CN105600820A - Green TiO2 and preparing method, modifying method and application thereof - Google Patents

Abstract

The invention relates to a green titanium dioxide and its preparation method, modification method and application. The preparation method comprises: preparing black titanium dioxide by an aluminum reduction method; dispersing the black titanium dioxide in water and ultrasonically treating it for 2-3 hours to obtain green Titanium dioxide. The green titanium dioxide of the present invention is obtained by ultrasonic treatment of black titanium dioxide. After ultrasonic treatment, the black titanium dioxide becomes green titanium dioxide, and the increase in the thickness of the amorphous layer and the increase in defects lead to enhanced absorption of green titanium dioxide in the visible light and near-infrared regions, and improved stability. , can be used as a photodynamic therapeutic agent induced by near-infrared light. The preparation method adopted in the present invention is simple, fast and reproducible. It successfully transforms black titanium dioxide into green titanium dioxide with stronger absorption in the near-infrared, and provides a control titanium dioxide A new approach to photoresponses in the visible and near-infrared.

Description

A kind of green titanium dioxide and its preparation method, modification method and application

technical field

The invention relates to a green titanium dioxide and its preparation method, modification method and application, belonging to the fields of nanometer materials and biomedical applications.

Background technique

Titanium dioxide semiconductor has good photocatalytic activity and chemical stability, and under the excitation of ultraviolet light, it can generate a large amount of reactive oxygen species, thereby inducing cell death. Therefore, it has attracted much attention as an inorganic photosensitizer with excellent performance in tumor photodynamic therapy. However, due to the large band gap of titanium dioxide (3.2eV for the anatase phase and 3.0eV for the rutile phase), active oxygen can only be generated under the excitation of ultraviolet light (λ=275–390nm), and its photodynamic activity has been greatly restricted. Big restrictions. The near-infrared light (λ=600-1350nm) is called the "biological window", and the absorption of normal tissues in this region is the lowest, which can overcome the shortcomings of shallow penetration depth of ultraviolet light and damage to normal tissues. Therefore, near-infrared laser-induced photodynamic/photothermal therapy has broader application prospects.

In order to enhance the absorption of titanium dioxide in the visible and near-infrared regions, scientists have made many attempts. The successful synthesis of black TiO2 and red TiO2 reported in recent years provides a new strategy for extending the response of TiO2 in the visible and near-infrared light regions. The oxygen vacancy concentration and Ti ³⁺ content of titanium dioxide are regulated by means of metal, non-metal and self-doping, so as to reduce the forbidden band width of titanium dioxide, thereby enhancing its absorption in the visible and near-infrared regions.

Mitochondria are the energy centers of cells and are widely distributed in the cytoplasm. Moreover, mitochondria are sensitive to heat and can induce cell death through reactive oxygen species generated within the organelle. Therefore, in recent years, mitochondria-targeted photodynamic and photothermal therapy has become a new way to improve the efficiency and safety of tumor treatment. In order to further reduce the laser power density and the dose of intravenous injection of materials, it is urgent to design and construct a photodynamic/photothermal synergistic therapeutic nanosystem targeting tumor cell mitochondria.

Contents of the invention

In response to the above requirements, the purpose of the present invention is to provide a green titanium dioxide, and to construct a photodynamic/photothermal synergistic therapeutic nanosystem based on green titanium dioxide targeting tumor cell mitochondria.

Herein, the present invention provides a green titanium dioxide and a preparation method thereof. The preparation method comprises: preparing black titanium dioxide by aluminum reduction; then dispersing the black titanium dioxide in water, and obtaining green titanium dioxide by ultrasonic treatment for 2-3 hours.

The green titanium dioxide of the present invention is obtained by ultrasonic treatment of black titanium dioxide. After ultrasonic treatment, the black titanium dioxide becomes green titanium dioxide, and the increase in the thickness of the amorphous layer and the increase in defects lead to enhanced absorption of green titanium dioxide in the visible light and near-infrared regions, and improved stability. , can be used as a photodynamic therapeutic agent induced by near-infrared light. The preparation method adopted in the present invention is simple, fast and reproducible. It successfully transforms black titanium dioxide into green titanium dioxide with stronger absorption in the near-infrared, and provides a control titanium dioxide A new approach to photoresponses in the visible and near-infrared.

The present invention also provides a modification method of green titanium dioxide, which comprises the step of preparing green titanium dioxide modified by a mitochondrial targeting ligand through a polyethylene glycol modification process and a mitochondrial targeting ligand modification process successively, wherein the mitochondrial targeting ligand The ligand modification process used 1-ethyl-carbodiimide hydrochloride EDC and triphenylphosphine TPP.

On the basis of green titanium dioxide, in order to further improve the therapeutic efficiency and safety, the green titanium dioxide modified by the mitochondrial targeting ligand was obtained by modifying the mitochondrial targeting ligand, and the green titanium dioxide modified by the mitochondrial targeting ligand was constructed. Photodynamic/photothermal therapy nanosystems for tumor cell mitochondria. The green titanium dioxide modified by the mitochondrial targeting ligand has a good mitochondrial targeting effect, and under the same wavelength of near-infrared laser excitation, the green titanium dioxide modified by the mitochondrial targeting ligand can simultaneously generate active oxygen and high heat, thereby destroying the tumor cells. The energy center - mitochondria, which in turn induces tumor cell death. The photodynamic/photothermal therapy nanosystem based on mitochondria-targeting ligand-modified green titanium dioxide targeting tumor cell mitochondria can be intravenously injected at lower laser power density (980nm, 0.72Wcm ^-2 ) and lower material The dose (8mgkg ^-1 , permouse) achieves better tumor photodynamic/photothermal therapy effect. The present invention not only provides a new method for enhancing the absorption of titanium dioxide in the visible and near-infrared regions, but also provides a new strategy for constructing photodynamic/photothermal therapy nanosystems targeting tumor organelles, which is helpful for promoting titanium dioxide in Applications in the biological field are of great significance.

In the present invention, the polyethylene glycol modification process includes: dispersing polyethylene glycol into an aqueous solution of green titanium dioxide, and ultrasonically treating it to obtain polyethylene glycol-modified green titanium dioxide, wherein the mass of green titanium dioxide and polyethylene glycol The ratio is 1:1～1:2. The ultrasonic treatment time is preferably 0.5 to 1 hour.

In the present invention, the modification process of the mitochondrial targeting ligand comprises: dissolving 1-ethyl-carbodiimide hydrochloride and the mitochondrial targeting ligand in an organic solution according to a mass ratio of 1:1 to 3:1 , adding polyethylene glycol-modified green titanium dioxide, centrifuging and collecting in the dark at room temperature to obtain mitochondrial targeting ligand-modified green titanium dioxide, wherein the mass ratio of polyethylene glycol-modified green titanium dioxide to mitochondrial targeting ligand is 1:1～5:1. The organic solution is preferably methanol.

Preferably, the polyethylene glycol is amino polyethylene glycol.

Preferably, the mitochondrial targeting ligand is triphenylphosphine (TPP).

The present invention also provides a green titanium dioxide modified by the mitochondrial targeting ligand obtained by the above modification method, the green titanium dioxide modified by the mitochondrial targeting ligand is made of green titanium dioxide through the polyethylene glycol modification process and the mitochondrial targeting ligand Prepared by modification process.

Preferably, the particle diameter of the green titanium dioxide modified with the mitochondrial targeting ligand is 15-35 nanometers.

The present invention also provides an application of the above-mentioned green titanium dioxide in the preparation of a photodynamic therapeutic agent induced by near-infrared light. The green titanium dioxide refers to green titanium dioxide obtained from black titanium dioxide through ultrasonic treatment.

The present invention also provides the application of the green titanium dioxide modified by the mitochondrial targeting ligand in the biological field, especially in the preparation of photodynamic/photothermal therapeutic agents.

The present invention also provides an application of the green titanium dioxide modified with the mitochondrial targeting ligand in the fields of tumor targeting and phototherapy.

The present invention also provides an application of the above-mentioned green titanium dioxide modified by the mitochondrial targeting ligand in the preparation of near-infrared-induced photodynamic and photothermal therapeutic agents.

The present invention also provides an application of the green titanium dioxide modified by the above-mentioned mitochondria-targeting ligand in the preparation of a near-infrared-induced photodynamic/photothermal synergistic therapeutic agent.

The present invention also provides an application of the green titanium dioxide modified by the above-mentioned mitochondria-targeting ligand in the preparation of a novel inorganic nano-photosensitizer for simultaneous photothermal/photodynamic synergistic therapy targeting tumor cell mitochondria.

Description of drawings

Fig. 1 is the high-resolution transmission electron micrograph and the corresponding digital photo of black titanium dioxide (a, b) and green titanium dioxide (c, d) respectively dispersed in water obtained in Example 1;

Fig. 2 is the EDS energy spectrum diagram of the green titanium dioxide that embodiment 1 makes;

Fig. 3 is the Raman collection of illustrative plates of the original white titanium dioxide, black titanium dioxide and green titanium dioxide that embodiment 1 makes;

Fig. 4 is the UV-Vis collection of illustrative plates of the black titanium dioxide that embodiment 1 makes and green titanium dioxide aqueous solution at the same concentration;

Fig. 5 is the test curve of the green titanium dioxide prepared in Example 1 under the irradiation of 980nm laser (power density is 0.72Wcm ^-2 ) to generate active oxygen;

Fig. 6 is the DLS particle size and Zeta potential diagram of the green titanium dioxide modified by aminopolyethylene glycol and TPP targeting ligands prepared in Example 1. Among them, a is a particle size distribution map, and b is a Zeta point map;

Fig. 7 is the FTIR spectrum of the green titanium dioxide after modified by aminopolyethylene glycol and TPP targeting ligands prepared in Example 1;

Fig. 8 is the heating curve of the green titanium dioxide aqueous solution prepared in Example 1 under the irradiation of different power densities of 980nm laser.

detailed description

The present invention will be further described below in conjunction with the drawings and the following embodiments. It should be understood that the drawings and the following embodiments are only used to illustrate the present invention rather than limit the present invention.

The present invention transforms black titanium dioxide (blacktitania, B-TiO _2-x ) into a new type of green titanium dioxide (greenitania, G-TiO _{2-x ) by ultrasonically treating the black titanium dioxide (black titania, G-TiO 2-x} ). The absorption in the infrared region is significantly enhanced. On this basis, further surface modification is carried out on green titanium dioxide. After the polyethylene glycol modification process and the mitochondrial targeting ligand modification process, the green titanium dioxide modified by the mitochondrial targeting ligand is obtained, and the green titanium dioxide modified by the mitochondrial targeting ligand is obtained. Titanium dioxide exhibits good dispersion and stability in aqueous solution, and has good biocompatibility and good mitochondrial targeting specificity.

In the preparation method from black titanium dioxide to green titanium dioxide provided by the present invention, black titanium dioxide is dispersed in water, and after a period of ultrasonic treatment, stable green titanium dioxide with stronger absorption in the near-infrared region is obtained (see Figure 4, under the same concentration Green titanium dioxide absorbs more), the particle size of the green titanium dioxide is 15-35 nanometers; at the same time, the color of the corresponding aqueous solution changes from black to green, and no foreign substances are introduced during the ultrasonic treatment process, and the preparation process is irreversible, namely Black titanium dioxide can obtain stable green titanium dioxide after ultrasonic treatment for a period of time, and green titanium dioxide cannot be reduced to black titanium dioxide after ultrasonic treatment. The green titanium dioxide has significantly enhanced absorption in the near-infrared region, and presents a maximum absorption peak at 920nm. As a preferred solution, the ultrasonic treatment time for the black titanium dioxide to be transformed into green titanium dioxide is 2-3 hours. The black titanium dioxide can be obtained by a high-temperature aluminum reduction method, and the particle size of the black titanium dioxide is 15 to 35 nanometers (references for the preparation process of black titanium dioxide: [1] Wang, Zhou, Yang, Chongyin, Lin, Tianquan, Yin, Hao, Chen, Ping, Wan, Dongyun, Xu, Fangfang, Huang, Fuqiang, Lin, Jianhua, Xie, Xiaoming, and Jiang, Mianheng. Visible-light photocatalytic, solar thermal and photoelectrochemical properties of aluminum-reduced black titania. [2] Chinese patent: Method for preparing black titanium dioxide by dual temperature zone reduction method, patent application number: 2013101536488).

The black TiO2 turns into green TiO2, and the increased thickness of the amorphous layer and the increase in defects lead to enhanced absorption of green TiO2 in the visible and near-infrared regions. Therefore, this green TiO2 can be used as a near-infrared light-induced photodynamic therapy agent.

In order to further improve the treatment efficiency and safety, the present invention further modifies the surface of the green titanium dioxide. The modification process includes aminopolyethylene glycol functionalization and connection of mitochondrial targeting ligand TPP. In order to attach TPP to the surface of green titania, it is first necessary to attach amino functional groups to the surface of green titania. This process is called aminopolyethylene glycol functionalization. As an example, it includes the following steps: Polyethylene glycol such as (H ₂ N-PEG ₅₀₀₀ -NH ₂ ) is dispersed in an aqueous solution of green titanium oxide, and ultrasonicated for a period of time (for example, 0.5-1 h) to obtain a green titanium oxide solution modified with aminopolyethylene glycol. Collect by centrifugation and freeze-dry for later use. The mass ratio of the green titanium dioxide and amino polyethylene glycol is preferably 1:1-1:2.

Then, an appropriate amount of 1-ethyl-carbodiimide hydrochloride and TPP were dissolved in methanol solution, and then green titanium dioxide modified with aminopolyethylene glycol was added, stirred at room temperature and protected from light for a period of time (for example, 24h) and collected by centrifugation , that is, TPP-modified green titanium dioxide is obtained. Wherein, the 1-ethyl-carbodiimide hydrochloride is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC). The mass ratio of the EDC to TPP is preferably 1:1-3:1, and the mass ratio of the green titanium dioxide modified with aminopolyethylene glycol to TPP is preferably 1:1-5:1.

Under near-infrared laser (980nm) irradiation, the TPP-modified green titanium oxide can generate a large number of reactive oxygen species (such as hydroxyl radicals, peroxyl radicals, hydrogen peroxide, etc.) (reactiveoxygenspecies, ROS), which can be used as a near-infrared excited Photodynamic therapy agent. At the same time, the TPP-modified green titanium oxide can also convert near-infrared laser light energy into thermal energy, so it can be used as a photothermal therapeutic agent. In addition, because mitochondria are sensitive to heat, they can induce cell death under the action of hyperthermia and reactive oxygen species. In the present invention, the mitochondria-targeting ligand triphenylphosphine (TPP) is grafted through the amidation reaction, and a photodynamic/photothermal therapy nanosystem (G-TiO _{2- x} -TPP), and explored its application in the field of biomedicine. Therefore, the present invention not only provides a novel preparation method of green titanium oxide, but also explores its application in tumor targeting therapy after further modifying it with a mitochondrial targeting ligand.

The beneficial effect of the invention is that the green titanium dioxide prepared by the invention has good dispersibility and stability in water, and has good biological safety. Modified with mitochondrial targeting ligands to have mitochondrial targeting specificity. Under the condition of safe laser power density (980nm, 0.72Wcm ^-2 ) and lower intravenous injection dose of material (8mgkg ^-1 , permouse), significant tumor photodynamic/photothermal therapy effects have been achieved. The preparation process of the invention is simple and fast, with little pollution and good repeatability; the absorption of titanium dioxide in the visible light and near-infrared light regions is enhanced; and the application of green titanium dioxide in tumor targeting therapy is explored at the same time. The green titanium dioxide modified by the mitochondrial targeting ligand obtained in the present invention can be used as a photodynamic/photothermal therapeutic agent with excellent performance, and can simultaneously realize efficient and safe treatment of various diseases, especially cancer, in the fields of materials science and medicine is of great significance.

Examples are given below to describe the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention, and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the above contents of the present invention all belong to the present invention scope of protection. The specific process parameters such as the ratio, time, temperature, etc. of the following examples are only an example of the appropriate range, that is, those skilled in the art can make a selection within the appropriate range through the description herein, and are not limited to the specific examples of the following examples. value.

Example 1.

1. Preparation of green titanium dioxide:

Disperse 100mg of the original black titanium dioxide prepared by the aluminum reduction method in 20mL of water, and sonicate for 2-3h. The reacted solution was collected by centrifugation and freeze-dried for future use.

Fig. 1 a is the high-resolution transmission electron micrograph of the original black titanium dioxide prepared in this example, in which the black titanium dioxide presents a special core-shell structure, that is, the crystallized titanium dioxide TiO ₂ is the core, and the outside is wrapped with a layer of amorphous titanium dioxide TiO _{2- x} shell, the particle size is about 20-30nm.

Figure 1b is a digital photo of the black titanium dioxide prepared in this example dispersed in water. In the picture, black titanium dioxide has poor dispersibility in water, serious agglomeration, and precipitates at the bottom of the cuvette, and the supernatant is water.

Figure 1c is a high-resolution transmission electron micrograph of the green titanium dioxide prepared in this example. In the figure, the particle size and shape of the green titanium dioxide have no obvious changes compared with the black titanium dioxide, but the thickness of the amorphous layer has increased significantly. It shows that the number of defects in the green titanium dioxide amorphous layer increases, and the concentration of oxygen vacancies increases.

Figure 1d is a digital photo of the green titanium dioxide prepared in this example dispersed in water. The green titanium dioxide aqueous solution in the picture is green visible to the naked eye, and is evenly dispersed in the aqueous solution, and the Tyndall effect appears obviously when the laser beam is irradiated.

Figure 2 is the EDS energy spectrum of the green titanium dioxide prepared in this example, which proves the presence of Ti and O.

Figure 3 is the Raman spectrum of the original white titanium dioxide, black titanium dioxide and green titanium dioxide prepared in this example, all of which are anatase phases, and the main Raman peaks are blue-shifted, again confirming that the concentration of oxygen vacancies in green titanium dioxide increases.

Figure 4 is the UV-Vis spectra of black titanium dioxide and green titanium dioxide prepared in this example. Compared with the black titanium dioxide with the same concentration, the absorption of green titanium dioxide in the visible and near-infrared regions is enhanced, and there is an obvious maximum absorption wavelength of 920nm.

Fig. 5 is the green titanium dioxide prepared in this example, under the irradiation of 980nm laser (power density: 0.72Wcm ^-2 ), the test curve of the ability to generate active oxygen. Compared with the green titanium dioxide in the figure, the content of active oxygen generated by laser irradiation is significantly increased.

2. Preparation of mitochondrial targeting ligand TPP modified green titanium dioxide:

1) Amino polyethylene glycol modified green titanium dioxide

Disperse 100 mg of polyethylene glycol with amino groups at both ends, such as (H ₂ N-PEG ₅₀₀₀ -NH ₂ ), into an aqueous solution of green titanium oxide, and ultrasonicate for a period of time to obtain a green titanium oxide solution modified with amino polyethylene glycol . Collected by centrifugation, freeze-dried for later use;

2) Mitochondrial targeting ligand modified green titanium dioxide

Dissolve 50 mg of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 20 mg of TPP in 20 mL of methanol solution, then add 100 mg of green titanium dioxide modified with aminopolyethylene glycol, After stirring at room temperature in the dark for 24 hours, it was collected by centrifugation to obtain TPP-modified green titanium dioxide.

Fig. 6a is a DLS particle size distribution diagram of the green titanium dioxide modified with aminopolyethylene glycol and TPP prepared in this example. The particle size of the green titanium dioxide after modification by aminopolyethylene glycol and TPP in the figure increases, the distribution becomes wider, and the distribution peak particle size increases from 59nm to 135nm and then to 196nm, which are respectively attributed to the successful modification of aminopolyethylene glycol and TPP .

Fig. 6b is a Zeta potential diagram of the green titanium dioxide modified with aminopolyethylene glycol and TPP prepared in this example. The potential of the green titanium dioxide moves to the positive direction after the aminopolyethylene glycol and TPP modification described in the figure, confirming the successful modification of the aminopolyethylene glycol and TPP targeting ligands.

Fig. 7 is the FTIR spectrum of the green titanium dioxide modified by aminopolyethylene glycol and TPP prepared in this example. The characteristic absorption peaks of Ti-N-O and P-O functional groups appear in the figure, indicating that aminopolyethylene glycol and TPP targeting ligands have successfully modified green titanium dioxide.

Fig. 8 is the temperature rise curve of the mitochondrial-targeted modified green titanium dioxide aqueous solution prepared in this example under irradiation with different power densities of 980nm lasers. The rising temperature of the green titanium dioxide aqueous solution in the figure gradually increases with the increase of the laser power density.

To sum up, the present invention provides a simple and fast method for preparing green titanium dioxide and constructs a nanosystem of photodynamic/photothermal synergistic therapy targeting tumor cell mitochondria based on green titanium dioxide. After ultrasonic treatment, black titanium dioxide turns into green titanium dioxide, and the increased thickness of the amorphous layer and the increase in defects lead to enhanced absorption of green titanium dioxide in the visible and near-infrared regions. Therefore, this green TiO2 can be used as a near-infrared light-induced photodynamic therapy agent. Subsequently, in order to further improve the therapeutic efficiency and safety, we modified the mitochondrial targeting ligand TPP to construct a photodynamic/photothermal therapy nanosystem based on the green titanium dioxide targeting tumor cell mitochondria. The TPP-modified green titanium dioxide has a good mitochondrial targeting effect, and under the same wavelength of near-infrared laser excitation, the green titanium dioxide can simultaneously generate active oxygen and high heat, thereby destroying the energy center of tumor cells-mitochondrion, and then inducing tumor cells die. The photodynamic/photothermal therapy nanosystem based on green titanium dioxide targeting tumor cell mitochondria can achieve better tumor photodynamic/photothermal therapy effect at lower laser power density and lower intravenous dose of materials . The present invention not only provides a new method for enhancing the absorption of titanium dioxide in the visible and near-infrared regions, but also provides a new strategy for constructing photodynamic/photothermal therapy nanosystems targeting tumor organelles. This is of great significance to promote the application of titanium dioxide in the biological field.

Claims (11)

1. A method for preparing green titanium dioxide, characterized in that the preparation method comprises: preparing black titanium dioxide by aluminum reduction; dispersing black titanium dioxide in water, and obtaining green titanium dioxide by ultrasonic treatment for 2 to 3 hours. 2. a kind of green titanium dioxide that is made by the preparation method described in claim 1. 3. a method for modifying green titanium dioxide as claimed in claim 2, characterized in that the green titanium dioxide is prepared through the modification process of polyethylene glycol and the modification process of the mitochondrial targeting ligand to obtain the green titanium dioxide modified by the mitochondrial targeting ligand. Titanium dioxide, where the mitochondrial targeting ligand modification process uses 1-ethyl-carbodiimide hydrochloride EDC and triphenylphosphine TPP. 4. modification method according to claim 3, is characterized in that, described polyethylene glycol modification process comprises: Polyethylene glycol is dispersed in the aqueous solution of green titanium dioxide, ultrasonic treatment obtains the green color of polyethylene glycol modification. Titanium dioxide, wherein the mass ratio of green titanium dioxide to polyethylene glycol is 1:1-1:2. 5. The modification method according to claim 3 or 4, characterized in that, the mitochondrial targeting ligand modification process comprises: according to the mass ratio of 1:1 to 3:1, 1-ethyl-carbonyl diethylene Amine hydrochloride and mitochondrial targeting ligand triphenylphosphine were dissolved in an organic solution, polyethylene glycol-modified green titanium dioxide was added, stirred at room temperature in the dark and then centrifuged to collect mitochondrial targeting ligand-modified green titanium dioxide, wherein , the mass ratio of polyethylene glycol-modified green titanium dioxide to the mitochondrial targeting ligand is 1:1-5:1. 6. The modification method according to any one of claims 3 to 5, characterized in that, the polyethylene glycol is amino polyethylene glycol. 7. The modification method according to any one of claims 3 to 6, characterized in that the organic solution is methanol. 8. A green titanium dioxide modified by the mitochondrial targeting ligand obtained by the modification method according to any one of claims 3 to 7. 9 . The green titanium dioxide modified with a mitochondrial targeting ligand according to claim 8 , wherein the particle size of the green titanium dioxide modified with a mitochondrial targeting ligand is 15 to 35 nanometers. 10. An application of the green titanium dioxide according to claim 2 in the preparation of a near-infrared light-induced photodynamic therapy agent. 11. The green titanium dioxide modified by a mitochondrial targeting ligand according to claim 8 is used in the biological field, especially in the preparation of a photodynamic/photothermal therapeutic agent.