CN115959635A - Monoatomic transition metal doped carbon nitride quantum dot, and chemical cutting preparation method and application thereof in water phase - Google Patents
Monoatomic transition metal doped carbon nitride quantum dot, and chemical cutting preparation method and application thereof in water phase Download PDFInfo
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Abstract
The invention provides a monoatomic transition metal doped carbon nitride quantum dot, a chemical cutting preparation method and application thereof in a water phase. The preparation method of the quantum dots comprises the following steps: dissolving melamine and transition metal salt in dimethyl sulfoxide (DMSO) to obtain solution A; fully dispersing cyanuric acid in dimethyl sulfoxide as a solvent to obtain a solution B; fully and uniformly mixing the solution B and the solution A to obtain a reaction solution, then carrying out ultrasonic reaction, filtering, washing and drying to obtain a supramolecular precursor; then calcining to prepare bulk monatomic transition metal doped carbon nitride; fully mixing and dispersing the block monoatomic transition metal doped carbon nitride with the aqueous hydrogen peroxide solution uniformly, and carrying out ultrasonic reaction, filtering and freeze-drying to obtain the catalyst. The preparation process is simple and low in cost; the obtained monoatomic transition metal doped carbon nitride quantum dots have uniform particle size distribution, good biocompatibility and great potential in the aspects of biological sterilization and wound inflammation diminishing.
Description
Technical Field
The invention relates to a monoatomic transition metal doped carbon nitride quantum dot, a chemical cutting preparation method and application thereof in a water phase, and belongs to the technical field of material synthesis.
Background
Diseases associated with bacterial infections represent a serious threat to human health. In order to eliminate infectious bacteria, conventional antibiotics have been widely used, which results in the production of many drug-resistant bacteria or superbacteria that are highly resistant to common antibiotics and thus are not killed, which makes it urgently necessary to develop novel antibacterial agents having good biocompatibility for treating diseases caused by drug-resistant bacteria. At present, the transition metal is widely applied in the antibacterial field, the DNA or protein of bacteria is damaged by transition metal ions released from transition metal nanoparticles to achieve the bactericidal effect, but the large loss of the transition metal ions in the bactericidal process causes harm to normal organisms. In addition, the U.S. environmental protection agency affirmed the broad-spectrum antibacterial properties of transition metals in 2008.
The prior art reports about transition metal/carbon nitride nano composite materials with bactericidal and bacteriostatic properties. For example, chinese patent document CN112850686a discloses a fenton-like copper monoatomic/aza-carbon nanomaterial and a preparation method and application thereof, which includes firstly stirring at normal temperature to obtain ZIF-8, then performing first high-temperature calcination to obtain nitrogen-doped porous carbon, and then introducing a copper-containing compound and performing second high-temperature calcination to obtain copper monoatomic/nitrogen-doped porous carbon Cu-N4. The Cu-N prepared by the invention 4 The nano material can realize the antibacterial therapy combining photo-thermal therapy and nano enzyme therapy. But can not be in close contact with bacteria due to the size of the material, so that the generated short-life hydroxyl free radicals are volatile during the moving process, and the Cu-N is reduced 4 The antibacterial effect of the nano enzyme. Chinese patent document CN114669317A discloses a nano enzyme with multi-stage enzyme-linked reaction performance, and a preparation method and application thereof. The nano enzyme is Cu/g-C 3 N 4 By modifying Cu to g-C 3 N 4 And (4) obtaining the nano-particles on the nano-chip. The preparation method comprises the following steps: mixing a Cu metal precursor with g-C 3 N 4 Adding the nanosheets into water, mixing and stirring uniformly, and drying to obtain a mixture; and sequentially calcining the mixture in an inert atmosphere, cooling, washing and drying to obtain the nano enzyme with the multi-stage enzyme-linked reaction performance. But is composed ofIn the preparation of Cu/g-C 3 N 4 Only surface copper atoms of the nano enzyme are used as active sites for reaction, so that the utilization rate of the copper atoms is reduced.
The carbon nitride quantum dots are zero-dimensional semiconductor nano-materials composed of layered heptazine units, and have the characteristics of large specific surface area, no toxicity and good compatibility; the structural characteristics of the metal ion-coated porous material make the metal ion-coated porous material hopeful to be an ideal matrix for coating metal ions. However, the main preparation methods of the carbon nitride quantum dots at present include an ultrasonic method, a hydrothermal method, an acid etching method and the like. For example by Wang et al using blocks F-C 3 N 4 Preparing F-C by long-time ultrasonic crushing in glycol 3 N 4 And (4) quantum dots. Zhou et al prepared carbon nitride quantum dots by a sulfuric acid etch of bulk carbon nitride, thereby enhancing electrocatalytic properties. Zheng et al prepared carbon nitride quantum dots using urea and sodium citrate at lower hydrothermal temperatures. However, conventional synthesis processes can result in random breakage of chemical bonds due to mechanical forces or acid etching, which can lead to breakage of transition metal-nitrogen coordination bonds in bulk transition metal-doped carbon nitride cavities, resulting in loss of transition metal encapsulated in the carbon nitride matrix.
Therefore, the research and development of a non-toxic nano material with high-efficiency broad-spectrum antibacterial property is urgently needed, and the vicious circle of the use of antibiotics on organisms can be reduced.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a monatomic transition metal doped carbon nitride quantum dot, and a chemical cutting preparation method and application thereof in a water phase. The preparation process is simple and low in cost; the obtained monoatomic transition metal doped carbon nitride quantum dots have uniform particle size distribution, good biocompatibility and great potential in the aspects of biological sterilization and wound inflammation diminishing.
The invention is realized by the following technical scheme:
a monoatomic transition metal doped carbon nitride quantum dot, wherein the monoatomic transition metal is doped into the carbon nitride quantum dot through coordination with nitrogen; the grain diameter of the monoatomic transition metal doped carbon nitride quantum dot is 3-5nm.
According to the invention, the doping amount of the monoatomic transition metal is preferably 1 to 3wt%. The doping amount refers to the mass content of the monoatomic transition metal in the monoatomic transition metal-doped carbon nitride quantum dots.
The chemical cutting preparation method of the monatomic transition metal doped carbon nitride quantum dot comprises the following steps:
(1) Dissolving a nitrogen source and a transition metal salt in dimethyl sulfoxide (DMSO) as a solvent to obtain a solution A; fully dispersing cyanuric acid in dimethyl sulfoxide (DMSO) as a solvent to obtain a solution B; fully and uniformly mixing the solution B and the solution A to obtain a reaction solution, then carrying out ultrasonic reaction, filtering, washing and drying to obtain a supramolecular precursor; then calcining to prepare bulk monatomic transition metal doped carbon nitride;
(2) Fully mixing and uniformly dispersing the block monatomic transition metal doped carbon nitride and aqueous hydrogen peroxide, and carrying out ultrasonic reaction, filtering and freeze-drying to obtain the monatomic transition metal doped carbon nitride quantum dot.
Preferably, in step (1), the nitrogen source is one or a combination of two or more of urea, cyanamide, dicyandiamide and melamine; preferably, the nitrogen source is melamine.
Preferably, in step (1), the transition metal salt is one or a combination of two or more of ferric chloride, ferric nitrate, ferric sulfate, cupric chloride, cupric nitrate, cupric sulfate, manganese chloride, manganese nitrate, manganese sulfate, cobalt chloride, cobalt nitrate, cobalt sulfate, zinc chloride, zinc nitrate, zinc sulfate, silver chloride, silver nitrate, silver sulfate, nickel chloride, nickel nitrate or nickel sulfate; preferably, the transition metal salt is a copper salt; most preferably, the transition metal salt is copper nitrate.
Preferably, in step (1), the mass ratio of the transition metal salt to the melamine is: (0.01-10): (0.01-1000); preferably, the mass ratio of the transition metal salt to the melamine is: (0.01-10): (0.01-500).
Preferably, in step (1), the volume ratio of the solvent in solution a to the solvent in solution B is: (0.5-1.5): (0.5-1.5); in the reaction liquid, the mass ratio of cyanuric acid to solvent is: (0.1-20): (1-50) g/mL; preferably, the ratio of mass of cyanuric acid to volume of solvent is: (0.1-20): (1-40) g/mL.
Preferably, in step (1), the mass ratio of melamine to cyanuric acid is: (0.1-1): (0.1-10).
Preferably, in the step (1), the ultrasonic reaction temperature is room temperature, and the ultrasonic reaction time is 10-180 min; preferably, the ultrasonic reaction time is 10-120 min; most preferably, the sonication reaction time is 60min.
Preferably, according to the present invention, in step (1), the calcination conditions are: under the protection of gas, the calcining temperature is 200-1000 ℃, and the calcining time is 1-12 h; preferably, the gas is nitrogen, argon or helium, the calcining temperature is 500-800 ℃, and the calcining time is 2-5 h; most preferably, the calcination temperature is 500 ℃ and the calcination time is 3 hours.
According to a preferred embodiment of the present invention, in the step (2), the aqueous hydrogen peroxide solution has a concentration of 10 to 30% by mass.
Preferably, in step (2), the ratio of the mass of the bulk monatomic transition metal-doped carbon nitride to the volume of the aqueous hydrogen peroxide solution is: 0.1; preferably, the mass ratio of the bulk monatomic transition metal doped carbon nitride to the volume ratio of the aqueous hydrogen peroxide solution is: 0.1.
Preferably, in the step (2), the ultrasonic reaction temperature is room temperature, and the ultrasonic reaction time is 4.5-36 h; preferably, the ultrasonic reaction time is 5-8 h; most preferably, the sonication reaction time is 5h.
According to the invention, in the step (2), the freeze-drying time is 5-120 h; preferably, the freeze drying time is 5 to 60 hours; most preferably, the freeze-drying time is 24h.
The application of the monoatomic transition metal doped carbon nitride quantum dot is used for sterilization or bacteriostasis of escherichia coli, staphylococcus aureus or rhizoctonia solani.
The invention has the following technical characteristics and beneficial effects:
1. the invention adopts melamine, transition metal salt and cyanuric acid to form a supermolecule precursor. Firstly, the transition metal is connected with nitrogen in melamine in a coordination manner; then cyanuric acid is connected with melamine through hydrogen bonds to form a supramolecular precursor, transition metal is embedded into a triazine ring cavity, and more complete precursor can be constructed by melamine and cyanuric acid in a proper proportion; then calcining at 550 ℃ to prepare the bulk monatomic transition metal doped carbon nitride.
2. According to the invention, a Fenton-like reaction is utilized, and a hydroxyl radical generated in situ by hydrogen peroxide attacks and chemically cuts a C-N = C structural unit on a block monoatomic transition metal doped carbon nitride heptazine ring in a free path of 2nm, so that the block monoatomic transition metal doped carbon nitride heptazine ring is broken, and the doped transition metal is prevented from being damaged and lost. The free path is reduced when the concentration of the hydroxyl free radical is high, and the free path is increased when the concentration is low, so that the bulk monatomic transition metal doped carbon nitride is decomposed to generate monatomic transition metal doped carbon nitride quantum dots with the size of about 3-5nm.
3. The monatomic transition metal doped carbon nitride quantum dot prepared by the invention has a structure that an abundant 'nitrogen tank' consisting of six nitrogen atoms in the carbon nitride quantum dot provides a large amount of active capture sites to coordinate with the monatomic transition metal; and simultaneously, sp2 hybridization is carried out on carbon and nitrogen atoms in the heptazine ring structure, so that an n-conjugated system with high delocalization is formed, the on-ring electron transmission is facilitated, the electron transfer is enhanced, and the peroxidase activity of the quantum dots is improved.
4. The preparation process is simple and low in cost; the obtained quantum dots have uniform particle size and are nontoxic. The prepared monoatomic transition metal-doped carbon nitride quantum dot enzyme-like catalytic system not only gives full play to the bactericidal performance of monoatomic transition metal, but also is cooperated with the carbon nitride quantum dot to further improve the bactericidal performance, avoids the damage of transition metal loss to organisms, and has great application potential in the aspects of biological sterilization and wound inflammation diminishing. It can penetrate the cell membrane of bacteria and enter the thallus, and the produced strong oxidative hydroxyl free radicals can destroy the DNA or protein of the bacteria.
5. Compared with the existing transition metal/carbon nitride composite nano material, the monoatomic transition metal-doped carbon nitride quantum dot has the advantages of higher transition metal atom utilization rate, stronger catalytic bactericidal activity and lower toxicity to organisms.
Drawings
Fig. 1 is a Transmission Electron Microscope (TEM) image of the bulk monatomic transition metal-doped carbon nitride prepared in example 1.
FIG. 2 is a (a) spherical aberration electron microscopy (HAADF-STEM) and (b) - (f) energy dispersive spectroscopy (STEM-EDS) of different elements for bulk monatomic transition metal-doped carbon nitride prepared in example 1.
Fig. 3 is a Transmission Electron Microscope (TEM) image of the monatomic transition metal-doped carbon nitride quantum dot prepared in example 1.
Fig. 4 is a spherical aberration microscope (STEM) plot of the monatomic transition metal-doped carbon nitride quantum dots prepared in example 1.
Fig. 5 is a particle size distribution diagram of the monoatomic transition metal-doped carbon nitride quantum dot prepared in example 1. Wherein, the abscissa is the particle size and the ordinate is the ratio.
Fig. 6 is a Cu spectrum of X-ray photoelectron spectroscopy (XPS) of the monoatomic transition metal-doped carbon nitride quantum dot prepared in example 1. Wherein the abscissa is the binding energy and the ordinate is the strength.
Fig. 7 is a graph of (a) Cu L3-edge normalized XANES spectra and (b) fourier EXAFS spectra in R-space of the monatomic transition metal-doped carbon nitride quantum dots prepared in example 1. Wherein, the abscissa in the graph (a) is binding energy, and the ordinate is an X-ray absorption near-edge structure; in the graph (b), the abscissa is the shell interval and the ordinate is the extended X-ray absorption fine structure.
Fig. 8 is a Transmission Electron Microscope (TEM) image of bulk carbon nitride without transition metal doping prepared in comparative example 1.
FIG. 9 is a Transmission Electron Microscope (TEM) pattern of the transition metal-doped carbon nitride materials prepared in comparative examples 3 to 7.
FIG. 10 is a graph showing the comparison of the survival rate of the E.coli cells incubated under different conditions in test example 1. Wherein the ordinate is the survival rate.
FIG. 11 is a graph showing the antibacterial effects of the monatomic transition metal-doped carbon nitride quantum dot prepared in example 1 and different nanomaterials and antibiotics on Escherichia coli and Staphylococcus aureus. Wherein the ordinate is the logarithm of the inactivation rate, E.coli is escherichia coli, and S.aureus is staphylococcus aureus.
FIG. 12 is a graph showing the comparison of the survival rate of Staphylococcus aureus cultured under different conditions in test example 2. Wherein the ordinate is the survival rate.
FIG. 13 is a photograph of different concentrations of the monoatomic transition metal-doped carbon nitride quantum dots prepared in example 1 incubated with Rhizoctonia solani under hydrogen peroxide in Experimental example 3.
Fig. 14 is a cytotoxicity test chart of the monoatomic transition metal-doped carbon nitride quantum dot prepared in example 1. Wherein, the abscissa is the concentration of the monatomic transition metal doped carbon nitride quantum dots, and the ordinate is the cell survival rate.
Detailed Description
The present invention is further illustrated by, but is not limited to, the following specific examples.
The raw materials used in the following examples are all commercially available products and analytically pure.
Example 1
A chemical cutting preparation method of a monatomic transition metal doped carbon nitride quantum dot comprises the following steps:
(1) Sequentially adding 0.5g of copper nitrate and 2g of melamine into 10mL of DMSO (dimethyl sulfoxide) solvent, and fully dissolving to obtain a solution A; adding 2g of cyanuric acid into 10mL of DMSO, and fully dispersing to form a solution B; and then adding the solution B into the solution A under magnetic stirring, carrying out ultrasonic treatment at room temperature for 60min, alternately washing precipitates obtained after centrifugation by using ethanol and deionized water to remove residual impurities, and drying at 60 ℃ for 12h to obtain the supramolecular precursor. The supramolecular precursor was placed in an alumina crucible with lid and heated at 500 ℃ for 3h under a nitrogen flow line (5 ℃/min). And finally, cooling to room temperature to obtain the bulk monatomic transition metal doped carbon nitride. The TEM topography of the bulk monatomic transition metal doped carbon nitride is shown in FIG. 1 and is of a sheet structure; HAADF-STEM image and EDS element mapping image as in fig. 2, successful loading of Cu element was demonstrated, with N element, C element, O element and Cu element uniformly distributed in the carbon nitride sheet structure.
(2) In a medium containing 5mL of 30% by mass of H 2 O 2 Adding 0.1g of block monoatomic transition metal doped carbon nitride into the aqueous solution, stirring the suspension until the mixture is uniformly mixed and dispersed, then carrying out ultrasonic treatment at room temperature for 5 hours, carrying out centrifugal filtration on the generated suspension, and carrying out freeze drying for 24 hours to obtain monoatomic copper doped carbon nitride quantum dots (Cu-CNQDs).
In the monatomic copper-doped carbon nitride quantum dot prepared in this example, the doping amount of the monatomic transition metal was 1.21wt%.
A Transmission Electron Microscope (TEM) spectrum of the monatomic transition metal-doped carbon nitride quantum dot prepared in this example is shown in fig. 3, and it can be seen in the transmission image of fig. 3 that the prepared quantum dot has a small size and a uniform particle size.
The observation of the single-atom copper-doped carbon nitride quantum dots Cu-CNQDs prepared in example 1 by a double-spherical aberration correction electron microscope confirms that the single-atom sites of the single-atom copper-doped carbon nitride quantum dots Cu-CNQDs are shown in FIG. 4. As shown in fig. 4 (a), metal luster bright spots obviously distributed in the monatomic carbon nitride quantum dots Cu-CNQDs can be observed from the HAADF-STEM image under a spherical aberration electron microscope, and after the metal luster bright spots are locally re-amplified, cu monatomic metal sites can be clearly seen under an atomic scale and are uniformly distributed in the carbon nitride quantum dot matrix, as shown in fig. 4 (b).
The particle size distribution of the monoatomic copper-doped carbon nitride quantum dots can be seen from the particle size distribution diagram in fig. 5, and is between 3 and 4.5 nm.
The Cu spectrum of X-ray photoelectron spectroscopy (XPS) of the monatomic copper-doped carbon nitride quantum dot prepared in this example is shown in fig. 6, and it can be seen that copper exists in valence states of +1 and +2. The peaks of the Cu 2p XPS spectrum consist of two peaks at Cu 2p3/2 (932.46 and 934.80 eV) and Cu 2p1/2 (952.46and 954.70eV), and the deconvolution results of the peaks of the XPS spectrum show that Cu species in the monatomic carbon nitride quantum dots Cu-CNQDs prepared in example 1 are oxidized, the peak positions at 934.80eV and 954.70eV correspond to Cu2+, the peak positions at 932.46eV and 952.46eV belong to Cu +, which is attributed to the electron interaction between the Cu monatomic and the carbon nitride quantum dot matrix.
The local coordination of Cu monoatomic atoms of Cu foil and the monoatomic copper-doped carbon nitride quantum dots of example 1 was investigated using X-ray absorption spectroscopy (XAS) tests, as shown in fig. 7a, b. FIG. 7a shows the XANES spectrum of Cu L3 side of the monatomic carbon nitride quantum dots Cu-CNQDs prepared in Cu foil and example 1, wherein the absorption side of the Cu-CNQDs is located at Cu 2 Between O and CuO, it is shown that the oxidation state of Cu atoms in Cu-CNQDs is higher than Cu + and lower than Cu2+. In FIG. 7b the Fourier transform k3 weighted FT-EXAFS spectra of Cu-CNQDs are shown in
Shows a dominant peak due mainly to scattering interactions between Cu and the first shell N atoms. The result of combining a spherical aberration electron microscope further proves that the copper metal atoms are loaded on the carbon nitride quantum dot matrix in the form of monoatomic Cu.
Example 2:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: copper nitrate is replaced by copper chloride in the step (1); the other steps and conditions were identical to those of example 1.
Example 3:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: copper sulfate is used for replacing copper nitrate in the step (1); the other steps and conditions were identical to those of example 1.
Example 4:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: stirring at room temperature for 120min in the step (1); the other steps and conditions were identical to those of example 1.
Example 5:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: replacing nitrogen with argon in the gas introduced into the tubular furnace in the step (1); the other steps and conditions were identical to those of example 1.
Example 6:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: replacing nitrogen with helium in the gas introduced into the tubular furnace in the step (1); the other steps and conditions were identical to those of example 1.
Example 7:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: in the step (1), the calcining temperature in the tubular furnace is 400 ℃; the other steps and conditions were identical to those of example 1.
Example 8:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: the calcining temperature in the tubular furnace is 600 ℃; the other steps and conditions were identical to those of example 1.
Example 9:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: the calcining temperature in the tubular furnace is 700 ℃; the other steps and conditions were identical to those of example 1.
Example 10:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: the reaction time in the tubular furnace in the step (1) is 1h; the other steps and conditions were identical to those of example 1.
Example 11:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: the reaction time in the tubular furnace in the step (1) is 3h; the other steps and conditions were identical to those of example 1.
Example 12:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: the reaction time in the tubular furnace in the step (1) is 4h; the other steps and conditions were identical to those of example 1.
Example 13:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: the dosage of the aqueous hydrogen peroxide solution in the step (2) is 2mL; the other steps and conditions were identical to those of example 1.
Example 14:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: the dosage of the aqueous hydrogen peroxide solution in the step (2) is 4mL; the other steps and conditions were identical to those of example 1.
Example 15:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: the dosage of the aqueous hydrogen peroxide solution in the step (2) is 6mL; the other steps and conditions were identical to those of example 1.
Example 16:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: the dosage of the aqueous hydrogen peroxide solution in the step (2) is 10mL; the other steps and conditions were identical to those of example 1.
Example 17:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: the adding amount of the blocky transition metal doped carbon nitride in the step (2) is 0.2g; the other steps and conditions were identical to those of example 1.
Example 18:
a chemical cutting preparation method of monatomic transition metal doped carbon nitride quantum dots, as described in example 1, except that: the adding amount of the blocky transition metal doped carbon nitride in the step (2) is 0.5g; the other steps and conditions were identical to those of example 1.
Example 19:
a chemical cutting preparation method of a monoatomic transition metal doped carbon nitride quantum dot, which is as described in example 1, except that: the adding amount of the blocky transition metal doped carbon nitride in the step (2) is 1.5g; the other steps and conditions were identical to those of example 1.
Comparative example 1:
a method of making a carbon nitride material, as described in example 1, except that: copper nitrate is not added in the step (1); the other steps and conditions were identical to those of example 1.
The specific method comprises the following steps:
(1) Adding 2g of melamine into 10mL of DMSO (dimethylsulfoxide) solvent, and fully dissolving to obtain a solution A; adding 2g of cyanuric acid into 10mL of DMSO, and fully dispersing to form a solution B; and then adding the solution B into the solution A under magnetic stirring, carrying out ultrasonic treatment at room temperature for 60min, alternately washing precipitates obtained after centrifugation by using ethanol and deionized water to remove residual impurities, and drying at 60 ℃ for 12h to obtain the supramolecular precursor. The supramolecular precursor was placed in an alumina crucible with a lid and heated at 500 ℃ for 3h under a nitrogen stream line flow (5 ℃/min). And finally, cooling to room temperature to obtain the bulk carbon nitride.
(2) In a medium containing 5mL of 30% by mass of H 2 O 2 Adding 0.1g of bulk carbon nitride into the aqueous solution, stirring the suspension until the mixture is uniformly mixed and dispersed, then carrying out ultrasonic treatment at room temperature for 5 hours, carrying out centrifugal filtration on the generated suspension, and carrying out freeze drying for 24 hours to obtain the carbon nitride material.
In the transmission image of FIG. 8, it can be seen that the morphology of bulk carbon nitride of undoped transition metal copper does not change much; but finally, quantum dots are prepared without chemical cutting, which shows that the transition metal plays an important role in the self-cutting process.
Comparative example 2:
a method of preparing Carbon Nitride Quantum Dots (CNQDs), as in comparative example 1, except that: step (2) was changed to 1g of the bulk carbon nitride material was stirred in a mixture of 20mL of concentrated sulfuric acid (98 wt%) and 20mL of concentrated nitric acid (68 wt%) at room temperature for about 2 hours, centrifuged, washed to neutrality with deionized water and dried. 100mg of the product was dispersed in 30ml of aqueous ammonia solution (25 wt%), and then the mixed suspension was transferred to a 50ml autoclave and heated at 180 ℃ for 12 hours, cooled to room temperature, sonicated for about 6 hours, and freeze-dried to give CNQDs.
Comparative example 3:
a method of making a monatomic transition metal doped carbon nitride material, as described in example 1, except that: the ultrasonic time in the step (2) is 0h; the other steps and conditions were identical to those of example 1.
The result is shown in fig. 9a, where the bulk monatomic transition metal doped carbon nitride is a complete sheet structure.
Comparative example 4:
a method of making a monatomic transition metal-doped carbon nitride material, as described in example 1, except that: the ultrasonic time in the step (2) is 1h; the other steps and conditions were identical to those of example 1.
The sharp edges of the monatomic transition metal doped carbon nitride nanoplates blurred after 1h of sonication, as shown in fig. 9b, due to contact with hydrogen peroxide; but the ultrasound and action time are too short, and the carbon quantum dots can not be obtained by chemical cutting.
Comparative example 5:
a method of making a monatomic transition metal-doped carbon nitride material, as described in example 1, except that: the ultrasonic time in the step (2) is 2h; the other steps and conditions were identical to those of example 1.
The in situ generated OH will form many pores on the basal planes of the monatomic transition metal-doped carbon nitride nanosheets (fig. 9 c). These pores act as capillaries, allowing H 2 O 2 Sufficient penetration is facilitated, which is beneficial to the self-cutting process of the monatomic transition metal doped carbon nitride nanosheet and the formation of a defect n-conjugated network; but the ultrasound and the action time are too short, so that the carbon quantum dots cannot be obtained by chemical cutting.
Comparative example 6:
a method of making a monatomic transition metal-doped carbon nitride material, as described in example 1, except that: the ultrasonic time in the step (2) is 3h; the other steps and conditions were identical to those of example 1.
As a result, as shown in fig. 9d, more and more pores appear on the surface of the monatomic transition metal-doped carbon nitride nanosheet, resulting in disappearance of the typical planar morphology; but the ultrasound and the action time are too short, so that the carbon quantum dots cannot be obtained by chemical cutting.
Comparative example 7:
a method of making a monatomic transition metal-doped carbon nitride material, as described in example 1, except that: the ultrasonic time in the step (2) is 4h; the other steps and conditions were identical to those of example 1. From the transmission diagram of fig. 9e, it can be seen that the monatomic transition metal doped carbon nitride nanosheets are split into nano-dot structures during the self-trimming process; but the ultrasound and the action time are insufficient, and carbon quantum dots with uniform particle size cannot be obtained.
Test example 1: escherichia coli bacteriostatic performance test
And (5) carrying out bacteriostatic performance test on the escherichia coli.
(1) Inoculating Escherichia coli in LB culture medium, and culturing at 37 deg.C for 200r min -1 Shake culturing for 12h, diluting the bacterial liquid, and determining the bacterial suspension concentration to be 10 7 CFU/mL. Six groups of 10mL diluted pathogenic escherichia coli liquid are taken, wherein one group is added with 100 mu L of the monoatomic transition metal doped carbon nitride quantum dot aqueous solution (20 mu g/mL) prepared in the example 1 and 100 mu L of 1mM H 2 O 2 Culturing in water solution under dark condition for 4 hr, spreading 100 μ L of the bacterial solution on LB solid medium, culturing in thermostat at 37 deg.C for 12 hr, and counting plate colonies. The above settings are Cu-CNQDs + H 2 O 2 And (4) grouping.
(2) The method according to (1) above, except that: the sample was replaced with the bulk monatomic transition metal doped carbon nitride prepared in example 1. The above arrangement is Cu-CN + H 2 O 2 And (4) grouping.
(3) The method according to (1) above, except that: without addition of H 2 O 2 And (4) adding the aqueous solution of the quantum dots, and then placing the quantum dots under the illumination condition (36 WLED lamp). The above settings are for the Cu-CNQDs + light group.
(4) The method according to (1) above, except that: the sample was replaced with the bulk monatomic transition metal doped carbon nitride prepared in example 1 without the addition of H 2 O 2 An aqueous solution. The above settings are Cu-CN groups.
(5) The method according to (1) aboveThe difference is that: without addition of H 2 O 2 An aqueous solution. The above settings are set as Cu-CNQDs groups.
(6) The method according to (1) above, except that: the aqueous solution of the sample is not added, only H 2 O 2 An aqueous solution. The above arrangement is H 2 O 2 And (4) grouping.
(7) The method according to (1) above, except that: without addition of aqueous sample solution, without addition of H 2 O 2 An aqueous solution. The above was set as a Control group (Control).
(8) According to the method of the above (1), except that: the sample was replaced with the carbon nitride material prepared in comparative example 2. The above setting is CNQDs + H 2 O 2 And (4) grouping.
(9) According to the method of the above (1), except that: the sample was replaced with the carbon nitride material prepared in comparative example 2 without addition of H 2 O 2 An aqueous solution. The above is set as the group CNQDs.
Calculating the survival rate of the escherichia coli, and evaluating the bacteriostatic performance; plate colony count of control group was recorded as A 0 And the colony number of the plate added with the sample is recorded as At, the survival rate of the Escherichia coli is calculated according to the following formula: survival rate (%) = a t /A 0 ×100％。
FIG. 10 is a graph showing the survival rate of E.coli bacteria liquid incubated with the monatomic transition metal-doped carbon nitride quantum dots prepared in example 1 and the carbon nitride quantum dots prepared in comparative example 2 under different conditions, wherein the sterilization rate of the monatomic copper carbon nitride quantum dots to E.coli under the condition of light or hydrogen peroxide is more than 99%.
Through further tests, the minimum inhibitory concentration of the monoatomic transition metal-doped carbon nitride quantum dot prepared in example 1 to Escherichia coli is 20 mug/mL.
FIG. 11 shows the single atom transition metal doped carbon nitride quantum dots and different nano materials (Ag, tiO) prepared in example 1 under the same experimental method (i.e., the method in Experimental example 1 (1)) ( 2 ) And antibiotic (van, vancomycin) on Escherichia coli, wherein con is a blank group, namely, an aqueous solution without a sample; finds the antibacterial effect of the monoatomic copper carbon nitride quantum dot Cu-CNQDsThe result is optimal.
Test example 2: staphylococcus aureus antibacterial performance test
The method for testing the bacteriostatic property of staphylococcus aureus is described in test example 1.
Fig. 12 is a graph comparing the survival rates of staphylococcus aureus bacteria solutions incubated by the monatomic transition metal-doped carbon nitride quantum dots prepared in example 1 and the carbon nitride quantum dots prepared in comparative example 2 under different conditions, and the sterilization rate of the monatomic copper carbon nitride quantum dots to staphylococcus aureus under the condition of light or hydrogen peroxide is more than 99%.
Through further tests, the minimum inhibitory concentration of the monatomic transition metal-doped carbon nitride quantum dot prepared in example 1 on staphylococcus aureus is 20 mug/mL.
FIG. 11 shows the single atom transition metal doped carbon nitride quantum dots and different nano materials (Ag, tiO) prepared in example 1 under the same experimental method (i.e., the method in Experimental example 1 (1)) ( 2 ) And antibiotic (van, vancomycin) against staphylococcus aureus, wherein con is a blank group, i.e. an aqueous solution without a sample; the single-atom copper carbon nitride quantum dot Cu-CNQDs are found to have the optimal antibacterial effect.
Test example 3: test of bacteriostatic property of Rhizoctonia solani
The monoatomic transition metal-doped carbon nitride quantum dots in example 1 were subjected to bacteriostatic performance tests on rhizoctonia solani.
All containers were autoclaved at 121 ℃ for 20 minutes. Rhizoctonia solani was cultured in 3.8% (m/v) PDA medium. Adding copper-doped carbon nitride quantum dots with different concentrations (the concentrations of the quantum dots in the culture medium), stirring at 300rpm for 10min, and mixing uniformly; 10 μ L of 0.1mM H was added 2 O 2 Mixing the aqueous solution uniformly; incubate at 28 ℃ for 12h. Growth of plaque was estimated by measuring plaque diameter. And meanwhile, setting a control group without adding copper doped carbon nitride quantum dots. FIG. 13 is a photo of a plate of Rhizoctonia solani incubated by using different concentrations of the monatomic transition metal-doped carbon nitride quantum dots under the condition of hydrogen peroxide, and it can be seen from the photo that the optimal inhibitory concentration of the Rhizoctonia solani is 100. Mu.g/mL.
Test example 4: cytotoxicity test
The monatomic transition metal-doped carbon nitride quantum dots in example 1 were subjected to cytotoxicity tests on HeLa cells.
HeLa cells were incubated with 0-200. Mu.g/mL of the aqueous solution of Cu-CNQDs prepared in example 1 at 37 ℃ for 6 or 12h. 200mL of fresh medium containing 20mL MTT (5 mg/mL in PBS) was then added and incubated for 4 hours at 37 ℃. Finally, 150ml DMSO was added to dissolve the purple crystalline formazan formed. The optical density was measured using a microplate reader at 570nm with pure DMSO as blank. Cytotoxicity after each treatment can be expressed as a percentage of cell viability relative to untreated control cells.
As a result, as shown in fig. 14, it was experimentally found that the monoatomic copper carbon nitride quantum dot prepared in example 1 was almost non-toxic to HeLa cells.
Claims (10)
1. A monoatomic transition metal doped carbon nitride quantum dot is characterized in that the monoatomic transition metal is doped into the carbon nitride quantum dot through coordination with nitrogen; the grain diameter of the single-atom transition metal doped carbon nitride quantum dot is 3-5nm.
2. The monatomic transition metal-doped carbon nitride quantum dot of claim 1, wherein the amount of monatomic transition metal doping is 1-3wt%.
3. The method for preparing the monatomic transition metal doped carbon nitride quantum dot in the water phase by chemical cutting according to any one of claims 1 or 2, comprising the steps of:
(1) Dissolving a nitrogen source and a transition metal salt in dimethyl sulfoxide (DMSO) as a solvent to obtain a solution A; fully dispersing cyanuric acid in dimethyl sulfoxide (DMSO) as a solvent to obtain a solution B; fully and uniformly mixing the solution B and the solution A to obtain a reaction solution, and then carrying out ultrasonic reaction, filtering, washing and drying to obtain a supramolecular precursor; then calcining to prepare bulk monatomic transition metal doped carbon nitride;
(2) Fully mixing and uniformly dispersing the block monatomic transition metal doped carbon nitride and aqueous hydrogen peroxide, and carrying out ultrasonic reaction, filtering and freeze-drying to obtain the monatomic transition metal doped carbon nitride quantum dot.
4. The chemical tailoring method for preparing monatomic transition metal doped carbon nitride quantum dots in aqueous phase according to claim 3, wherein step (1) comprises one or more of the following conditions:
i. the nitrogen source is one or the combination of more than two of urea, cyanamide, dicyandiamide or melamine; preferably, the nitrogen source is melamine;
ii. The transition metal salt is one or a combination of more than two of ferric chloride, ferric nitrate, ferric sulfate, cupric chloride, cupric nitrate, cupric sulfate, manganese chloride, manganese nitrate, manganese sulfate, cobalt chloride, cobalt nitrate, cobalt sulfate, zinc chloride, zinc nitrate, zinc sulfate, silver chloride, silver nitrate, silver sulfate, nickel chloride, nickel nitrate or nickel sulfate; preferably, the transition metal salt is a copper salt; most preferably, the transition metal salt is copper nitrate;
and iii, the mass ratio of the transition metal salt to the melamine is as follows: (0.01-10): (0.01-1000); preferably, the mass ratio of the transition metal salt to the melamine is: (0.01-10): (0.01 to 500);
iv, the volume ratio of the solvent in the solution A to the solvent in the solution B is (0.5-1.5) to (0.5-1.5); in the reaction liquid, the mass ratio of cyanuric acid to solvent is: (0.1-20): (1-50) g/mL; preferably, the ratio of mass of cyanuric acid to volume of solvent is: (0.1-20): (1-40) g/mL;
v, the mass ratio of melamine to cyanuric acid is: (0.1-1): (0.1-10).
5. The chemical cutting preparation method of the monoatomic transition metal-doped carbon nitride quantum dot in the water phase according to claim 3, wherein in the step (1), the ultrasonic reaction temperature is room temperature, and the ultrasonic reaction time is 10-180 min; preferably, the ultrasonic reaction time is 10-120 min; most preferably, the sonication reaction time is 60min.
6. The method for preparing the monatomic transition metal doped carbon nitride quantum dot in the chemical cutting in the water phase according to the claim 3, wherein in the step (1), the calcining condition is as follows: under the protection of gas, the calcining temperature is 200-1000 ℃, and the calcining time is 1-12 h; preferably, the gas is nitrogen, argon or helium, the calcining temperature is 500-800 ℃, and the calcining time is 2-5 h; most preferably, the calcination temperature is 500 ℃ and the calcination time is 3 hours.
7. The method for preparing the monoatomic transition metal-doped carbon nitride quantum dot according to claim 3, wherein the step (2) comprises one or more of the following conditions:
i. the mass concentration of the aqueous hydrogen peroxide solution is 10-30%;
ii. The mass ratio of the mass of the block monatomic transition metal doped carbon nitride to the volume of the aqueous hydrogen peroxide solution is as follows: 0.1; preferably, the mass ratio of the bulk monatomic transition metal doped carbon nitride to the volume ratio of the aqueous hydrogen peroxide solution is: 0.1:5g/mL.
8. The chemical cutting preparation method of the monoatomic transition metal-doped carbon nitride quantum dot in the water phase according to claim 3, wherein in the step (2), the ultrasonic reaction temperature is room temperature, and the ultrasonic reaction time is 4.5-36 h; preferably, the ultrasonic reaction time is 5-8 h; most preferably, the sonication reaction time is 5h.
9. The chemical cutting preparation method of the monoatomic transition metal doped carbon nitride quantum dot in the water phase according to claim 3, wherein in the step (2), the freeze-drying time is 5-120 h; preferably, the freeze drying time is 5 to 60 hours; most preferably, the freeze-drying time is 24h.
10. The use of the monatomic transition metal-doped carbon nitride quantum dot according to any one of claims 1 or 2, for the sterilization or bacteriostasis of escherichia coli, staphylococcus aureus, or rhizoctonia solani.
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| CN115770601A (en) * | 2021-09-08 | 2023-03-10 | 南京工业大学 | Cobalt-doped porous carbon nitride catalyst and preparation method and application thereof |
| CN116510777A (en) * | 2023-07-04 | 2023-08-01 | 江苏省农业科学院 | Plant microenvironment response type diatomic nanoenzyme and preparation method and application thereof |
| CN117587538A (en) * | 2024-01-17 | 2024-02-23 | 江苏青昀新材料有限公司 | Dissolution process of antibacterial and antioxidant composite modifier for flash evaporation cloth |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115770601A (en) * | 2021-09-08 | 2023-03-10 | 南京工业大学 | Cobalt-doped porous carbon nitride catalyst and preparation method and application thereof |
| CN116510777A (en) * | 2023-07-04 | 2023-08-01 | 江苏省农业科学院 | Plant microenvironment response type diatomic nanoenzyme and preparation method and application thereof |
| CN116510777B (en) * | 2023-07-04 | 2023-09-12 | 江苏省农业科学院 | Plant microenvironment response type diatomic nanoenzyme and preparation method and application thereof |
| CN117587538A (en) * | 2024-01-17 | 2024-02-23 | 江苏青昀新材料有限公司 | Dissolution process of antibacterial and antioxidant composite modifier for flash evaporation cloth |
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