A self-driven Au-Zn nanomotor and its preparation method and application

Abstract

The present invention discloses a self-driven Au-Zn nanomotor, its preparation method and application. The self-driven Au-Zn nanomotor is tubular, with a length of 3 to 7 μm, an outer diameter of 320 to 500 nm, an inner diameter of 150 to 260 nm, an atomic percentage of Au of 85 to 95%, and an atomic percentage of Zn of 5 to 15%. No bubbles are generated during the propulsion of the motor, which can avoid the influence of bubbles on the movement of the self-driven Au-Zn nanomotor. The interaction mode between the self-driven Au-Zn nanomotor and the passive particles switches between attraction and repulsion, which can provide new ideas for the organizational behavior of active materials in biological evolution, the formation of condensates and cell component clusters. In addition, the self-driven Au-Zn nanomotor can also be used for biomolecule detection and biological information collection.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomotors, and in particular relates to a self-driven Au-Zn nanomotors and a preparation method and application thereof. Background Art

[0002] A nanomotor is a tiny device that can convert other forms of energy into kinetic energy, enabling it to move in liquid media and simultaneously perform complex tasks. Depending on the energy source driving the nanomotor, it can be divided into nanomotors driven by chemical energy generated by chemical reactions or by external physical energy (light energy, sound energy, magnetic energy, or electrical energy). A chemical energy-driven nanomotor is a nanomotor powered by chemical reactions. Currently, most reports use H2O2, HCl, N2H4, I2, and other fuels. Physical energy-driven nanomotors, on the other hand, are nanomotors driven by energy provided by external physical fields, such as light-driven nanomotors, sound-driven nanomotors, magnetic-driven nanomotors, and electric-driven nanomotors.

[0003] Among these, bubble-driven nanomotors, a common chemical propulsion method, utilize a suitable chemical fuel to generate bubbles through a chemical reaction, which then detach from the nanomotor and create a counter-thrust force to propel the nanomotor. However, practical applications of bubble-driven nanomotors present several challenges. For example, the viscous drag of the liquid medium can affect the nanomotor's efficiency. Furthermore, bubbles generated during propulsion can interfere with the nanomotor's motion. Therefore, there is an urgent need to develop a nanomotor that can adaptively adjust its direction of motion based on environmental changes, thereby minimizing interference with the nanomotor's motion. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a self-driven Au-Zn nanomotor and its preparation method and application. The self-driven Au-Zn nanomotor in the present invention does not generate bubbles during the movement process, thereby avoiding the influence of bubbles on the movement of the self-driven Au-Zn nanomotor, and the image formed during the movement of the self-driven Au-Zn nanomotor can be used to prepare complex patterns in biological detection. In addition, in addition to interacting with passive particles, the self-driven Au-Zn nanomotor in the present invention can also interact with active substances and even biological entities, which can provide new ideas for the organizational behavior of active materials in biological evolution, the formation of condensates and cell component clusters.

[0005] A first aspect of the present invention provides a self-driven Au-Zn nanomotor, wherein the self-driven Au-Zn nanomotor is in the shape of a hollow tube.

[0006] According to the first aspect of the present invention, in some embodiments of the present invention, the length of the self-driven Au-Zn nanomotor is 3 to 7 μm.

[0007] In some preferred embodiments of the present invention, the outer diameter of the self-driven Au-Zn nanomotor is 320-500 nm, and the inner diameter is 150-260 nm.

[0008] In some more preferred embodiments of the present invention, the outer diameter of the self-driven Au-Zn nanomotor is 417 nm and the inner diameter is 204 nm.

[0009] In some preferred embodiments of the present invention, one end of the self-driven Au-Zn nanomotor is made of Au-containing material, and the other end is made of Zn-containing material.

[0010] In some preferred embodiments of the present invention, the atomic percentage of Au in the self-driven Au-Zn nanomotor is 85-95%, and the atomic percentage of Zn is 5-15%.

[0011] In some more preferred embodiments of the present invention, the atomic percentage of Au in the self-driven Au-Zn nanomotor is 91.9%, and the atomic percentage of Zn is 8.1%.

[0012] In some more preferred embodiments of the present invention, the length of the tube containing the Au material end of the self-driven Au-Zn nanomotor is 1 to 2 μm, and the length of the tube containing the Zn material end is 2 to 5 μm.

[0013] In some more preferred embodiments of the present invention, the Au material includes Au or a salt thereof, preferably Au.

[0014] In some more preferred embodiments of the present invention, the Zn material includes Zn or a salt thereof, preferably Zn.

[0015] In some preferred embodiments of the present invention, the driving force of the self-propelled Au-Zn nanomotor comes from water.

[0016] In some preferred embodiments of the present invention, no bubbles are generated during the propulsion process of the self-driven Au-Zn nanomotor.

[0017] In some more preferred embodiments of the present invention, the formation of the hollow tubular structure of the self-propelled Au-Zn nanomotor is controlled by the deposition voltage of electrochemical deposition.

[0018] The second aspect of the present invention provides a method for preparing the self-driven Au-Zn nanomotor according to the first aspect of the present invention, the preparation method comprising the following steps:

[0019] (1) providing a gold layer on one side of a polycarbonate filter membrane having a transparent pore structure, wherein the gold layer is used to seal the pores on one side of the polycarbonate filter membrane, thereby obtaining a deposition mold, wherein the diameter of the pores is 250 to 500 nm, the length is 10 to 20 μm, and the thickness of the gold layer is 60 to 150 nm;

[0020] (2) depositing Au and Zn into the holes in the deposition mold on the side away from the closed gold layer;

[0021] (3) Removing the deposition mold to obtain a self-driven Au-Zn nanomotor.

[0022] According to the second aspect of the present invention, in some embodiments of the present invention, electrochemical deposition adopts a three-electrode system, wherein the working electrode is a polycarbonate filter membrane, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a graphite rod electrode.

[0023] In some preferred embodiments of the present invention, the pore size of the polycarbonate filter membrane in step (1) is 400 nm.

[0024] In some preferred embodiments of the present invention, the length of the polycarbonate filter membrane in step (1) is 15 μm.

[0025] In some preferred embodiments of the present invention, the gold layer in step (1) is deposited on one side of the polycarbonate filter membrane by evaporation.

[0026] In some preferred embodiments of the present invention, the thickness of the gold layer in step (1) is 100 nm.

[0027] In some preferred embodiments of the present invention, the Au deposition method in step (2) is electrochemical deposition, wherein the electroplating solution is a commercially available electroplating solution containing sodium gold sulfite, the model is 24k gold water, and the purchase manufacturer is Weilan Technology Co., Ltd.

[0028] In some preferred embodiments of the present invention, in the deposition of Au in step (2), the voltage of the electrochemical deposition is -0.5 to -1.2V.

[0029] In some more preferred embodiments of the present invention, in the deposition of Au in step (2), the voltage of the electrochemical deposition is -0.9V.

[0030] In some preferred embodiments of the present invention, in the deposition of Au in step (2), the electrochemical deposition time is 10 to 20 minutes.

[0031] In some more preferred embodiments of the present invention, in the deposition of Au in step (2), the electrochemical deposition time is 15 minutes.

[0032] In some preferred embodiments of the present invention, the Zn deposition method in step (2) is electrochemical deposition, wherein the electroplating solution is a mixture of ZnSO4·7H2O and H3BO3.

[0033] In some more preferred embodiments of the present invention, the volume of the mixture is 30 to 70 mL.

[0034] In some more preferred embodiments of the present invention, the volume of the mixture is 50 mL.

[0035] In some preferred embodiments of the present invention, in the deposition of Zn in step (2), the voltage of the electrochemical deposition is -0.8 to -2V.

[0036] In some more preferred embodiments of the present invention, in the deposition of Zn in step (2), the voltage of the electrochemical deposition is -1.23V.

[0037] In some preferred embodiments of the present invention, in the deposition of Zn in step (2), the electrochemical deposition time is 10 to 20 minutes.

[0038] In some more preferred embodiments of the present invention, in the deposition of Zn in step (2), the electrochemical deposition time is 15 min.

[0039] In some more preferred embodiments of the present invention, in the mixture of ZnSO4·7H2O and H3BO3, the initial concentration ratio of ZnSO4·7H2O to H3BO3 is (1-3):(0.5-2).

[0040] In some more preferred embodiments of the present invention, the initial concentration of ZnSO4·7H2O in the mixture is 0.1 to 0.3 mol / L.

[0041] In some more preferred embodiments of the present invention, the initial concentration of ZnSO4·7H2O in the mixture is 0.2 mol / L.

[0042] In some more preferred embodiments of the present invention, the initial concentration of H3BO3 in the mixture is 0.05 to 0.2 mol / L.

[0043] In some more preferred embodiments of the present invention, the initial concentration of H3BO3 in the mixture is 0.1 mol / L.

[0044] In some preferred embodiments of the present invention, the method for removing the gold layer on the surface of the polycarbonate filter membrane in the deposition mold in step (3) is a physical friction method.

[0045] In some preferred embodiments of the present invention, the method for removing the polycarbonate filter membrane in the deposition mold in step (3) is a solution dissolution method.

[0046] In some more preferred embodiments of the present invention, the solution in step (3) is one or more of dichloromethane and tetrahydrofuran.

[0047] In some more preferred embodiments of the present invention, the dissolution time in step (3) is 5 to 15 minutes.

[0048] In some more preferred embodiments of the present invention, the dissolution time in step (3) is 10 minutes.

[0049] In a third aspect, the present invention provides a carrier system, comprising the self-propelled Au-Zn nanomotor according to the first aspect of the present invention, a charged substrate, and an H-containing aqueous solution.

[0050] According to the third aspect of the present invention, in some embodiments of the present invention, the H-containing aqueous solution is water.

[0051] In some preferred embodiments of the present invention, the material of the charged substrate includes glass.

[0052] In some more preferred embodiments of the present invention, the charged substrate is a glass slide.

[0053] In some preferred embodiments of the present invention, the charged substrate carries a positive charge or a negative charge.

[0054] In some preferred embodiments of the present invention, the carrier system further comprises passive particles.

[0055] In some more preferred embodiments of the present invention, the passive particles are positively or negatively charged.

[0056] In some more preferred embodiments of the present invention, the passive particles are charged polystyrene beads (PS beads).

[0057] In some more preferred embodiments of the present invention, the PS beads may have amino groups or carboxyl groups.

[0058] In some preferred embodiments of the present invention, the motion of the self-propelled Au-Zn nanomotors in the carrier system of the present invention is adaptive, which can provide new ideas for the organizational behavior of active materials in biological evolution, the formation of condensates and cell component clusters.

[0059] The fourth aspect of the present invention provides the use of the self-propelled Au-Zn nanomotor described in the first aspect of the present invention or the carrier system described in the third aspect of the present invention in biomolecule detection and bioinformation collection.

[0060] The beneficial effects of the present invention are:

[0061] 1. The driving force for the movement of the self-driven Au-Zn nanomotor in the present invention comes from water, and the reaction between Zn and water is relatively slow. No bubbles are generated during the entire process of the self-driven Au-Zn nanomotor's propulsion, which can avoid the influence of the generated bubbles on the movement of the self-driven Au-Zn nanomotor, allowing the self-driven Au-Zn nanomotor to work continuously for 4-5 days.

[0062] 2. The motion of the self-propelled Au-Zn nanomotor in the present invention is adaptive and can switch between two interaction modes: attraction and repulsion. The interaction is not limited to passive particles, but can also be another active substance or even a biological entity. It can provide new ideas for the organizational behavior of active materials in biological evolution, the formation of condensates and cell component clusters.

[0063] 3. The movement of the self-propelled Au-Zn nanomotor in the present invention can be controlled by the relative position of the self-propelled Au-Zn nanomotor and the passive particles and the charge carried by the substrate, and the patterned structure formed during the movement of the self-propelled Au-Zn nanomotor can be subsequently used as a template to prepare complex patterns for use in biological detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 a is a schematic diagram of the preparation of the self-driven Au-Zn nanomotor prepared in an embodiment of the present invention; Figure 1 b is a SEM image of the self-propelled Au-Zn nanomotor prepared in an embodiment of the present invention after the deposition mold is removed, the scale bar is 1 μm; Figure 1 c is the SEM side view of the self-driven Au-Zn nanomotor prepared in the embodiment of the present invention, the scale bar is 3 μm ( Figure 1 Inset in c: Front view of the gold nozzle of the self-driven Au-Zn nanomotor, scale bar 0.2 μm); Figure 1 d is the distribution of length and outer diameter of the self-propelled Au-Zn nanomotor;

[0065] Figure 2 EDS elemental mapping of the self-propelled Au-Zn nanomotor prepared in an embodiment of the present invention. The scale bar is 2 μm, where the atomic percentage of Au is 91.9% and the atomic percentage of Zn is 8.1%.

[0066] Figure 3 The motion trajectory of the self-propelled Au-Zn nanomotor in deionized water (within 10 seconds), the scale bar is 50 μm;

[0067] Figure 4 The surface Zn of the self-propelled Au-Zn nanomotor 2+ Schematic diagram of H2 diffusion, self-driven Au-Zn nanomotor to Zn 2+Movement in high-concentration areas;

[0068] Figure 5 The fitted mean square displacement (MSD) analysis of the self-propelled Au-Zn nanomotor in deionized water, 5% glucose solution, and phosphate buffered saline solution, where UP is deionized water, GO is 5% glucose solution, and PBS is phosphate buffered saline solution. The dotted values represent the actual measured values, and the solid line represents the fitted results.

[0069] Figure 6 This is a blue fluorescence image of an inverted microscope. The blue fluorescence in the red circle represents Zn 2+ The distribution of the scale bar is 100 μm;

[0070] Figure 7 a is a cross-sectional view of the self-built electric field and electroosmotic flow generated by the self-driven Au-Zn nanomotor; Figure 7 b shows the trajectory and speed of amino PS beads and carboxyl PS beads (yellow indicates high speed, blue indicates low speed), the scale bar is 5 μm; Figure 7 c is a diagram showing the attraction process of the self-propelled Au-Zn nanomotor to the amino PS beads during propulsion. The red circles represent the amino PS beads, and the green and blue lines represent the motion trajectories of the amino PS beads. The scale bar is 20 μm. Figure 7 d is the trajectory and speed of the amino PS beads chasing the self-propelled Au-Zn nanomotor (yellow indicates high speed, blue indicates low speed), the scale bar is 10 μm; Figure 7 e is a schematic diagram of amino PS beads chasing the self-propelled Au-Zn nanomotor, and the red beads represent amino PS beads; Figure 7 f is the trajectory of the self-driven Au-Zn nanomotor redirecting after adsorbing amino PS beads, the scale bar is 10 μm; Figure 7 g is a schematic diagram of the interaction between the self-propelled Au-Zn nanomotor and amino PS beads; Figure 7 h is the trajectory of the circular motion of the self-driven Au-Zn nanomotor due to the interaction with amino PS beads, the scale bar is 10 μm, and all results are observed under a negatively charged substrate;

[0071] Figure 8 a is a schematic diagram of the self-propelled Au-Zn nanomotor stopping on a negatively charged substrate, where the amino PS beads are first adsorbed and then ejected. The scale bar is 10 μm. Figure 8 b is the migration velocity diagram of amino PS beads when the self-propelled Au-Zn nanomotor is adsorbed on a negatively charged substrate; Figure 8 c is the aggregation pattern of 10 μm PS beads (negatively charged, without groups) when self-driven Au-Zn nanomotors appear on negatively charged substrates. The scale bar is 100 μm. Figure 8The black dots in c are 10 μm PS beads; Figure 8 d is the trajectory of the amino PS beads when the self-propelled Au-Zn nanomotor stops on a positively charged substrate, the scale bar is 10 μm; Figure 8 e is the migration velocity of amino PS beads when the self-propelled Au-Zn nanomotor is adsorbed on a positively charged substrate; Figure 8 f is the aggregation pattern of 10 μm PS beads (negatively charged, without groups) when self-driven Au-Zn nanomotors appear on a positively charged substrate. The scale bar is 100 μm. Figure 8 The black dots in f are 10 μm PS beads;

[0072] Figure 9 a is the Zn simulated by COMSOL 2+ Potential diagram of the self-built electric field formed by outward diffusion (V represents the unit of voltage); Figure 9 b is a schematic diagram of the electroosmotic flow formed by the self-propelled Au-Zn nanomotor suspended in the solution. At a position far away from the negatively charged substrate, Zn 2+ The positively charged protons adsorbed on the negatively charged substrate are repelled, resulting in electroosmotic flow from the self-propelled Au-Zn nanomotor to the substrate. Figure 9 c Schematic diagram of the electroosmotic flow formed when the self-driven Au-Zn nanomotor approaches a negatively charged substrate. 2+ The positively charged protons adsorbed on the negatively charged substrate are repelled, resulting in electroosmotic flow from the self-propelled Au-Zn nanomotor to the substrate. Figure 9 d is a schematic diagram of the electroosmotic flow formed when the self-driven Au-Zn nanomotor approaches a positively charged substrate. 2+ The generated electrostatic field attracts OH adsorbed on the positively charged substrate. - , thus generating an electroosmotic flow from the substrate to the self-driven Au-Zn nanomotor. The symbol + near the self-driven Au-Zn nanomotor represents Zn 2+ ;

[0073] Figure 10 Schematic diagram of the effective "pressure" difference along the substrate caused by the thickness concentration gradient of the negatively charged substrate double layer. DETAILED DESCRIPTION

[0074] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, and such modifications and replacements fall within the scope of protection of the present invention.

[0075] The purchase sources of the materials involved in the following content are shown in Table 1.

[0076] Table 1:

[0077]

[0078]

[0079] Synthesis of self-propelled Au-Zn nanomotors

[0080] The self-propelled Au-Zn nanomotor was prepared by electrochemical deposition. The preparation process adopted a three-electrode system, with a graphite rod electrode as the counter electrode, Ag / AgCl as the reference electrode, and a polycarbonate filter membrane as the working electrode for electrochemical deposition.

[0081] The polycarbonate filter membrane of the working electrode has several transparent holes at both ends. The diameter of the holes is 400nm and the length is 15μm. A 100nm thick gold layer is evaporated on one end of the polycarbonate filter membrane to seal the holes at that end and form a conductive layer.

[0082] Self-propelled Au-Zn nanomotors were prepared by electrochemical deposition:

[0083] (1) Au deposition: The electroplating solution is a commercially available 24k gold solution containing sodium gold sulfite. The electrochemical deposition voltage is -0.9 V and the deposition time is 15 min.

[0084] (2) Zn deposition: The electroplating solution was a mixture of ZnSO4·7H2O and H3BO3, with a volume of 50 mL. In this mixture, the initial concentration of ZnSO4·7H2O was 0.2 mol / L, and the initial concentration of H3BO3 was 0.1 mol / L. The electrochemical deposition voltage was -1.23 V, and the deposition time was 15 min.

[0085] (3) After the electrochemical deposition is completed, the gold layer on the surface of the polycarbonate filter membrane in the working electrode is removed by physical friction. The polycarbonate filter membrane is then dissolved with dichloromethane (dissolution time is 10 min) and washed with ethanol and deionized water to obtain a self-propelled Au-Zn nanomotor. Finally, the nanomotor is dispersed in deionized water and stored for use.

[0086] Figure 1 a is a schematic diagram of the preparation of the self-driven Au-Zn nanomotor prepared in an embodiment of the present invention.

[0087] Characterization results of self-driven Au-Zn nanomotors

[0088] (1) Morphology characterization and elemental analysis:

[0089] The self-driven Au-Zn nanomotor prepared in the above embodiment was observed using a Phenom scanning electron microscope to obtain its scanning electron microscope (SEM) image and energy dispersive X-ray spectrum (EDS), wherein the acceleration voltage was set to 15 kV.

[0090] Figure 1 b is an SEM image of the self-driven Au-Zn nanomotor prepared in an embodiment of the present invention after the deposition mold is removed, and the scale bar is 1 μm. Figure 1 c is the SEM side view of the self-driven Au-Zn nanomotor prepared in the embodiment of the present invention, and its scale is 3 μm. The inset is the front view of the Au nozzle of the self-driven Au-Zn nanomotor, and its scale is 0.2 μm. Figure 1 As can be seen from Figure c, the outer diameter of the nanomotor prepared in the embodiment of the present invention is about 417 nm, and the inner diameter is about 204 nm. Figure 1 d is the distribution diagram of the tube length and outer diameter of the self-propelled Au-Zn nanomotor prepared in the embodiment of the present invention, Figure 1 As can be seen in d, the average length of the entire tube is 4.76 ± 1.3 μm. Figure 2 The EDS element mapping of the self-propelled Au-Zn nanomotor prepared in the embodiment of the present invention is shown in the figure. The scale bar is 2 μm. Figure 2 The coexistence and distribution of Au and Zn can be clearly seen in the figure, where the atomic percentage of Au is 91.9% and the atomic percentage of Zn is 8.1%.

[0091] (2) Movement observation:

[0092] The calculation method of the movement speed of the self-propelled Au-Zn nanomotor is as follows: the coordinates of the motor are recorded at 200ms time intervals, the instantaneous speed is obtained by dividing the distance by the time interval, and then the average speed is obtained by taking the average.

[0093] Movement of the self-propelled Au-Zn nanomotor: 10 μL of a deionized water solution of the self-propelled Au-Zn nanomotor was placed on a glass slide and imaged using an inverted microscope (Nikon Ti2-A). The movement trajectory of the self-propelled Au-Zn nanomotor was recorded using a 40x microscope and a video was recorded using NIS-Element Viewer. The experiment found that the self-propelled Au-Zn nanomotor prepared in the embodiment of the present invention can move spontaneously in deionized water, such as Figure 3 As shown in Figure 2, the average speed of the self-propelled Au-Zn nanomotor is calculated to be 5-8 μm s -1 .

[0094] (3) Movement direction:

[0095] For the movement of the self-propelled Au-Zn nanomotor, the driving force comes from the reaction between the Zn segment and water, as shown in the chemical reaction formula (1). The inert Au does not undergo chemical reaction during the propulsion process. Therefore, the nanomotor is driven by diffusion electrophoresis. The self-propelled Au-Zn nanomotor absorbs H on the surface of the Zn tube. + and release Zn 2+ The propulsion mechanism of diffusion electrophoresis can be expressed by formula (2):

[0096]

[0097]

[0098] Equation (2) expresses the velocity of the diffusing electrophoretic particles near the slide. In Equation (2), U is the particle velocity, C is the electrolyte concentration, and D C and D A are the diffusion coefficients of cations and anions, k b is the Boltzmann constant, T is the temperature, e is the elementary charge, ε is the dielectric constant of the solution, η is the viscosity of the solution, ζ w is the zeta potential of the slide, ζ P is the zeta potential of the particle.

[0099] Zeta potential was measured using a Malvern Zetasizer Nano ZS with a He-Ne laser at a wavelength of 633 nm and a test temperature of 25°C.

[0100] Equation (2) Represents a part of the electrostatic field. In the self-driven Au-Zn nanomotor prepared in the above embodiment, only Zn is generated on the surface of the nanomotor. 2+ , so D A =0.

[0101] Part 2 It is the effective "pressure" difference along the glass slide caused by the thickness gradient of the double layer of the charged glass slide. Since the thickness of the double layer on the glass slide depends largely on the concentration of the electrolyte in the solution, the electrolyte concentration gradient will lead to a double layer thickness gradient along the glass slide. The concentration gradient of the double layer thickness produces an effective "pressure" difference along the glass slide, causing the fluid (deionized water) to flow from the area with higher electrolyte concentration to the area with lower electrolyte concentration, thereby causing the nanomotor to move in the opposite direction, that is, towards the Zn tube with higher electrolyte concentration. The schematic diagram of the effective "pressure" difference produced by the concentration gradient of the double layer thickness along the glass slide is shown in the figure below. Figure 10 shown.

[0102] H in water + is reduced in the presence of Zn segments to produce H2 and Zn2+ , but no bubbles were observed under the microscope. This ensures that the movement of the self-driven Au-Zn nanomotor system will not be disturbed by bubbles, so that the movement of the motor can be better observed. As the reaction proceeds, Zn 2+ The concentration of Zn decreases gradually from Zn to Au, forming a concentration gradient, and then forming a self-built electric field. The direction of the self-built electric field is from the Zn tube to one end of the Au tube. Under the action of the electric field force brought by the self-built electric field, the nanomotor is pushed in the direction of Zn, and the Zn on the surface of the self-driven Au-Zn nanomotor is 2+ The schematic diagram of H2 diffusion is as follows Figure 4 shown.

[0103] The mean square displacement (MSD) value is fitted with time, and the results are as follows: Figure 5 As shown in the figure, the MSD increases linearly with time. Furthermore, the performance of the self-propelled Au-Zn nanomotor in deionized water and 5% glucose solution is similar, indicating that the presence of glucose molecules does not affect the propulsion capability of the self-propelled Au-Zn nanomotor. The mobility of the self-propelled Au-Zn nanomotor is hampered in PBS buffer solution, primarily because the pH buffering of PBS alters the rate of the proton-dependent zinc oxidation reaction and changes the surface charge of the self-propelled Au-Zn nanomotor.

[0104] Use Zn 2+ Detection of Zn generated during the motion of self-propelled Au-Zn nanomotors using the fluorescent probe Zinquin 2+ , the fluorescent probe can be 2+ The specific operation is: add 10μL of 1mM Zinquin (deionized water: DMSO = 9:1) to 10μL of self-propelled Au-Zn nanomotor dispersion, and then use an inverted fluorescence microscope to image. It can be found that in the presence of Zn 2+ Fluorescence (blue) image ( Figure 6 ), the blue fluorescent area highlighted by the red circle represents the fluorescent products generated by probe polymerization and the Zn from the self-propelled Au-Zn nanomotor 2+ The dark area in the red circle has almost no fluorescent beads, which is the forbidden area for the nanomotor to produce. Only some fluorescent products are excluded from the outside. As the nanomotor continuously reacts with water to generate Zn 2+ , and Zn 2+ The nanomotor continuously aggregates with fluorescent probes, so it continuously ejects fluorescent beads.

[0105] Self-propelled Au-Zn nanomotor carrier system

[0106] The self-propelled Au-Zn nanomotor uses a glass slide (either positively or negatively charged) as a substrate and can spontaneously move in deionized water toward one end of the Zn tube. The electroosmotic flow generated by the self-propelled Au-Zn nanomotor can drive the PS beads. The movement pattern of the PS beads driven by the electroosmotic flow generated by the self-propelled Au-Zn nanomotor and the resulting aggregation morphology of the PS beads are determined by the charge type of the glass slide and the position of the self-propelled Au-Zn nanomotor.

[0107] Observation of the interaction between the self-propelled Au-Zn nanomotor and PS beads: 10 μL of an aqueous solution of the self-propelled Au-Zn nanomotor and 10 μL of a PS bead solution (1 μm amino PS beads, 1 μm carboxyl PS beads, or 10 μm PS beads, purchased from Sigma) were placed on a glass slide and imaged using an inverted microscope (Nikon Ti2-A). The motion trajectory was recorded using a 40x microscope and video was recorded using NIS-ElementViewer.

[0108] (1) Negatively charged glass slide (CITOTEST 1A5101, ζw = -85 mV), passive particles are carboxyl PS beads (hereinafter referred to as cPS beads, ζcPS = -34 mV, diameter 1 μm)

[0109] As the self-propelled Au-Zn nanomotor continuously reacts with water, a Zn nanomotor is formed around it, which is far away from the surface of the nanomotor. 2+ Gradient fields, such as Figure 7 As shown in a, an electrostatic field away from the surface of the nanomotor is formed, and the direction of the electrostatic field is away from the self-driven Au-Zn nanomotor. For a negatively charged glass slide, positively charged protons will be adsorbed on the glass slide. Zn 2+ The electrostatic field generated away from the self-propelled Au-Zn nanomotor acts on the protons, causing repulsion and outward electroosmotic flow from the nanomotor to the glass slide. Since the fluid is continuous, a fluid inward pointing to the nanomotor will be generated in the liquid in the upper space. 2+ Under the repulsion generated by the electric field, the self-propelled Au-Zn nanomotor is suspended in deionized water. 2+ The generated electrostatic field away from the self-propelled Au-Zn nanomotor direction hinders the motion of the positively charged amino PS beads and accelerates the motion of the negatively charged cPS beads.

[0110] When cPS beads were added to the solution as passive particles, within the range of 2 μm of a single self-propelled Au-Zn nanomotor, cPS beads that fell near the nanomotor could be quickly adsorbed to the surface of the nanomotor (this was due to the Zn 2+The self-generated electric field and the electroosmotic flow directed toward the motor form a quasi-stable nanomotor-cPS complex, which may be the equilibrium position of surface slip flow. Then, because the self-propelled Au-Zn nanomotor is far away from the glass slide, the cPS beads are not repelled by the electroosmotic flow below. The speed of 15 cPS beads when they were absorbed was recorded, and the recorded movement speed of the cPS beads can reach 12.5±4μm s. -1 , indicating that there is an attractive field around the self-driven Au-Zn nanomotor.

[0111] (2) The glass slide was negatively charged (CITOTEST 1A5101, ζw = -85 mV), and the passive particles were amino PS beads (hereinafter referred to as aPS beads, ζaPS = +38 mV, diameter 1 μm)

[0112] When aPS beads were added to the solution as passive particles, the zeta potential of the aPS beads and the zeta potential of the glass slide were detected: it can be found that ζaPS = +38 mV, ζw = -85 mV. Since the zeta potential of the aPS beads is smaller than that of the glass slide, the electroosmotic flow is dominant for the self-propelled Au-Zn nanomotors and aPS beads, which is sufficient to overcome the swimming of the particles, as shown in Figure 2. Figure 7 As shown in Figure c, the self-propelled Au-Zn nanomotor adsorbed two aPS beads during its forward movement. This attraction-without-repulsion interaction is not common in traditional active-passive particle systems. It is possible that the continuous motion of the nanomotor hinders the interaction between the electroosmotic flow and the PS beads. These results indicate that when the self-propelled Au-Zn nanomotor is moving and away from the glass slide, it interacts with the PS beads in a manner that is conducive to absorption and the formation of a quasi-stable complex. In addition, the average speed of the aPS beads during the absorption process was found to be 10.6 ± 2.0 μm s -1 , the speed is not significantly different from that of the cPS beads, which means that the electrostatic force does not play a major role in the interaction process between the self-driven Au-Zn nanomotors and PS beads.

[0113] The motion trajectories of aPS beads and cPS beads are shown in Figure 2. Figure 7 As shown in Figure b, the color indicates the movement speed, with yellow indicating high speed and blue indicating low speed. It can be observed that the PS particle speed decreases with increasing distance from the nanomotor, meaning that the closer to the self-propelled Au-Zn nanomotor, the higher the electroosmosis speed. Since only slight differences in adsorption were observed between aPS and cPS beads, aPS beads were used as passive particles.

[0114] Interaction modes of self-propelled Au-Zn nanomotors with passive particles at different positions

[0115] If the aPS beads can be attracted by a moving self-propelled Au-Zn nanomotor, a chasing phenomenon will occur and the passive particles should have a long-distance high-speed motion, e.g. Figure 7 As shown in Figure d, an interesting chasing phenomenon can be observed between the self-propelled Au-Zn nanomotor and the aPS bead. As the self-propelled Au-Zn nanomotor moves to the right, the aPS bead is attracted by the adsorption field of the self-propelled Au-Zn nanomotor. The aPS bead is observed to accelerate and thus catch up with the self-propelled Au-Zn nanomotor, and then combine to form a quasi-stable aPS-nanomotor complex. The chasing diagram is shown in Figure d. Figure 7 As shown in e. During the chase process, the speed of aPS beads can reach 17 μm s -1 . When the self-driving Au-Zn nanomotor paused moving (bound to the glass slide and no longer displaced), the aPS beads fell off, probably because the surface slip equilibrium position flow of the self-driving Au-Zn nanomotor changed. In the above-mentioned chasing phenomenon, the adsorption of the PS beads did not change the movement direction of the self-driving Au-Zn nanomotor. An interesting phenomenon occurs when the PS beads face the moving self-driving Au-Zn nanomotor. When the self-driving Au-Zn nanomotor rotates counterclockwise to adsorb the aPS beads in front, the rotation direction of the self-driving Au-Zn nanomotor will be reversed to clockwise, and the aPS beads are adsorbed to the middle of the self-driving Au-Zn nanomotor, as shown in FIG. Figure 7 f. This phenomenon may be due to the self-driven Au-Zn nanomotor moving towards high Zn at the beginning. 2+ When the aPS beads are absorbed, the local chemical reaction of the self-propelled Au-Zn nanomotor is hindered, resulting in the Zn on both sides of the self-propelled Au-Zn nanomotor. 2+ The concentration is reversed, thereby reversing the rotation direction of the self-driven Au-Zn nanomotor. The schematic diagram of the interaction between the self-driven Au-Zn nanomotor and the aPS beads is shown in Figure 7 g. In addition, from Figure 7 As can be seen in Figure h, the adsorption position of the PS beads does affect the motion direction of the self-propelled Au-Zn nanomotor. Based on the motion direction of the self-propelled Au-Zn nanomotor, the aPS beads are believed to be adsorbed on the Zn side of the self-propelled Au-Zn nanomotor. As the aPS beads are continuously loaded onto the Zn side, the self-propelled Au-Zn nanomotor moves in a circular pattern toward the Au / aPS side. While the other side is unaffected, the trajectory deviates toward the Au / aPS side. The response of the self-propelled Au-Zn nanomotor to the adsorbed passive particles demonstrates the flexibility of the self-propelled Au-Zn nanomotor's motion. Furthermore, the interaction is not limited to passive particles but can also involve other active substances or even biological entities, providing new insights into the organizational behavior of active materials in biological evolution, the formation of condensates, and the formation of cellular component clusters.

[0116] Effect of glass slide on the interaction between self-propelled Au-Zn nanomotors and passive particles

[0117] The direction of fluid flow is also affected by the direction of the electrostatic field generated by the self-propelled Au-Zn nanomotor. 2+ The direction of the electrostatic field formed by diffusion points away from the self-propelled Au-Zn nanomotor. When the self-propelled Au-Zn nanomotor approaches the negatively charged glass slide, the Zn 2+ The electric field acts on protons absorbed by the negatively charged glass slide, causing repulsion and outward electroosmotic flow from the self-powered Au-Zn nanomotor to the glass slide. Similarly, because the fluid is a continuous loop, inward flow is generated in the upper solution.

[0118] like Figure 8 As shown in Figure a, when the self-propelled Au-Zn nanomotor stops on a negatively charged glass slide, the aPS beads on the upper layer are first carried toward the self-propelled Au-Zn nanomotor by the inward fluid above the self-propelled Au-Zn nanomotor, and then repelled and ejected by the outward electroosmotic flow near the self-propelled Au-Zn nanomotor. When close to the glass slide, the area near the self-propelled Au-Zn nanomotor is dominated by a strong outward electroosmotic flow, which is not conducive to the attraction and combination of the aPS beads and the self-propelled Au-Zn nanomotor into a quasi-stable complex. At this time, in response to changes in the environment, the interaction mode between the self-propelled Au-Zn nanomotor and the aPS beads becomes repulsive. During the ejection process, the speed of the aPS beads can reach 10μm s -1 ( Figure 8 b). This attraction-repulsion interaction leads to a forbidden zone effect in both the active and passive particle systems (self-propelled Au-Zn nanomotors and aPS beads). As a result, a circular forbidden zone is formed around the self-propelled Au-Zn nanomotors, and the aPS beads are repelled outside the forbidden zone.

[0119] The forbidden zone phenomenon can be clearly shown using 10 μm PS beads (negatively charged, without groups). Figure 8 c) It can be found that during this process, the self-driven Au-Zn nanomotors will condense. The more self-driven Au-Zn nanomotors produce, the more Zn 2+ The higher the concentration, the 2+ The larger the area of the gradient field, the larger the restricted area. The size of the restricted area is related to Zn 2+ This is because Zn 2+ The gradient provides an electrostatic field, which drives the electroosmotic flow and thus promotes the movement of particles. Therefore, the size of the restricted area is related to the Zn 2 + Proportional to the size of the distribution area.

[0120] In order to further investigate the attraction / repulsion force of the self-driven Au-Zn nanomotor, the negatively charged glass slide was replaced with a positively charged glass slide (CITOTEST 188105W) on the surface of which OH was adsorbed. - Due to the self-built Zn 2+ Under the action of the electrostatic field, the reversal of the zeta potential of the glass slide causes the direction of the electroosmotic flow between the self-driven Au-Zn nanomotor and the glass slide to change from outward repulsion to inward attraction. Figure 8 As shown in (d), the self-propelled Au-Zn nanomotor is attracted to the glass slide due to the electrostatic field, and two aPS beads are adsorbed into the center of the self-propelled Au-Zn nanomotor. No restricted area appears when using 10 μm PS beads (negatively charged and without groups). The 10 μm PS beads and the self-propelled Au-Zn nanomotor either form clusters or are dispersed around them. This result is consistent with our expectations. As the inward electroosmotic flow becomes dominant, the interaction between the self-propelled Au-Zn nanomotor and the passive particles becomes attractive. This indicates that the interaction between the self-propelled Au-Zn nanomotor and the passive particles is adaptive for different charged glass slides. Intracellular components aggregate into condensates at appropriate times and spaces to perform their respective functions. The transport of intracellular substances can be achieved through active processes based on nonspecific, purely physical mechanisms, a phenomenon that remains poorly studied. The controlled pattern formation driven by the self-propelled Au-Zn nanomotor holds promise for the formation of membraneless condensates and their physicochemical properties.

[0121] The above reasons are analyzed by COMSOL simulation, specifically using COMSOL Multiphysics to simulate the electric field. 2+ The distribution of derives from the ion flux on the surface of the self-propelled Au-Zn nanomotor and is further affected by ion diffusion, convection, and migration (Eq. (3)). In this model, it is solved by the conservation equation (Eq. (4)) at steady state.

[0122]

[0123]

[0124] Where, in formula (4), u is the fluid velocity, F is the Faraday constant, is the electrostatic potential, R is the gas constant, T is the absolute temperature, c i is the concentration of species i, D i is the diffusion coefficient of species i, z i is the charge of species i.

[0125] The electrostatic potential in equation (4) Calculate using Poisson's equation:

[0126]

[0127] Among them, in formula (5), ρ e is the volume charge density, z + and z - is the charge of the cation and anion, c + and c - is the concentration of cations and anions, ε0 is the dielectric constant of vacuum, ε r is the dielectric constant relative to the fluid medium.

[0128] Zn 2+ The flux at the zinc surface is determined by: v = ΔC / Δt and f = v / A (6)

[0129] In formula (6), the value of Δt is 346000s; the value of ΔC is determined by the number of pores in the polycarbonate filter membrane and the Zn volume of a single nanomotor; A represents the area, and the value of A is determined by the number of pores in the polycarbonate filter membrane and the Zn area of a single nanomotor. In the above embodiment, the number of pores in the polycarbonate filter membrane is 3.98×10 -5 According to the SEM images, the area and volume of a single self-driven Au-Zn nanomotor are 8.9 μm 2 and 0.37 μm 3 .

[0130] Other COMSOL simulation parameters of the self-built electric field of the self-driven Au-Zn nanomotor in this embodiment are shown in Table 2:

[0131] Table 2 COMSOL simulation parameters of the nanomotor's self-generated electric field

[0132]

[0133] COMSOL is used to simulate Zn 2+ The self-built electric field formed by outward diffusion ( Figure 9 a), from Figure 9 In a, it can be seen that the Zn 2+ An electrostatic field is generated outward from the self-propelled Au-Zn nanomotor. When the glass slide where the self-propelled Au-Zn nanomotor is located is negatively charged, there are protons inside the double electric layer of the glass slide. The electrostatic field of the self-propelled Au-Zn nanomotor acts on the protons, thereby generating an electroosmotic flow outward from the glass slide. Since the fluid is continuous, a fluid toward the glass slide will be generated in the upper solution. When the self-propelled Au-Zn nanomotor is suspended on the glass slide, the inward fluid toward the glass slide dominates near the self-propelled Au-Zn nanomotor, such as Figure 9As shown in b. Therefore, the self-driven Au-Zn nanomotor has the function of capturing passive particles when moving. When the self-driven Au-Zn nanomotor is close to the glass slide, the electroosmotic flow generated from the self-driven Au-Zn nanomotor to the glass slide is dominant, as shown in Figure 9 c. The self-propelled Au-Zn nanomotor can repel nearby particles, and after continuous attraction-repulsion interactions, a restricted area is formed around the self-propelled Au-Zn nanomotor.

[0134] As the slide becomes positively charged, the slide absorbs negatively charged OH - , the electrostatic field of the self-driven Au-Zn nanomotor remains unchanged and acts on the OH - , thereby generating an electroosmotic flow from the glass slide to the self-driven Au-Zn nanomotor, as shown in Figure 9 d. In addition, under the action of the electrostatic field formed by the glass slide to the self-propelled Au-Zn nanomotor, the glass slide to the self-propelled Au-Zn nanomotor and the glass slide attract each other. Therefore, if a positively charged glass slide is used, the self-propelled Au-Zn nanomotor will not float on the glass slide.

[0135] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A self-driven Au-Zn nanomotor, characterized in that: The self-propelled Au-Zn nanomotor is in the shape of a hollow tube with a length of 3-7 μm, an outer diameter of 320-500 nm, and an inner diameter of 150-260 nm. One end of the self-propelled Au-Zn nanomotor is made of Au-containing material, and the other end is made of Zn-containing material. In the self-propelled Au-Zn nanomotor, the atomic percentage of Au is 85-95%, and the atomic percentage of Zn is 5-15%.

2. The self-driven Au-Zn nanomotor according to claim 1, characterized in that: In the self-driven Au-Zn nanomotor, the length of the tube at the end containing the Au material is 1-2 μm, and the length of the tube at the end containing the Zn material is 2-5 μm.

3. The self-propelled Au-Zn nanomotor according to claim 1, characterized in that: The Au material includes Au or a salt thereof; the Zn material includes Zn or a salt thereof.

4. The self-driven Au-Zn nanomotor according to claim 3, characterized in that: The Au material is Au.

5. The self-driven Au-Zn nanomotor according to claim 3, characterized in that: The Zn material is Zn.

6. The method for preparing the self-driven Au-Zn nanomotor according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) A gold layer is provided on one side of a polycarbonate filter membrane having a transparent pore structure, wherein the gold layer is used to seal the pores on one side of the polycarbonate filter membrane, thereby obtaining a deposition mold, wherein the diameter of the pores is 250 to 500 nm, the length is 10 to 20 μm, and the thickness of the gold layer is 60 to 150 nm; (2) depositing Au and Zn into the holes on the side of the deposition mold away from the closed gold layer; (3) Removing the deposition mold to obtain a self-driven Au-Zn nanomotor.

7. The method according to claim 6, characterized in that In step (2), the deposition methods of Au and Zn are both electrochemical deposition, wherein, when depositing Au, the electroplating solution contains sodium gold sulfite, the electrochemical deposition voltage is -0.5~-1.2 V, and the deposition time is 10~20 min; when depositing Zn, the electroplating solution is a mixture of ZnSO4·7H2O and H3BO3, the electrochemical deposition voltage is -0.8~-2 V, and the deposition time is 10~20 min; The electrochemical deposition uses a three-electrode system, wherein the working electrode is a polycarbonate filter membrane, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a graphite rod electrode.

8. The method according to any one of claims 6 to 7, characterized in that In the mixture of ZnSO4·7H2O and H3BO3, the initial concentration ratio of ZnSO4·7H2O and H3BO3 is (1~3):(0.5~2).

9. A vector system, characterized in that The carrier system comprises the self-propelled Au-Zn nanomotor according to any one of claims 1 to 5, a charged substrate, and an aqueous solution containing H, wherein the aqueous solution containing H is water.

10. The carrier system according to claim 9, characterized in that The material of the charged substrate includes glass, and the charged substrate carries positive charge or negative charge.

11. The vector system according to claim 9 or 10, characterized in that The carrier system further comprises passive particles, which are positively charged or negatively charged.

12. The vector system according to claim 11, characterized in that The passive particles are charged polystyrene beads.

13. Use of the self-propelled Au-Zn nanomotor according to any one of claims 1 to 5 or the carrier system according to any one of claims 9 to 11 in biomolecule detection and bioinformation collection.

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