Tannic acid surface modified MXene nanomaterial and preparation method and application thereof

Abstract

This invention belongs to the field of nanobiomaterials technology, and provides a tannic acid-modified MXene nanomaterial, its preparation method, and applications. Non-covalent surface modification is achieved by forming hydrogen bonds / coordination bonds between tannic acid and MXene nanosheets, retaining the structural and performance advantages of MXene while endowing it with antioxidant properties, thus solving the problems of limited functionality and insufficient antioxidant capacity of existing MXene nanomaterials. This nanomaterial is obtained by mixing and reacting an MXene nanosheet dispersion with a tannic acid alkaline buffer solution, followed by purification and washing. This process is mild and simple. The nanomaterial provided by this invention retains the near-infrared photothermal conversion properties of MXene and also possesses broad-spectrum and highly efficient reactive oxygen species scavenging capabilities, achieving synergistic effects of photothermal therapy and antioxidant activity. It is suitable for applications in the biomedical field such as photothermal therapy and antioxidant preparation.

Description

Technical Field

[0001] This invention belongs to the field of nanobiomaterials technology, and relates to the surface modification and application of MXene nanomaterials, specifically to a tannic acid-modified MXene nanomaterial, its preparation method and application. Background Technology

[0002] MXenes are a new class of two-dimensional transition metal carbides, nitrides, or carbonitrides with the general chemical formula M. n+ 1X n Tx (n=1-3), where M represents an early transition metal (such as Ti, Nb, Ta, Mo, etc.), X represents carbon and / or nitrogen, and Tx represents a surface terminal functional group (such as -OH, =O, -F). Since its first report in 2011, MXene has shown broad application prospects in many fields such as energy storage, catalysis, sensing, and biomedicine due to its unique layered structure, metallic conductivity, hydrophilicity, and tunable physicochemical properties.

[0003] In the biomedical field, MXene has attracted significant attention due to the following characteristics: ① Highly efficient photothermal conversion capability: MXene exhibits strong absorption in the near-infrared region, and its photothermal conversion efficiency is typically higher than many traditional photothermal agents (such as gold nanomaterials and carbon-based materials); ② Large specific surface area: Its two-dimensional layered structure provides an extremely high specific surface area, which is beneficial for light absorption and drug loading; ③ Good hydrophilicity and biocompatibility: Abundant hydrophilic functional groups on its surface enable good dispersibility in water; ④ Easy functionalization modification: Surface functional groups facilitate the grafting of functional molecules. Based on these properties, MXene has been widely studied and applied in photothermal therapy, drug delivery, biosensing, and tissue engineering.

[0004] However, existing MXene nanomaterials still suffer from the following technical limitations in practical applications. **Stability Issues:** MXene nanosheets are prone to oxidative degradation in physiological environments, leading to structural and performance deterioration. Studies have shown that their surfaces are gradually oxidized to form corresponding metal oxides (such as TiO2 and Nb2O5), thus losing their original photothermal conversion capabilities and hydrophilicity. This problem severely limits the long-term application and clinical translation of MXene in the biomedical field. **Functional Limitation:** In the treatment of infectious diseases, single photothermal sterilization is often insufficient to completely eliminate bacteria, and the high energy required for photothermal therapy may cause thermal damage to surrounding healthy tissues. Simultaneously, infectious lesions are often accompanied by excessive reactive oxygen species (ROS), leading to oxidative stress damage, which in turn triggers inflammatory responses and delays tissue repair. Therefore, ideal therapeutic materials should possess multiple functions such as antibacterial, antioxidant, and anti-inflammatory properties, but existing MXene materials struggle to simultaneously meet these requirements. In particular, their reactive oxygen species scavenging ability is lacking; existing research on MXene materials focuses primarily on their photothermal properties, with insufficient development and utilization of their antioxidant properties. Although a few studies have reported that MXene itself has a certain free radical scavenging ability, its effect is limited and cannot meet clinical needs.

[0005] Tannic acid is a water-soluble natural plant polyphenol compound widely found in plants such as gallnut, tea, and grape skin. Its molecular structure contains numerous catechol and pyrogallol groups, endowing tannic acid with a variety of unique chemical and biological properties: ① Strong adhesion—it can firmly bind to various substrates through non-covalent interactions such as hydrogen bonding, hydrophobic interactions, and coordinate bonds; ② Strong reducing properties—the phenolic hydroxyl groups are easily oxidized, giving it highly efficient antioxidant and free radical quenching capabilities; ③ Metal ion complexing ability—the ortho-phenolic hydroxyl groups can act as ligands to form stable chelates with various metal ions; ④ Various biological activities such as anti-inflammatory, antibacterial, and angiogenesis-promoting effects. These properties make tannic acid an ideal candidate molecule for surface functionalization modification of materials.

[0006] Therefore, developing a surface modification method that can simultaneously improve the stability of MXene, endow it with efficient antioxidant capacity, and maintain its excellent photothermal properties, and preparing an MXene-based nanocomposite material with both photothermal conversion and reactive oxygen species scavenging functions, is of great significance for expanding the application of MXene in the biomedical field (especially in the treatment of infectious diseases and tissue repair). Summary of the Invention

[0007] The purpose of this invention is to provide a tannic acid-modified MXene nanomaterial, its preparation method, and its application. By non-covalently modifying the surface of MXene nanosheets with hydrogen bonds / coordination bonds of tannic acid, the MXene nanomaterial is endowed with efficient antioxidant properties while retaining its excellent photothermal conversion performance, thereby solving the problems of single function and insufficient antioxidant capacity of existing MXene nanomaterials.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: a tannic acid-modified MXene nanomaterial, wherein the nanomaterial is composed of an MXene nanosheet matrix and a tannic acid modification layer coated on its surface, wherein the tannic acid is bonded to the surface of the MXene nanosheet through hydrogen bonds and / or coordination bonds.

[0009] Preferably, the absolute value of the Zeta potential of the nanomaterial in an aqueous medium is 30-40 mV, and the nanomaterial has a two-dimensional sheet structure.

[0010] Preferably, the MXene nanosheets are selected from at least one of Nb2C MXene, Ti3C2 MXene, Ti2C MXene, Ta4C3MXene, V2C MXene, and Mo2C MXene.

[0011] Preferably, the MXene nanosheets are Nb2C MXene.

[0012] The present invention further provides a method for preparing the above-mentioned MXene nanomaterials modified with tannic acid.

[0013] Preferably, the steps include:

[0014] (1) An MXene nanosheet dispersion was obtained by ultrasonic exfoliation.

[0015] (2) Dissolve tannic acid in alkaline buffer solution to obtain tannic acid reaction solution;

[0016] (3) Mix the MXene nanosheet dispersion obtained in step (1) with the tannic acid reaction solution obtained in step (2) and stir to react;

[0017] (4) After the reaction is complete, the product is purified and separated, and unreacted tannic acid is washed away to obtain MXene nanomaterials modified with tannic acid.

[0018] Preferably, the MXene nanosheets in step (1) are prepared by etching MAX phase ceramic materials, wherein the MAX phase ceramic materials are selected from at least one of Nb2AlC, Ti3AlC2, Ti2AlC, Ta4AlC3, V2AlC, and Mo2AlC.

[0019] Preferably, the mass ratio of the MXene nanosheets to the tannic acid in step (3) is 1:2 to 2:1.

[0020] The present invention further provides the application of the above-mentioned tannic acid surface-modified MXene nanomaterials in the preparation of antioxidants.

[0021] The present invention further provides the application of the above-mentioned tannic acid surface-modified MXene nanomaterials in photothermal therapy.

[0022] The beneficial effects of this invention are:

[0023] (1) Excellent antioxidant properties: Tannic acid rich in phenolic hydroxyl groups was successfully grafted onto the surface of MXene through tannic acid surface modification. Experiments showed that the obtained tannic acid-modified MXene (MT) nanomaterials have a concentration-dependent high efficiency in scavenging various reactive oxygen / nitrogen species such as DPPH, ABTS, hydroxyl radicals, hydrogen peroxide and superoxide anions. The concentration required to remove half of the reactive species is in the microgram per milliliter range.

[0024] (2) Photothermal properties: The MT nanomaterial modified with tannic acid retains the original high efficiency of photothermal conversion of MXene, and exhibits a concentration-dependent heating effect and good photothermal stability under 808 nm laser irradiation.

[0025] (3) Stability and dispersibility: The tannic acid modification layer effectively prevents the aggregation of MXene nanosheets, enabling them to maintain good dispersibility and colloidal stability in aqueous solution, with the Zeta potential remaining stable at around -33.3 mV.

[0026] (4) Simple method and mild conditions: The present invention uses the self-polymerization reaction of tannic acid under weak alkaline conditions to modify the surface of MXene. The operation is simple, the reaction conditions are mild, it is green and environmentally friendly, and it is easy to scale up production. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation process of the MT nanomaterials prepared in this invention.

[0028] Figure 2 Transmission electron microscopy (TEM) image of the MT nanomaterial in this invention.

[0029] Figure 3 The Fourier transform infrared (FT-IR) spectrum of the MT nanomaterials in this invention confirms the successful modification with tannic acid.

[0030] Figure 4 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the MT nanomaterial in this invention, which analyzes the surface elemental chemical state.

[0031] Figure 5 The following figures show the photothermal performance test results of the MT nanomaterials in this invention: (a) shows the temperature rise curves of different concentrations of MT under 808 nm laser irradiation, and (b) shows the cyclic photothermal stability test results.

[0032] Figure 6 The graph shows the test results of the reactive oxygen species scavenging ability of the MT nanomaterial in this invention ((a) DPPH scavenging rate, (b) ABTS scavenging rate, (c) hydrogen peroxide scavenging rate, (d) hydroxyl radical scavenging rate, (e) superoxide anion scavenging rate). Detailed Implementation

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0034] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Example 1: Preparation and characterization of MXene (MT) nanomaterials modified with tannic acid surface

[0037] 1. Preparation of MT nanomaterials

[0038] The specific steps are as follows (preparation process is as follows) Figure 1 (as shown)

[0039] (1) Preparation of MXene nanosheet dispersion: In a polytetrafluoroethylene reaction vessel, 20 mL of concentrated hydrochloric acid (approximately 12 M) was added, and 1.6 g of LiF solid powder was slowly added under stirring. The mixture was stirred for 10 min to ensure complete dissolution and in-situ generation of hydrofluoric acid. 1.0 g of Nb2AlC MAX phase powder was weighed and slowly added to the above solution in portions. The reaction system was placed in a 40 ℃ water bath and stirred for 48 hours. After the reaction was completed, the supernatant was repeatedly centrifuged and washed with 1 M dilute hydrochloric acid and deionized water until the pH of the supernatant was greater than 6.5, resulting in a precipitate (Nb2C MXene nanosheets). The precipitate was dispersed in deoxygenated ultrapure water and ultrasonically treated in an ice bath (120 W) for 2 hours (intermittent 30 min ultrasonic treatment). The supernatant was collected by centrifugation at 3500 rpm to obtain a few-layer Nb2C MXene nanosheet dispersion.

[0040] (2) Preparation of tannic acid reaction solution: Dissolve 100 mg of tannic acid in 100 mL of Tris-HCl buffer (pH=8.5) to prepare a tannic acid reaction solution of 1 mg / mL.

[0041] (3) Tannic acid surface modification: Take 100 mg of Nb2C MXene nanosheets prepared in step (1) and disperse them in the tannic acid reaction solution in step (2) above. Stir rapidly at room temperature for 24 hours.

[0042] (4) Obtaining nanomaterials: After the reaction is complete, the reaction solution is centrifuged at 16500 r / min for 20 minutes, the precipitate is collected, and washed repeatedly with deionized water 3-5 times to remove unreacted tannic acid, thus obtaining the final product, namely tannic acid surface-modified MXene (MT) nanomaterials. The obtained product is redispersed in deionized water to obtain a dispersion of tannic acid surface-modified MXene (MT) nanomaterials, which is then sealed and stored at 4 ℃ for later use.

[0043] In this embodiment, Nb2C MXene nanosheets are selected. In addition, Ti3C2 MXene, Ti2C MXene, Ta4C3 MXene, V2C MXene, Mo2C MXene, and Nb2C MXene have the same structure and functional groups, and can achieve the same technical effects as in this embodiment. Specifically: All of the above MXenes are typical two-dimensional transition metal carbides / nitrides, and their surfaces contain active functional groups such as -OH, -F, and =O. These functional groups can non-covalently bind with the phenolic hydroxyl groups in tannic acid molecules through hydrogen bonds and / or coordination bonds, achieving stable coating of tannic acid on the MXene surface. Simultaneously, the above MXenes all possess a two-dimensional sheet structure, large specific surface area, and excellent near-infrared photothermal conversion performance, consistent with the tannic acid modification method of this invention. After modification, they can all retain their photothermal properties, and the phenolic hydroxyl groups of tannic acid impart antioxidant capacity, achieving the photothermal + antioxidant dual-function technical effect of this invention. In this embodiment, Nb2C MXene is selected for the experiment.

[0044] In this embodiment, MXene nanosheets were prepared by etching a MAX phase ceramic material, which was Nb2AlC. Ti3AlC2, Ti2AlC, Ta4AlC3, V2AlC, Mo2AlC, and Nb2AlC have similar properties; specifically, all of the above MAX phases have the general formula M... n+1 AX nIn layered ceramic materials (M is a transition metal, A is Al, and X is C), the Al atoms between the layers can be effectively removed by hydrofluoric acid etching to form corresponding two-dimensional MXene nanosheets. The surface of the various MXene nanosheets obtained by etching retains the above-mentioned active functional groups, which can undergo non-covalent bonding with tannic acid. Therefore, various MXene nanosheets can be prepared by using the etching method in this embodiment, and the subsequent tannic acid modification process does not need to be adjusted, and stable modification can be achieved.

[0045] 2. Morphology and structural characterization of MT nanomaterials

[0046] TEM characterization: A suitable amount of MT nanomaterial prepared in Example 1 was diluted and dropped onto an ultrathin carbon support film, then allowed to air dry. Its morphology was observed using a transmission electron microscope (Talos F200X). The results showed that MT exhibited a typical two-dimensional layered structure. Figure 2 ).

[0047] Zeta potential characterization: The zeta potential of the samples was measured using a Malvern particle size analyzer. The results are shown in Table 1. The surface zeta potential of the MT nanomaterials was -33.3 mV, indicating good dispersion stability.

[0048] Table 1. Zeta potential diagram of MT nanomaterials

[0049]

[0050] Comparative Example 1

[0051] The difference from Example 1 is that no "tannic acid surface modification" was performed, and the resulting Nb2C MXene nanosheets are denoted as Mx. Solid tannic acid (TA) powder, Mx, and MT samples were tested using an infrared spectroscopy instrument. The results showed that, compared to Mx, the MT sample exhibited better performance in the 3500-3200 cm⁻¹ range. -1 The hydroxyl absorption peak at 1600 cm⁻¹ is significantly enhanced and broadened, and reaches 1600 cm⁻¹. -1 A new absorption peak belonging to the C=C skeleton vibration of the aromatic ring appeared nearby. Figure 3 This confirms the successful modification of tannic acid.

[0052] Elemental analysis of the sample surface was performed using X-ray photoelectron spectroscopy. The results showed that characteristic peaks of Nb, C, O, and F elements were clearly observed in the full spectrum of the Mx sample. Figure 4 After modification with tannic acid, the characteristic peak intensities of C and O elements in the MT sample were significantly enhanced, while the peak intensity of F element was significantly weakened. This indicates that the carbon and oxygen-rich tannic acid coating layer formed a relatively complete organic layer, which masked the F element signal in MXene.

[0053] Example 2: Evaluation of the photothermal properties of MT nanomaterials

[0054] Prepare 200 μL of MT aqueous solutions with concentrations of 25, 50, 75, 100, and 125 μg / mL. Use an 808 nm near-infrared laser (power density 1.0 W / cm²). 2 The solution was irradiated for 5 minutes, and the temperature change was recorded in real time using a thermal imager to plot a temperature-time curve. The results showed that the endpoint temperature of the MT solution increased significantly with increasing concentration. Figure 5 (a) exhibits concentration-dependent photothermal conversion capability.

[0055] To evaluate its photothermal stability, a 125 μg / mL MT solution was subjected to five cycles of laser-switched irradiation (each cycle lasting 5 minutes, followed by natural cooling to room temperature before starting the next cycle). The results showed that the temperature rise curves of the five cycles largely overlapped, and the peak temperature did not show a significant decrease. Figure 5 (b) confirms that MT has good photothermal stability.

[0056] Example 3 Evaluation of the reactive oxygen species scavenging ability of MT nanomaterials

[0057] DPPH and ABTS free radical scavenging assays: Following the kit instructions (DPPH and ABTS activity assay kits were purchased from White Shark Life Sciences), different concentrations of MT solutions were mixed with DPPH or ABTS working solutions. After incubation in the dark for 20 minutes, absorbance was measured at 517 nm and 734 nm, respectively, and the scavenging rate was calculated. The results showed that the scavenging effect of MT on DPPH and ABTS was concentration-dependent, with concentrations required to scavenge 50% of free radicals being less than 50 μg / mL and 4 μg / mL, respectively. Figure 6 b- Figure 6 (c)

[0058] Hydrogen peroxide (H2O2) removal experiment: Different concentrations of MT were reacted with 4 mM H2O2 solution at 37 ℃ in the dark for 120 minutes. The residual H2O2 concentration was then measured using a hydrogen peroxide detection kit. The results showed that MT could effectively remove H2O2, and the removal ability increased with increasing concentration. Figure 6 (d).

[0059] Hydroxyl radical (•OH) scavenging assay: The scavenging rate of •OH by different concentrations of MT was determined using a hydroxyl radical scavenging ability assay kit. The results showed that the scavenging of •OH by MT was concentration-dependent, and the concentration required to scavenge 50% of •OH was approximately 125 μg / mL. Figure 6 (e).

[0060] Superoxide anion (O2) -• Scavenging assay: The effect of MT on O2 was evaluated using a total superoxide dismutase activity assay kit (H2O2 assay kit, SOD activity assay kit, and •OH activity assay kit were all purchased from White Shark Life Sciences). - • Scavenging ability. Results showed that MT has a strong effect on O2 removal. - • The removal of O2 is concentration-dependent, removing 50% of O2. - • The required concentration is approximately 20 μg / mL ( Figure 6 (f)

[0061] The above results indicate that the MT nanomaterials prepared in this invention have a broad-spectrum and highly efficient reactive oxygen species scavenging ability. The mechanism can be attributed to the synergistic effect of the free radical quenching effect of the abundant phenolic hydroxyl groups in tannic acid molecules and the adsorption and enrichment effect of MXene's large specific surface area.

[0062] In summary, this invention successfully prepared a tannic acid-modified MXene nanomaterial. This material not only retains the excellent photothermal conversion properties of MXene but also possesses highly efficient reactive oxygen species scavenging capabilities through surface modification with tannic acid. It is a high-performance, multifunctional nanoplatform with broad application prospects in the biomedical field (especially in antioxidant and photothermal therapy).

[0063] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A tannic acid surface-modified MXene nanomaterial, characterized in that, The nanomaterial consists of an MXene nanosheet matrix and a tannic acid modification layer coated on its surface, wherein the tannic acid is bonded to the MXene nanosheet surface through hydrogen bonds and / or coordination bonds.

2. The tannic acid surface-modified MXene nanomaterial of claim 1, wherein, The absolute value of the zeta potential of the nanomaterial in an aqueous medium is 30-40 mV, and the nanomaterial has a two-dimensional sheet structure.

3. The MXene nanomaterial with tannic acid surface modification according to claim 1, characterized in that, The MXene nanosheets are selected from at least one of Nb2C MXene, Ti3C2 MXene, Ti2C MXene, Ta4C3 MXene, V2C MXene, and Mo2C MXene.

4. The MXene nanomaterial with tannic acid surface modification according to claim 3, characterized in that, The MXene nanosheets are Nb2C MXene.

5. The method for preparing MXene nanomaterials with tannic acid surface modification according to any one of claims 1-4, characterized in that, Includes the following steps: (1) An MXene nanosheet dispersion was obtained by ultrasonic exfoliation. (2) Dissolve tannic acid in alkaline buffer solution to obtain tannic acid reaction solution; (3) Mix the MXene nanosheet dispersion obtained in step (1) with the tannic acid reaction solution obtained in step (2) and stir to react; (4) After the reaction is complete, the product is purified and separated, and unreacted tannic acid is washed away to obtain MXene nanomaterials modified with tannic acid.

6. The preparation method according to claim 5, characterized in that, The MXene nanosheets in step (1) are prepared by etching MAX phase ceramic materials, wherein the MAX phase ceramic materials are selected from at least one of Nb2AlC, Ti3AlC2, Ti2AlC, Ta4AlC3, V2AlC, and Mo2AlC.

7. The preparation method according to claim 5, characterized in that, The alkaline buffer solution mentioned in step (2) is selected from at least one of Tris-HCl buffer, phosphate buffer, carbonate buffer, and borate buffer, with a pH value of 8-9.

8. The preparation method according to claim 5, characterized in that, The mass ratio of MXene nanosheets to tannic acid in step (3) is 1:2 to 2:

1.

9. The application of tannic acid-modified MXene nanomaterials according to any one of claims 1-4 in the preparation of antioxidants.

10. The application of tannic acid-modified MXene nanomaterials according to any one of claims 1-4 in photothermal therapy.

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