] As shown in Figure 1 The system shown in the middle A is used to image and analyze the electrochemical reaction of a single silver nanoparticle (AgNP), which specifically includes:

[0066] A glass sheet with an ITO coating is used as a working electrode, and 1M KSCN is used as a reaction solution and placed in an electrochemical cell. Under the condition of applying 0.1V (relative to Ag / AgCl reference) on the electrochemical workstation, 5μL of 0.1mg / mL AgNP aqueous solution with a diameter of 30nm is added to the KSCN solution. The AgNPs continuously diffuse and hit the ITO surface, and an oxidation and dissolution reaction occurs: Ag + 2SCN - -e - → Ag (SCN) 2 - During this process, the scattering intensity of the AgNPs falling on the surface gradually weakens due to dissolution, and their positions also undergo nanoscale displacement due to interaction with the surface. The image acquisition device records the optical images of the entire process, and synchronizes the optical signal and the electrical signal of the electrochemical workstation to the control module.

[0067] When the field of view of the system is 200μm x 200μm, the image collected by the image acquisition device is as shown in Figure 1 The middle C. Each bright spot is an AgNP. As can be seen, the system can image hundreds of single nanoparticles in each frame, achieving measurement of about 1000 single particle reactions per second, and has the ability of high-throughput nanoparticle imaging.

[0068] As shown in Figure 2Figure A shows the dissolution process of a randomly selected single AgNP, including four representative optical images from the time it falls onto the ITO surface until the oxidative dissolution is completed. It can be seen that the AgNP undergoes an electrochemical dissolution reaction.

[0069] like Figure 2 B in the figure shows Figure 2 The optical intensity (I) curve measured from the image sequence of a single AgNP (A) as it approaches, contacts, and dissolves completely in ITO is plotted over time. The I curve shows an increase in the interferometric scattering intensity as the AgNP approaches the ITO surface. Upon contact, the reaction begins, causing the AgNP to decrease in size and a corresponding decrease in intensity until it returns to baseline levels after complete dissolution.

[0070] The current i at different times can be calculated from the It curve according to the following formula:

[0071]

[0072] Among them, ρ Ag is the density of Ag, m Ag is the mass of an Ag nanoparticle, k is a constant, which is 2.6 in this patent. The calculation result is as follows Figure 2 The current-time (it) diagram shown in C.

[0073] According to the shape of the current peak, it can be divided into four stages ( Figure 2 C in the middle is marked with different colors): (i) pre-reaction stage, when the particles have not yet landed on the surface and the current is approximately zero; (ii) current increase stage, when the reaction begins and continues until the maximum current is reached; (iii) current decrease stage, when the current begins to decrease; (iv) completion stage, when the current drops to zero.

[0074] The optical images recorded by the image acquisition device can also extract the position change (i.e., speed) information of the AgNP reaction process, such as Figure 2 As shown in D. Using the TrackMate plug-in in the FIJI software, the center of mass of each frame is located to obtain the coordinates of the imaging plane [x(t), y(t)]. The equivalent rate v can be calculated by the change in the coordinates of the previous and next two frames as shown in formula (4):

[0075]

[0076] Where Δx is the difference between the horizontal coordinate position of AgNP of the next frame and the previous frame in the acquired image sequence, Δy is the difference between the vertical coordinate position of AgNP of the next frame and the previous frame in the acquired image sequence, and Δt is the time difference between the next frame and the previous frame.

[0077] WillFigure 2 The rate calculated by D in the same time Figure 2 Combined with the current data in C, we get Figure 2 Figure E shows the relationship between the movement rate of a single AgNP and the current.

[0078] Will Figure 2 The data of E were statistically analyzed according to the above four stages, and the results were obtained. Figure 2 Figure F. The four stages form distinct clusters, indicating a different dependence of current on velocity in each phase. The current ramp phase, in particular, exhibits a lower velocity. This result suggests that low velocities (i.e., when there is strong interaction with the surface) favor charge transfer.

[0079] The above conclusions are only drawn from a single AgNP. In order to further verify the universality of the conclusions, 20 random AgNPs were selected to calculate the average movement rate of the nanoparticles at each stage. The results are as follows: Figure 1 As shown in G. The results once again confirm that the charge transfer rate is fast when the movement rate is low.

[0080] Example 2

[0081] The same method as in Example 1 was used Figure 3 The system shown in Figure A is used to image and analyze the electrochemical reactions of AgNPs modified with different molecules to further explore the effects of surface group modification on the electrochemical reactions, including:

[0082] AgNPs functionalized with different groups were used, including amino-functionalized AgNPs with a diameter of 30 nm (AgNP-NH2), carboxyl-functionalized AgNPs with a diameter of 30 nm (AgNP-COOH), and streptavidin-functionalized AgNPs with a diameter of 60 nm (AgNP-SA).

[0083] The modification method for AgNP-NH2 and AgNP-COOH is as follows: 500 μL of a 0.1 mg / mL AgNPs solution was centrifuged at 16,000 g for 2 minutes, and the supernatant was removed. After washing with deionized water and centrifugation, a 1 mM HS-PEG-COOH or HS-PEG-NH2 aqueous solution was added to the centrifuge tube and incubated overnight at room temperature. After incubation, the solution was centrifuged at 16,000 g and the supernatant was removed. The particles were rinsed three times with deionized water to remove unbound thiol molecules and then dissolved in 500 μL of water to obtain AgNP-COOH and AgNP-NH2. AgNP-SA was purchased from Nanjing Jicang Nanotechnology Co., Ltd.

[0084] Using ITO as the working electrode, 5 μL of a 0.1 mg / mL surface-functionalized AgNP solution was added to a 1 M KSCN solution at an applied oxidation potential of 0.1 V (vs. Ag / AgCl reference). An image acquisition device recorded the image sequence during the reaction.

[0085] The results are as follows Figure 3 As shown in Figure 3A, the collected images show a decrease in the reactivity of the various modified AgNPs, due to the fact that the modified molecular layer blocks electron transfer. For the unmodified AgNPs, 3786 out of 3928 AgNPs underwent electrochemical reactions (a reaction ratio of 96.38%); while only 10 out of 1021 AgNP-NH2 particles reacted (a reaction ratio of 0.98%). The reaction ratios for AgNP-SA and AgNP-COOH were 1.45% and 0.00%, respectively.

[0086] Although most modified AgNPs do not react, those that do react (possibly due to incomplete blocking by the modified molecules) often exhibit It curves different from those of bare AgNPs. Figure 3 Figure B shows four images of the collision and reaction process of AgNP-NH2.

[0087] Figure 3 Middle C shows Figure 2 The It diagram of AgNP-NH2 in B from approaching to contacting ITO until the end of the reaction. Compared with the It diagram of unmodified AgNP ( Figure 3 A comparison in (B) reveals different reaction patterns. The AgNP-NH2 reaction exhibits a rapid, staged reaction, while the AgNP exhibits a continuous, slow reaction. This is because the presence of amino groups strengthens the interaction between the particles and ITO, increasing the electron transfer rate.

[0088] Figure 3 In the figure D, the position of AgNP-NH2 at different moments is tracked. According to formula (4), the movement rate (v) of AgNP-NH2 at different stages can be calculated.

[0089] According to formula (1), Figure 3 The It curve of C in the middle is transformed to obtain Figure 3 The it diagram shown in E shows the changes in current in the four stages of a single AgNP-NH2. Figure 3 Figure F shows the relationship between the current i and the velocity v extracted from the particle motion. It can be seen that the region with high electron transfer rate appears in the low-velocity domain.

[0090] Figure 1The statistical results of G show that the movement rates v of bare AgNP, AgNP-NH2 and AgNP-SA are significantly different, which is due to the different strengths of interaction with the ITO surface caused by different modifications. In addition, the current peak (i p ), current peak width (i w ) and current peak area (i A These results further demonstrate the important influence of the surface properties of nanoparticles on their electrochemical behavior and surface interactions.

[0091] Example 3

[0092] Use Figure 4 The system shown in Figure 1A is a high-resolution and high-throughput detection method for the electrochemical reaction of AgNWs. The specific steps include: depositing AgNWs on the ITO surface and adding 1M KSCN solution, applying a 0.5V potential (relative to the Ag / AgCl reference) to trigger the reaction, and recording the optical image of the AgNWs.

[0093] Figure 4 Center A shows the optical images of an AgNW at different times, reflecting its dissolution process. Figure 4 B shows different parts of this AgNW ( Figure 4 The optical intensity changes of three parts (numbered 1-3) are marked in Figure A. The intensity changes of the three parts are synchronized with time, indicating that the AgNW has good contact with the surface during the reaction and is evenly dissolved.

[0094] Figure 4 C in the middle shows the corresponding current changes of different parts of the AgNW. The current (i) is calculated as follows:

[0095]

[0096] where I is the optical signal intensity of AgNW in the image, and t is the time. Figure 5 Center C shows that the currents of the three parts are synchronized in time, which again illustrates that the AgNW reacts uniformly.

[0097] Figure 4 Figure A shows the reaction process of another AgNW. Figure 5 Different from Figure A, the reaction of this AgNW is faster at one end than the other (as marked in the figure, the green end is faster than the red end). Figure 5 Figure B shows the current signals at both ends changing with time (calculated by formula (2)), which shows that their changes are not synchronous.

[0098] Figure 5 Figure C provides another reaction scenario, where the two ends of the AgNW (marked in red and blue) react before the middle (marked in green).Figure 5 The current signals of the three parts over time (calculated by equation (2)) are shown in Fig. 2D, which again indicates the inconsistency of the reaction in different regions of a single AgNW. In summary, Figure 4 The two examples in Fig. 2A and Fig. 2B show that even in the same AgNW, there are still differences in the reaction sites and reaction times. This cannot be reflected in traditional electrochemical measurements based on AgNW clusters, highlighting the advantages of the method of the present patent.

[0099] Figure 5 And Figure 6 The AgNWs in Fig. 2A and Fig. 2B are all adsorbed on the ITO surface as a whole, and during the entire reaction process, the AgNW does not move; while Figure 7 Fig. 2C shows a reaction case of an AgNW that is not completely adsorbed. One end of this AgNW is adsorbed on the ITO electrode surface, and the other end can swing freely. After applying a potential of 0.5 V (relative to Ag / AgCl reference), the free end of the swinging end dissolves first. Since the free end is less likely to contact the electrode, it is inferred that this observation is due to directional electron transport in the nanowire: electrons are transported from the free distal end through the nanowire to the fixed end, and then to the ITO electrode, completing the electron transfer and dissolution reaction.

[0100] Figure 7 Fig. 2D shows a more complex example: multiple AgNWs interact with each other during movement and trigger new dissolution reactions through interaction. Figure 7 Fig. 2A shows that by increasing the deposition density of AgNWs on ITO, a situation of AgNW interweaving and overlapping is created (5 AgNWs are marked in the figure, numbered 1-5). After applying a potential of 0.5 V (relative to Ag / AgCl reference), it is observed that AgNWs 1 and 2 react first, followed by AgNW 3. AgNW 4 is pressed under AgNW 3, and when AgNW 3 dissolves, AgNW 4 moves violently from left to right (indicated by the arrow in the figure) and presses on AgNW 5. Due to the force, AgNW 5 is more tightly attached to the surface and quickly dissolves. Finally, AgNW 4 is also dissolved. ​ Fig. 2B shows the current change of each AgNW during the entire process. These results again illustrate the unique advantages of this method in studying the interaction and electrochemical behavior of individual bodies in complex systems.

[0101] The above examples are only used to help understand the method of the present invention and its core idea. It should be noted that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A monitoring system for high-throughput imaging of electrochemical reactions of single nanoparticles, characterized in that: Includes electrochemical module, optical imaging module and control module; The electrochemical module includes an electrochemical workstation and an electrochemical cell. The working electrode, reference electrode and counter electrode in the electrochemical cell are connected to the electrochemical workstation; the working electrode is a glass sheet with a conductive film; The optical imaging module includes a light source, a lens, a beam splitter, an imaging magnification device, a light shielding sheet and an image acquisition device; The light source emits laser light, and the laser incident angle is adjusted to be above the total internal reflection angle, so that the laser light passes through the imaging amplification device and irradiates the working electrode to generate an evanescent field. The light shielding plate is arranged at the rear focal plane of the imaging amplification device, and is used to block the reflected light and pass through the scattered light of the nano-individuals and the scattered light generated by the surface roughness of the electrode, and the optical signal is collected by the image acquisition device. The light shielding plate includes a supporting frame and a blocking plate fixed within the frame, and the blocking plate is used to block the reflected light. A path for scattered light is provided between the blocking plate and the supporting light frame. The blocking plate is made of a low-transmittance material. The control module is used to collect data signals from the image acquisition device and the electrochemical workstation and control the operating parameters of the image acquisition device and the electrochemical workstation; calculate the electrochemical signal of a single nano-individual based on the optical signal collected by the image acquisition device, and realize the dynamic behavior monitoring of the nano-individual in the electrochemical reaction; The nano-individual includes nanoparticles or nanowires. When the nano-individual is a nanoparticle, the optical signal calculation of the electrochemical signal of a single nano-individual is performed according to formula (1). The optical intensity I of a single nanoparticle collected by an image acquisition device is used to calculate the current i of the single nanoparticle at different times t: where ρ x is the density of nanoparticle x, m x is the mass of a single x nanoparticle, k is a constant 2.6; When the nano-individual is a nanowire, the optical signal calculation of the electrochemical signal of a single nano-individual is performed according to formula (2), and the current i of the single nanowire at different times t is calculated using the optical intensity I of the single nanowire collected by the image acquisition device; 2. The monitoring system for high-throughput imaging of electrochemical reactions of single nanoparticles according to claim 1, characterized in that: The reference electrode is one or more of silver / silver chloride and saturated calomel electrode; the counter electrode is one or more of platinum wire and carbon electrode; The working electrode is a glass sheet coated with an ITO film.

3. The monitoring system for high-throughput imaging of electrochemical reactions of single nanoparticles according to claim 1, characterized in that: The light source is laser or other monochromatic light source.

4. The monitoring system for high-throughput imaging of electrochemical reactions of single nanoparticles according to claim 1, characterized in that: The depth of the evanescent field is within 300 nm; and the illumination area is larger than 200 μm×200 μm.

5. The monitoring system for high-throughput imaging of electrochemical reactions of single nanoparticles according to claim 1, characterized in that: The image acquisition device is one or more of a high frame rate CMOS camera and a CCD camera.

6. A method for high-throughput imaging of electrochemical reactions of single nanoparticles, characterized in that: The method is carried out using the monitoring system according to any one of claims 1 to 5, comprising the steps of: Step S1, depositing nanoparticles on a working electrode and adding a reaction solution to an electrochemical cell; Step S2, adjusting the incident angle of the light source so that the light source generates an evanescent field on the working electrode after passing through the imaging amplification device, using a light shielding plate disposed at the rear focal plane of the imaging amplification device to block the reflected light in the electrochemical cell from passing through the scattered light, and collecting the optical signal of the nano-individual through the image acquisition device; Start the electrochemical workstation and apply potential to the three electrodes to make the nano-individuals react; Step S3, calculating the electrochemical signal of a single nano-individual based on the optical signal collected by the image acquisition device, thereby realizing dynamic behavior monitoring of the nano-individual in the electrochemical reaction; The nano-individual includes a nanoparticle or a nanowire. When the nano-individual is a nanoparticle, the optical signal calculation of the electrochemical signal of a single nano-individual in step S3 is performed according to formula (1), and the optical intensity I of the single nanoparticle collected by the image acquisition device is used to calculate the current i of the single nanoparticle at different times t: where ρ x is the density of nanoparticle x, m x is the mass of a single x nanoparticle, k is a constant 2.6; When the nano-individual is a nanowire, the optical signal calculation of the electrochemical signal of a single nano-individual in step S3 is performed according to formula (2), and the current i of the single nanowire at different times t is calculated using the optical intensity I of the single nanowire collected by the image acquisition device;

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