Photo-thermal driving bowl-shaped polydopamine nano motor and preparation method thereof

Abstract

The invention provides a photo-thermal driving bowl-shaped polydopamine nano motor and a preparation method thereof, and belongs to the technical field of micro-nano devices.The photo-thermal driving bowl-shaped polydopamine nano motor comprises a hollow bowl-shaped structure constructed by polydopamine, the hollow bowl-shaped structure is obtained by polymerizing polydopamine on one side of the polyacrylic acid nano-particles to form a single-side asymmetric structure and removing the polyacrylic acid nano-particles. The photo-thermal driving bowl-shaped polydopamine nano-motor provided by the invention is high in driving capability, high in movement speed, easy in surface functionalization, simple in preparation method and capable of realizing macro preparation, and has a wide application prospect in the fields of environmental governance, micro-nano processing, biological medicine and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano devices, and in particular to a photothermally driven bowl-shaped polydopamine nanomotor and a preparation method thereof. Background Art

[0002] A micro-nano motor is a micro-nano device that can convert other forms of energy into kinetic energy to achieve autonomous movement. Its driving performance will determine its application scenario. Among them, photothermal-driven micro-nano motors have attracted widespread attention due to their advantages such as remote control, strong driving power, fast response time and good biocompatibility. The driving force of photothermal-driven micro-nano motors is closely related to their structure. At present, the reported photothermal-driven micro-nano motors include spherical, tubular, conical, bowl-shaped and Janus-shaped structures. Compared with other structures, the bowl-shaped photothermal-driven micro-nano motor has a special restrictive inner cavity, which can hinder the diffusion of internal heat, form a larger temperature gradient, and thus generate a stronger driving force.

[0003] At present, a variety of methods have been developed, including template method, emulsion-induced growth method, kinetic controlled self-assembly method, etc., for the preparation of bowl-shaped photothermally driven micro-nanomotors. Cui et al. used polystyrene nanospheres as templates to prepare a bowl-shaped polydopamine (PDA) photothermally driven nanomotor with surface-loaded nanogold. This method includes multiple polymerization reactions and calcination processes. The preparation process is complicated and the product morphology is uneven (paper, Nano Letter, 2020, 20, 7350−7358). Zhao et al. used emulsion-induced growth method to prepare a bowl-shaped PDA@MOF mesoporous nanomotor. The preparation method has harsh reaction conditions, requires long-term high-temperature reaction, and the reaction steps are cumbersome, making it difficult to achieve large-scale preparation (paper, Materials Today Sustainability, 2022, 18, 100129).

[0004] Given that the current bowl-shaped photothermal-driven micro-nanomotors have a series of problems such as expensive equipment, complex synthesis steps, limited control of material morphology, and difficulty in scaling up, developing a photothermal-driven motor with a simple synthesis method, large-scale production, and efficient movement has become a major issue that urgently needs to be addressed. Summary of the invention

[0005] In response to the technical problems existing in the background technology, the present application provides a photothermally driven bowl-shaped polydopamine nanomotor and a preparation method thereof, aiming to solve the technical problems of the small number of photothermally driven micro-nanomotors with bowl-shaped structures and the limited preparation methods.

[0006] In a first aspect, an embodiment of the present invention provides a photothermally driven bowl-shaped polydopamine nanomotor, which comprises a hollow bowl-shaped structure constructed with polydopamine.

[0007] In the technical solution of the embodiment of the present invention, polydopamine is directly used as the skeleton material to construct a unique bowl-shaped structure, and the resulting photothermal drive motor can maintain efficient driving capabilities in a variety of media such as water, culture medium, and serum.

[0008] In some embodiments of the present invention, the particle size of the empty bowl-shaped structure in the photothermally driven bowl-shaped polydopamine nanomotor is 100-150 nm, and the opening diameter thereof is 60-80 nm.

[0009] In the second aspect, an embodiment of the present invention provides a method for preparing a photothermally driven bowl-shaped polydopamine nanomotor, specifically: by adjusting the surface tension and lattice mismatch between polyacrylic acid and polydopamine, polydopamine is polymerized on one side of the polyacrylic acid nanoparticles to form a unilateral asymmetric structure, and then the polyacrylic acid nanoparticles are removed by washing to obtain a hollow bowl-shaped structure.

[0010] In the technical solution of the embodiment of the present invention, the preparation method is simple and highly repeatable, and has the potential for large-scale preparation.

[0011] Preferably, in the above preparation method, the following steps are specifically included: S1, adjusting the polarity of the polyacrylic acid solution to obtain a solution containing polyacrylic acid nanospheres; S2, adding dopamine hydrochloride to the system of step S1 to prepare polyacrylic acid-polydopamine eccentric nanoparticles; S3. Treating polyacrylic acid-polydopamine eccentric nanoparticles with water to obtain bowl-shaped polydopamine nanomotors.

[0012] More preferably, in the above preparation method, the particle size of the polyacrylic acid nanospheres obtained in step S1 is 80-140 nm.

[0013] In the above preparation method, the method of adjusting the polarity in step S1 is: take a polyacrylic acid solution, add alkali and deionized water to mix, and then add an organic solvent to obtain polyacrylic acid nanospheres; wherein the organic solvent is selected from isopropanol, ethanol, acetone and methanol, and the alkali is selected from ammonia water, sodium hydroxide, potassium hydroxide and sodium carbonate. For example, in some embodiments, step S1 is specifically: take 0.1-1 g / mL of polyacrylic acid solution and put it into a flask, add 20-100 μL of alkali solution and 5-10 mL of deionized water, and stir at room temperature for 10 minutes; add 10-100 mL of isopropanol to the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0014] More preferably, in the above preparation method, step S2 is specifically: taking a solution containing polyacrylic acid nanospheres, adding a certain amount of alkali, adjusting the pH to 8-9, and then adding dopamine hydrochloride at 30-70°C to react to obtain polyacrylic acid-polydopamine eccentric nanoparticles.

[0015] On the third aspect, an embodiment of the present invention provides a micro-nano device capable of autonomous movement, which uses a photothermally driven bowl-shaped polydopamine nanomotor as an active ingredient; in view of the strong driving ability, fast movement speed and wide range of applicable media of the nanomotor, it can be applied alone or after loading other functional molecules to various fields such as environmental governance, micro-nano processing and biomedicine.

[0016] The photothermally driven bowl-shaped polydopamine nanomotor provided by the present invention has abundant functional groups and its surface is easily functionalized, so it is easy to load various functional molecules (including drugs, response components such as enzymes, etc.).

[0017] Compared with the prior art, the present invention has the following beneficial effects: Compared with existing polydopamine nanomotors, the photothermally driven bowl-shaped polydopamine nanomotor provided by the present invention has a unique bowl-shaped structure, strong driving ability, fast movement speed, and can move efficiently in different media; at the same time, the nanomotor has a large specific surface area and the surface is easy to functionalize. After loading different functional molecules, it can be widely used in various fields such as environmental governance, micro-nano processing, and biomedicine.

[0018] The preparation method of the photothermally driven bowl-shaped polydopamine nanomotor in the present invention is simple and has good repeatability, and the size of the obtained product is uniform and controllable, which can achieve large-scale preparation, and effectively solves the problems of high synthesis cost and difficult morphology control of photothermally driven motors in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings used in the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 Schematic diagram of the structure and driving mechanism of the photothermally driven bowl-shaped polydopamine nanomotor in an embodiment of the present invention; Figure 2 This is a preparation roadmap for the photothermally driven bowl-shaped polydopamine nanomotor in Example 1 of the present application; Figure 3 The scanning electron microscope image (A) and the transmission electron microscope image (B) of the photothermally driven bowl-shaped polydopamine nanomotor prepared in Example 1 of the present invention; Figure 4 The motion trajectory, mean square displacement and diffusion coefficient of the photothermally driven bowl-shaped polydopamine nanomotor in deionized water in Example 4 of the present invention; Figure 5 The motion trajectory, mean square displacement and diffusion coefficient of the photothermally driven bowl-shaped polydopamine nanomotor in phosphate buffer, Luria-Bertani medium and fetal bovine serum in Example 5 of the present invention. DETAILED DESCRIPTION

[0021] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0023] In view of the problem that bowl-shaped photothermally driven micro-nanomotors can generate stronger driving force and the difficulty in synthesizing existing bowl-shaped nanomotors, the present invention provides a photothermally driven bowl-shaped polydopamine nanomotors and a preparation method thereof. Specifically, the present invention constructs a bowl-shaped structure using only polydopamine as a skeleton material, thereby effectively reducing the synthesis cost while obtaining a uniform and high-driving-force bowl-shaped nanomotors.

[0024] Please refer to Figure 1 In the first aspect, an embodiment of the present invention provides a photothermally driven bowl-shaped polydopamine nanomotor, and its driving mechanism is: in view of the photothermal conversion ability of polydopamine, under light, the bowl-shaped structure of the nanomotor causes the water molecules around the motor to absorb uneven heat, forming a temperature gradient; the enclosed space of the motor causes the water in the cavity to be heated, causing volume expansion; the heated water will spray out from the opening, thereby triggering the autonomous movement of the nanorobot.

[0025] Please refer to Figure 2 In the second aspect, an embodiment of the present application provides a method for preparing a photothermally driven bowl-shaped polydopamine nanomotor, which achieves heterogeneous growth by adjusting the surface tension and interfacial compatibility between polyacrylic acid particles and the polydopamine shell. Specifically, polyacrylic acid forms nanospheres in a solvent with a certain polarity; then, polydopamine is polymerized on one side of the polyacrylic acid spheres, and continuously deposited under the control of an energy barrier to form a unilateral asymmetric structure; the polyacrylic acid spheres are removed by water washing to obtain a bowl-shaped photothermally driven nanomotor.

[0026] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0027] Example 1 In this example, a photothermal driven bowl-shaped polydopamine nanomotor was prepared, and the preparation process included the following steps: (1) Preparation of polyacrylic acid nanospheres.

[0028] Take 0.2 g / mL PAA solution and put it into a flask. Add 40 μL ammonia water and 7 mL deionized water and stir at room temperature for 10 minutes. Add 30 mL isopropanol dropwise into the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0029] (2) Preparation of polyacrylic acid-polydopamine eccentric nanoparticles.

[0030] Take 37 mL of the polyacrylic acid nanosphere solution obtained in step (1), add a certain amount of ammonia water to adjust the pH to 8-9, and heat to 50°C in an oil bath; add 3 mL of 5 mg / mL dopamine hydrochloride solution to the oil bath, react for 3.5 hours, and collect by centrifugation to obtain polyacrylic acid-polydopamine eccentric nanoparticles.

[0031] (3) Preparation of bowl-shaped polydopamine nanomotors.

[0032] An appropriate amount of deionized water was added to the polyacrylic acid-polydopamine eccentric nanoparticles, and the mixture was evenly dispersed and then centrifuged to remove the supernatant to obtain a bowl-shaped polydopamine nanomotor.

[0033] Example 2 In this example, a photothermal driven bowl-shaped polydopamine nanomotor was prepared, and the preparation process included the following steps: (1) Preparation of polyacrylic acid nanospheres.

[0034] Take 0.5 g / mL PAA solution and put it into a flask. Add 60 μL 3 mM sodium hydroxide and 10 mL deionized water and stir at room temperature for 10 minutes. Add 50 mL ethanol into the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0035] (2) Preparation of polyacrylic acid-polydopamine eccentric nanoparticles.

[0036] Take 60 mL of the polyacrylic acid nanosphere solution obtained in step (1), add a certain amount of sodium hydroxide solution to adjust the pH to 8-9, and heat it to 50°C in an oil bath; add 5 mL of 5 mg / mL dopamine hydrochloride solution to the oil bath, react for 5 hours, and collect by centrifugation to obtain polyacrylic acid-polydopamine eccentric nanoparticles.

[0037] (3) Preparation of bowl-shaped polydopamine nanomotors.

[0038] An appropriate amount of deionized water was added to the polyacrylic acid-polydopamine eccentric nanoparticles, and the mixture was evenly dispersed and then centrifuged to remove the supernatant to obtain a bowl-shaped polydopamine nanomotor.

[0039] Example 3 (1) Preparation of polyacrylic acid nanospheres.

[0040] Take 0.2 g / mL PAA solution and put it into a flask. Add 100 μL 5 mM sodium carbonate and 5 mL deionized water and stir at room temperature for 10 minutes. Add 35 mL acetone into the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0041] (2) Preparation of polyacrylic acid-polydopamine eccentric nanoparticles.

[0042] Take 40 mL of the polyacrylic acid nanosphere solution obtained in step (1), add a certain amount of sodium carbonate solution to adjust the pH to 8-9, and heat to 50°C in an oil bath; add 5 mL of 5 mg / mL dopamine hydrochloride solution to the oil bath, react for 5 hours, and collect by centrifugation to obtain polyacrylic acid-polydopamine eccentric nanoparticles.

[0043] (3) Preparation of bowl-shaped polydopamine nanomotors.

[0044] An appropriate amount of deionized water was added to the polyacrylic acid-polydopamine eccentric nanoparticles, and the mixture was evenly dispersed and then centrifuged to remove the supernatant to obtain a bowl-shaped polydopamine nanomotor.

[0045] The morphology of the bowl-shaped polydopamine nanomotors prepared in the above examples was characterized. Figure 3 The scanning electron microscope image (A) and transmission electron microscope image (B) of the bowl-shaped polydopamine nanomotor prepared in Example 1, the scale bars are 50 nm and 100 nm respectively. The morphology characterization image shows that the overall average particle size of the bowl-shaped polydopamine nanomotor is 131.2±12.3 nm, and its average opening diameter is 71.1±6.8 nm.

[0046] Example 4 Taking the photothermal driven bowl-shaped polydopamine nanomotor prepared in Example 1 as an example, this example demonstrates its ability to move as an autonomous micro-nano device. The specific operation is as follows: the photothermal driven bowl-shaped polydopamine nanomotor is placed in deionized water and irradiated with power densities of 0, 0.25, 0.5, 0.75, 1, and 1.5 W / cm 2 The laser has a wavelength of 660 nm.

[0047] The motion trajectory of the bowl-shaped polydopamine nanomotor is shown in Figure 2. Figure 4 As shown in A, its mean square displacement changes as follows Figure 4 B, its diffusion coefficient changes as Figure 4 As shown in C, it can be seen from the figure that: with the increase of power density, the motor moving distance and diffusion coefficient are gradually increasing, indicating that the bowl-shaped polydopamine nanoparticles can move effectively under light; the mean square displacement (MSD) slope presents a parabolic shape, indicating that the nanomotor exhibits accelerated autonomous movement.

[0048] The above results show that compared with the existing reported bowl-shaped photothermal driven micro-nanomotors, the bowl-shaped polydopamine nanomotors exhibit excellent movement ability. For example, the gold-polymer bowl-shaped nanomotors designed and prepared by Wang et al. (J., Wang, et al. Nature Communications, 2024, 15, 4878) can only reach 1.7 μm at a power of 0.75 W. 2 / s, while the bowl-shaped polydopamine nanomotor designed in the present invention has a diffusion coefficient of 2.3 μm at the same power. 2 / s.

[0049] Example 5 Referring to Example 4, this example further demonstrates the motility of the photothermally driven bowl-shaped polydopamine nanomotor of the present invention in other media such as phosphate buffered saline (PBS), Luria-Bertani medium (LB), and fetal bovine serum (FBS).

[0050] Figure 5 The motion trajectory, mean square displacement and diffusion coefficient of the motor in phosphate buffered saline (PBS), Luria-Bertani medium (LB), and fetal bovine serum (FBS) are shown in the trajectory diagram. The motor exhibits obvious motion trajectories in all three media under light. Compared with the diffusion coefficient in deionized water, the motor can maintain more than 83% of its motility in complex media.

[0051] Comparative Example 1 This example provides a polydopamine nanoparticle, the preparation process of which includes the following steps: (1) Preparation of polyacrylic acid nanospheres.

[0052] Take 0.2 g / mL PAA solution and put it into a flask. Add 40 μL ammonia water and 7 mL deionized water and stir at room temperature for 10 minutes. Add 30 mL isopropanol dropwise into the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0053] (2) Preparation of polyacrylic acid-polydopamine nanoparticles.

[0054] Take 37 mL of the polyacrylic acid nanosphere solution obtained in step (1), add tris-hydrochloric acid buffer with a pH of 8.5, adjust the pH to 8-9, and heat to 50°C in an oil bath; add 3 mL of 5 mg / mL dopamine hydrochloride solution to the oil bath, react for 7 hours, and collect by centrifugation to obtain polyacrylic acid-polydopamine nanoparticles.

[0055] (3) Preparation of polydopamine nanoparticles.

[0056] Add an appropriate amount of deionized water to the polyacrylic acid-polydopamine nanoparticles, disperse them uniformly, and then centrifuge to remove the supernatant to obtain polydopamine nanoparticles. The particle size of the polydopamine nanoparticles prepared in this example is about 300 nm, and the surface is smooth and has a complete spherical structure. Since it does not have asymmetry, it cannot provide structural conditions for the generation of an asymmetric thermal field.

[0057] Comparative Example 2 This example provides a method for preparing polydopamine nanoparticles, the preparation process comprising the following steps: (1) Preparation of polyacrylic acid nanospheres.

[0058] Take 0.2 g / mL PAA solution and put it into a flask. Add 2.4 mg calcium hydroxide, 40 μL ammonia water and 7 mL deionized water, and stir at room temperature for 30 minutes. Add 30 mL isopropanol into the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0059] (2) Preparation of polyacrylic acid-polydopamine nanoparticles.

[0060] Take 37 mL of the polyacrylic acid nanosphere solution obtained in step (1), add a certain amount of ammonia water to adjust the pH to 8-9, and heat to 50°C in an oil bath. Add 3 mL of 5 mg / mL dopamine hydrochloride solution to the oil bath, react for 3.5 hours, and collect by centrifugation to obtain polyacrylic acid-polydopamine nanoparticles.

[0061] (3) Preparation of polydopamine nanoparticles.

[0062] Add appropriate amount of deionized water to the polyacrylic acid-polydopamine nanoparticles, disperse them uniformly, and then centrifuge to remove the supernatant to obtain polydopamine nanoparticles. The polydopamine nanoparticles prepared in this example partially have a relatively obvious open bowl-shaped structure, with a particle size of about 120 nm and an opening size of about 110 nm; however, the particle shape is not uniform, and there is a large amount of amorphous polydopamine between the particles.

[0063] The raw materials listed in the present invention, as well as the upper and lower limits and interval values ​​of the raw materials of the present invention, and the upper and lower limits and interval values ​​of the process parameters (such as temperature, time, etc.) can all realize the present invention, and the embodiments are not listed one by one here.

[0064] In summary, the bowl-shaped nanomotor constructed only with polydopamine as the skeleton in the present invention has excellent mobility and wide applicability, and the preparation method is simple and low-cost. By controlling the preparation conditions, a large number of bowl-shaped photothermal-driven nanomotors with uniform size and controllable morphology can be quickly obtained, which has good potential for industrial production and application.

[0065] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a photothermally driven bowl-shaped polydopamine nanomotor, characterized in that: The photothermally driven bowl-shaped polydopamine nanomotor comprises a hollow bowl-shaped structure constructed with polydopamine, wherein the hollow bowl-shaped structure is obtained by polymerizing polydopamine on one side of a polyacrylic acid nanoparticle to form a unilateral asymmetric structure and then removing the polyacrylic acid nanoparticle.

2. The preparation method according to claim 1, characterized in that: The following steps are involved: S1, adjusting the polarity of the polyacrylic acid solution to obtain a solution containing polyacrylic acid nanospheres; S2, adding dopamine hydrochloride to the system of step S1 to prepare polyacrylic acid-polydopamine eccentric nanoparticles; S3. Treating polyacrylic acid-polydopamine eccentric nanoparticles with water to obtain bowl-shaped polydopamine nanomotors.

3. The preparation method according to claim 2, characterized in that The particle size of the polyacrylic acid nanospheres is 80-140 nm.

4. The preparation method according to claim 2, characterized in that: Step S1 specifically comprises: taking a polyacrylic acid solution, adding alkali and deionized water to mix well, and then dropping an organic solvent to obtain polyacrylic acid nanospheres; the organic solvent is selected from isopropanol, ethanol, acetone and methanol.

5. The preparation method according to claim 4, characterized in that: The base is selected from ammonia water, sodium hydroxide, potassium hydroxide and sodium carbonate.

6. The preparation method according to claim 5, characterized in that: Step S2 specifically comprises: taking a solution containing polyacrylic acid nanospheres, adding alkali, and then adding dopamine hydrochloride at 30-70° C. to react to obtain polyacrylic acid-polydopamine eccentric nanoparticles.

7. A photothermally driven bowl-shaped polydopamine nanomotor prepared according to any one of claims 1-6.

8. The photothermally driven bowl-shaped polydopamine nanomotor according to claim 7, characterized in that: The particle size of the hollow bowl-shaped structure is 100-150 nm, and the opening diameter is 60-80 nm.

9. A micro-nano device, characterized in that: The photothermally driven bowl-shaped polydopamine nanomotor as described in claim 7 is used as the active ingredient.

10. The micro-nano device according to claim 9, characterized in that: The surface of the photothermally driven bowl-shaped polydopamine nanomotor is connected to at least one functional molecule.

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