A photothermal-driven bowl-shaped polydopamine nanomotor and a preparation method thereof

Abstract

The application provides a photothermal driving bowl-shaped polydopamine nanomotor and a preparation method thereof, and belongs to the technical field of micro-nano devices, wherein the photothermal driving bowl-shaped polydopamine nanomotor comprises a hollow bowl-shaped structure constructed by polydopamine, and the hollow bowl-shaped structure is obtained by removing polyacrylic acid nanoparticles after polydopamine is polymerized on one side of the polyacrylic acid nanoparticles to form a single-sided asymmetric structure. The photothermal driving bowl-shaped polydopamine nanomotor provided by the application has strong driving capacity, fast movement speed, and an easy-to-functionalize surface, and the preparation method is simple and can be used for macro preparation, so that the photothermal driving bowl-shaped polydopamine nanomotor has a wide application prospect in the fields of environmental governance, micro-nano processing and biological medicine.

Description

Technical Field

[0001] This invention relates to the field of micro-nano device technology, specifically to a photothermal driven bowl-shaped polydopamine nanomotor and its preparation method. Background Technology

[0002] Micro-nanomotors are micro- and nano-devices capable of converting other forms of energy into kinetic energy to achieve autonomous motion. Their driving performance determines their application scenarios. Among them, photothermal-driven micro- and nano-motors have attracted widespread attention due to their advantages such as remote control, strong driving force, fast response time, and good biocompatibility. The driving force of photothermal-driven micro- and nano-motors is closely related to their structure. Currently reported photothermal-driven micro- and nano-motors include spherical, tubular, conical, bowl-shaped, and Janus-like structures. Compared to other structures, bowl-shaped photothermal-driven micro- and nano-motors have a special confined internal cavity that can hinder internal heat diffusion, forming a larger temperature gradient and thus generating a stronger driving force.

[0003] Several methods have been developed to prepare bowl-shaped photothermal driven micro / nanomotors, including template methods, emulsion-induced growth methods, and kinetic-controlled self-assembly methods. Cui et al. prepared a bowl-shaped polydopamine (PDA) photothermal driven nanomotor with gold nanoparticles loaded on its surface using polystyrene nanospheres as templates. This method involves multiple polymerization reactions and calcination processes, making the preparation process complex and resulting in non-uniform product morphology (paper, Nano Letter, 2020, 20, 7350−7358). Zhao et al. prepared a bowl-shaped PDA@MOF mesoporous nanomotor using emulsion-induced growth. This method has harsh reaction conditions, requiring long-term high-temperature reactions and cumbersome steps, making large-scale preparation difficult (paper, Materials Today Sustainability, 2022, 18, 100129).

[0004] Given the current problems of bowl-shaped photothermal driven micro / nano motors, such as expensive equipment, complex synthesis steps, limited material morphology control, and difficulty in scaling up, developing a photothermal driven motor with a simple synthesis method, large-scale production capability, and efficient motion has become an urgent problem to be solved. Summary of the Invention

[0005] To address the technical problems existing in the background art, this application provides a photothermal driven bowl-shaped polydopamine nanomotor and its preparation method, aiming to solve the technical problems of the scarcity of bowl-shaped photothermal driven micro / nanomotors and the limitation of preparation methods.

[0006] In a first aspect, embodiments of the present invention provide a photothermal driven bowl-shaped polydopamine nanomotor, which includes a hollow bowl-shaped structure constructed of polydopamine.

[0007] In the technical solution of this invention embodiment, polydopamine is directly used as the skeleton material to construct a unique bowl-shaped structure, and the resulting photothermal drive motor can maintain high driving efficiency in various 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 its opening diameter is 60-80 nm.

[0009] Secondly, embodiments of the present invention provide a method for preparing a photothermal 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 water washing to obtain a hollow bowl-shaped structure.

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

[0011] Preferably, the above preparation method specifically includes the following steps:

[0012] S1. Adjust the polarity of the polyacrylic acid solution to obtain a solution containing polyacrylic acid nanospheres;

[0013] S2. Add dopamine hydrochloride to the system in step S1 to prepare polyacrylic acid-polydopamine eccentric nanoparticles.

[0014] S3. Treat polyacrylic acid-polydopamine eccentric nanoparticles with water to obtain bowl-shaped polydopamine nanomotors.

[0015] More preferably, in the above preparation method, the particle size of the polyacrylic acid nanospheres obtained in step S1 is 80-140 nm.

[0016] In the above preparation method, the method for adjusting the polarity in step S1 is as follows: take a polyacrylic acid solution, add alkali and deionized water, mix well, and then add an organic solvent dropwise to obtain polyacrylic acid nanospheres; wherein, the organic solvent is selected from isopropanol, ethanol, acetone and methanol, and the alkali is selected from ammonia, sodium hydroxide, potassium hydroxide and sodium carbonate. In some embodiments, step S1 specifically involves: taking a 0.1-1 g / mL polyacrylic acid solution and placing it in a flask, adding 20-100 μL of alkali solution and 5-10 mL of deionized water, and stirring at room temperature for 10 minutes; then adding 10-100 mL of isopropanol dropwise to the solution at a rate of 1 mL / min to obtain well-dispersed polyacrylic acid nanospheres.

[0017] More preferably, in the above preparation method, step S2 specifically involves: 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℃ to react and obtain polyacrylic acid-polydopamine eccentric nanoparticles.

[0018] Thirdly, the present invention provides a micro / nano device capable of autonomous movement, which uses a photothermal-driven bowl-shaped polydopamine nanomotor as its active ingredient. Given the strong driving ability, high speed and wide applicability of this nanomotor, it can be applied to various fields such as environmental remediation, micro / nano fabrication and biomedicine, either alone or loaded with other functional molecules.

[0019] The photothermal driven bowl-shaped polydopamine nanomotor provided by this invention has abundant functional groups and its surface is easy to functionalize, so it can easily realize the loading of various functional molecules (including drugs, response components such as enzymes, etc.).

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] Compared with existing polydopamine nanomotors, the photothermal driven bowl-shaped polydopamine nanomotor provided by this invention has a unique bowl-shaped structure, strong driving capability, fast movement speed, and can move efficiently in different media. At the same time, the nanomotor has a large specific surface area and its surface is easy to functionalize. After loading different functional molecules, it can be widely used in various fields such as environmental remediation, micro-nano fabrication, and biomedicine.

[0022] The method for preparing the photothermally driven bowl-shaped polydopamine nanomotor in this invention is simple, reproducible, and the resulting product has uniform and controllable size, enabling large-scale preparation. This effectively solves the problems of high synthesis cost and difficult morphology control of photothermally driven motors in the prior art. Attached Figure Description

[0023] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0024] Figure 1 This is a schematic diagram illustrating the structure and driving mechanism of the photothermal-driven bowl-shaped polydopamine nanomotor in an embodiment of the present invention;

[0025] Figure 2 This is a flowchart illustrating the fabrication process of the photothermally driven bowl-shaped polydopamine nanomotor in Example 1 of this application.

[0026] Figure 3The images shown are scanning electron microscope (SEM) image (A) and transmission electron microscope (TEM) image (B) of the photothermal driven bowl-shaped polydopamine nanomotor prepared in Example 1 of the present invention.

[0027] Figure 4 The trajectory, mean square displacement, and diffusion coefficient of the photothermally driven bowl-shaped polydopamine nanomotor in deionized water in Example 4 of this invention are shown.

[0028] Figure 5 The image shows the 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 this invention. Detailed Implementation

[0029] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0031] To address the challenges of generating stronger driving force in cup-shaped photothermal driven micro / nanomotors and the difficulty in synthesizing existing cup-shaped nanomotors, this invention provides a photothermal driven cup-shaped polydopamine nanomotor and its preparation method. Specifically, this invention uses only polydopamine as the framework material to construct the cup-shaped structure, thereby obtaining a uniform and high-driving-force cup-shaped nanomotor while effectively reducing the synthesis cost.

[0032] Please refer to Figure 1 In a first aspect, embodiments of the present invention provide a photothermal driven bowl-shaped polydopamine nanomotor, and its driving mechanism is as follows: given the photothermal conversion capability of polydopamine, under light irradiation, the bowl-shaped structure of the nanomotor causes water molecules around the motor to absorb uneven heat, forming a temperature gradient; the sealed space of the motor causes the water inside the cavity to be heated, resulting in volume expansion; the heated water will spray out from the opening, thereby triggering the autonomous movement of the nanorobot.

[0033] Please refer to Figure 2Secondly, embodiments of this application provide a method for preparing a photothermally driven bowl-shaped polydopamine nanomotor. This method 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; subsequently, polydopamine polymerizes on one side of the polyacrylic acid nanospheres, and continuously deposits under the control of an energy barrier to form a unilateral asymmetric structure; the polyacrylic acid nanospheres are removed by washing with water to obtain a bowl-shaped photothermally driven nanomotor.

[0034] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0035] Example 1

[0036] This example demonstrates the fabrication of a photothermally driven bowl-shaped polydopamine nanomotor, the fabrication process of which includes the following steps:

[0037] (1) Preparation of polyacrylic acid nanospheres.

[0038] Take 0.2 g / mL PAA solution and put it into a flask. Add 40 μL of ammonia and 7 mL of deionized water and stir at room temperature for 10 minutes. Add 30 mL of isopropanol dropwise to the solution at a rate of 1 mL / min to obtain well dispersed polyacrylic acid nanospheres.

[0039] (2) Preparation of polyacrylic acid-polydopamine eccentric nanoparticles.

[0040] Take 37 mL of the polyacrylic acid nanosphere solution obtained in step (1), add a certain amount of ammonia to adjust the pH to 8-9, heat it to 50℃ 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 the polyacrylic acid-polydopamine eccentric nanoparticles by centrifugation.

[0041] (3) Preparation of bowl-shaped polydopamine nanomotors.

[0042] Add an appropriate amount of deionized water to polyacrylic acid-polydopamine eccentric nanoparticles, disperse them evenly, and then centrifuge to remove the supernatant to obtain a bowl-shaped polydopamine nanomotor.

[0043] Example 2

[0044] This example demonstrates the fabrication of a photothermally driven bowl-shaped polydopamine nanomotor, the fabrication process of which includes the following steps:

[0045] (1) Preparation of polyacrylic acid nanospheres.

[0046] Take 0.5 g / mL PAA solution and put it into a flask. Add 60 μL of 3 mM sodium hydroxide and 10 mL of deionized water and stir at room temperature for 10 minutes. Add 50 mL of ethanol dropwise to the solution at a rate of 1 mL / min to obtain well dispersed polyacrylic acid nanospheres.

[0047] (2) Preparation of polyacrylic acid-polydopamine eccentric nanoparticles.

[0048] 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, heat it to 50℃ in an oil bath; add 5 mL of 5 mg / mL dopamine hydrochloride solution to the oil bath, react for 5 hours, and collect the polyacrylic acid-polydopamine eccentric nanoparticles by centrifugation.

[0049] (3) Preparation of bowl-shaped polydopamine nanomotors.

[0050] Add an appropriate amount of deionized water to polyacrylic acid-polydopamine eccentric nanoparticles, disperse them evenly, and then centrifuge to remove the supernatant to obtain a bowl-shaped polydopamine nanomotor.

[0051] Example 3

[0052] (1) Preparation of polyacrylic acid nanospheres.

[0053] Take 0.2 g / mL PAA solution and put it into a flask. Add 100 μL of 5 mM sodium carbonate and 5 mL of deionized water and stir at room temperature for 10 minutes. Add 35 mL of acetone dropwise to the solution at a rate of 1 mL / min to obtain well dispersed polyacrylic acid nanospheres.

[0054] (2) Preparation of polyacrylic acid-polydopamine eccentric nanoparticles.

[0055] 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, heat in an oil bath to 50℃; 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.

[0056] (3) Preparation of bowl-shaped polydopamine nanomotors.

[0057] Add an appropriate amount of deionized water to polyacrylic acid-polydopamine eccentric nanoparticles, disperse them evenly, and then centrifuge to remove the supernatant to obtain a bowl-shaped polydopamine nanomotor.

[0058] The morphology of the bowl-shaped polydopamine nanomotors prepared in the above embodiments was characterized, among which... Figure 3 Scanning electron microscope (SEM) image (A) and transmission electron microscope (TEM) image (B) of the bowl-shaped polydopamine nanomotor prepared in Example 1, with scale bars of 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.

[0059] Example 4

[0060] Taking the photothermally driven bowl-shaped polydopamine nanomotor prepared in Example 1 as an example, this example demonstrates its mobility as a self-moving micro / nano device. Specifically, the photothermally driven bowl-shaped polydopamine nanomotor was placed in deionized water and irradiated with power densities of 0, 0.25, 0.5, 0.75, 1, and 1.5 W / cm², respectively. 2 A laser with a wavelength of 660 nm.

[0061] The motion trajectory of the bowl-shaped polydopamine nanomotor is as follows Figure 4 As shown in Figure A, its mean square displacement variation is as follows: Figure 4 As shown in Figure B, its diffusion coefficient changes as follows: Figure 4 As shown in Figure C, it can be seen that as the power density increases, the motor moving distance and diffusion coefficient gradually increase, indicating that the bowl-shaped polydopamine nanoparticles can move effectively under light. The mean square displacement (MSD) slope exhibits a parabolic shape, indicating that the nanomotor exhibits accelerated autonomous motion.

[0062] These results demonstrate that, compared to previously reported bowl-shaped photothermal driven micro / nanomotors, the bowl-shaped polydopamine nanomotor exhibits superior motion capabilities. For example, the gold-polymer bowl-shaped nanomotor designed and fabricated by Wang et al. (J., Wang, et al. Nature Communications, 2024, 15, 4878) only achieved a diameter of 1.7 μm at a power of 0.75 W. 2 The diffusion coefficient is 0.5 μm / s, while the bowl-shaped polydopamine nanomotor designed in this invention can achieve a diffusion coefficient of 2.3 μm at the same power. 2 / s.

[0063] Example 5

[0064] 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).

[0065] Figure 5The plots show the motor's trajectory, mean square displacement, and diffusion coefficient in phosphate-buffered saline (PBS), Luria-Bertani medium (LB), and fetal bovine serum (FBS). The trajectory plots demonstrate that the motor exhibits a clear trajectory in all three media under illumination. Compared to the diffusion coefficient in deionized water, the motor retains over 83% of its motion capability in the complex media.

[0066] Comparative Example 1

[0067] This example provides a polydopamine nanoparticle, the preparation process of which includes the following steps:

[0068] (1) Preparation of polyacrylic acid nanospheres.

[0069] Take 0.2 g / mL PAA solution and put it into a flask. Add 40 μL of ammonia and 7 mL of deionized water and stir at room temperature for 10 minutes. Add 30 mL of isopropanol dropwise to the solution at a rate of 1 mL / min to obtain well dispersed polyacrylic acid nanospheres.

[0070] (2) Preparation of polyacrylic acid-polydopamine nanoparticles.

[0071] Take 37 mL of the polyacrylic acid nanosphere solution obtained in step (1), add tris-hydrochloric acid buffer solution with pH 8.5, adjust the pH to 8-9, heat in an oil bath to 50℃; 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.

[0072] (3) Preparation of polydopamine nanoparticles.

[0073] An appropriate amount of deionized water was added to polyacrylic acid-polydopamine nanoparticles, and after uniform dispersion, the supernatant was removed by centrifugation to obtain polydopamine nanoparticles. The polydopamine nanoparticles prepared in this example have a particle size of approximately 300 nm, and have a smooth surface and a complete spherical structure. Because they lack asymmetry, they cannot provide the structural conditions for the generation of an asymmetric thermal field.

[0074] Comparative Example 2

[0075] This example provides a method for preparing polydopamine nanoparticles, the preparation process of which includes the following steps:

[0076] (1) Preparation of polyacrylic acid nanospheres.

[0077] Take 0.2 g / mL PAA solution and put it into a flask. Add 2.4 mg calcium hydroxide, 40 μL ammonia and 7 mL deionized water and stir at room temperature for 30 minutes. Add 30 mL isopropanol dropwise to the solution at a rate of 1 mL / min to obtain well dispersed polyacrylic acid nanospheres.

[0078] (2) Preparation of polyacrylic acid-polydopamine nanoparticles.

[0079] Take 37 mL of the polyacrylic acid nanosphere solution obtained in step (1), add a certain amount of ammonia to adjust the pH to 8-9, heat it to 50℃ 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 the polyacrylic acid-polydopamine nanoparticles by centrifugation.

[0080] (3) Preparation of polydopamine nanoparticles.

[0081] Add an appropriate amount of deionized water to polyacrylic acid-polydopamine nanoparticles, disperse them evenly, and then centrifuge to remove the supernatant to obtain polydopamine nanoparticles.

[0082] The polydopamine nanoparticles prepared in this example have some with 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 are a large number of amorphous polydopamine particles between the particles.

[0083] All the raw materials listed in this invention, as well as the upper and lower limits and ranges of the raw materials and the upper and lower limits and ranges of the process parameters (such as temperature, time, etc.), can realize this invention. Examples are not listed one by one here.

[0084] In summary, the bowl-shaped nanomotor constructed using polydopamine as a framework in this invention has excellent motion capabilities and wide applicability. Moreover, 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 rapidly obtained, which has good potential for industrial production and application.

[0085] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A micro- or nano-device, characterized in that, A photothermally driven bowl-shaped polydopamine nanomotor as an active ingredient, the photothermally driven bowl-shaped polydopamine nanomotor is a hollow bowl-shaped structure constructed of polydopamine, the particle size of the hollow bowl-shaped structure is 131.2±12.3 nm and the opening diameter thereof is 71.1±6.8 nm, the photothermally driven bowl-shaped polydopamine nanomotor autonomously moves under light and its diffusion coefficient reaches 2.3 μm 2 / s under 0.75 W power.

2. The micro-nano device according to claim 1, wherein, The preparation of the hollow bowl structure comprises the following steps: S1, taking 0.1-1 g / mL polyacrylic acid solution, adding 20-100 μL alkali and 50-10 mL deionized water, and then adding 10-100 mL isopropyl alcohol to obtain polyacrylic acid nanoballs; the alkali is selected from ammonia, sodium hydroxide, potassium hydroxide and sodium carbonate; S2, taking the solution containing polyacrylic acid nanoballs, adding alkali, adjusting the pH to 8-9, and then adding hydrochloric acid dopamine at 30-70°C to react, to obtain polyacrylic acid-polydopamine eccentric nanoparticles; S3, treating the polyacrylic acid-polydopamine eccentric nanoparticles with water, and the polyacrylic acid-polydopamine eccentric nanoparticles are obtained.

3. The micro-nano device according to claim 1, wherein, The photo-thermal driven bowl-shaped polydopamine nanomotor is connected with at least one functional molecule on the surface.

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