CN113122800A

CN113122800A - Porous magnetic nano robot and preparation method and application thereof

Info

Publication number: CN113122800A
Application number: CN202110410946.5A
Authority: CN
Inventors: 郑裕基; 宋小霞
Original assignee: Southwest University of Science and Technology
Current assignee: Southwest University of Science and Technology
Priority date: 2021-04-16
Filing date: 2021-04-16
Publication date: 2021-07-16
Anticipated expiration: 2041-04-16
Also published as: CN113122800B

Abstract

The invention provides a porous magnetic nano robot and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) coating a sacrificial material on a hard substrate to obtain a sacrificial template; (2) coating glue on the sacrificial template to obtain a blank template; (3) copying the pattern of the soft template onto a blank template by a nano-imprinting technology to obtain a target template; (4) evaporating a magnetic metal onto a target template to obtain a magnetic template; (5) etching the magnetic template by adopting plasma to obtain a porous template; (6) removing the hard substrate and the sacrificial layer to obtain the porous magnetic nano robot; the whole preparation process does not involve complex chemical reactions, the prepared porous magnetic nano robot can be accurately controlled, has direction controllability, can be used in a human body for a short time or a long time, does not cause potential toxicity to the human body, and has important research value.

Description

Porous magnetic nano robot and preparation method and application thereof

Technical Field

The invention belongs to the technical field of nano materials, and particularly relates to a porous magnetic nano robot and a preparation method and application thereof.

Background

In the last two decades, movable micro-nano robots have become an emerging field of robots. The micro-nano robot is an engine with a small structure capable of converting various energies into motions or driving to execute a pre-programming task, and is widely applied to medical treatment, biotechnology, environmental remediation and other potential fields. In the medical field, these tiny robotic surgeons can let us remotely access hard to reach body parts and perform different medical procedures, facilitating medical and diagnostic treatment of patients; the magnetic driving micro-nano robot has unique potential in medical application in non-transparent tissues with high penetration depth.

On a small scale, the micro-nano robot cannot load an energy device like a conventional large robot, and the motion of the micro-nano robot is controlled by low Reynolds number and Brownian motion, so that the primary consideration for designing the micro/nano robot is a driving technology, which is also the research core of the micro-nano robot. Driving methods of the micro-nano robot are roughly classified into a physical method, a chemical method, a biological method, and a hybrid method. The common physical driving method is realized through mechanisms such as magnetism, electricity, light, heat, sound, piezoelectricity and the like, wherein the application of the magnetic driving is the most extensive, and the magnetic driving has the advantages of strong penetrating power, capability of remotely driving, nondestructive driving of living biological materials and the like, and has very large biomedical application potential.

Influenced by the narrow factor of the diameter of the blood vessel of the human body, the nano-scale robot is more suitable for practical application. Currently, methods of nano-robot fabrication are mainly electrochemical methods, template/coating structuring, 3D printing, glancing angle deposition and roll-up lithography, and these novel technologies provide new design functions, allowing for the addition of functions by design. And the designed porous nano robot increases the surface area of the robot, has high drug loading capacity and provides greater potential for the robot in drug transportation.

At present, many researches and reports are carried out on micro-nano robots. CN111705299A discloses a method for preparing a nano robot, which comprises coating a wude alloy film on the surface of a substrate, and etching the wude alloy film into a protrusion. And then, plating and covering the raised magnetic film on the surface of the protrusion, wherein a corresponding raised cavity is formed in the magnetic film, and the cavity can be used for carrying medicine. And then heating the projections made of the Wude alloy material to separate the magnetic film from the substrate, and finally cutting the magnetic film to obtain the nano robot. The speed of plating the magnetic film on the surface of the substrate by the film plating equipment is very high, so that the manufacturing cost of the nano robot can be effectively reduced; the thickness of the magnetic film prepared by the coating equipment is generally uniform, all components forming the magnetic film can be fully mixed, and the compactness of the magnetic film can be obviously improved. CN102431966A discloses a tubular porous micron motor, a preparation method and application thereof, wherein the preparation steps of the porous micron motor are as follows: preparing an aluminum oxide film with a nanopore array on the surface by anodic oxidation; depositing a multilayer film with a prestress gradient on the anodic aluminum oxide film; carrying out graphical processing on the multilayer film; selectively corroding the porous anodic aluminum oxide under the multilayer film, and self-curling the multilayer film into a micron tube with a nano hole on the tube wall; transferring the porous microtube into a solution to become a micromotor; the porous micro motor with the special structure has large surface area, higher catalytic efficiency and faster movement speed; the movement direction of the micrometer motor can be controlled by using a magnetic field so as to be used for transporting the micro-nano level object. The high-speed moving micro motor has great application prospect in the aspects of drug transportation, biological detection and separation, single cell analysis and the like. CN111663995A discloses a chemical energy driven nano engine, a method for providing power and a nano robot. The invention provides a nano engine, comprising: the upper part in the shell is an oil layer, and the lower part in the shell is a water layer; the upper part of the shell is provided with an opening which is covered with a semipermeable membrane allowing gas to pass through; and the metal sodium can be separated from the inner wall of the upper part of the shell, the density of the metal sodium is greater than that of an oil layer, the nano engine provided by the invention can utilize the reaction of the metal sodium and water to release a large amount of hydrogen as the driving force of the nano engine, and the motion rate of the nano robot provided with the nano engine can be well ensured. Meanwhile, according to the chemical property of sodium element, the nano engine provided by the invention adopts different liquids to construct a double-layer reaction space, and by adjusting the proportion of an oil layer and a water layer, the reaction rate of sodium and water can be reasonably controlled, the safety coefficient of the nano engine in the running process is improved, and the braking duration of the nano engine is prolonged effectively.

However, although the above document can produce a porous micron-sized robot, relying on an asymmetric distribution to produce this pattern of motion does not allow for accurate control of the motion by humans. And the chemical drive has high toxicity, the durability is not good, the robot can be inactivated after long-term use, and the prepared robot is unstable.

Therefore, the development of a porous magnetic nano robot with strong direction controllability, stable performance and simple preparation method is a key problem to be solved in the field.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a porous magnetic nano robot and a preparation method and application thereof; the preparation method comprises the steps of respectively coating a sacrificial material and glue on a hard substrate to obtain a blank template, copying a pattern on a soft template onto the blank template through a nano-imprinting technology, and finally successfully preparing the porous magnetic nano robot with controllable directionality and stable performance through the steps of evaporating magnetic metal, plasma etching, removing the hard substrate and the like; the adopted nanoimprint technology has good forming consistency, the preparation is quick and simple, and the optional imprint materials are diversified; the whole preparation process does not involve complex chemical reaction, and the preparation method does not cause potential toxicity to human bodies when being applied to the medical field, and has important research significance.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for preparing a porous magnetic nano robot, comprising the following steps:

(1) coating a sacrificial material on a hard substrate to obtain a sacrificial template;

(2) coating glue on the sacrificial material layer of the sacrificial template obtained in the step (1) to obtain a blank template;

(3) copying the pattern of the soft template to the blank template obtained in the step (2) by a nano-imprinting technology to obtain a target template;

(4) evaporating a magnetic metal onto the target template obtained in the step (3) to obtain a magnetic template;

(5) etching the magnetic template obtained in the step (4) by using plasma to obtain a porous template;

(6) and (5) removing the hard substrate and the sacrificial material layer of the porous template obtained in the step (5) to obtain the porous magnetic nano robot.

The technological process diagram of the preparation method of the porous magnetic nano robot provided by the invention is shown in figure 1, wherein 1 represents a hard substrate, 2 represents a sacrificial material layer, 3 represents a glue layer, 4 represents a soft template, 5 represents a magnetic metal layer, and 6 represents the porous magnetic nano robot; firstly, coating a sacrificial material on a hard substrate 1 to obtain a sacrificial template with a sacrificial material layer 2 on the surface; coating glue on the sacrificial material layer 2 of the obtained sacrificial template to obtain a blank template with a glue layer 3 on the surface; then copying the pattern of the soft template 4 to a blank template by a nano-imprinting technology to obtain a target template; then, evaporating and plating magnetic metal on the target template to obtain a magnetic template with a magnetic metal layer 5 on the surface; etching the magnetic template by using plasma, wherein the plasma can generate a hole structure on the surface of the magnetic template; and finally, removing the hard substrate and the sacrificial material layer on the magnetic template to obtain the porous magnetic nano robot.

The target template obtained by the nano-imprinting technology adopted in the preparation method of the porous magnetic nano-robot provided by the invention has uniform surface, so that the finally obtained nano-robot can be ensured to have more stable performance, and the nano-imprinting technology has good forming consistency and is quick and simple to prepare; scanning electron microscope images of the magnetic template before and after plasma etching in the step (5) are shown in fig. 2 and fig. 3, wherein 6-1 in fig. 2 represents a nano robot to be etched and separated; in FIG. 3, 6-2 represents the nano-robot to be separated; comparing fig. 2 and fig. 3, it can be seen that the magnetic template surface after plasma etching has a fine pore structure, and the nano robot with the pore structure can greatly improve the biomedical application potential of the robot, such as drug loading capacity; the porous magnetic nano robot obtained by the whole preparation method through steps of nano imprinting, magnetization, pore forming and the like can be accurately controlled, the directionality is controllable, no complex chemical reaction is involved in the whole preparation process, the porous magnetic nano robot can be used in a human body for a short time or a long time, no potential poison is caused to the human body, and the porous magnetic nano robot has important research value.

Preferably, the hard substrate of step (1) comprises a silicon wafer or a glass plate.

Preferably, the coating method in step (1) is spin coating, and further preferably spin coating at a rotation speed of 800-1200 rpm/min (e.g. 830rpm/min, 860rpm/min, 890rpm/min, 930rpm/min, 960rpm/min, 990rpm/min, 1030rpm/min, 1060rpm/min, 1090rpm/min, 1130rpm/min, 1160rpm/min or 1190rpm/min, etc.).

Preferably, the coating time in step (1) is 0.5-1.5 min, such as 0.6min, 0.7min, 0.8min, 0.9min, 1min, 1.1min, 1.2min, 1.3min or 1.4min, and the specific values therebetween are not exhaustive, and for brevity and clarity, the invention is not exhaustive.

Preferably, the thickness of the sacrificial material layer on the sacrificial template in step (1) is 90-110 nm, such as 92nm, 94nm, 96nm, 98nm, 100nm, 102nm, 104nm, 106nm or 108nm, and the specific values therebetween are limited by space and for brevity, the invention is not exhaustive.

Preferably, the sacrificial material in step (1) comprises any one of or a combination of at least two of dextran, polyvinyl alcohol, polyacrylamide or sodium polyacrylate.

Preferably, the coating method in the step (2) is spin coating, preferably spin coating at a rotation speed of 2800-3200 rpm/min (e.g. 2830rpm/min, 2860rpm/min, 2890rpm/min, 2930rpm/min, 2960rpm/min, 2990rpm/min, 3030rpm/min, 3060rpm/min, 3090rpm/min, 3130rpm/min, 3160rpm/min or 3190rpm/min, etc.).

Preferably, the coating time in step (2) is 0.5-1.5 min, such as 0.6min, 0.7min, 0.8min, 0.9min, 1min, 1.1min, 1.2min, 1.3min or 1.4min, and the specific values therebetween are not exhaustive, and for brevity and clarity, the invention is not exhaustive.

Preferably, the thickness of the glue layer on the blank template in the step (2) is 200-500 nm, such as 240nm, 280nm, 320nm, 360nm, 400nm, 420nm, 460nm or 480nm, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the soft template in step (3) is prepared by reverse-mold copying the pattern on the hard template to the soft substrate.

Preferably, the soft substrate comprises a polydimethylsiloxane substrate or a polyacryl-phthalein amine substrate.

Preferably, the hard template is prepared by an electron beam exposure technique.

Preferably, the nanoimprinting technique of step (3) is an ultraviolet nanoimprinting technique.

Preferably, the exposure time of the nanoimprint technology is 1-3 min, such as 1.2min, 1.4min, 1.6min, 1.8min, 2min, 2.2min, 2.4min, 2.6min or 2.8min, and the specific point values between the above point values are limited by space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the magnetic metal in step (4) comprises any one of nickel, gold or titanium or a combination of at least two of nickel, gold and titanium.

Preferably, the evaporation method in step (4) is electron beam evaporation.

Preferably, the thickness of the magnetic metal layer on the magnetic template in step (4) is 60-80 nm, such as 62nm, 64nm, 66nm, 68nm, 70nm, 72nm, 74nm, 76nm or 78nm, and the specific values therebetween are limited by space and for brevity, the invention is not exhaustive.

Preferably, the plasma etching in the step (5) further comprises a step of etching with an acidic solution.

As a preferred technical scheme of the present invention, the preparation method provided by the present invention further comprises a step of placing the obtained magnetic template in an acidic aqueous solution for acidic etching before performing plasma etching, and this step can reduce the coating amount of the magnetic metal on the magnetic template, control the coating amount to facilitate the visibility of the preparation process, and improve the preparation accuracy.

Preferably, the acidic solution comprises an aqueous solution of nitric acid and/or an aqueous solution of acetic acid.

Preferably, the plasma of step (5) comprises O₂Plasma, Ar plasma, N₂Plasma or CO₂Any one of or a combination of at least two of the plasmas. .

Preferably, the etching power of step (5) is 90-110W, such as 92W, 94W, 96W, 98W, 100W, 102W, 104W, 106W or 108W, and the specific values therebetween, which are limited by the space and for brevity, are not exhaustive.

Preferably, the etching time in step (5) is 0.5-1.5 min, such as 0.6min, 0.7min, 0.8min, 0.9min, 1min, 1.1min, 1.2min, 1.3min or 1.4min, and the specific values therebetween are not exhaustive, and for brevity and clarity, the invention is not exhaustive.

Preferably, the removing method in step (6) is ultrasonic treatment.

Preferably, the time of the ultrasonic treatment is 2-4 min, such as 2.2min, 2.4min, 2.6min, 2.8min, 3min, 3.2min, 3.4min, 3.6min or 3.8min, and the specific values therebetween are limited by the space and for the sake of brevity, and the invention is not exhaustive.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) spin-coating a sacrificial material on a hard substrate for 0.5-1.5 min at a rotating speed of 800-1200 rpm/min to obtain a sacrificial template with a sacrificial material layer thickness of 90-110 nm; the sacrificial material comprises any one or a combination of at least two of glucan, polyvinyl alcohol, polyacrylamide or sodium polyacrylate;

(2) spin coating glue on the sacrificial material layer of the sacrificial template obtained in the step (1) for 0.5-1.5 min at the rotating speed of 2800-3200 rpm/min to obtain a blank template with the glue layer thickness of 200-500 nm;

(3) copying the pattern of the soft template onto the blank template obtained in the step (2) by an ultraviolet nano-imprinting technology to obtain a target template; the exposure time of the ultraviolet nanoimprint technology is 1-3 min;

(4) evaporating a magnetic metal electron beam onto the target template obtained in the step (3) to obtain a magnetic template with a magnetic metal layer thickness of 60-80 nm;

(5) etching the magnetic template obtained in the step (4) for 0.5-1.5 min under the condition of 90-110W by adopting plasma to obtain a porous template;

(6) and (5) carrying out ultrasonic treatment for 2-4 min to remove the hard substrate and the sacrificial material layer on the porous template obtained in the step (5) to obtain the porous magnetic nano robot.

In a second aspect, the present invention provides a porous magnetic nano-robot, which is prepared by the method according to the first aspect.

In a third aspect, the invention provides a use of the porous magnetic nano robot as described in the second aspect in medical devices, biology or environmental remediation.

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method of the porous magnetic nano robot provided by the invention comprises the steps of respectively coating a sacrificial material and glue on a hard substrate to obtain a blank template; then copying the pattern on the soft template to the blank template by a nano-imprinting technology; finally, the porous magnetic nano robot is successfully prepared through the steps of evaporating magnetic metal, plasma etching, removing a hard substrate and the like; the nano-imprinting technology has the advantages of consistent molding, quick and simple preparation, diversification of selectable imprinting materials and the like.

(2) The porous magnetic nano robot obtained by the preparation method provided by the invention can be accurately controlled, has controllable directivity and does not involve complex chemical reactions, so that the obtained nano robot cannot cause potential toxicity to a human body, can be used in a short term or a long term in the human body, has a high drug loading capacity of 64-72%, and has an important research value because the drug loading capacity of the nano robot obtained in the prior art is only 58-61%.

Drawings

Fig. 1 is a process flow diagram of a preparation method of a porous magnetic nano robot provided by the invention, wherein 1-a hard substrate, 2-a sacrificial material layer, 3-a glue layer, 4-a soft template, 5-a magnetic metal layer, and 6-the porous magnetic nano robot;

FIG. 2 is a scanning electron microscope image of the magnetic template before etching in the preparation method provided by the present invention, wherein 6-1-the nano robot to be etched and separated;

fig. 3 is a scanning electron microscope image of the etched magnetic template in the preparation method provided by the invention, wherein 6-2-the nano robot to be separated.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

A preparation method of a porous magnetic nano robot comprises the following steps:

(1) spin-coating a glucan sacrificial material on a hard substrate for 1min at the rotating speed of 1000rpm/min to obtain a sacrificial template with the glucan sacrificial material layer thickness of 100 nm;

(2) spin-coating imprinting glue (SU 82000.5) on the sacrificial material layer of the sacrificial template obtained in the step (1) for 1min at the rotating speed of 3000rpm/min to obtain a blank template with the imprinting glue layer thickness of 300 nm;

(3) copying the pattern of the soft template (obtained by copying a hard template on a polydimethylsiloxane substrate (Dow Corning SYLGARDTM184, USA) in a reverse mode, wherein the hard template is obtained by preparing a pattern on a silicon wafer by adopting an electron beam exposure technology) to the blank template obtained in the step (2) by adopting an ultraviolet nanoimprint technology to obtain a target template; the exposure time of the ultraviolet nanoimprint is 2 min;

(4) evaporating nickel on the target template obtained in the step (3) by using electron beam evaporation to obtain a magnetic template with the thickness of the magnetic metal layer being 70 nm;

(5) etching the magnetic template obtained in the step (4) by using 1mol/L nitric acid aqueous solution, and then using O₂Etching the magnetic template for 1min by the plasma under the condition of 100W to obtain a porous template;

(6) and (5) ultrasonically treating the porous template obtained in the step (5), and removing the hard substrate and the sacrificial layer to obtain the porous magnetic nano robot.

Example 2

(1) spin-coating a glucan sacrificial material on a hard substrate for 1.5min at the rotating speed of 800rpm/min to obtain a sacrificial template with the glucan sacrificial material layer thickness of 90 nm;

(2) spin-coating imprint glue (SU 82000.5) on the sacrificial material layer of the sacrificial template obtained in the step (1) for 1.5min at the rotation speed of 2800rpm/min to obtain a blank template with the thickness of an imprint glue layer of 200 nm;

(3) a soft template was placed (by printing on a polydimethylsiloxane substrate (SYLGARD Dow Corning, USA)^TM184) Copying a hard template by a reverse mold, wherein the hard template is obtained by preparing a pattern on a glass plate by adopting an electron beam exposure technology) and copying the pattern to the blank template obtained in the step (2) by adopting an ultraviolet nano-imprinting technology to obtain a target template; the exposure time of the ultraviolet nanoimprint is 1 min;

(4) evaporating titanium onto the target template obtained in the step (3) by using electron beam evaporation to obtain a magnetic template with the thickness of the magnetic metal layer being 60 nm;

(5) etching the magnetic template obtained in the step (4) by using 1mol/L acetic acid aqueous solution, and then using O₂The magnetic template is etched for 1.5min by the plasma under the condition of 90W, so as to obtain a porous template;

(6) and (5) ultrasonically treating the porous template obtained in the step (5) for 2min, and removing the hard substrate and the sacrificial layer to obtain the porous magnetic nano robot.

Example 3

(1) spin-coating a glucan sacrificial material on a hard substrate for 0.5min at the rotating speed of 1200rpm/min to obtain a sacrificial template with the glucan sacrificial material layer thickness of 110 nm;

(2) spin-coating imprint gel (SU 82000.5) on the sacrificial material layer of the sacrificial template obtained in the step (1) for 0.5min at the rotating speed of 3200rpm/min to obtain a blank template with the imprint gel layer thickness of 500 nm;

(3) a soft template was placed (by printing on a polydimethylsiloxane substrate (SYLGARD Dow Corning, USA)^TM184) Copying a hard template by a reverse mold, wherein the hard template is obtained by preparing a pattern on a glass plate by adopting an electron beam exposure technology) and copying the pattern to the blank template obtained in the step (2) by adopting an ultraviolet nano-imprinting technology to obtain a target template; the exposure time of the ultraviolet nanoimprint is 3 min;

(4) evaporating gold onto the target template obtained in the step (3) by using electron beam evaporation to obtain a magnetic template with the thickness of the magnetic metal layer being 80 nm;

(5) etching the magnetic template obtained in the step (4) by using 1mol/L acetic acid aqueous solution, and then using O₂The magnetic template is etched for 0.5min under the condition of 110W by the plasma to obtain a porous template;

(6) and (5) ultrasonically treating the porous template obtained in the step (5) for 4min, and removing the hard substrate and the sacrificial layer to obtain the porous magnetic nano robot.

Example 4

A preparation method of a porous magnetic nano robot, which is different from the embodiment 1 only in that the hydrogel is adopted to replace the stamping glue (SU 82000.5) in the step (2), and the other conditions and steps are the same as the embodiment 1.

Example 5

(3) a soft template was placed (by printing on a polydimethylsiloxane substrate (SYLGARD Dow Corning, USA)^TM184) Copying a hard template by a reverse mold, wherein the hard template is obtained by preparing patterns on a silicon wafer by adopting an electron beam exposure technology) and copying the patterns to the blank template obtained in the step (2) by adopting an ultraviolet nano-imprinting technology to obtain a target template; the exposure time of the ultraviolet nanoimprint is 2 min;

(5) by using O₂Etching the magnetic template obtained in the step (4) for 1min by the plasma under the condition of 100W to obtain a porous template;

Comparative example 1

A preparation method of a magnetic nano robot specifically comprises the following steps:

(5) etching the magnetic template obtained in the step (4) by using 1mol/L nitric acid aqueous solution to obtain a primary template;

(6) and (5) ultrasonically treating the primary template obtained in the step (5) for 3min, and removing the hard substrate and the sacrificial layer to obtain the magnetic nano robot.

Comparative example 2

A nano robot, the preparation method comprises:

(1) forming an ordered porous anodic aluminum oxide film (sacrificial layer) on the surface of an aluminum plate through anodic oxidation, and specifically comprising the following steps of placing a container containing 1mol/L phosphoric acid electrolyte in a water bath at room temperature, taking an aluminum foil cleaned by ethanol and deionized water in advance as an anode and a graphite sheet as a cathode, immersing the aluminum foil in the electrolyte, carrying out anodic oxidation treatment for 30-60 min under the condition of constant voltage of 10-20V, taking out the oxidized aluminum foil after the anodic oxidation treatment is finished, cleaning the oxidized aluminum foil by deionized water to remove electrolyte residues on the surface, naturally airing, placing the dried aluminum foil in a muffle furnace, heating to 650 ℃ at the heating rate of 5-8 ℃/min, preserving heat for 2-4 hours, and cooling to room temperature along with the furnace, wherein the surface of the aluminum foil has a nano-porous structure;

(2) depositing a Ni/Ti film on the substrate (1) by adopting a physical vapor deposition method to obtain a film deposited with Ni/Ti;

(3) and (3) ultrasonically treating the sacrificial layer deposited with the Ni/Ti film obtained in the step (2) for 3min by using a potassium hydroxide solution with the mass percentage of 20% to remove the sacrificial layer, so as to obtain the nano robot.

And (3) performance testing:

drug loading capacity: preparing a nanomotiter loaded with Doxorubicin (DOX) using an ultrasonic dialysis method; the method comprises the following specific steps: dissolving 10mg DOX & HCl in 5mL PBS, and performing ultrasonic treatment for 5min to obtain DOX solution; dispersing 20mg of the nano robot obtained in the above examples and comparative examples in 10mL of deionized water to obtain a nano robot solution; mixing the DOX solution and the nano-robot solution for ultrasonic treatment; then transferring the mixed solution into a dialysis tube, and dialyzing with ultrapure water at room temperature for 48 h;

testing the concentration of DOX in the supernatant by using an enzyme-labeling instrument at 480 nm; the drug loading calculation formula is as follows: the drug loading capacity% (% of drug added DOX-amount of drug DOX in supernatant)/nano robot × 100%.

The porous magnetic nano robots obtained in examples 1 to 5 and the robots obtained in comparative examples 1 to 2 were tested according to the above test method, and the test results are shown in table 1:

TABLE 1

	Drug loading (%)
		Example 1	65
Example 2	72
		Example 3	66
Example 4	68
		Example 5	64
Comparative example 1	61
		Comparative example 2	58

As can be seen from the data in table 1: the drug loading capacity of the porous magnetic nano robot obtained in the examples 1 to 5 is 64 to 72%, while the drug loading capacity of the nano robot obtained in the comparative example 1 without the plasma etching treatment is only 61%, and the drug loading capacity of the nano robot prepared in the comparative example 2 by using a conventional method is 58%, which shows that the porous magnetic nano robot obtained by the invention has high drug loading capacity.

The applicant states that the present invention is described by the above embodiments, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must rely on the above process steps to be implemented. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.

Claims

1. The preparation method of the porous magnetic nano robot is characterized by comprising the following steps:

2. The production method according to claim 1, wherein the hard substrate of step (1) comprises a silicon wafer or a glass plate;

preferably, the coating method in the step (1) is spin coating, and further preferably is spin coating with the rotating speed of 800-1200 rpm/min;

preferably, the coating time in the step (1) is 0.5-1.5 min;

preferably, the thickness of the sacrificial material layer on the sacrificial template in the step (1) is 90-110 nm;

3. The preparation method according to claim 1 or 2, wherein the coating method in the step (2) is spin coating, preferably spin coating at a rotation speed of 2800-3200 rpm/min;

preferably, the coating time in the step (2) is 0.5-1.5 min;

preferably, the thickness of the glue layer on the blank template in the step (2) is 200-500 nm.

4. The method according to any one of claims 1 to 3, wherein the soft template in the step (3) is prepared by reverse-mold replication of a pattern on a hard template onto a soft substrate;

preferably, the soft substrate comprises a polydimethylsiloxane substrate or a polyacryl-phthalein amine substrate;

preferably, the hard template is prepared by an electron beam exposure technology;

preferably, the nanoimprint technology of step (3) is an ultraviolet nanoimprint technology;

preferably, the exposure time of the nanoimprint technology is 1-3 min.

5. The method according to any one of claims 1 to 4, wherein the magnetic metal in the step (4) comprises any one of nickel, iron or cobalt or a combination of at least two thereof;

preferably, the evaporation method in the step (4) is electron beam evaporation;

preferably, the thickness of the magnetic metal layer on the magnetic template in the step (4) is 60-80 nm.

6. The manufacturing method according to any one of claims 1 to 5, characterized in that the step (5) of etching the plasma further comprises a step of etching with an acidic solution;

preferably, the acidic solution comprises an aqueous nitric acid solution and/or an aqueous acetic acid solution;

preferably, the plasma of step (5) comprises O₂Plasma, Ar plasma, N₂Plasma or CO₂Any one of or a combination of at least two of the plasmas;

preferably, the etching power in the step (5) is 90-110W;

preferably, the etching time in the step (5) is 0.5-1.5 min.

7. The method according to any one of claims 1 to 6, wherein the removing in step (6) is ultrasonic treatment;

preferably, the time of ultrasonic treatment is 2-4 min.

8. The production method according to any one of claims 1 to 7, characterized by comprising the steps of:

9. A porous magnetic nano robot, characterized in that the porous magnetic nano robot is prepared by the method of any one of claims 1 to 8.

10. Use of the porous magnetic nanoprobe of claim 9 in medical devices, biology or environmental remediation.