Functionalized carbon quantum dots and their preparation method and application

Abstract

The present invention discloses a functionalized carbon quantum dot, a preparation method, and an application thereof, with a structural formula of formula (1) or formula (2): #imgabs0# formed by grafting carbon quantum dots with chelating agent ligands. The functionalized carbon quantum dot material of the present invention can effectively chelate nuclides, thereby improving the efficiency of surface decontamination of nuclides. After the functionalized carbon quantum dot material binds to the nuclides, it agglomerates, resulting in an increase in particle size, which can prevent transdermal absorption and prevent the nuclides from entering the blood circulation after penetrating the skin and causing internal contamination. After the functionalized carbon quantum dot material binds to the nuclides, the fluorescence intensity is gradually quenched. During the decontamination process, the changes in the nuclides content can be monitored in real time, achieving integrated decontamination and monitoring.

Description

Technical Field

[0001] The present invention relates to the field of chemical synthesis, and in particular to functionalized carbon quantum dots and a preparation method and application thereof. Background Art

[0002] The rise of today's nuclear energy industry inevitably raises nuclear safety issues. The generation of radioactive waste, the recycling of nuclear fuel, and nuclear accidents at large nuclear facilities pose nuclear risks to workers at potential occupational risk and the unprotected public. Conventional safeguards cannot address these risks. Therefore, while developing nuclear energy, it is crucial to develop nuclear emergency response technologies to safeguard nuclear energy development. For example, radionuclide surface decontamination agents, part of nuclear emergency response technology, can effectively remove surface radioactive contamination caused by radioactive elements leaked during nuclear accidents, preventing their deposition and reducing ongoing hazards.

[0003] Based on surface radionuclide contamination, my country's GBZ / T 216-2009, "Specifications for the Treatment of Radionuclide Contamination on Human Surfaces," recommends the use of 1% DTPA or 10% EDTA solutions for decontamination of plutonium and transplutonium elements, while 1.4% bicarbonate solution can be used for uranium contamination. The World Health Organization (WHO) and the International Atomic Agency (IAEA) primarily recommend the use of warm water or soapy water for decontamination of intact skin, while potassium permanganate or low-concentration bleach are also recommended. These surface radionuclide decontamination products primarily rely on physical action, removing surface radionuclides through scouring, which has limited effectiveness in delayed decontamination. Furthermore, potassium permanganate and bleach are skin irritants and can easily cause skin damage.

[0004] By adding chelating agents such as DTPA and EDTA, the chelating agents can effectively chelate radionuclides on the body surface during physical flushing, which can significantly improve the decontamination effect. Based on this, in order to further improve the decontamination effect, researchers have applied organophosphate chelating agents with stronger affinity for actinides to the decontamination of body surface radionuclides. Hydroxyethylidene diphosphonic acid (HEDP) has a strong chelating ability for plutonium and uranium, and can effectively remove plutonium and uranium from the body surface. However, studies have found that the complexes of HEDP and actinides easily penetrate the skin. After 24 hours of interaction between HEDP and uranium or plutonium on the skin surface of rats, approximately 23.4% of the uranium or 17.9% of the plutonium entered the dermis, and then entered the blood circulation, causing internal contamination.

[0005] Exogenous substances can enter the dermis through cells and intercellular spaces within the epidermis, as well as through hair follicles and sweat glands. Their absorption characteristics are related to the substance's physicochemical properties, such as solubility, particle size, shape, and skin affinity. Studies have shown that nanoparticles larger than 40 nm cannot penetrate the stratum corneum, while particles smaller than 40 nm can enter the dermis through intercellular spaces, hair follicles, and sweat glands. Therefore, increasing the particle size of chelating agents may be a promising approach to circumventing the transdermal absorption of actinides caused by decontamination agents. Based on this, the French Institute for Radiation Protection and Nuclear Safety (INPARK) incorporated calixarene into paraffin oil containing an ionic surfactant to produce a calixarene nanoemulsion. This nanoemulsion, with a particle size of 150-200 nm, is capable of chelating uranium upon contact with uranium solutions. The material's size effectively prevents skin penetration, suggesting promising applications for surface radionuclide decontamination. However, its particle size and limited surface chelation sites prevent it from fully chelating uranium. Furthermore, the hepatotoxicity of calixarene limits its application. In addition, in actual nuclear emergency scenarios, conventional decontamination agents cannot monitor the decontamination effect, which can easily lead to excessive use of decontamination agents and produce a large amount of radioactive waste liquid. There are major problems in the post-treatment of these radioactive waste liquids, which brings inconvenience to nuclear emergency treatment. Therefore, scientific researchers are forced to develop new low-toxic and high-efficiency radionuclide surface decontamination fluids.

[0006] In order to solve the above problems, the present invention proposes to apply functionalized carbon quantum dot materials to the field of nuclide decontamination. Carbon quantum dot materials (CQDs) are a kind of zero-dimensional carbon nanomaterials with significant fluorescence properties. They have good biocompatibility, excellent water solubility and chemical stability, and are widely used in environmental detection, cancer treatment, antibacterial and other aspects. In the present invention, Cm-3,2-HOPO with strong uranium chelating ability is screened out, and Cm-3,2-HOPO is modified onto carbon quantum dots to obtain Cm-HOPO-CQDs with uniform particle size. It is found that Cm-HOPO-CQDs aggregate after binding with nuclides, and the particle size agglomerates from 2-3nm to about 1000nm. While effectively chelating nuclides, it prevents the transdermal absorption of the complex and avoids internal contamination. In addition, the fluorescence intensity of Cm-HOPO-CQDs is gradually quenched after complexing with nuclides. During the decontamination process, the changes in nuclide content can be monitored in real time, so as to achieve integrated decontamination monitoring. Subsequently, by matching the uranium coordination pattern, a new type of phosphate ligand DPC with strong chelating ability was designed and modified on the carbon quantum dots to obtain DPC-CQDs with uniform particle size. Similarly, the material aggregated and fluorescence quenched after binding with radionuclide ions, achieving skin absorption resistance and real-time fluorescence monitoring while decontamination. It can be seen that functionalized carbon quantum dot materials have a certain universality in surface decontamination, absorption resistance and real-time monitoring. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a functionalized carbon quantum dot and its preparation method and application, and to modify a chelating agent ligand with a nuclide decontamination function onto the carbon quantum dots to obtain a new chelating agent with uniform particle size. After binding with the nuclide, the chelating agent agglomerates, and the particle size agglomerates from 2-3nm to about 1000nm. While effectively chelating the nuclide, it prevents the transdermal absorption of the complex and avoids internal contamination. After the new chelating agent is complexed with the nuclide, the fluorescence intensity is gradually quenched. During the decontamination process, the changes in the nuclide content can be monitored in real time, achieving integrated decontamination and monitoring.

[0008] In order to solve the above technical problems, the present invention provides a functionalized carbon quantum dot having the structural formula (1) or (2):

[0009]

[0010] The second aspect of the present invention provides a method for preparing functionalized carbon quantum dots according to the first aspect, which is prepared by amidating the amino groups on the surface of carbon quantum dots (CQDs) of formula (3) with the carboxyl groups of a chelating agent ligand, wherein the chelating agent ligand is a compound of formula (4) (Cm-3,2-HOPO) or a compound of formula (5) (DPC), and the reaction route is:

[0011]

[0012] The present invention grafts CQDs with chelating agent ligands Cm-3,2-HOPO or DPC to obtain new chelating agents Cm-HOPO-CQDs and DPC-CQDs, respectively. The new chelating agents aggregate after binding with the nuclides, and the particle size aggregates from 2-3nm to about 1000nm. While effectively chelating the nuclides to achieve surface decontamination of the nuclides, they also prevent the complex from being absorbed through the skin, thus preventing it from penetrating into the skin and entering the blood circulation to cause internal contamination. In addition, the fluorescence intensity of the new chelating agent is gradually quenched after complexing with the nuclides. Based on the fluorescence quenching experiment, the changes in the nuclides content can be monitored in real time during the decontamination process, achieving integrated decontamination and monitoring. The chelating agent-functionalized CQDs material aggregates and precipitates after binding with the nuclides. In addition, the material can be monitored in real time, which effectively controls the amount of decontamination agent used. Aggregates in the waste liquid can be collected as solid waste by filtration, effectively alleviating the pressure of waste liquid post-processing and having strong nuclear emergency response.

[0013] Furthermore, the grafting step is as follows: adding an activator and a condensing agent to a chelating agent ligand solution under ice bath conditions, transferring the solution to a constant temperature of 20-35° C., adding a carbon quantum dot solution, and reacting to obtain functionalized carbon quantum dots;

[0014] Wherein, when the chelating agent ligand is a compound of formula (4), the reaction conditions are: adding a catalyst palladium / carbon and removing the benzyl group on the hydroxypyridone under a hydrogen atmosphere.

[0015] Furthermore, the mass ratio of the chelating agent ligand to the carbon quantum dots is 1:(1-3).

[0016] Furthermore, the solvent of the carbon quantum dot solution is deionized water.

[0017] Furthermore, when the chelating agent ligand is a compound of formula (4), the solvent of the chelating agent ligand solution is N,N-dimethylformamide (DMF) or methanol, and the constant temperature condition is an oil bath. After the reaction is completed, palladium / carbon (Pd / C) is filtered and separated, and most of the water and DMF in the filtrate are removed by rotary evaporation. The remaining mixture is diluted with water and filtered, and the filtrate is concentrated again and dialyzed for 2-3 days. The purified solution is concentrated and freeze-dried to obtain a brown powder Cm-HOPO-CQDs.

[0018] Furthermore, when the chelating agent ligand is a compound of formula (5), the solvent of the chelating agent ligand solution is deionized water. After the reaction is completed, the solution is dialyzed, concentrated, and freeze-dried to obtain brown powder DPC-CQDs.

[0019] Furthermore, the activator is one or more of N-hydroxysuccinimide (NHS), 2,2-dihydroxymethylpropionic acid (DMPA), and 1-hydroxybenzotriazole (HOBT).

[0020] Furthermore, the condensing agent is one or more of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC), N,N-dicyclohexylcarbodiimide (DCC), and N,N'-diisopropylcarbodiimide (DIC).

[0021] Furthermore, the carbon quantum dots are prepared by mixing a citric acid (CA) monohydrate solution with a branched polyethyleneimine solution, and reacting the mixture at 160-200° C. to obtain the carbon quantum dots.

[0022] Furthermore, the solvents of the citric acid monohydrate solution and the branched polyethyleneimine solution are both water, the branched polyethyleneimine solution is heated to 40-60° C. and stirred to dissolve, and after the reaction, it is dialyzed, concentrated, and freeze-dried to form yellow powder carbon quantum dots.

[0023] The preparation method of the chelating agent ligand compound of formula (4) of the present invention has been disclosed in patent CN 106928132 A and will not be described in detail here.

[0024] Furthermore, the preparation method of the compound of formula (5) is:

[0025] S1. Add ethyl bromoacetate and a catalyst to the organic solution of the compound of formula (6), and react in an ice-water bath to obtain the intermediate of formula (7). The reaction route is:

[0026]

[0027] S2, the intermediate of formula (7) reacts with an acid under boiling water bath conditions to obtain the compound of formula (5).

[0028] Furthermore, the catalyst is one or more of sodium bis(trimethylsilyl)amide, sodium methoxide, sodium ethoxide, and quaternary ammonium base.

[0029] Furthermore, the solvent of the organic solution of the compound of formula (6) is tetrahydrofuran (THF) and / or DMF.

[0030] Furthermore, the acid is hydrochloric acid or glacial acetic acid.

[0031] Furthermore, after the reaction of S1 is completed, the solvent is distilled off under reduced pressure, dichloromethane (DCM) and / or chloroform are added to dissolve, the insoluble matter is removed by filtration, the filtrate is collected and concentrated, and the product is purified by column chromatography (gradually increasing the polarity from pure EA to EA / MeOH = 10 / 1).

[0032] The third aspect of the present invention provides the use of the functionalized carbon quantum dots described in the first aspect in body surface radionuclide decontamination.

[0033] Furthermore, the nuclides are one or more of the actinide elements uranium, thorium, neptunium, plutonium, americium, the lanthanide elements europium, cerium, lanthanum, and the heavy metals mercury, chromium, and lead.

[0034] Beneficial effects of the present invention:

[0035] The functionalized carbon quantum dot material of the present invention can effectively chelate nuclides and improve the efficiency of surface decontamination of nuclides; after the functionalized carbon quantum dot material combines with the nuclides, it agglomerates to increase the particle size, which can prevent transdermal absorption, avoid penetrating into the skin, and cause internal contamination after entering the blood circulation. After the functionalized carbon quantum dot material of the present invention is complexed with the nuclides, the fluorescence intensity is gradually quenched. During the decontamination process, the change of the nuclide content can be monitored in real time, and the decontamination monitoring can be integrated; after the chelating agent functionalized carbon quantum dot material combines with the nuclides, it agglomerates and precipitates, and can be monitored in real time, which can effectively control the amount of decontamination agent used. The aggregates in the waste liquid can be collected as solid waste by filtration, which effectively alleviates the pressure of waste liquid post-processing and has strong nuclear emergency response. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a hydrogen nuclear magnetic resonance spectrum of the ethyl bisphosphate intermediate of the present invention;

[0037] Figure 2 is a hydrogen nuclear magnetic resonance spectrum of the organic bisphosphate ligand of the present invention;

[0038] Figure 3 is the particle size distribution of CQDs, Cm-HOPO-CQDs, and DPC-CQDs;

[0039] Figure 4 are the infrared spectra of CQDs, HOPO, Cm-HOPO-CQDs, DPC, and DPC-CQDs;

[0040] Figure 5 In the figure, (a) is a schematic diagram of the aggregation of Cm-HOPO-CQDs and DPC-CQDs with uranium, (b) is the particle size change of Cm-HOPO-CQDs before and after complexation with uranyl ions, and (c) is the particle size change of DPC-CQDs before and after complexation with uranyl ions;

[0041] Figure 6 is the change in fluorescence intensity of Cm-HOPO-CQDs and DPC-CQDs after interaction with uranium;

[0042] Figure 7 In the figure, (a) is a schematic diagram of the decontamination of uranium on the pig skin surface by a decontamination agent; (b) is a diagram showing the decontamination efficiency of DTPA, Cm-HOPO-CQDs, and DPC-CQDs on the pig skin surface;

[0043] Figure 8 In the figure, (a) and (b) are the size and morphology of Cm-HOPO-CQDs before and after uranium decontamination, (c) and (d) are the size and morphology of DPC-CQDs before and after uranium decontamination, (e) is a schematic diagram of the absorption resistance test, and (f) is the uranium content remaining on the skin surface two hours after the skin is contaminated with uranium, uranium, and a disinfectant (DTPA, Cm-HOPO-CQDs, or DPC-CQDs).

[0044] Figure 9 In the figure, (a) and (b) are the fluorescence intensity changes of Cm-HOPO-CQDs and DPC-CQDs solutions during uranium decontamination, respectively. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0046] Example 1

[0047] This embodiment relates to a method for preparing functionalized carbon quantum dots, comprising the following steps:

[0048] (1) Synthesis of CQDs of compound (3)

[0049] Weigh 0.16g of CA and place it in a 15mL centrifuge tube. Add 11mL of water and ultrasonically dissolve it to obtain a CA solution for use. Weigh 0.06g of BPEI and place it in a beaker. Add 1mL of water and place it on a stirrer. Heat it to 50℃ to dissolve it. Then add it to the CA solution, mix it thoroughly, and transfer it to a 20mL Teflon-lined reactor. After heating in an oven at 180℃ for 6 hours, cool it to room temperature, take out the reaction solution, dialyze it, concentrate it, and finally freeze-dry it to form yellow powder CQDs.

[0050] (2) Synthesis of compound Cm-3,2-HOPO of formula (4)

[0051] 11.1 g of 2,3-dihydroxypyridine was weighed into a reaction flask, and 83.5 g of ethyl bromoacetate was added. N₂ was then introduced below the reaction surface and stirred for 1 hour. The mixture was then refluxed at 150°C under N₂ protection for 24 hours. After the reaction, the reaction flask was removed from the oil bath and cooled to room temperature to allow the solid to precipitate. The reaction solution was then filtered, washed 3-5 times with acetone, and recrystallized from ethanol. After drying in a vacuum oven for 24 hours, an off-white intermediate product was obtained. This intermediate was dissolved in 300 mL of 90% aqueous methanol, and the pH of the solution was adjusted to approximately 12 with aqueous NaOH. 25 g of benzyl chloride was then added, and the reaction was refluxed at 80°C at pH 12 for 8 hours. During the reaction, the solution gradually turned from colorless to reddish-brown. After the reaction was completed, the reaction mixture was cooled to room temperature and the methanol was removed by rotary evaporation. Add 100 mL of H₂O to the remaining reaction solution. Extract the aqueous solution twice with 50 mL of dichloromethane. Adjust the pH of the reaction solution to 1 with dilute hydrochloric acid until a precipitate forms. Filter the precipitate and dry it in a vacuum oven for 24 hours. Recrystallize it from methanol and dry it to obtain white needle-like crystals of Cm-3,2-HOPO.

[0052] (3) Synthesis of compound DPC of formula (5)

[0053] A 25 mL three-necked flask was evacuated and then flushed with nitrogen. 490 mg (1.70 mmol, 1 eq) of tetraethylmethylene diphosphate and 10 mL of anhydrous THF were added. Under an ice-water bath, 1.10 g (40% in THF, 2.75 mmol, 1.6 eq) of sodium bis(trimethylsilyl)amide was slowly added by injection, causing the solution to turn light brown. 710 mg of ethyl bromoacetate (4.25 mmol, 2.5 eq) was then added by injection, causing the solution to turn red. The reaction was stirred at approximately 0°C. The reaction was monitored by thin-layer chromatography (EA / MeOH = 10 / 1) during the reaction. The reaction was complete after stirring for approximately 22 hours. The solvent was removed by distillation under reduced pressure to yield a yellow viscous product. DCM was added for dissolution, and the insoluble material was removed by filtration. The filtrate was collected and concentrated. Column chromatography (gradually increasing the polarity of EA from pure EA to EA / MeOH = 10 / 1) afforded 460 mg of the ethyl bisphosphate intermediate as a pale yellow oil in approximately 73% yield. The results of H NMR spectrum test are shown in Figure 1 , specifically: 1 H NMR (400MHz, CDCl3): δ4.18 (m, 10H), 3.11 (tt, J = 16Hz, 4.4Hz, 1H), 6.72 (td, J = 10.4Hz, 4Hz, 2H), 1.33 (td, J = 4.4Hz, 1.6Hz, 12H), 1.28 (t, J = 4.8Hz, 3H).

[0054] 500 mg (1.34 mmol) of ethyl bisphosphate intermediate was added to a round-bottom flask, and 30 mL of 1 M hydrochloric acid solution was added. The mixture was refluxed for 24 h and the solvent was removed by distillation under reduced pressure to obtain a colorless transparent liquid. After vacuum drying, 300 mg of white solid organic bisphosphate ligand (DPC) was obtained. The yield was about 96%. The results of the H NMR test are shown in Figure 2 , specifically: 1 H NMR (400 MHz, D2O): δ2.81 (m, 3H); m / z calculated based on LC-MS [MH] results is 232.96, and the experimental result is 232.93.

[0055] (4) Synthesis of Cm-HOPO-CQDs from formula (1)

[0056] 0.4g of Cm-3,2-HOPO ligand was dissolved in 20mL of DMF and stirred on ice for 30min. 0.38g of EDC and 0.23g of NHS were added and the mixture was stirred on ice for another 30min. The mixture was then transferred to a 30°C oil bath and stirred at constant temperature for 1h. 0.6g of CQDs was dissolved in 10mL of deionized water and added dropwise to the above solution. After reacting for 24h, 40mg of Pd / C (10%) was added and stirred under a hydrogen atmosphere for 6h. The Pd / C was separated by filtration, and most of the water and DMF in the filtrate were removed by rotary evaporation. The remaining mixture was diluted with water and filtered. The filtrate was concentrated again and dialyzed for 2-3 days. Finally, the purified solution was concentrated and lyophilized to obtain brown powder Cm-HOPO-CQDs.

[0057] (5) Synthesis of DPC-CQDs using formula (2)

[0058] 0.33 g of DPC was dissolved in 20 mL of deionized water and stirred in an ice bath for 0.5 h. Subsequently, 0.34 g of EDC and 0.2 g of NHS were added. After 30 min, the reaction was transferred to room temperature and reacted for 1 h. 0.55 g of CQDs was dissolved in 10 mL of deionized water and added to the reaction solution. The reaction lasted for 1 day, then dialyzed, concentrated, and freeze-dried to form brown powder DPC-CQDs.

[0059] Test Case

[0060] (1) Characterization of Cm-HOPO-CQDs and DPC-CQDs

[0061] Figure 3 The particle size distribution diagram of CQDs, Cm-HOPO-CQDs and DPC-CQDs shows that the average particle size of CQDs is 1.9 nm (PDI = 0.014). After functional modification of DPC and Cm-HOPO, the particle size increases to about 2-4 nm. This is because the overall particle size increases after DPC and Cm-HOPO are grafted onto the surface of CQDs.

[0062] Figure 4 The Fourier transform infrared spectra of CQDs, HOPO of formula (4), DPC of formula (5), Cm-HOPO-CQDs, and DPC-CQDs are shown in Figure 1. In the infrared spectrum of CQDs, 3400 cm -1 is the stretching vibration peak of the NH bond, 1650cm -1 The NH bond bending vibration peak is at 1434 cm, indicating that the molecular structure of PEI exists on the surface of CQDs in the form of amino groups during the synthesis of CQDs. After DPC modified CQDs, the infrared spectrum of DPC-CQDs contains DPC at 1434 cm -1 P=O bond stretching vibration, and 1650cm -1The C=O bond absorption band at 1543 cm -1 The NH symmetric and symmetrical stretching and bending vibrations of the secondary amide at the Cm-HOPO-CQDs are also observed. -1 ) and -CH(3050cm -1 The above results show that DPC and Cm-HOPO were successfully modified onto CQDs.

[0063] (2) Aggregation and fluorescence quenching behavior of Cm-HOPO-CQDs and DPC-CQDs after complexation with radionuclides

[0064] refer to Figure 5 a, Schematic diagram of the aggregation of Cm-HOPO-CQDs and DPC-CQDs after complexation with nuclides. Figure 5 b and 5c, in ultrapure water, the average particle size of Cm-HOPO-CQDs was 2.33 nm. When 2 mg of Cm-HOPO-CQDs and DPC-CQDs were added to a 4 mg / mL uranyl ion solution, the HOPO functional groups on the surface of the functionalized CQDs rapidly complexed with the uranyl ions, and the hydrated particle size of the complexes increased to approximately 1000 nm. This shows that under the induction of radionuclide ions, Cm-HOPO-CQDs and DPC-CQDs aggregated when encountering radionuclide, showing a certain absorption resistance potential.

[0065] refer to Figure 6 , the changes in fluorescence intensity of Cm-HOPO-CQDs and DPC-CQDs under the induction of gradient concentration of uranyl ions. It can be seen that when the uranyl ion concentration gradually increases from 0 ppm to 400 ppm, the fluorescence intensity of Cm-HOPO-CQDs and DPC-CQDs gradually decreases. The changes in hydrated particle size and fluorescence intensity can both reflect that uranyl ions induce the aggregation of Cm-HOPO-CQDs and DPC-CQDs and lead to fluorescence quenching.

[0066] (3) Decontamination experiments of Cm-HOPO-CQDs and DPC-CQDs

[0067] Prepare a 2g / L uranium solution as a simulated poisoning solution, 2% DTPA, 2% Cm-HOPO-CQDs and 2% DPC-CQDs solutions as disinfectants. Cut the pigskin into 1.2×1.2cm 2 Use a marker to mark a 1×1cm rectangle. 2The infected area was large enough to be handled with forceps, leaving enough space for skin removal. The samples were divided into 60-second and 2-hour groups based on the decontamination delay time. Each group was further divided into deionized water, 2% DTPA, 2% Cm-HOPO-CQDs, and 2% DPC-CQDs groups based on the decontamination material. Three replicates were set up for each group.

[0068] (a) Characterization of the decontamination efficiency of Cm-HOPO-CQDs and DPC-CQDs

[0069] Use a pipette to apply 20 μL of a 2g / L uranium solution to the designated area of ​​the pig skin, trying to cover the entire area as much as possible. Before and after the exposure, the pig skin was weighed on an electronic balance to obtain its accurate exposure volume. After the exposure, different solutions were decontaminated according to the delay time. The deionized water, 2% DTPA, 2% Cm-HOPO-CQDs and 2% DPC-CQDs groups were all decontaminated with 2mL of detergent, followed by rinsing with 3mL of deionized water. The decontaminated solution was placed in a centrifuge tube, and the exact mass of the solution in the tube was calculated by weighing the difference between the empty tube and the centrifuge tube containing the mixed solution. The decontamination solution was diluted about 1.5 times with a 2% HNO3 solution and filtered with a 220nm water filter. Finally, the uranium concentration in each sample was determined by ICP-AES. The decontamination rate was calculated according to the following formula:

[0070] Decontamination rate (%) = (uranium concentration in the test solution × total mass of the test solution) / (concentration of the poisoned uranium solution × mass of the poisoned uranium solution) × 100%.

[0071] like Figure 7 Schematic diagrams and decontamination efficiency graphs for DTPA, Cm-HOPO-CQDs, and DPC-CQDs are shown. Overall, the 2-hour decontamination group showed reduced decontamination rates compared to the 60-second group. This is due to some uranium penetrating the epidermis and subsequently the dermis. In the 60-second immediate decontamination group, the removal efficiencies of 2% Cm-HOPO-CQDs and 2% DPC-CQDs were 75.4% and 80.0%, respectively, both superior to deionized water (64.5%) and DTPA (74.3%). With a 2-hour delay in decontamination, the removal efficiency of 2% DPC-CQDs was 54.3%, slightly higher than the 47.2% of Cm-HOPO-CQDs. Deionized water and 2% DTPA solutions only removed 25% and 27% of the uranium, respectively. It can be seen that Cm-HOPO-CQDs and DPC-CQDs have significantly improved the decontamination efficiency of deionized water and DTPA.

[0072] (b) Particle size monitoring and absorption characterization of Cm-HOPO-CQDs and DPC-CQDs during decontamination

[0073] To monitor the aggregation behavior of Cm-HOPO-CQDs and DPC-CQDs during uranium decontamination, the above-mentioned immediate decontamination process was repeated, during which the rinse solution and deionized water were collected for DLS and TEM measurements, respectively. Figure 8 a-8d reflect the size and morphology of Cm-HOPO-CQDs and DPC-CQDs particles before and after uranium decontamination. It can be seen that during the decontamination process, most Cm-HOPO-CQDs and DPC-CQDs particles (2-4 nm) chelated uranyl ions and aggregated into loose aggregates of micrometer size (950-1720 nm, e.g. Figure 8 b and 8d). This demonstrates that Cm-HOPO-CQDs and DPC-CQDs have the function of chelating with uranium and aggregating into large particles during the decontamination process.

[0074] Then, the absorption resistance simulation experiment was carried out and the ex vivo pig skin was cut into 2×2.8cm 2 and score each skin to form a 2×2.4cm rectangle. 2 The contaminated area and 2×0.4cm 2 400 μL of solutions containing 4 mg / L uranium, 4 mg / L uranium and 2 g / L DTPA, 4 mg / L uranium and 2 g / L Cm-HOPO-CQDs, and 4 mg / L uranium and 2 g / L DPC-CQDs were applied to the contaminated area of ​​each skin sample to simulate decontamination residues. Figure 8 e. After 2 h, each skin was rinsed with 8 mL of deionized water, and the washing solution was collected for ICP-OES analysis. Figure 8 As shown in Figure f, the Cm-HOPO-CQDs group and the DPC-CQDs group recovered 697.2 ng and 824.5 ng of uranium, respectively. The amount of uranium recovered by the DPC-CQDs group was 3.15 times and 1.44 times that of the deionized water group (261.8 ng) and the DTPA group (571.5 ng), respectively. The amount of uranium recovered by the Cm-HOPO-CQDs group was 2.59 times and 1.19 times that of the deionized water group (261.8 ng) and the DTPA group (571.5 ng), respectively, indicating that Cm-HOPO-CQDs and DPC-CQDs have significant absorption resistance.

[0075] (c) Dynamic monitoring of fluorescence intensity during the decontamination process of Cm-HOPO-CQDs and DPC-CQDs

[0076] Based on the fact that the fluorescence of Cm-HOPO-CQDs and DPC-CQDs can be quenched by uranyl ions, we prepared a 4g / L uranium solution as a simulated poisoning solution and a 2mg / mL Cm-HOPO-CQDs and DPC-CQDs decontamination solution. 2 Area, where 1×1cm is marked with a marker 2 The remaining area is convenient for picking up with tweezers.

[0077] Use a pipette to apply 80 μL of uranium solution to the designated area of ​​the pig skin. After 20 minutes, rinse with Cm-HOPO-CQDs and DPC-CQDs solutions, respectively. Rinse four times, 0.2 mL each time. Collect the decontamination solution in four steps and test its fluorescence intensity to reflect the degree of uranium decontamination on the body surface. Comparison of the fluorescence intensity of Cm-HOPO-CQDs and DPC-CQDs after four rinses with the initial fluorescence intensity. Figure 9 As shown in Figures 9a and 9b, the fluorescence intensity of the decontamination solution collected during the first decontamination operation is significantly lower than the initial fluorescence intensity. However, during the subsequent decontamination collections, the fluorescence intensity gradually recovered, reaching the fourth collection level, which is almost identical to that of the initial solution. This demonstrates that the fluorescence intensity changes of Cm-HOPO-CQDs and DPC-CQDs can be used as a means of real-time monitoring of decontamination levels, offering the potential for integrated decontamination and detection capabilities.

[0078] This invention, for the first time, exploits the aggregation and fluorescence quenching properties of Cm-HOPO-CQDs and DPC-CQDs for uranium to develop a uranium skin decontaminant with absorption resistance and real-time monitoring capabilities. By modifying carbon quantum dots with Cm-3,2-HOPO and DPC units, which have high uranium chelating abilities, the novel skin decontaminants, Cm-HOPO-CQDs and DPC-CQDs, were rationally designed and synthesized. Skin decontamination experiments demonstrated that Cm-HOPO-CQDs and DPC-CQDs exhibited significant decontamination advantages compared to deionized water and a 2% DTPA solution. The advantages of Cm-HOPO-CQDs and DPC-CQDs increased with longer decontamination delays. Furthermore, the aggregation reaction of Cm-HOPO-CQDs and DPC-CQDs with uranyl ions effectively limits their penetration into the skin. Compared to deionized water, their absorption resistance was 2.59 times and 3.15 times greater, respectively. Furthermore, the fluorescence quenching properties of Cm-HOPO-CQDs and DPC-CQDs in the presence of uranyl ions also provide immediate feedback on the decontamination effect. The uranium-induced aggregation and fluorescence quenching of Cm-HOPO-CQDs and DPC-CQDs solutions make them promising candidates for uranium decontamination agents with integrated absorption resistance and real-time monitoring capabilities, providing a new approach for the design of skin decontamination products.

[0079] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A functionalized carbon quantum dot, characterized in that The structural formula is formula (1) or formula (2):

2. A method for preparing functionalized carbon quantum dots according to claim 1, characterized in that: It is formed by amidation of the amino groups on the surface of the carbon quantum dots of formula (3) with the carboxyl groups of the chelating agent ligand, wherein the chelating agent ligand is a compound of formula (4) or a compound of formula (5), and the reaction route is:

3. The method for preparing functionalized carbon quantum dots according to claim 2, wherein: The specific steps of grafting are: adding an activator and a condensing agent to a chelating agent ligand solution under ice bath conditions, transferring the solution to a constant temperature of 20-35°C, adding a carbon quantum dot solution, and reacting to obtain functionalized carbon quantum dots; When the chelating agent ligand is a compound of formula (4), the reaction conditions are: adding palladium / carbon and removing the benzyl group on the hydroxypyridone under a hydrogen atmosphere.

4. The method for preparing functionalized carbon quantum dots according to claim 3, wherein: The activator is one or more of N-hydroxysuccinimide, 2,2-dihydroxymethylpropionic acid, and 1-hydroxybenzotriazole.

5. The method for preparing functionalized carbon quantum dots according to claim 3, wherein: The condensing agent is one or more of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, N,N-dicyclohexylcarbodiimide, and N,N'-diisopropylcarbodiimide.

6. The method for preparing functionalized carbon quantum dots according to claim 2, wherein: The preparation method of the carbon quantum dots comprises the following steps: mixing a citric acid monohydrate solution with a branched polyethyleneimine solution, and reacting the mixture at 160-200° C. to obtain the carbon quantum dots.

7. The method for preparing functionalized carbon quantum dots according to claim 2, wherein: The preparation method of the compound of formula (5) is: S1. Add ethyl bromoacetate and a catalyst to the organic solution of the compound of formula (6), and react in an ice-water bath to obtain the intermediate of formula (7). The reaction route is: S2, the intermediate of formula (7) reacts with an acid under boiling water bath conditions to obtain the compound of formula (5).

8. The method for preparing functionalized carbon quantum dots according to claim 7, wherein: The catalyst is one or more of sodium bis(trimethylsilyl)amide, sodium methoxide, sodium ethoxide and quaternary ammonium base.

9. Use of the functionalized carbon quantum dots according to claim 1 in body surface radionuclide decontamination.

10. The use according to claim 9, characterized in that The nuclides are one or more of the actinide elements uranium, thorium, neptunium, plutonium, americium, the lanthanide elements europium, cerium, lanthanum, and the heavy metals mercury, chromium, and lead.

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