Fe2O3 (at) g-C3N4S type heterojunction material as well as preparation method and application thereof
By constructing Fe2O3@g-C3N4S-type heterojunction materials, and utilizing S-type heterojunctions and Fenton-like reactions, the problems of low ROS production and interference from reducing species were solved, achieving highly efficient photodynamic therapy for tumors.
Patent Information
- Application Number
- CN202511763356.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-02-10
AI Technical Summary
Existing photosensitizers, such as ROS, have low yields, are easily affected by reducing species in the tumor microenvironment, and lack photostability, resulting in poor therapeutic effects and significant side effects.
A Fe2O3@g-C3N4S-type heterojunction material was constructed. Through the synergistic effect of the S-type heterojunction and the Fenton-like reaction, the separation and transport of photogenerated carriers were realized. Fe2+ was used to catalyze the decomposition of H2O2 to consume GSH, thereby increasing ROS production and enhancing photodynamic therapy efficiency.
It significantly increased the production of singlet oxygen and superoxide radicals, enhanced the efficiency of tumor photodynamic therapy, reduced the interference of reducing species on ROS, and improved the photocatalytic activity and stability of the material.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of photosensitizer technology, and relates to a Fe2O3@g-C3N4S type heterojunction material, its preparation method, and its application. Background Technology
[0002] With the continuous development of medical technology, cancer treatment remains a key area of focus in the medical field, and numerous innovative therapies are emerging. Photodynamic therapy is one of the most promising, opening up new avenues for cancer treatment.
[0003] Photodynamic therapy (PDT) has demonstrated unique advantages in the field of cancer treatment due to its unique mechanism of action. Its core lies in photosensitizers, a class of remarkable compounds capable of precisely absorbing light energy of specific wavelengths and efficiently transferring the absorbed energy to reactants, such as oxygen molecules. Leveraging this property, PDT can achieve precise targeting of tumor cells, and its widespread application in tumor treatment has made it a powerful weapon against cancer.
[0004] As research progresses, photosensitizers are continuously iterating and upgrading. Significant progress has been made in third-generation photosensitizers, with boron-dipyrromethene (BODIPY) derivatives and near-infrared absorbing materials being typical examples. Researchers have successfully enhanced their photostability and significantly improved singlet oxygen yield through structural modification, with some products even achieving absorption in the near-infrared region (>700 nm). Near-infrared light has stronger tissue penetration capabilities, giving third-generation photosensitizers a greater advantage in treating deep tumors and bringing new hope for improving tumor treatment outcomes.
[0005] However, existing photosensitizer technologies still face many unresolved issues. Low reactive oxygen species (ROS) production is a primary challenge; ROS are crucial "weapons" in photodynamic therapy for killing tumor cells, and insufficient production directly impacts treatment efficacy. Complex reducing species within tumors can interfere with photosensitizers, reducing their efficiency. Furthermore, the toxicity and side effects of photosensitizers cannot be ignored, potentially placing an additional burden on patients. In addition, limited tissue penetration makes it difficult for photosensitizers to reach deep tumor sites, and poor targeting can lead to damage to surrounding healthy tissues while killing tumor cells. Moreover, the photostability of some photosensitizers still needs improvement; they are prone to decomposition under light conditions, affecting the continuity and stability of treatment. Solving these problems is key to further advancing photodynamic therapy. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention provides a Fe2O3@g-C3N4S heterojunction material, its preparation method, and its application, thereby solving the technical problems of low ROS yield and interference from reducing species in the prior art.
[0007] This invention is achieved through the following technical solution: A method for preparing Fe2O3@g-C3N4S type heterojunction material includes the following steps: S1: After calcining cyanuric acid, it is placed in liquid nitrogen and shaken to obtain carbon nitride; S2: Carbon nitride is added to an ethanol solution of ferric nitrate, stirred and dried, and the product is calcined under a mixed atmosphere of O2 and N2 to obtain the Fe2O3@g-C3N4S type heterojunction material.
[0008] Preferably, in step S1, before calcining the cyanuric acid, it is ground to an average particle size of 5-10 mm.
[0009] Preferably, in step S1, the calcination temperature of cyanuric acid is 500-550℃ and the time is 2-4 h.
[0010] Preferably, the calcined cyanuric acid is placed on a rotary oscillator for oscillation treatment. The rotation speed of the rotary oscillator is 30-50 rpm / min, and the oscillation time is 8-12 h.
[0011] Preferably, in step S2, the ratio of carbon nitride to ferric nitrate ethanol solution is 500 mg:(25~75) mL, and the concentration of ferric nitrate ethanol solution is 6.68 mg / mL.
[0012] Preferably, in step S2, the calcination temperature is 500-550℃ and the time is 2-4 h.
[0013] Preferably, in step S2, oxygen accounts for 5% of the total volume of the mixed atmosphere of O2 and N2.
[0014] Preferably, in step S2, after calcination, the product is further washed by centrifugation using PBS solution.
[0015] A Fe2O3@g-C3N4S type heterojunction material was prepared by the above method.
[0016] The above-mentioned Fe2O3@g-C3N4S heterojunction material is used in the preparation of antitumor drugs.
[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing Fe2O3@g-C3N4S-type heterojunction materials. This method effectively solves the technical problems of low ROS yield and interference from reducing species by constructing S-type heterojunctions and synergistic effect of Fenton-like reaction.
[0018] First, an S-type heterojunction is formed by combining carbon nitride (g-C3N4) with α-Fe2O3, and a built-in electric field is constructed using the appropriate band positions of both. Under illumination, electrons flow from the Fe2O3 conduction band to the g-C3N4 conduction band, while holes accumulate in the Fe2O3 valence band, forming spatially separated redox centers. This charge transfer mechanism not only achieves efficient carrier separation but also retains the strong oxidizing property of the Fe2O3 valence band holes (generating ·OH) and the strong reducing property of the g-C3N4 conduction band electrons (generating ·O2). - ), significantly improving singlet oxygen ( 1 O2) and superoxide radicals (·O2) - The total yield of ROS was determined. XRD and FT-IR tests confirmed that Fe-O bonds and CN bonds coexist at the heterojunction interface, and the characteristic peak of Fe2O3 was enhanced with increasing Fe content, indicating that the proportion of heterojunctions increased and the ROS yield increased accordingly.
[0019] Secondly, high concentrations of glutathione (GSH) in the tumor microenvironment consume ROS, reducing photodynamic efficiency. This invention addresses this by introducing Fe... 3+ / Fe 2+ The circulating system utilizes Fe under light. 2+ The Fenton-like reaction that catalyzes the decomposition of H2O2 continuously consumes GSH and generates ·OH, effectively mitigating the quenching effect of reducing species on ROS.
[0020] In summary, this material optimizes the transport pathway of photogenerated carriers through the construction of heterojunctions, enabling the generation of more reactive oxygen species. Furthermore, the iron ions within it can consume high concentrations of reduced glutathione in tumor cells under light irradiation through a Fenton-like effect, thereby significantly improving the efficiency of photodynamic therapy for tumors. This dual-mechanism synergistic breakthrough overcomes the technical bottlenecks of low ROS yield and susceptibility to interference in traditional photosensitizers, providing a high-performance material for tumor photodynamic therapy.
[0021] Furthermore, in step S1, before calcining the cyanuric acid, it is ground to an average particle size of 5-10 mm. This helps to make the cyanuric acid particles uniform in size, increases the contact area between particles during calcination, makes the calcination reaction more complete and uniform, and improves the quality and performance consistency of the final product.
[0022] Furthermore, in step S1, the calcination treatment of cyanuric acid is carried out at a temperature of 500-550℃ for 2-4 hours. This temperature and time allow cyanuric acid to undergo thermal decomposition and other reactions under suitable conditions, generating precursor materials with specific structures and properties, laying the foundation for the subsequent preparation of high-quality Fe2O3@g-C3N4S heterojunction materials. If the temperature is too high or the time is too long, it will lead to product structure damage or over-reaction; if the temperature is too low or the time is too short, the reaction will be incomplete, affecting the product performance.
[0023] Furthermore, the calcined cyanuric acid was placed on a gyroscope for vibration treatment. The rotation speed of the gyroscope was 30-50 rpm / min, and the vibration time was 8-12 h. Vibration treatment can make the calcined product more dispersed, avoid particle agglomeration, and help to fully mix and react with other raw materials in the subsequent process, thereby improving the uniformity and performance of the final heterojunction material.
[0024] Furthermore, in step S2, the ratio of carbon nitride to ferric nitrate in ethanol is 500 mg:(25~75) mL, and the concentration of ferric nitrate in ethanol is 6.68 mg / mL. The precise ratio and concentration of the solution can accurately control the amount of each substance in the reaction system, thereby precisely controlling the ratio and structure of Fe2O3 and g-C3N4 in the Fe2O3@g-C3N4S-type heterojunction material, which is beneficial to obtaining heterojunction materials with excellent performance.
[0025] Furthermore, in step S2, the calcination treatment is carried out at a temperature of 500-550℃ for 2-4 h. These conditions are conducive to the reaction of carbon nitride and iron nitrate to generate Fe2O3@g-C3N4S type heterojunctions with specific structures and properties. Within this temperature and time range, the diffusion and bonding between atoms can be promoted to form a stable heterojunction structure and improve the photocatalytic and other properties of the material.
[0026] Furthermore, in step S2, in the mixed atmosphere of O2 and N2, oxygen accounts for 5% of the total volume of the mixed gas. The specific mixed atmosphere can provide a suitable redox environment for the reaction, which helps to form an S-type heterojunction structure between Fe2O3 and g-C3N4. This structure can promote the effective separation and transport of photogenerated charge carriers, thereby improving the photocatalytic activity and stability of the material.
[0027] Furthermore, in step S2, after calcination, the product is centrifuged and washed using PBS solution. PBS solution is a buffer solution with certain ionic strength and pH stability, which can gently and effectively remove impurities and unreacted raw materials adsorbed on the surface of the product, improve the purity of the product, and thus enhance the performance and reliability of the Fe2O3@g-C3N4S heterojunction material. Attached Figure Description
[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0029] Figure 1 The XRD patterns (a) and FT-IR (b) of the carbon nitride (CN) prepared in this invention and the Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3 are shown. Figure 2 The image shows a SEM image of 0.5FeCN obtained in Example 2 of this invention. Figure 3 TEM images of carbon nitride (CN) prepared in this invention and Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3; Figure 4 The EDS mapping spectrum of 0.5FeCN was obtained in Example 2 of this invention; Figure 5 XPS images of carbon nitride (CN) prepared in this invention and Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3, wherein (a) is the total spectrum, and (be) is the C1s spectrum, N1s spectrum, O1s spectrum, and Fe2p spectrum. Figure 6 The figures show the EPR images of carbon nitride (CN) prepared in this invention and the Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3, wherein (a) is the superoxide radical (·O2) free ... - (b) represents singlet oxygen ( 1 O2), and (c) are hydroxyl radicals (·OH); Figure 7 (a) is a schematic diagram of the band structure of the Fe2O3@g-C3N4S heterojunction material, (b) is a TEM image of Ag deposited on 0.5FeCN, (c) is a capture experiment of ·OH, and (d) is a capture experiment of ·O2. - The capture experiment, (e) shows the cyclic voltammetry results of CN and 0.5FeCN; Figure 8 Blue: material, green: cytoskeleton, red: cell nucleus for detecting endocytosis in samples using fluorescence confocal microscopy, and combined fluorescence intensity of CLSM images for quantitative analysis (n = 6). Figure 9 The results of CCK8 tests for different concentrations of photosensitizer under dark conditions; Figure 10 CCK8 test results for photosensitizers at different concentrations under illumination (a), and CCK8 test results for photosensitizers (250 μg / mL) at different times under illumination (b). Figure 11 Light was switched on / off for different samples (420 nm, 20 mW / cm²). 2 Fluorescence images of cells stained with Calcein-AM (green) and PI (red) after treatment (20 min); Figure 12 The flowchart of PDT in tumor mice (a), photo of photoelectric implantation in mice (b), and PDT photo of tumor mice (c) are shown. Figure 13 In vivo fluorescence imaging of tumor-bearing mice (a) and fluorescence signal statistical histogram (b) (420 nm, 20 mW / cm²). 2 (20 min irradiation, n = 3) Figure 14 Images of tumor resection in mice (a) and tumor volume statistics (b). Detailed Implementation
[0030] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.
[0031] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.
[0032] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values (including integers and fractions) within those ranges.
[0033] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”
[0034] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.
[0035] This invention provides a method for preparing Fe2O3@g-C3N4S type heterojunction materials, comprising the following steps: S1: After calcining cyanuric acid, it is placed in liquid nitrogen and shaken to obtain carbon nitride; Specifically, the above process is as follows: Weigh 4 g of cyanuric acid, grind it to an average particle size of 5-10 mm, and place it in a 20 mL covered crucible. Heat the crucible in air at a rate of 10 °C / min to 500-550 °C and keep it at that temperature for 2-4 h to obtain a pale yellow solid. After cooling to room temperature, grind the product and add it to a container containing liquid nitrogen. Place the container on a gyroscope with a rotation speed of 30-50 rpm / min and shake for 8-12 h to ensure that the liquid nitrogen is in full contact with the material. After drying and grinding the obtained solid, carbon nitride is obtained and labeled as CN.
[0036] S2: Carbon nitride is added to an ethanol solution of ferric nitrate, stirred and dried, and the product is calcined under a mixed atmosphere of O2 and N2 to obtain the Fe2O3@g-C3N4S type heterojunction material.
[0037] Specifically, the process is as follows: 500 mg of CN is weighed and added to a 100 mL beaker, followed by (25, 50, 75 mL) of Fe(NO3)3·9H2O solution with a concentration of 6.68 mg / mL. The Fe(NO3)3·9H2O solution uses 20 mL of ethanol solution as the solvent. The mixture is mechanically stirred for 30 min. Subsequently, it is dried for 12 h and transferred to a covered crucible, where it is calcined at 500-550℃ in a 5% O2 / N2 mixed atmosphere for 2-4 h. In the O2 / N2 mixed atmosphere, the volume percentages of O2 and N2 are 5% and 95%, respectively, meaning that oxygen accounts for 5% of the total volume of the mixed gas.
[0038] After cooling, grind, wash, and dry the material, then add PBS solution. Centrifuge at 7000 rpm / min for 20 min and collect the product in the supernatant. Centrifuge the supernatant (12000 rpm / min, 20 min), discard the supernatant, and dry at room temperature to obtain a red powder, namely the Fe2O3@g-C3N4S type heterojunction material.
[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.
[0040] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.
[0041] Example 1 A method for preparing Fe2O3@g-C3N4S type heterojunction material includes the following steps: S1: Weigh 4 g of cyanuric acid, grind it, and place it in a 20 mL covered crucible. Heat the crucible to 520 °C at a rate of 10 °C / min and keep it at that temperature for 4 h to obtain a pale yellow solid. After cooling to room temperature, grind the product and add it to a container containing liquid nitrogen. Place the container on a gyroscope with a rotation speed of 30 rpm / min and shake for 12 h. After drying and grinding the obtained solid, carbon nitride is obtained and labeled as CN.
[0042] S2: Weigh 500 mg CN and add it to a 100 mL beaker, then add 25 mL of Fe(NO3)3·9H2O solution with a concentration of 6.68 mg / mL. The Fe(NO3)3·9H2O solution uses 20 mL of ethanol solution as the solvent. Stir mechanically for 30 min. Then, dry for 12 h and transfer to a covered crucible. Calcinate at 500℃ under a 5% O2 / N2 mixed atmosphere for 4 h. After cooling, grind, wash, and dry, then add PBS solution. Centrifuge at 7000 rpm / min for 20 min and collect the supernatant. Centrifuge the supernatant (12000 rpm / min, 20 min), discard the supernatant, and dry at room temperature to obtain a red powder, namely the Fe2O3@g-C3N4S type heterojunction material. The product is labeled as 0.25FeCN.
[0043] Example 2 The difference between this embodiment and Example 1 is that in step S2, 50 mL of a Fe(NO3)3·9H2O solution with a concentration of 6.68 mg / mL is added. The product is labeled as 0.5FeCN.
[0044] Example 3 The difference between this embodiment and Example 1 is that in step S2, 75 mL of a Fe(NO3)3·9H2O solution with a concentration of 6.68 mg / mL is added. The product is labeled as 0.75FeCN.
[0045] Example 4 A method for preparing Fe2O3@g-C3N4S type heterojunction material includes the following steps: S1: Weigh 4 g of cyanuric acid, grind it to an average particle size of 5 mm, and place it in a 20 mL covered crucible. Heat the crucible to 500 °C in air at a rate of 10 °C / min and keep it at that temperature for 4 h to obtain a pale yellow solid. After cooling to room temperature, grind the product and add it to a container containing liquid nitrogen. Place the container on a rotary shaker at a speed of 30 rpm / min and shake for 12 h to ensure that the liquid nitrogen is in full contact with the material. After drying and grinding the obtained solid, carbon nitride is obtained.
[0046] S2: Weigh 500 mg CN and add it to a 100 mL beaker, then add 25 mL of a 6.68 mg / mL Fe(NO3)3·9H2O solution, wherein 20 mL of ethanol solution is used as the solvent for the Fe(NO3)3·9H2O solution. Stir mechanically for 30 min. Then, dry for 12 h and transfer to a covered crucible, calcine at 500 °C under a mixed atmosphere of O2 and N2 for 4 h. The volume percentages of O2 and N2 in the mixed atmosphere are 5% and 95%, respectively.
[0047] After cooling, grind, wash, and dry the material, then add PBS solution. Centrifuge at 7000 rpm / min for 20 min and collect the product in the supernatant. Centrifuge the supernatant (12000 rpm / min, 20 min), discard the supernatant, and dry at room temperature to obtain a red powder, namely the Fe2O3@g-C3N4S type heterojunction material.
[0048] Example 5 A method for preparing Fe2O3@g-C3N4S type heterojunction material includes the following steps: S1: Weigh 4 g of cyanuric acid, grind it to an average particle size of 10 mm, and place it in a 20 mL covered crucible. Heat the crucible to 550 °C in air at a rate of 10 °C / min and keep it at that temperature for 4 h to obtain a pale yellow solid. After cooling to room temperature, grind the product and add it to a container containing liquid nitrogen. Place the container on a gyratory shaker with a rotation speed of 50 rpm / min and shake for 8 h to ensure that the liquid nitrogen is in full contact with the material. After drying and grinding the obtained solid, carbon nitride is obtained.
[0049] S2: Weigh 500 mg CN and add it to a 100 mL beaker, then add 75 mL of a 6.68 mg / mL Fe(NO3)3·9H2O solution, wherein 20 mL of ethanol solution is used as the solvent for the Fe(NO3)3·9H2O solution. Stir mechanically for 30 min. Then, dry for 12 h and transfer to a covered crucible, calcine at 550 °C under a mixed atmosphere of O2 and N2 for 2 h. The volume percentages of O2 and N2 in the mixed atmosphere are 5% and 95%, respectively.
[0050] After cooling, grind, wash, and dry the material, then add PBS solution. Centrifuge at 7000 rpm / min for 20 min and collect the product in the supernatant. Centrifuge the supernatant (12000 rpm / min, 20 min), discard the supernatant, and dry at room temperature to obtain a red powder, namely the Fe2O3@g-C3N4S type heterojunction material.
[0051] Example 6 A method for preparing Fe2O3@g-C3N4S type heterojunction material includes the following steps: S1: Weigh 4 g of cyanuric acid, grind it to an average particle size of 7 mm, and place it in a 20 mL covered crucible. Heat the crucible to 520 °C in air at a rate of 10 °C / min and keep it at that temperature for 3 h to obtain a pale yellow solid. After cooling to room temperature, grind the product and add it to a container containing liquid nitrogen. Place the container on a rotary shaker at a speed of 40 rpm / min and shake for 10 h to ensure that the liquid nitrogen is in full contact with the material. After drying and grinding the obtained solid, carbon nitride is obtained.
[0052] S2: Weigh 500 mg CN and add it to a 100 mL beaker, then add 50 mL of a 6.68 mg / mL Fe(NO3)3·9H2O solution, wherein 20 mL of ethanol solution is used as the solvent for the Fe(NO3)3·9H2O solution. Stir mechanically for 30 min. Then, dry for 12 h and transfer to a covered crucible, calcine at 530 °C under a mixed atmosphere of O2 and N2 for 3 h. The volume percentages of O2 and N2 in the mixed atmosphere are 5% and 95%, respectively.
[0053] After cooling, grind, wash, and dry the material, then add PBS solution. Centrifuge at 7000 rpm / min for 20 min and collect the product in the supernatant. Centrifuge the supernatant (12000 rpm / min, 20 min), discard the supernatant, and dry at room temperature to obtain a red powder, namely the Fe2O3@g-C3N4S type heterojunction material.
[0054] Figure 1The XRD patterns (a) and FT-IR (b) of the carbon nitride (CN) prepared in this invention and the Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3 are shown. Figure 1 As shown in Figure a, the characteristic diffraction peaks of CN appear at 13° (100 crystal plane) and 27.1° (002 crystal plane), which are typical characteristic peaks of g-C3N4, indicating that CN has a layered structure. The subsequent structures of 0.25FeCN, 0.5FeCN, and 0.75FeCN all match the standard PDF card JCPDS NO.33-0664, indicating that the synthesized Fe2O3 is α-Fe2O3 (hematite), and also exhibits the characteristic peaks of CN. This proves the successful synthesis of the Fe2O3@g-C3N4 photosensitizer. Furthermore, it can be seen that as the Fe content gradually increases, the characteristic peaks of CN gradually weaken, while the characteristic peaks of Fe2O3 gradually strengthen, indicating that the addition of different Fe contents affects the change in the crystal structure of the photosensitizer. The diffraction peaks of Fe2O3@g-C3N4 correspond to the following crystal planes: (012) crystal plane: a diffraction peak appears at a 2θ angle of 24.1°; (104) crystal plane: a diffraction peak appears at a 2θ angle of 33.1°; (110) crystal plane: a diffraction peak appears at a 2θ angle of 35.6°; (113) crystal plane: a diffraction peak appears at a 2θ angle of 40.8°; (024) crystal plane: a diffraction peak appears at a 2θ angle of 49.5°; (116) crystal plane: a diffraction peak appears at a 2θ angle of 54.1°; (214) crystal plane: a diffraction peak appears at a 2θ angle of 62.4°. The decrease in intensity of the corresponding CN diffraction peaks indicates that its crystallinity is lower than that of α-Fe2O3. Furthermore, the absence of other impurity peaks indicates that the composite material has high purity.
[0055] The molecular structure and chemical composition of CN, 0.25FeCN, 0.5FeCN, and 0.75FeCN were analyzed by FT-IR spectroscopy. Figure 2 As shown in Figure b. CN is located at 1300-1600 cm. -1 Absorption peaks appear within the range of 1600-1700 cm⁻¹, corresponding to the stretching vibrations of CN bonds, indicating the presence of sp² hybridized carbon and nitrogen bonds in the material, corresponding to CN bonds; -1 Absorption peaks appear within the range of 3000-3600 cm⁻¹, corresponding to the stretching vibrations of C=C bonds, further confirming the conjugated structure of the material and corresponding to C=C bonds; absorption peaks appear within the range of 3000-3600 cm⁻¹. -1The presence of broad absorption peaks within the range corresponds to the stretching vibrations of NH and -OH bonds, indicating the presence of hydroxyl, amino, or imino groups in the material. This demonstrates that the synthesized CN exhibits typical g-C3N4 characteristic absorption peaks. Furthermore, in the characteristic absorption peaks corresponding to 0.25FeCN, 0.5FeCN, and 0.75FeCN, in addition to the characteristic peaks containing CN, there are also peaks in the 500-600 cm⁻¹ range. -1 The absorption peaks appear within the range, corresponding to the Fe-O bonds in Fe2O3.
[199] It can also be seen that with the increase of Fe content, the relative characteristic absorption peak of CN gradually decreases, while the characteristic absorption peak of Fe-O bond gradually increases. This is due to the decrease in the relative content of CN. FT-IR testing also confirms the successful synthesis of Fe2O3@g-C3N4 photosensitizer.
[0056] Figure 2 The image shows a SEM image of 0.5FeCN prepared in Example 2 of this invention. As can be seen from the image, Fe2O3 is square and uniformly dispersed on the surface of CN nanosheets, with almost no aggregation, indicating that Fe2O3 has successfully attached to the CN surface.
[0057] Figure 3 The images show TEM images of the carbon nitride (CN) prepared in this invention and the Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3. As can be seen from the images, the CN surface thickness is basically uniform, and the shadows indicate its layered structure. However, after incorporating Fe2O3, as... Figure 3 As shown in b~3d, it can be seen that there are obvious square stacks on the surface of CN nanosheets, which not only indicates the successful synthesis of Fe2O3@g-C3N4, but also that the shaded agglomerates gradually increase with the increase of Fe content, indicating that as the Fe concentration increases, the degree of agglomeration will increase, which is not conducive to the uniform dispersion of Fe2O3.
[0058] Figure 4 The EDS mapping spectrum of 0.5FeCN prepared in Example 2 of this invention shows that C and N elements are basically uniformly distributed, while O and Fe elements are basically concentrated in the square stacked region. From the perspective of elemental composition, this also proves the successful synthesis of the composite photosensitizer and its attachment to the surface of CN nanosheets.
[0059] Figure 5 XPS images of carbon nitride (CN) prepared in this invention and Fe2O3@g-C3N4S-type heterojunction materials prepared in Examples 1-3 are shown, where (a) is the total spectrum, and (be) are the C1s, N1s, O1s, and Fe2p spectra. XPS testing was used to analyze the chemical composition and heterojunction formation of the composite photosensitizer Fe2O3@g-C3N4. First, as... Figure 5 As shown in Figure a, the full XPS spectrum reveals that, compared to the C1s, N1s, and O1s characteristic peaks observed in CN, 0.25FeCN, 0.5FeCN, and 0.75FeCN all exhibit weak Fe 2p characteristic peaks, with corresponding enhanced O peak intensities. This indicates that Fe2O3 successfully adhered to the CN surface. Further analysis of the C1s spectrum, as shown in Figure a... Figure 5 As shown in b, both CN and the composite Fe2O3@g-C3N4 exhibited characteristic peaks at 288.2 eV and 284.8 eV, corresponding to NC=N and CC bonds, respectively. Furthermore, the relative intensity and position of the characteristic peaks remained largely unchanged, indicating that these photosensitizers maintained the C1s spectrum of CN, and that the heterojunction formed by Fe2O3 and g-C3N4 did not occur at the C bond. To further investigate the location and interface of the heterojunction, N1s spectrum analysis was performed (…). Figure 5 c) The O1s spectrum maintained the same trend as the C1s spectrum, without significant changes or shifts. 400.7 eV and 398.7 eV correspond to NC=N and CNC bonds, respectively. This also proves that heterojunctions do not occur at N bonds. Therefore, the O1s spectrum was analyzed, as shown below. Figure 5 As shown in d, the characteristic peak of CN at 532.6 eV corresponds to -OH and H2O, and the characteristic peak at 532.6 eV corresponds to CO and C=O bonds, which is attributed to the rich hydroxyl groups on the surface of the ultrathin CN. Compared with CN, the composite photosensitizer Fe2O3@g-C3N4 shows significant changes. The characteristic peak at 531.6 eV corresponds to the binding energy of CO and C=O bonds. The characteristic peak of Fe2O3 at 529.3 eV gradually shifts to higher binding energies with increasing Fe content, indicating that the heterojunction occurs at the Fe-O bond. The increase in Fe content leads to a gradual decrease in the electron cloud density near the O element, and electrons accumulate near the Fe element. At the same time, no characteristic peak appears at 532.6 eV, indicating that the surface hydroxyl groups are reduced or replaced. This also indirectly proves that due to high-temperature calcination, the surface hydroxyl groups of the ultrathin CN rich in hydroxyl groups undergo oxidation and dehydrogenation, and then combine with the generated Fe2O3 at this interface to form a heterojunction structure. The final Fe2p spectrum further verifies the hypothesis, such as... Figure 5 As shown in Figure e, photosensitizers with different Fe contents all exhibited characteristic peaks at 724.4 eV and 710.8 eV, corresponding to Fe content, respectively. 3+ 2p 1 / 2 and Fe 3+ 2p 2 / 3 The orbital appeared at 719.7 eV, but as the Fe content increased, a corresponding Fe orbital appeared at 719.7 eV. 2+ 2p 2 / 3The characteristic peaks are attributed to the partial substitution of hydroxyl groups on the CN surface by O in Fe2O3, forming a heterojunction.
[0060] Figure 6 The figures show the EPR images of carbon nitride (CN) prepared in this invention and the Fe2O3@g-C3N4S heterojunction materials prepared in Examples 1-3, where ·O2 - (b) is 1 O2, (c) is ·OH, from Figure 6 a and Figure 6 As can be seen from b, compared to CN, the superoxide radical and singlet oxygen signals of 0.25FeCN and 0.5FeCN gradually increased with increasing Fe content, and only decreased after the Fe content further increased to 0.75FeCN, with 0.5FeCN exhibiting the highest ROS production. Meanwhile, the production of hydroxyl radicals measured by fluorescence method showed basically the same trend. Figure 6 c) indicates that the formation of heterojunctions by Fe2O3 and g-C3N4 can significantly increase ROS production. When the Fe2O3 content is too high, the decrease in ROS production may be attributed to the saturation of heterojunction formation sites and the decrease in the proportion of heterojunctions.
[0061] To further investigate the electron-hole transfer pathways between CN and Fe2O3 heterojunctions, electron and hole capture experiments were conducted. Figure 7 (a) is a schematic diagram of the band structure of the Fe2O3@g-C3N4S heterojunction material, (b) is a TEM image of Ag deposited on 0.5FeCN, (c) is a capture experiment of ·OH, and (d) is a capture experiment of ·O2. - The capture experiment, (e) shows the cyclic voltammetry results of CN and 0.5FeCN. First, as Figure 7 As shown in Figure a, CN and Fe2O3 have suitable band positions, and this is further demonstrated by the photodeposition experiment of Ag ions ( Figure 7 b) and hole trapping experiment ( Figure 7 c) It was found that Ag ions were mainly deposited on the CN surface, and the emission peak corresponding to the ·OH production decreased but did not disappear after the addition of the trapping agent. These all indicate that electrons are concentrated in the CN conduction band. Subsequent electron trapping experiments ( Figure 7d) and cyclic voltammetry tests (7e) show that holes are primarily concentrated in the valence band of Fe2O3. This is because the signal intensity of superoxide radicals remained essentially unchanged after the addition of KI as a trapping agent, and the reduction potential decreased from 0.658 V to 0.568 V. Therefore, based on the electron and hole transfer paths, the heterojunction at the construction site is determined to be an S-type heterojunction. Before the contact between CN and Fe2O3, the band structure remained unchanged. After contact, electrons and holes concentrated at the heterojunction interface, forming a built-in electric field pointing from Fe2O3 to CN. Finally, after illumination, the band structures bend, and after carrier separation, electrons flow from the conduction band of Fe2O3 to the valence band of CN, ultimately accumulating in the conduction band of CN, while holes remain in the valence band of Fe2O3. This constructed S-type heterojunction, compared to traditional type I, type II, and type Z heterojunctions, exhibits superior characteristics. It not only possesses efficient carrier separation and strong redox capabilities, which can significantly improve ROS production, but also avoids problems such as narrow light absorption range, poor interface stability, difficult interface charge transport, and complex preparation. Therefore, it shows excellent application prospects in PDT for glioma.
[0062] Before conducting in vivo PDT testing, intracellular PDT testing is required, using the GL261 cell line as the cell model. Whether the photosensitizer retains excellent endocytic performance after modification was demonstrated using fluorescence staining co-localization, observed under a fluorescence confocal microscope. The cytoskeleton stained with phalloidin showed green fluorescence, the cell nucleus stained with Draq5 showed red fluorescence, and the photosensitizer showed blue fluorescence. Figure 8 As shown, Figure 8 The graph shows the combined fluorescence intensity (n = 6) of the CLSM image for detecting endocytosis in samples using fluorescence confocal microscopy (blue: material, green: cytoskeleton, red: cell nucleus), and quantitative analysis of the endocytosis signal. As can be seen, the endocytosis signal intensity of 0.5FeCN is nearly an order of magnitude higher than that of CN. From a physical perspective, this indicates that the Fe2O3 composite did not alter the nanosheet structure of the photosensitizer after forming the heterojunction. From a biological perspective, the absence of reduced hydrophilicity and thus lower endocytosis efficiency in 0.5FeCN due to the occupied hydroxyl sites is attributed to a decrease in its negative zeta potential.
[0063] Biocompatibility was verified using the CCK8 test, and the test results are as follows: Figure 9 As shown, Figure 9The CCK8 assay results for different concentrations of photosensitizer under dark conditions show that, under dark conditions, cell viability remained close to 100% as the photosensitizer concentration increased to 250 μg / mL. It only began to decline slightly from 300 μg / mL, and at 400 μg / mL, at least 80% viability was still maintained, indicating that the photosensitizer did not exhibit significant biotoxicity after entering the cells and possessed good biosafety.
[0064] After biocompatibility was verified, the PDT performance of CN and 0.5FeCN was further tested using CCK8. Figure 10 As shown, Figure 10 CCK8 tests were performed on photosensitizers at different concentrations under illumination (a), and on photosensitizers at different illumination times (250 μg / mL) under illumination (b). Firstly, as follows... Figure 10 As shown in Figure a, after light exposure, the cell viability of both decreased sharply with increasing photosensitizer concentration. At a concentration of 250 μg / mL, 0.5FeCN essentially reached equilibrium, with a cell viability of only 7.6%, while CN at the same concentration showed a cell viability of 18.3%, and had not yet reached equilibrium. Considering the concentration standards corresponding to biosafety, the PDT effect of 0.5FeCN was 2.4 times better than that of CN. Furthermore, as... Figure 10 As shown in b, after 20 min of PDT, OD values were measured every 2 min to obtain a scatter plot of cell viability. The fitted line shows that compared to CN with a slope of -0.036, the slope of 0.5FeCN is only -0.022, indicating a 1.64-fold increase in PDT efficiency. Furthermore, the fitted line R... 2 A value ≥ 0.99 indicates that the model fits the actual value closely.
[0065] Furthermore, to further investigate the effectiveness of PDT, cell viability was assessed using PI and Calcein-AM dyes. PI cannot penetrate the cell membrane of living cells but can enter the nucleus of dead cells, emitting red fluorescence (excitation wavelength 535 nm, emission wavelength 617 nm). Since dead cells lack esterases, Calcein-AM was only used for testing the viability of living cells and for short-term labeling. Calcein-AM is hydrolyzed by intracellular esterases, generating the membrane-impermeable polar molecule Calcein, which is thus retained within the cell and emits strong green fluorescence (excitation wavelength 490 nm, emission wavelength 515 nm). Results are as follows... Figure 11 As shown, Figure 11 Light was switched on / off for different samples (420 nm, 20 mW / cm²). 2Fluorescence images of cells stained with Calcein-AM (green) and PI (red) after treatment (20 min). The scale bar size is 50 μm. It can be seen that compared with the PBS group and the PBS + Light group, the groups with added CN and 0.5FeCN showed obvious red fluorescence, demonstrating the PDT effect. Among them, the tumor-killing effect of 0.5FeCN was 3.5 times that of the CN group, proving that the photosensitizer after constructing heterojunction has excellent photodynamic therapy effect.
[0066] After successfully passing the cellular-level PDT test, an in vivo PDT test was performed in mice with orthotopic tumors. Figure 12 As shown, Figure 12 The diagram shows the PDT (Prognostics and Treatment) flowchart in tumor-bearing mice (a), a photograph of the mouse optoelectronic implantation (b), and a PDT photograph of the tumor-bearing mice (c). Figure 12 As shown in Figure a, the GL261 cell line was first injected into the intracranial cavity of mice using a stereotaxic device. Over the following seven days, photoelectrodes were implanted into the lesions using dental cement. Figure 12 b). Seven days later, using a stereotaxic instrument, a photosensitizer at a concentration of 250 μg / mL was injected into the lesion site of the mice. After the mice returned to normal activity, they were treated with light irradiation (≥420 nm, 20 mW / cm², 20 min) every two days. Figure 12 c), until the end of day 10. During this period, in situ in vivo imaging and biosafety tests (body weight, blood biochemistry analysis) were performed on mice before and after treatment.
[0067] In this invention, the administration method has been changed, using in-situ tumor injection instead of the original intravenous injection. The main reasons are: direct action on the target tissue: direct injection of the drug into the tumor tissue or other specific sites allows for rapid achievement of high concentrations, reducing systemic drug distribution. Significant local effects: suitable for experiments requiring high local drug concentrations. Improved drug utilization: rapid accumulation at the target site effectively improves drug utilization.
[0068] Therefore, due to the convenience and unique characteristics of the changed drug delivery method, the distribution study of the drug at the lesion site was omitted in the initial stage of the experiment. During the treatment, mice were divided into three groups: the Blank group (mice without photoelectrode implantation), the Control group (mice with photoelectrode implantation but no treatment), and the 0.5FeCN group (mice with photoelectrode implantation and treatment). After 10 days of treatment, in vivo fluorescence testing was performed on mice in each group. Using luciferase (d-luciferin potassium salt) as an indicator, the mice were injected intraperitoneally, and imaging analysis was performed after the light signal reached its strongest stable plateau period (10-15 min). The results are as follows: Figure 13 As shown, Figure 13In vivo fluorescence imaging of tumor-bearing mice (a) and fluorescence signal statistical histogram (b) (420 nm, 20 mW / cm²). 2 After 20 min of irradiation (n = 3), it can be seen that the fluorescence intensity of tumors in the Blank and Control groups increased by nearly one-third after 10 days, while the fluorescence intensity in the 0.5FeCN group decreased by nearly 60%, demonstrating its good PDT performance. However, compared with the therapeutic effect at the cellular level, the therapeutic effect in tumor mice was reduced. This may be attributed to the fact that the continuous Fenton-like reaction rapidly consumed the oxygen of tumor cells, exacerbating the hypoxic environment of tumor cells, and thus limiting the ROS production of tumor cells in mice to O2 concentration.
[0069] Three mice from each group were treated for 10 days, and tumor tissue was extracted. For example... Figure 14 As shown, Figure 14 Images of tumor resection in mice (a) and tumor volume statistics (b) show that the tumor volume in the 0.5FeCN group was significantly smaller than that in the Blank and Control groups. To verify the treatment trend, tumors from two mice were removed after each treatment for volume statistics, and the results are as follows. Figure 14 As shown in b, the tumor growth rates in the Blank and Control groups were essentially the same, demonstrating that the implantation of photoelectrodes did not affect the normal physiological metabolism and intracranial microenvironment of the mice. The tumor volume in the 0.5FeCN group also maintained a relatively stable rate of decline, indicating a significant therapeutic effect on the tumors in the mice.
[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a Fe2O3@g-C3N4 S-type heterojunction material, characterized in that, Includes the following steps: S1: After calcining cyanuric acid, it is placed in liquid nitrogen and shaken to obtain carbon nitride; S2: Carbon nitride is added to an ethanol solution of ferric nitrate, stirred and dried, and the product is calcined under a mixed atmosphere of O2 and N2 to obtain the Fe2O3@g-C3N4 S-type heterojunction material.
2. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, In step S1, before calcining cyanuric acid, it is ground to an average particle size of 5-10 mm.
3. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, In step S1, the calcination temperature of cyanuric acid is 500-550℃, and the time is 2-4 h.
4. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, The calcined cyanuric acid was placed on a gyratory shaker and shaken for 8-12 hours at a speed of 30-50 rpm / min.
5. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, In step S2, the ratio of carbon nitride to ferric nitrate ethanol solution is 500 mg:(25~75) mL, and the concentration of ferric nitrate ethanol solution is 6.68 mg / mL.
6. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, In step S2, the calcination temperature is 500-550℃ and the time is 2-4 h.
7. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, In step S2, in the mixed atmosphere of O2 and N2, oxygen accounts for 5% of the total volume of the mixed gas.
8. The method for preparing a Fe2O3@g-C3N4 S-type heterojunction material according to claim 1, characterized in that, In step S2, after calcination, the product is further washed by centrifugation using PBS solution.
9. A Fe2O3@g-C3N4 S-type heterojunction material, characterized in that, It is prepared by the method described in any one of claims 1 to 8.
10. The application of the Fe2O3@g-C3N4 S-type heterojunction material as described in claim 9 in the preparation of antitumor drugs.