A self-driven Janus polydopamine micromotor with nanochannel ion rectification and a preparation method thereof

Abstract

The application discloses a kind of nanochannel ion rectification self-driven Janus polydopamine micro motor and preparation method thereof, and it relates to a kind of self-driven Janus polydopamine micro motor and preparation method thereof.The application is to solve the problem of low efficiency, poor salt tolerance of traditional motor.The application constructs Janus polydopamine (PDA) shell layer with sub-nanometer pore channel (~0.9 nm) on the surface of active core (such as calcium carbonate).The pore size matches the Debye length of the environment medium, producing a significant ion current rectification (ICR) effect.The sub-nanopore acts as a "kinetic pump", breaking the symmetry of ion transport, efficiently converting chemical energy into directional kinetic energy, and shielding the interference of high concentration environmental electrolyte.The application belongs to the technical field of micro-nano robots and nanofluidics.

Description

Technical Field

[0001] This invention relates to a self-driven Janus polydopamine micromotor and its preparation method, belonging to the field of micro-nano robotics and nanofluidics technology. Background Technology

[0002] Micro-nanomotors (MNMs) are a class of active colloidal particles capable of converting chemical, light, or electromagnetic energy from their surroundings into directed mechanical motion. They hold immense application potential in fields such as biomedical delivery, microenvironment monitoring, and complex water remediation. Among them, chemically driven diffusiophoretic motors are the most common. Their basic principle is to utilize surface asymmetric chemical reactions to generate a solute gradient, which then generates propulsion through an electro-diffusion coupling mechanism.

[0003] Despite the development of various Janus-based motors based on metal catalysis or acid-base reactions over the past two decades, the efficiency of chemical energy conversion to mechanical energy is generally extremely low (typically below 0.1%). This inefficiency stems from isotropic electrochemical relaxation. In traditional surface-reaction-driven motor systems (such as Pt-SiO2 motors), the ionic products generated after the chemical reaction on the active surface are directly released into the bulk solution and rapidly diffuse outwards. Due to the lack of effective flux control, most of the chemical energy is lost through uncontrolled ion diffusion, making it difficult to convert into effective slip current at the motor surface. In practical biomedical applications, micro- and nano-motors often need to operate in high-ionic-strength environments (such as blood). High concentrations of environmental electrolytes produce a strong Debye shielding effect, causing the electric double layer on the motor surface to be compressed, resulting in a rapid reduction in the Debye length. In traditional motors, the shortened Debye length significantly reduces the ability of the motor's surface electric field to control ion flux, leading to the failure of most electrostatic-based dynamic mechanisms. Therefore, existing chemical motors often lose their directional movement capability in high-salt environments. Although nanofluidics research has found that when the channel size is reduced to the sub-nanometer level and matched with the Debye length, a significant ion current rectification effect is generated due to the electric double layer overlap (EDL overlap), this effect is currently mostly applied to bulk permeation energy generation or nanofluidic diodes.

[0004] Coupled with the rectification effect of ion transport in confined spaces and the dynamics of active matter, this invention aims to suppress gradient relaxation by adjusting ion flux and shield against interference from high-salt environments. These are key scientific problems and technical challenges that urgently need to be addressed in the field of micro / nano motors. This invention aims to transform "disordered diffusion" into "confined rectification" through nanofluidics, thereby improving propulsion performance. Furthermore, existing photothermal responsive drug delivery systems largely rely on passive diffusion or polymer thermal response behavior, lacking the ability to actively control ion transport processes and local chemical potential gradients, making it difficult to achieve stable and precise release of functional molecules in complex high-salt environments. Therefore, combining nanofluidic ion rectification, active matter motion, and near-infrared responsive transport processes to achieve active, non-equilibrium, and controllable delivery is an important development direction in the field of intelligent micro / nano systems. Meanwhile, inflammatory diseases, infectious diseases, and tumor-associated inflammatory microenvironments are often accompanied by local acidification, elevated levels of reactive oxygen species (ROS), and ion homeostasis imbalance. Existing drug delivery systems mostly rely on passive diffusion release, making it difficult to achieve precise control based on changes in the lesion microenvironment, and they are prone to decreased release efficiency in high-ionic-strength physiological environments. Therefore, developing an integrated micro / nano platform that combines active motion, ion rectification and regulation, near-infrared response release, and antioxidant functions is of great significance for improving drug utilization efficiency, reducing dosage, and achieving precision treatment. (Invention Content) To address the problems of low efficiency, poor salt tolerance, and difficulty in precisely controlling the release behavior of existing drug delivery systems, this invention proposes a self-driven Janus polydopamine micromotor based on nanochannel ion rectification and its preparation method.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows: The self-driven Janus polydopamine micromotor with nanochannel ion rectification of the present invention includes an active core and an asymmetric shell. The active core is composed of a power source that can generate ions, and the asymmetric shell is a porous material layer covering the surface of the active core. The structure of the asymmetric shell is asymmetrically distributed to form a Janus structure, and the surface of the asymmetric shell is provided with sub-nanometer-scale pores.

[0006] Furthermore, the diameter of the sub-nanometer pores ranges from 0.3 nm to 50 nm.

[0007] Furthermore, the active core is one or more of the following: carbonate, metal, metal oxide, hydroxide, and porous carrier microspheres supported on a catalyst.

[0008] Furthermore, the polydopamine shell and / or active core can load drug molecules, bioactive factors, proteins, peptides, nucleic acid drugs, diagnostic molecules, or nanomedicines for the storage, transport, and release of functional molecules.

[0009] The method for preparing a self-driven Janus polydopamine micromotor with nanochannel ion rectification according to the present invention is achieved through the following steps: Step 1: Polymerize on the surface of the active core to form a polymer coating layer containing a structure-directing agent; Step 2: Remove the structure guiding agent using an etchant, and obtain a coating shell with sub-nanometer pores by adjusting the etching parameters; Step 3: Spatially selectively modify the covering shell to construct the Janus asymmetric structure.

[0010] Furthermore, the structure directing agent in step 1 is hexadecyltrimethylammonium bromide.

[0011] Furthermore, the etching agent in step 2 is an alcoholic solution of ammonium nitrate.

[0012] Furthermore, in step 2, the aperture can be controlled and adjusted between 0.9 nm, 10 nm, and 15 nm by adjusting the heat treatment temperature and etching time.

[0013] The beneficial effects of this invention are as follows: By constructing a Janus polydopamine (PDA) shell with sub-nanometer-scale pores (preferably about 0.9 nm) on the surface of the active core, the pore size matches the Debye length in the environmental medium, forming an overlapping electric double layer inside the pores, thereby generating a significant ion current rectification (ICR) effect. These sub-nanometer channels can selectively regulate the ion transport process, suppress the rapid relaxation loss of ion products, establish a continuous and stable chemical potential gradient, and achieve efficient conversion of chemical energy into mechanical energy. Compared with existing micro / nano motors that rely on direct surface chemical reactions for driving, this invention utilizes sub-nanometer channels to confinedly regulate ion flux, transforming the disordered diffusion process in traditional systems into a controlled rectification process, thereby significantly improving propulsion efficiency and motion stability. The sub-nanometer channels described in this invention can produce differentiated transport behaviors for ions of different valence states, achieving asymmetric release and selective transport of cations and anions, which is beneficial for maintaining non-equilibrium ion distribution and local electrochemical potential differences within a confined space, providing a new approach for micro / nano-scale energy conversion. The Janus structure described in this invention further amplifies the local concentration gradient and fluid field asymmetry, enhancing the diffusion-electrophoretic driving force and enabling the micro / nano motor to maintain good motion performance even in high ion intensity environments. Even in environments close to physiological saline concentrations, it can maintain stable propulsion, overcoming the technical bottleneck of traditional diffusion-electrophoretic motors being susceptible to inactivation due to the Debye shielding effect.

[0014] The polydopamine material used in this invention possesses excellent biocompatibility, chemical stability, and abundant surface-active groups, further endowing micro- and nano-motors with excellent functionalization potential. The polydopamine shell can serve as a functional molecule loading platform for the storage, adsorption, and transport of functional substances such as drug molecules, bioactive factors, proteins, peptides, nucleic acid drugs, and nanomedicines. The polydopamine shell of this invention also exhibits excellent near-infrared photothermal conversion capabilities, capable of regulating the local temperature field, ion transport behavior, and chemical potential gradient under near-infrared light irradiation, thereby achieving the regulation of motor motion behavior and material transport processes, providing a technical foundation for constructing photoresponsive intelligent micro- and nano-systems. Furthermore, the catechol and quinone structures in polydopamine possess excellent free radical scavenging capabilities, effectively scavenging reactive oxygen species (ROS) and alleviating oxidative stress damage, thus expanding the application value of this invention in fields such as anti-oxidation, bioprotection, and environmental purification. The sub-nanopores of this invention can not only regulate motor motion behavior but also serve as nanofluid transport channels to achieve selective transport and exchange of ions, molecules, and nanoparticles within a confined space. Therefore, this invention can be widely applied in fields such as micro-nano robots, intelligent delivery systems, nanofluidic devices, microscale energy conversion, biological detection, environmental remediation, and active transport systems. The sub-nanopores described in this invention can achieve selective transport of different ions, molecules, and nanoparticles by adjusting the pore size, thus providing a new technical solution for constructing active transport systems with size sieving characteristics. Attached Figure Description

[0015] Figure 1 This is a scanning electron microscope schematic diagram of the sub-nanopore micro / nano motor prepared in Embodiment 1 of the present invention; Figure 2 This is a transmission electron microscope (TEM) mapping image of the micro-nano motor in Embodiment 1 of the present invention, where (a) is a HAADF image, and (b)-(d) are the elemental distribution maps of C, N, O and Ca, respectively. Figure 3 This is a scanning electron microscope (SEM) schematic diagram of the mesopore micro / nano motor prepared in Embodiment 2 of the present invention; Figure 4 This is a scanning electron microscope (SEM) schematic diagram of the macroporous micro / nano motor prepared in Embodiment 3 of the present invention; Figure 5 This is a comparison diagram of the nitrogen adsorption-desorption isotherms and corresponding aperture distribution curves of the motors obtained in Embodiments 1, 2 and 3 of the present invention. Figure 6 The X-ray photoelectron spectroscopy (XPS) full spectrum and high-resolution spectra of C 1s, N 1s, O 1s and Ca 2p are obtained during the fabrication process of the micro-nano motor of this invention. Figure 7These are graphs showing the mean square displacement (MSD) of motors with different apertures prepared in Examples 1, 2, and 3 as a function of time in different concentrations of fuel. Figure 8 Figure A shows the mean square displacement (MSD) of the subnanoporous motor JPC-0.9 over time in salt solutions of different concentrations. Figure B shows the speed of the subnanoporous motor JPC-0.9 at different salt concentrations. Figure 9 The graphs show the mean square displacement (MSD) of the subnanopore motor JPC-0.9 under different chemical fields as a function of time (A) and the motion speed of the subnanopore motor JPC-0.9 under different chemical fields (B). Figure 10 These are flow field diagrams of the PIV (pivot-effect) of the JPC-0.9 subnanopore motor under different chemical fields. Figure 11 The JPC-0.9 sub-nanopore motor utilizes the abundant redox active catechol groups in the PDA shell to achieve ROS scavenging effect, including (A) DPPH free radical scavenging ability and (B) hydroxyl free radical (·OH) scavenging ability; Figure 12 The instantaneous concentration ratio of calcium ions to bicarbonate ions during the operation of the JPC-0.9 motor was monitored using an ion-selective electrode (ISE). Figure 13 These are comparative diagrams showing the calcium ion accumulation behavior of the motors obtained in Embodiments 1, 2, and 3 of this invention during the reaction process; wherein, (A) is the calcium ion accumulation behavior inside the JPC-0.9 motor. 2+ (A) is a time-series fluorescence image of the accumulated fluorescence; (B) is a graph showing the change of relative fluorescence intensity inside the three aperture motors over time. Detailed Implementation

[0016] Specific Implementation Method 1: The self-driven Janus polydopamine micromotor with nanochannel ion rectification described in this embodiment includes an active core and an asymmetric shell. The active core is composed of a power source that can generate ions, and the asymmetric shell is a porous material layer covering the surface of the active core. The structure of the asymmetric shell is asymmetrically distributed to form a Janus structure, and the surface of the asymmetric shell is provided with sub-nanometer-scale pores.

[0017] The average pore size of the sub-nanometer pores ranges from 0.3 nm to 50 nm, preferably from 0.3 nm to 2.0 nm.

[0018] In this embodiment, the size of the sub-nanometer pores is matched with the Debye length of the external medium, and an electric double layer overlap is formed inside the pores to achieve charge selectivity of ion transport. Most preferably, the average pore size is 0.8 nm to 1.0 nm to induce ion rectification effect.

[0019] The active core is selected from at least one of carbonates, metals, metal oxides, hydroxides, or porous carrier microspheres supported on catalysts; preferably, the active core is calcium carbonate (CaCO3) microspheres.

[0020] The asymmetric shell is composed of polydopamine (PDA) or its derivatives; the shell has free radical scavenging activity and can still maintain directional propulsion capability in media with ionic strength greater than 100 mM.

[0021] Specific Implementation Method Two: The preparation method of the self-driven Janus polydopamine micromotor with nanochannel ion rectification described in this embodiment is achieved through the following steps: Step 1: Prepare active core microspheres (such as CaCO3); use co-precipitation method to prepare porous microspheres with a diameter of about 2.8 μm under PSS regulation; Step 2: Construct a PDA shell containing a structure-directing agent; add core microspheres, dopamine and CTAB to Tris buffer at pH ~10, and form a PDA@CTAB composite shell by oxidative self-polymerization; Step 3, Precise pore size control; Sub-nanopores (~0.9 nm): Microspheres are placed in ammonium nitrate / ethanol solution and refluxed at 60°C for 2 hours to etch away CTAB and obtain sub-nanopores; Pre-formed spheres without CTAB are thermally annealed in air at 150°C-200°C for 6-15 hours to obtain mesopores with a diameter of 10-15 nm through polymer chain rearrangement; Step 4: Construct Janus asymmetry; adjust the thickness of the unilateral shell through space-constrained growth or secondary polymerization to form a Janus structure.

[0022] Example Example 1 Fabrication of sub-nanoporous Janus rectifier micro / nano motor (JPC-0.9) Step (1): Synthesize active core CaCO3 microspheres: 0.5 g of sodium polystyrene sulfonate (PSS) was weighed and added to deionized water as a morphology modifier. A mixture of 0.016 mol calcium chloride (CaCl2) solution and 0.008 mol sodium carbonate (Na2CO3) solution was added at room temperature, followed by the addition of the PSS solution. The mixture was stirred vigorously at 500 rpm for 1 minute, then allowed to settle and precipitate. The solid product was collected by centrifugation at 5000 rpm, washed three times with deionized water, and vacuum dried to obtain monodisperse porous CaCO3 microspheres with a particle size of approximately 2.8 μm.

[0023] Step (2), construct the PDA@CTAB shell: Weigh 121.14 mg of tris(hydroxymethyl)aminomethane (Tris) and dissolve it in 40 mL of deionized water. Add 260 mg of the CaCO3 microspheres prepared in step (1), 80 mg of dopamine hydrochloride (DA·HCl), and 40 mg of hexadecyltrimethylammonium bromide (CTAB) sequentially. Adjust the pH of the system to 10.0 using 4.5 M NaOH solution. Stir magnetically overnight at room temperature to allow dopamine to oxidize and self-polymerize on the CaCO3 surface, forming polydopamine (PDA)-coated microspheres containing CTAB micelles. Centrifuge and wash until the supernatant is colorless.

[0024] Step (3), etching sub-nanopores: Sub-nanometer etching: 240 mg of ammonium nitrate was dissolved in 300 mL of ethanol to prepare the etching solution. The coated microspheres were added, and the mixture was refluxed at 60 °C for 2 h. The structure-directing agent was removed by utilizing the specific solvation effect of ammonium nitrate on CTAB. After the reaction was completed, the mixture was centrifuged, washed, dried, and the solid was collected.

[0025] Step (4): Construct the Janus asymmetric structure: The microspheres obtained in step (2) are spread on the surface of a glass substrate. Then, using physical vapor deposition or spatially confined polymerization, secondary dopamine growth or metal layer modification is performed on the exposed hemispherical surface of the microspheres to form a Janus structure with an asymmetric shell thickness, thus obtaining the JPC-0.9 micro-nano motor.

[0026] Example 2 Preparation of a medium-pore control motor (JPC-10) The basic steps are the same as in Example 1, except that CTAB structure directing agent is not added in step (2). Step 3 is replaced by placing the obtained PDA@CaCO3 microspheres in a tube furnace and performing heat annealing in an air atmosphere at a temperature of 150°C for 6 hours. Hollow structures are obtained through polymer chain rearrangement.

[0027] Example 3 Preparation of a large-pore comparative motor sample (JPC-15) In step (2), no CTAB structure-directing agent is added. The obtained PDA@CaCO3 microspheres are placed in a tube furnace at 200°C for 15 hours. Other steps and parameters are the same as in specific embodiment one. The resulting motor, as shown by BET testing, has an average pore size of approximately 15 nm.

[0028] Example 4 Structure and pore size characterization like Figure 1 , Figure 3 and Figure 4 As shown, SEM revealed that JPC-0.9 motors, JPC-10, and JPC-15 exhibit selective thickening on one side, resulting in a Janus heterostructure with asymmetric shell thickness. The motor particle size is approximately 3.4 μm. TEM mapping confirmed that N elements are uniformly distributed in the PDA shell, and the thickened hemisphere shows enhanced N signal, verifying the Janus modification. Figure 2 XPS spectra confirmed the chemical composition of the PDA shell and the chemical stability of the CaCO3 core during preparation. Figure 6 Nitrogen adsorption-desorption tests showed that it exhibited tiered desorption characteristics, with an average pore size of 0.9 nm, which falls within the sub-nanometer range. Figure 5 ).

[0029] Example 5 Verification of the selectivity and rectification mechanism of ion transport Changes in ion concentration during the operation of the JPC-0.9 motor were monitored using an ion-selective electrode (ISE). (See attached figure.) Figure 12 As shown, HCO3 - With Ca 2+ The concentration of HCO3 released by JPC-0.9 increased non-linearly over time; within a 360-second monitoring window, the concentration of HCO3 released by JPC-0.9 was [missing information]. - With Ca 2+ The molar ratio deviated significantly. For the first 240 s, the ratio remained above 1.6, then stabilized around 1.6. This value (1.6) falls between the theoretical stoichiometric ratios of the partial reaction (1.0) and the complete reaction (2.0), demonstrating the physical retention effect of the sub-nanometer channels on specific ions. Since the channel size (0.9 nm) falls within the range overlapping with the Debye length, the negatively charged pore walls contribute to the retention of HCO3-. - It produces a significant rectification effect, improving its transmembrane flux, while also affecting divalent Ca. 2+ This results in kinetic hysteresis. This significant deviation from the 1:2 ratio (complete reaction equilibrium) demonstrates that the sub-nanometer rectification effect disrupts the detailed equilibrium and establishes a sustained chemical potential gradient.

[0030] To further confirm the ion interception and kinetic hysteresis effect of sub-nanopores from a spatial perspective, this embodiment uses a Fluo-4 calcium ion fluorescent probe combined with confocal microscopy to study the Ca ions inside the motor. 2+ In-situ monitoring of the distribution (refer to Figure 13): Experimental phenomena: As shown in Figure 13A, the internal fluorescence intensity of the JPC-0.9 motor exhibited a continuous and significant enhancement process after contact with fuel. Quantitative analysis results (Figure 13B) showed that the relative fluorescence intensity (ΔF / F0) inside JPC-0.9 continuously increased from 1.26 to 1.87, indicating a large amount of Ca generated. 2+ The ions were effectively "locked" inside the sub-nanometer shell. Comparative analysis: In stark contrast, the internal fluorescence intensity of the control samples with mesopores (JPC-10) and macropores (JPC-15) almost instantaneously reached equilibrium with the bulk environment after the reaction began, with no obvious ion accumulation observed. Technical conclusion: This in-situ fluorescence data corroborates the aforementioned ISE monitoring data, jointly confirming that the 0.9 nm sub-nanometer shell acts as a powerful transport barrier. This dynamic interception of ionic products successfully captures the chemical potential energy (▽μ) within the confined space of the motor, providing a persistent power source for electro-diffusion aspiration. This is also the physical essence of the motor's robustness in high-salt environments.

[0031] Example 6 Fluid field characterization and salt resistance performance testing 1. Flow field characterization: Particle image velocimetry (PIV) revealed a strong asymmetric jet flow at the motor opening, verifying the conversion of ion flux into mechanical work. Figure 10 ).

[0032] 2. Salt tolerance: As shown in the attached document. Figure 8 Figure A shows the mean square displacement curves of the motor under different salt concentrations; as attached. Figure 8 As shown in B, although the motor speed decreases slightly with increasing salt concentration, the motor can still maintain a directional movement speed of 3-7 μm / s in simulated physiological saline at 130-150 mM. Figure 8 B). This demonstrates the significant advantage of sub-nanometer rectification mechanisms in shielding the Debye shielding effect.

[0033] Example 7 Multifunctional application verification (1) ROS removal: The motor was functionalized by utilizing the abundant redox-active catechol groups in the PDA shell (see attached). Figure 11 (as shown) DPPH free radical scavenging: When motor was added to a DPPH solution, the characteristic absorption peak (517 nm) of DPPH almost disappeared when the motor concentration was 0.05 mg / mL, proving its efficient free radical scavenging ability.

[0034] Hydroxyl radical (·OH) quenching: In the Fenton-TMB system, the addition of motor significantly reduced the absorbance at 652 nm, indicating that it can effectively alleviate oxidative stress and endow motor with anti-inflammatory and bioprotective functions.

[0035] (2) NIR modulation: The motor system is irradiated with near-infrared light with a wavelength of 808 nm. The excellent photothermal conversion efficiency of the PDA shell is utilized to increase the local temperature of the system.

[0036] The results are shown (as attached). Figure 9 As shown in the figure, under the combined action of NIR+HCl+EDTA, the motor speed reaches a maximum of 41.35 μm / s. Since the PDA shell possesses both excellent drug adsorption capacity and photothermal conversion performance, the Janus micro-nano motor described in this invention can also serve as a near-infrared responsive drug delivery platform. By loading functional molecules into the PDA shell or active core, near-infrared light can be used to modulate the local temperature field, ion transport behavior, and chemical potential gradient, thereby achieving regulation of the drug release process.

[0037] Example 8 The difference between this embodiment and Embodiment 1 is that the composition of the active core is changed: In step (1), the active core is replaced with an equimolar mass of magnesium carbonate or porous silica microspheres loaded with silver nanoparticles. Other steps and parameters are the same as in Specific Example 1. This example aims to demonstrate the universal regulatory effect of the sub-nanopore rectification mechanism on different power sources. Test results show that the motor still exhibits significant ion rectification drive characteristics after core replacement, proving that the sub-nanopore rectification mechanism described in this invention has good universality with power sources.

[0038] Example 9 The difference between this embodiment and Embodiment 1 is that the concentration of the etching agent is changed: in step (2), the amount of ammonium nitrate added is adjusted to 120 mg or 480 mg, and the reflux time is adjusted accordingly to 4 h or 1 h. Other steps and parameters are the same as in Embodiment 1. Experiments have shown that sub-nanopores with similar rectification effects can be obtained by adjusting the etching parameters, demonstrating the robustness of this preparation process within a certain range.

[0039] Working principle The micro-nano motor described in this invention utilizes the ion rectification effect generated by the overlap of the electric double layer to regulate the chemical reaction flux by constructing sub-nanometer-scale channels (~0.9 nm) on the surface of the active core.

[0040] As the chemical basis of this invention, the decomposition of the active core (taking CaCO3 as an example) in an acidic medium follows a specific stoichiometric relationship: under the complete reaction pathway, CaCO3 + 2H+ + → Ca² + The reaction of CO2 + H2O produces a product with a cation / anion molar ratio approaching 0.5 (i.e., HCO3-). - / Ca² + =2); while in the kinetically limited partial reaction pathway, CaCO3+ H + → Ca²⁺HCO₃ - Its molar ratio tends to 1.0. The core of this invention lies in inducing a significant deviation of the ion flux from the above equilibrium state through the rectifying effect of sub-nanometer channels, thereby constructing an efficient driving gradient.

[0041] The driving mechanism of the micro / nano motor described in this invention utilizes the electrical double-layer overlap effect generated by sub-nano pores (~0.9 nm) to induce rectification during the ion release process, thereby causing HCO3- to... - Prioritize directed export, while Ca 2+ This generates dynamic hysteresis, thereby disrupting the charge balance and establishing a driving gradient, enabling the self-driven motion of the ion-rectified micro / nano motor.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A self-driven Janus polydopamine micromotor with nanochannel ion rectification, comprising an active core and an asymmetric shell, wherein the active core is composed of a power source capable of generating ions, and the asymmetric shell is a porous material layer coating the surface of the active core; characterized in that, The asymmetric shell structure is asymmetrically distributed to form a Janus structure, and the surface of the asymmetric shell has sub-nanometer-scale pores.

2. The self-driven Janus polydopamine micromotor with nanochannel ion rectification according to claim 1, characterized in that, The diameter of the sub-nanometer pores ranges from 0.3 nm to 50 nm.

3. The self-driven Janus polydopamine micromotor with nanochannel ion rectification according to claim 1, characterized in that, The active core is one or more of the following: carbonate, metal, metal oxide, hydroxide, or porous support microspheres loaded with catalyst.

4. The self-driven Janus polydopamine micromotor with nanochannel ion rectification according to claim 1, characterized in that, The asymmetric shell is composed of polydopamine.

5. A method for preparing a micromotor according to any one of claims 1 to 4, characterized in that, The specific steps include: Step 1: Polymerize on the surface of the active core to form a polymer coating layer containing a structure-directing agent; Step 2: Remove the structure guiding agent using an etchant, and obtain a coating shell with sub-nanometer pores by adjusting the etching parameters; Step 3: Spatially selectively modify the covering shell to construct the Janus asymmetric structure.

6. The method for preparing a self-driven Janus polydopamine micromotor with nanochannel ion rectification according to claim 5, characterized in that, The structure directing agent in step 1 is hexadecyltrimethylammonium bromide.

7. The method for preparing a self-driven Janus polydopamine micromotor with nanochannel ion rectification according to claim 5, characterized in that, The etching agent in step 2 is an alcoholic solution of ammonium nitrate.

8. The method for preparing a self-driven Janus polydopamine micromotor with nanochannel ion rectification according to claim 5, characterized in that, In step 2, the aperture can be controlled to be adjusted between 0.9 nm, 10 nm, and 15 nm by adjusting the heat treatment temperature and etching time.

Images