Light-driven ion pump and preparation method thereof

Abstract

The invention provides a light-driven ion pump with ultraviolet light-driven ion active transportation and a preparation method thereof, and the light-driven ion pump comprises an alumina porous membrane, methyltrimethoxysilane, titanium dioxide nanoparticles, a light-emitting diode (LED) light source, a light-emitting diode (LED) light-emitting diode and a light-emitting diode (LED) light-emitting diode. The methyltrimethoxysilane and the titanium dioxide nanoparticles are distributed on the surface of the aluminum oxide porous membrane and in pore channels close to the surface to form a thin layer. The preparation method of the light-driven ion pump has the advantages of simplicity and convenience in operation, low cost and the like, a complicated preparation process is not needed, the concentration difference range reversed by ultraviolet light-driven ion active transportation is wide, and the light-driven ion pump can be further applied to the fields of biosensing, energy conversion, desalination and the like.

Description

Technical Field

[0001] The present invention relates to the field of biomimetic bio-nanochannels, and specifically to the field of ion pumps. Background Art

[0002] In nature, the precise and active control of ion movement across membranes by ion pumps is crucial for life. Different from bioionic channels with passive ion transport properties, ion pumps with active ion transport properties can transport ions across cells and organelles against the concentration gradient, which lays the foundation for many important activities such as nerve conduction, muscle contraction, and photosynthesis. Light, as one of the most widely used energy sources in nature, can be controlled with precisely regulated wavelengths, directions, irradiation areas, and intensities in space and time, which makes the prepared devices have greater flexibility in various complex application fields. By mimicking the structure of biological ion pumps, the inventors of the present application have prepared light-driven ion pumps based on polyethylene terephthalate (Sci.Adv., 2016, 2, e1600689), graphene (Nat. Commun., 2019, 10, 1171), C3N4 (Nat. Commun., 2019, 10, 74.), conductive polymers (Angew. Chem. Int. Ed., 2022, 61, e202201138), and covalent organic frameworks (J. Am. Chem. Soc. 2024, 146, 33973 - 33982). However, most of these methods have disadvantages such as complex operations and high costs. Therefore, it is of great significance to develop a new type of light-driven ion pump and its preparation method. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the inventors of the present invention have found through in-depth research that the light-driven ion pump of the present application can perform ultraviolet light-driven active ion transport, and has characteristics such as a wide range of reversed concentration differences, simple operation, and low cost.

[0004] The present invention includes the following components.

[0005] One aspect of the present invention provides a light-driven ion pump, which is a bilayer-structured membrane capable of performing ultraviolet light-driven active ion transport. It contains an alumina porous membrane, methyltrimethoxysilane, and titanium dioxide nanoparticles. The methyltrimethoxysilane and titanium dioxide nanoparticles are distributed on the surface and in the pores close to the surface of the alumina porous membrane to form a thin film.

[0006] Here, the "bilayer structure" refers to the layer formed by the alumina porous membrane and the layer formed by the methyltrimethoxysilane and titanium dioxide nanoparticles. The layer formed by the methyltrimethoxysilane and titanium dioxide nanoparticles is distributed on the surface and in the pores close to the surface of the alumina porous membrane layer.

[0007] "Ultraviolet light-driven ion active transport" here refers to the transport of ions from a low concentration to a high concentration under ultraviolet light irradiation without an externally applied voltage. The larger the concentration difference that the ion transport can reverse, the stronger the performance of its ion active transport.

[0008] In the light-driven ion pump of the present invention, preferably, the surface of the aforementioned titanium dioxide nanoparticles has hydroxyl functional groups, and the particle diameter is 20 to 100 nm. The titanium dioxide nanoparticles with hydroxyl functional groups are crosslinked together through the hydrolysis reaction of methyltrimethoxysilane.

[0009] In the light-driven ion pump of the present invention, preferably, the thickness of the aforementioned alumina porous membrane is 90 to 100 μm, and the pore diameter is 70 to 110 nm.

[0010] In the light-driven ion pump of the present invention, preferably, the thickness of the layer formed by the aforementioned methyltrimethoxysilane and titanium dioxide nanoparticles is 6 to 24 μm.

[0011] Another aspect of the present invention also provides a method for preparing a light-driven ion pump, which includes the following steps: mixing methyltrimethoxysilane, TiO2 nanoparticles, methanol, and hydrochloric acid and stirring for 1 to 10 hours to obtain a TiO2 sol, and then coating the TiO2 sol on the surface of the alumina porous membrane to form a thin film, and naturally drying at room temperature for 12 to 24 hours to form a light-driven ion pump.

[0012] In the preparation method of the present invention, preferably, the surface of the aforementioned titanium dioxide nanoparticles has hydroxyl functional groups, and the particle diameter is 20 to 100 nm.

[0013] In the preparation method of the present invention, preferably, the thickness of the aforementioned alumina porous membrane is 90 to 100 μm, and the pore diameter is 70 to 110 nm.

[0014] In the preparation method of the present invention, preferably, the thickness of the thin layer formed by the aforementioned methyltrimethoxysilane and titanium dioxide nanoparticles is 6 to 24 μm. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of the light-driven ion pump of the present invention.

[0016] Figure 2 is a scanning electron micrograph of the cross-section of the light-driven ion pump prepared in Example 1.

[0017] Figure 3 is a device diagram for testing the ultraviolet light-driven ion active transport ability of the light-driven ion pump prepared in Example 1.

[0018] Figure 4It is a current-time curve graph generated by the photo-driven ion pump prepared in Example 1 during the reverse concentration difference transport of ions (active transport) under ultraviolet light irradiation and zero-volt voltage. Detailed implementation manners

[0019] To better understand the present invention, the present invention will be further described in detail below in conjunction with embodiments. However, the scope of protection required by the present invention is not limited to the scope shown in the embodiments. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present disclosure.

[0020] [Photo-driven ion pump]

[0021] The photo-driven ion pump of the present invention with ultraviolet light-driven ion active transport contains an alumina porous membrane, methyltrimethoxysilane, and titanium dioxide nanoparticles. Among them, methyltrimethoxysilane and titanium dioxide nanoparticles are distributed on the surface and in the pores close to the surface of the alumina porous membrane to form a thin film. Figure 1 It is a schematic structural diagram of the photo-driven ion pump of the present invention. As Figure 1 shown, the surface of the alumina porous membrane has columnar pores, and titanium dioxide nanoparticles are distributed on the surface of the alumina porous membrane. The surface of the titanium dioxide nanoparticles contains methyltrimethoxysilane, and methyltrimethoxysilane and titanium dioxide nanoparticles are distributed on the surface and in the pores close to the surface of the alumina porous membrane to form a thin film.

[0022] In some preferred implementation manners, the surface of the aforementioned titanium dioxide nanoparticles has hydroxyl functional groups, and the diameter of the aforementioned titanium dioxide nanoparticles is 20 - 100 nm.

[0023] In some preferred implementation manners, the thickness of the aforementioned alumina porous membrane is 90 - 100 μm, and the pore diameter is 70 - 110 nm.

[0024] In some preferred implementation manners, the thickness of the thin film formed by the aforementioned methyltrimethoxysilane and the aforementioned titanium dioxide nanoparticles is 6 - 24 μm.

[0025] In some preferred implementation manners, the wavelength range of the aforementioned ultraviolet light is 300 - 400 nm, and the light intensity is 10 - 50 mW / cm 2 .

[0026] In some preferred implementation manners, the concentration difference range that can be reversed by the aforementioned ultraviolet light-driven ion active transport is 1.05 - 4 times.

[0027] [Preparation method of photo-driven ion pump]

[0028] The preparation method of the light-driven ion pump in some embodiments is as follows: Mix methyltrimethoxysilane, TiO2 nanoparticles with a hydroxyl group on the surface and a mass fraction of 8-18%, hydrochloric acid, and methanol and stir for 1-10 hours to obtain a TiO2 colloid, where the volume ratio of methanol to methyltrimethoxysilane is 15-20, and the volume ratio of methanol to hydrochloric acid is 300-400. The prepared TiO2 colloid suspension can be coated on one side of an anodic aluminum oxide porous membrane substrate, for example, by a doctor blade method, to form a thin film. After drying at room temperature for 12-24 hours, a cation-selective ion pump with a bilayer structure is obtained.

[0029] Characterize and test the performance of the prepared light-driven ion pump, which mainly includes the following parts:

[0030] (1) Morphology characterization:

[0031] Use the SU8020 field emission scanning electron microscope of Hitachi, Japan to characterize the morphology of the light-driven ion pump prepared in the example.

[0032] (2) Characterization of ultraviolet light-driven ion active transport:

[0033] Place the ion pump with a bilayer structure obtained in the example in the middle of the self-made double-chamber electrochemical cell as shown in Figure 3 . Place a low-concentration potassium chloride solution in one side chamber of the electrochemical cell and a high-concentration potassium chloride solution in the other side chamber. Place a pair of silver / silver chloride electrodes in the two chambers of the electrochemical cell to form a circuit. Use a Keithley 6487 picoammeter to measure the current generated by ion transport. When there is no ultraviolet light irradiation, potassium ions diffuse from the high concentration to the low concentration side, generating an ion current. Under ultraviolet light irradiation, potassium ions are transported against the concentration gradient from the low concentration to the high concentration, and the direction of the current is reversed.

[0034] Example

[0035] Example 1

[0036] Mix 10 mL of methanol, 500 μL of methyltrimethoxysilane, 25 μL of hydrochloric acid, and TiO2 nanoparticles with a mass fraction of 8% at room temperature and stir for 1 h to obtain a TiO2 colloid. Scrape 50 μL of the colloid suspension onto the surface of the alumina porous membrane and dry it at room temperature for 12 hours to obtain a light-driven ion pump 1. Figure 2 Shown is the cross-sectional view of the obtained light-driven ion pump. From Figure 2 it can be seen that its upper layer is a titanium dioxide nanoparticle thin film with regular pores and particles, and the lower surface is the regular pore structure of the alumina porous membrane.

[0037] Perform ultraviolet light-driven ion active transport tests on the light-driven ion pump 1 obtained in Example 1. The results are as shown in Figure 4。The low-concentration and high-concentration potassium chloride solutions are 0.9 mM and 1 mM respectively. When there is no ultraviolet light irradiation, potassium ions diffuse from the high concentration to the low concentration, generating an ionic current of -0.5 nA. When irradiated with ultraviolet light (365 nm) at 10 mW / cm 2 , the ionic current is 1 nA. The direction of the ionic current during illumination is opposite to that during non-illumination, realizing the active transport of potassium ions from the low concentration to the high concentration against the concentration gradient. The possible reason for this is as follows: In the potassium chloride solution, one side of the titanium dioxide nanoparticle film is negatively charged and has cation selectivity. When there is no light, potassium ions in the solution will preferentially diffuse from the high concentration to the low concentration, generating a negative ionic current. When irradiated with ultraviolet light, photogenerated electrons accumulate on the surface of the titanium dioxide nanoparticles, generating an electric field from the low concentration to the high concentration direction, which drives the active transport of potassium ions from the low concentration to the high concentration against the concentration gradient.

[0038] Example 2

[0039] Mix 10 mL of methanol, 600 μL of methyltrimethoxysilane, 30 μL of hydrochloric acid, and TiO2 nanoparticles with a mass fraction of 18% and stir at room temperature for 1 h to prepare a TiO2 colloid. Scrape 50 μL of the colloid suspension onto the surface of the alumina porous membrane and dry at room temperature for 12 hours to obtain the light-driven ion pump 2.

[0040] Example 3

[0041] Mix 10 mL of methanol, 550 μL of methyltrimethoxysilane, 28 μL of hydrochloric acid, and TiO2 nanoparticles with a mass fraction of 12% and stir at room temperature for 1 h to prepare a TiO2 colloid. Scrape 50 μL of the colloid suspension onto the surface of the alumina porous membrane and dry at room temperature for 12 hours to obtain the light-driven ion pump 3.

[0042] Example 4

[0043] Mix 10 mL of methanol, 550 μL of methyltrimethoxysilane, 28 μL of hydrochloric acid, and TiO2 nanoparticles with a mass fraction of 12% and stir at room temperature for 10 h to prepare a TiO2 colloid. Scrape 50 μL of the colloid suspension onto the surface of the alumina porous membrane and dry at room temperature for 24 hours to obtain the light-driven ion pump 4.

[0044] Perform morphological characterization and light-driven ion active transport tests on the light-driven ion pumps 2-4 obtained in Examples 2-4. Through morphological characterization, it can be seen that the upper surface of the light-driven ion pumps 2-4 is a porous membrane composed of titanium dioxide nanoparticles, and the lower surface is a regular pore structure of the alumina porous membrane. And all have the property of light-driven ion active transport. As the concentration of titanium dioxide increases, the thickness of the titanium dioxide nanoparticle layer increases, and the concentration difference that can be reversed by the light-driven ion active transport increases.

[0045] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the specification of the present invention, which will be obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention will be obvious to those skilled in the art. The specification and examples of this application are merely exemplary.

Claims

1. A light-driven ion pump, which is a bilayer-structured membrane capable of performing ultraviolet light-driven active ion transport. It contains an alumina porous membrane, methyltrimethoxysilane, and titanium dioxide nanoparticles, and the methyltrimethoxysilane and titanium dioxide nanoparticles are distributed on the surface of the alumina porous membrane and in the pores close to the surface to form a thin film.

2. The opto-driven ion pump according to claim 1, wherein, The surface of the titanium dioxide nanoparticles has hydroxyl functional groups, and the diameter of the titanium dioxide nanoparticles is 20 - 100 nm.

3. The opto-driven ion pump according to claim 1 or 2, wherein, The thickness of the alumina porous membrane is 90 - 100 μm, and the pore diameter is 70 - 110 nm.

4. The opto-driven ion pump according to claim 1 or 2, wherein, The thickness of the thin film formed by methyltrimethoxysilane and the titanium dioxide nanoparticles is 6 - 24 μm.

5. The opto-driven ion pump according to claim 1, wherein, The wavelength range of the ultraviolet light is 300-400 nm, and the light intensity is 10-50 mW / cm 2 .

6. The opto-driven ion pump according to claim 1, wherein, The concentration difference range that can be reversed by the ultraviolet light-driven active ion transport is 1.05 - 4 times.

7. A method for preparing the light-driven ion pump according to any one of claims 1 - 6, which includes the following steps: Mix methyltrimethoxysilane, TiO2 nanoparticles, methanol, and hydrochloric acid and stir for 1 - 10 hours to obtain a TiO2 colloid. Coat the TiO2 colloid on the surface of the alumina porous membrane to form a thin film, and naturally dry it at room temperature for 12 - 24 hours to form a light-driven ion pump.

8. The preparation method of the photo-driven ion pump according to claim 7, wherein, The surface of the titanium dioxide nanoparticles has hydroxyl functional groups, and the diameter of the titanium dioxide nanoparticles is 20 - 100 nm.

9. The preparation method of the light-driven ion pump according to claim 7, wherein, The thickness of the alumina porous membrane is 90 - 100 μm, and the pore diameter is 70 - 110 nm.

10. The preparation method of the opto-driven ion pump according to claim 7, wherein, The thickness of the thin film formed by methyltrimethoxysilane and the titanium dioxide nanoparticles is 6 - 24 μm.

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