Device and method for measuring surface potential of single nanoparticles

Abstract

The present invention discloses a device and method for measuring the surface potential of a single nanoparticle, belonging to the technical field of nanoparticle measurement. The device and method comprise an imaging mechanism, an image collector, an electric field applying mechanism, and a computing host. The imaging mechanism comprises a microscope objective lens and an excitation light source arranged opposite to the image collector, a sample stage arranged opposite to the microscope objective lens, and a filter component arranged between the image collector and the microscope objective lens. The electric field applying mechanism comprises an electrode plate arranged on the sample stage, and the electrode plate is connected to a voltage regulator. The image collector and the voltage regulator are both connected to the computing host. The device and method for measuring the surface potential of a single nanoparticle are used to detect the surface potential of a single nanoparticle.

Description

Technical Field

[0001] The present invention relates to the technical field of nanoparticle measurement, and in particular to a device and method for measuring the surface potential of a single nanoparticle. Background Art

[0002] In the field of biological testing, fluorescent particle detection is used for cell detection. Existing technologies involve particles attaching a layer of positive and negative ions to the surface of a solution. These ions form an ion barrier on the particle surface, resulting in a surface potential for the particles within the solution. Traditionally, surface potential measurements have been performed using electrophoretic light scattering. This method requires the particles to be uniformly dissolved in an aqueous solution for scattering measurements. While this method typically yields a surface potential distribution, it is not possible to measure the surface potential of a single sample particle. Summary of the Invention

[0003] The purpose of the present invention is to provide a device and method for measuring the surface potential of a single nanoparticle, thereby realizing the measurement of the surface potential of a single nanoparticle.

[0004] To achieve the above-mentioned object, the present invention provides a device for measuring the surface potential of a single nanoparticle, comprising an imaging mechanism, an image collector, an electric field applying mechanism, and a computing host;

[0005] The imaging mechanism includes a microscope objective lens and an excitation light source arranged opposite to the image collector, a sample stage arranged opposite to the microscope objective lens, and a filter component arranged between the image collector and the microscope objective lens;

[0006] The electric field applying mechanism includes an electrode plate arranged on the sample stage, and the electrode plate is connected to a voltage regulator;

[0007] The image collector and the voltage regulator are both connected to the computing host.

[0008] Preferably, the filter assembly includes a first filter and a second filter which are arranged in sequence, the first filter is a dichroic mirror and is arranged opposite to the excitation light source, and the second filter is arranged between the image collector and the first filter.

[0009] A measurement method based on the above-mentioned single nanoparticle surface potential measurement device, the specific steps are as follows:

[0010] Step S1: placing the nanoparticle solution to be tested on the sample stage;

[0011] Step S2: The excitation light source is activated. The excitation light source reaches the sample stage through the dichroic mirror and the microscope objective lens, and one of the nanoparticles to be tested is captured by optical tweezers. The generated fluorescence signal passes through the microscope objective lens, the dichroic mirror, and the second filter to reach the image collector, and the image collector collects N initial images.

[0012] Step S3: starting the voltage regulator so that the electrode plate generates a uniform electric field with a set electric field strength. The nanoparticles to be measured are deflected under the action of the uniform electric field, and N images after deflection are collected again by the image collector;

[0013] Step S4: Calculate the offset distance. According to the fluorescent points of the N initial images and the N offset images, obtain the initial center point and the offset center point respectively. The difference between the initial center point and the offset center point is the offset distance.

[0014] Step S5: Calculate the surface potential of the nanoparticle to be measured according to the electric field strength and the offset distance.

[0015] Preferably, in step S5, the relationship between the electric field strength and the offset distance is as follows:

[0016]

[0017] Where E is the electric field intensity, U is the potential difference between the two electrode plates, and d is the distance between the electrode plates;

[0018] F=qE=Dk

[0019] Where F is the force on the nanoparticle in the electric field, q is the charge of the nanoparticle, D is the offset distance, and k is the potential well stiffness of the optical tweezers.

[0020] The specific formula for the Gaussian distribution of nanoparticle motion is as follows:

[0021]

[0022] Where x is the distance between the nanoparticle and the center point of the corresponding Gaussian distribution, k is obtained by fitting the Gaussian distribution function, and the initial center point and the offset center point are calculated based on N initial images and N offset images. B is the Boltzmann constant, and T is the test temperature.

[0023] Preferably, the relationship between the surface potential of the nanoparticles to be measured and the charge of the nanoparticles is as follows:

[0024]

[0025] e is the elementary charge, ε s is the dielectric constant of the nanoparticle, ε0 is the dielectric constant of vacuum, κ is the Debye length, sinh(.) is the hyperbolic sine function, E r is the reference energy at room temperature.

[0026] Preferably, N is greater than or equal to 1000.

[0027] Therefore, the present invention adopts the above-mentioned single nanoparticle surface potential measurement device and measurement method, which has the following beneficial effects: nanoparticles have surface potential in water, and when they are pushed by the electric field force in a uniform electric field, they are offset. The magnitude of the optical tweezers optical force is calculated by the offset distance and the electric field intensity, thereby obtaining the surface potential of the single particle, which solves the problem that the existing surface potential measurement technology cannot measure the surface potential of a single nanoparticle.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of a device for measuring the surface potential of a single nanoparticle according to the present invention;

[0030] Figure 2 This is a flow chart of the measurement method of the present invention. DETAILED DESCRIPTION

[0031] Example

[0032] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention. In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections or electrical connections; they can be direct connections, or they can be indirectly connected through an intermediate medium, or they can be internal connections between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 As shown, a device for measuring the surface potential of a single nanoparticle includes an imaging mechanism, an image collector, an electric field applying mechanism and a computing host.

[0035] The imaging mechanism includes a microscope objective lens and an excitation light source positioned opposite an image collector. A sample stage is positioned opposite the microscope objective lens, and a filter assembly is positioned between the image collector and the microscope objective lens. The filter assembly includes a first filter and a second filter positioned sequentially. The first filter is a dichroic mirror and positioned opposite the excitation light source. The second filter is positioned between the image collector and the first filter.

[0036] The electric field applying mechanism comprises an electrode plate arranged on the sample stage, and the electrode plate is connected to a voltage regulator for adjusting the electric field intensity.

[0037] The image collector and voltage regulator are both connected to the computing host to facilitate the acquisition of image data and the control of electric field intensity.

[0038] like Figure 2 As shown, a measurement method based on a single nanoparticle surface potential measurement device, the specific steps are as follows:

[0039] Step S1: Place the nanoparticle solution to be tested on the sample stage.

[0040] Step S2: Start the excitation light source, which reaches the sample stage through the dichroic mirror and the microscope objective lens, and captures one of the nanoparticles to be tested through optical tweezers. The generated fluorescence signal reaches the image collector through the microscope objective lens, dichroic mirror, and the second filter, and 1,000 initial images are collected through the image collector.

[0041] Step S3: Start the voltage regulator to make the electrode plate generate a uniform electric field with a set electric field strength. The nanoparticles to be measured are deflected under the action of the uniform electric field, and 1000 images after deflection are collected again by the image collector.

[0042] Step S4: Calculate the offset distance. The nanoparticles to be tested perform Brownian motion within a certain range under the action of optical tweezers. The initial center point and the offset center point are obtained based on the fluorescence points of 1000 initial images and 1000 offset images, respectively. The difference between the initial center point and the offset center point is the offset distance.

[0043] Step S5: Calculate the surface potential of the nanoparticle to be measured according to the electric field strength and the offset distance.

[0044] The specific calculation process is as follows:

[0045] In step S5, the relationship between the electric field strength and the offset distance is as follows:

[0046]

[0047] Where E is the electric field intensity, U is the potential difference between the two electrode plates, and d is the distance between the electrode plates;

[0048] F=qE=Dk

[0049] Where F is the force on the nanoparticle in the electric field, q is the charge of the nanoparticle, D is the offset distance, and k is the potential well stiffness of the optical tweezers.

[0050] The specific formula for the Gaussian distribution of nanoparticle motion is as follows:

[0051]

[0052] Where x is the distance between the nanoparticle and the center point of the corresponding Gaussian distribution, k is obtained by fitting the Gaussian distribution function, and the initial center point and the offset center point are calculated based on N initial images and N offset images. B is the Boltzmann constant, and T is the test temperature.

[0053] The relationship between the surface potential of the nanoparticles to be measured and the charge of the nanoparticles is as follows:

[0054]

[0055] e is the elementary charge, ε s is the dielectric constant of the nanoparticle, ε0 is the dielectric constant of vacuum, κ is the Debye length, sinh(.) is the hyperbolic sine function, E r is the reference energy at room temperature.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A measurement method based on a single nanoparticle surface potential measurement device, characterized in that: The device includes an imaging mechanism, an image collector, an electric field applying mechanism and a computing host; The imaging mechanism includes a microscope objective lens and an excitation light source arranged opposite to the image collector, a sample stage arranged opposite to the microscope objective lens, and a filter component arranged between the image collector and the microscope objective lens; The electric field applying mechanism includes an electrode plate arranged on the sample stage, and the electrode plate is connected to a voltage regulator; The image collector and the voltage regulator are both connected to the computing host; The filter assembly includes a first filter and a second filter which are sequentially arranged, wherein the first filter is a dichroic mirror and is arranged opposite to the excitation light source, and the second filter is arranged between the image collector and the first filter; The measuring method comprises the following specific steps: Step S1: placing the nanoparticle solution to be tested on the sample stage; Step S2: The excitation light source is activated. The excitation light source reaches the sample stage through the dichroic mirror and the microscope objective lens, and one of the nanoparticles to be tested is captured by optical tweezers. The generated fluorescence signal passes through the microscope objective lens, the dichroic mirror, and the second filter to reach the image collector, and the image collector collects N initial images. Step S3: starting the voltage regulator so that the electrode plate generates a uniform electric field with a set electric field strength. The nanoparticles to be measured are deflected under the action of the uniform electric field, and N images after deflection are collected again by the image collector; Step S4: Calculate the offset distance. According to the fluorescent points of the N initial images and the N offset images, obtain the initial center point and the offset center point respectively. The difference between the initial center point and the offset center point is the offset distance. Step S5: Calculate the surface potential of the nanoparticle to be measured according to the electric field strength and the offset distance.

2. The measuring method according to claim 1, wherein: In step S5, the relationship between the electric field strength and the offset distance is as follows: Where E is the electric field intensity, U is the potential difference between the two electrode plates, and d is the distance between the electrode plates; Where F is the force on the nanoparticle in the electric field, q is the charge of the nanoparticle, D is the offset distance, and k is the potential well stiffness of the optical tweezers. The specific formula for the Gaussian distribution of nanoparticle motion is as follows: Where x is the distance between the nanoparticle and the center point of the corresponding Gaussian distribution, k is obtained by fitting the Gaussian distribution function, and the initial center point and the offset center point are calculated based on N initial images and N offset images. is the Boltzmann constant, is the test temperature.

3. The measuring method according to claim 2, wherein: The relationship between the surface potential of the nanoparticles to be measured and the charge of the nanoparticles is as follows: is the elementary charge, is the dielectric constant of the nanoparticles, is the dielectric constant of vacuum, is the Debye length, sinh(.) is the hyperbolic sine function, is the reference energy at room temperature.

4. The measuring method according to claim 3, wherein: N is greater than or equal to 1000.

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