A mesoporous rare earth composite antibacterial material and preparation method thereof

Abstract

The present invention provides a mesoporous rare earth composite antibacterial material and a preparation method thereof, the method comprising the following steps: step 1 is to mix dicyandiamide, guanidine hydrochloride and rare earth salt uniformly, add sulfuric acid thereto, stir under heating conditions, cool to room temperature after the reaction is complete, and obtain a mixture; step 2 is to put the mixture into an inner liner, and react in an autoclave, and obtain an intermediate after the reaction is completed; step 3 is to dry and calcine the intermediate to obtain the mesoporous rare earth composite antibacterial material. The mesoporous rare earth composite antibacterial material of the present invention is synthesized from dicyandiamide, guanidine hydrochloride and rare earth salt as raw materials. After acidification, the graphite phase carbon nitride formed by high temperature polycondensation of dicyandiamide and guanidine hydrochloride has many pore structures, which provides many sites for introducing rare earth ions, and thus increases the doping amount of rare earth elements on the surface of the two-dimensional material carbon nitride, thereby improving the antibacterial performance of the material.

Description

Technical Field

[0001] The invention belongs to the field of antibacterial, and in particular relates to a mesoporous rare earth composite antibacterial material and a preparation method thereof. Background Art

[0002] The development and application of new nanomaterials has become one of the important ways to solve the problem of drug-resistant bacterial infections today. Nanomaterials not only have a high specific surface area but also have special physical and chemical properties, which has attracted much attention. At present, nanomaterials used in the field of antibacterial can be divided into 0-3D nanomaterials according to their morphology. The antibacterial activity of traditional 0D materials (nanoparticles) and 1D materials (nanofibers / nanotubes) mainly comes from precious metals, including silver, gold, palladium and metal oxides such as ZnO, TiO 2 Two-dimensional (2D) nanomaterials are divided into metal-containing 2D materials and metal-free 2D materials. The former include transition metal sulfides (TMDs, such as MoS 2 ) and two-dimensional transition metal nitrides or carbides (MXenes). The latter include graphene and its derivatives, such as graphene oxide (GO) and reduced graphene oxide (RGO), graphitic carbon nitride (gC 3 N 4 In order to avoid direct or potential heavy metal contamination, metal-free 2D nanomaterials should be preferred in applications involving health and safety, such as the development of new antibacterial materials.

[0003] As an important metal-free carbon-based nanomaterial, g-C 3 N 4 It has a unique nanosheet structure and can be easily prepared by calcination from low-cost raw materials such as urea and melamine. The dense layered structure is formed by the polycondensation of tri-s-triazine units and assembled by van der Waals forces, which has high chemical inertness and structural stability. 3 N 4 In order to improve the antibacterial activity of carbon nitride and broaden its effective wavelength range, many studies have combined it with different nanomaterials, including metals or metal oxides, graphene and thioaluminum. On the other hand, two-dimensional nanomaterials such as graphene oxide, molybdenum disulfide and boron nitride can cause bacterial cell rupture and death by directly interacting with the cell membrane. Rare earth elements have special electron transition capabilities, and doping rare earth lanthanum into mesoporous two-dimensional carbon nitride can improve the antibacterial properties of the material. Summary of the invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and proposes a mesoporous rare earth composite antibacterial material and a preparation method thereof.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] The present invention provides a method for preparing a mesoporous rare earth composite antibacterial material, comprising the following steps:

[0007] Step 1 is to mix dicyandiamide, guanidine hydrochloride and rare earth salt uniformly, add sulfuric acid thereto, stir under heating conditions, and cool to room temperature after the reaction is complete to obtain a mixture;

[0008] Step 2 is to put the mixture into the liner and react in an autoclave to obtain an intermediate after the reaction is completed;

[0009] Step 3 is to dry and calcine the intermediate to obtain the mesoporous rare earth composite antibacterial material.

[0010] The reaction for preparing the mesoporous rare earth composite antibacterial material is shown in formula (I)-formula (II).

[0011]

[0012] Formula (I)

[0013]

[0014] Formula (II)

[0015] Furthermore, the rare earth salt in step 1 is a rare earth nitrate and / or a rare earth halide; the rare earth element in the rare earth salt in step 1 is at least one of lanthanum, cerium, gadolinium, yttrium or samarium; the rare earth salt in step 1 is La(NO 3 ) 3 •6H 2 O、Ce(NO 3 ) 3 •6H 2 O、Y(NO 3 ) 3 •6H 2 O.Gd(NO 3 ) 3 •6H 2 O、Sm(NO 3 ) 3 •6H 2 O,LaCl 3 •7H 2 O、CeCl 3 •6H 2 O, YCl 3 •6H 2 O, GdCl 3 •6H 2 O or SmCl 3 •6H 2 At least one of O.

[0016] Furthermore, the solid-to-liquid ratio of dicyandiamide, guanidine hydrochloride, rare earth salt and sulfuric acid in step 1 is 1-3 g: 1-4 g: 2-4 g: 1 mL; and the mass concentration of the sulfuric acid is 40-70%.

[0017] Preferably, the solid-to-liquid ratio of dicyandiamide, guanidine hydrochloride, rare earth salt and sulfuric acid in step 1 is 1 g:3 g:3 g:1 mL.

[0018] Furthermore, the temperature of the heating step in step 1 is 70-100°C.

[0019] Furthermore, the material of the lining in step 2 is polytetrafluoroethylene.

[0020] Furthermore, the reaction temperature in step 2 is 150-200° C. and the reaction time is 1-4 hours.

[0021] Furthermore, the calcination step in step 3 is carried out at a temperature of 500-600° C., for a time of 1-4 hours, and at a heating rate of 5-10° C. / min.

[0022] The invention also provides a mesoporous rare earth composite antibacterial material prepared by the preparation method.

[0023] The precursor dicyandiamide and guanidine hydrochloride generate triazine rings during high temperature stirring. The triazine ring further removes the terminal amino group under high temperature acidic conditions. The rare earth ions form coordination bonds with the nitrogen element of the triazine ring during the process of removing the amino group of the triazine ring. Further high temperature annealing and calcination are performed to finally form a composite material of rare earth and carbon nitride. The amino group removed from the terminal hinders the polymerization reaction. Secondly, the coordination bond formed by the rare earth and the nitrogen element forms a steric effect, which also blocks the polymerization reaction, so that the final reactant forms a porous state.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The mesoporous rare earth composite antibacterial material described in the present invention is synthesized using dicyandiamide, guanidine hydrochloride and rare earth salt as raw materials. After acidification, the graphite phase carbon nitride formed by high-temperature polycondensation of dicyandiamide and guanidine hydrochloride has a large number of pore structures, which provides a large number of sites for introducing rare earth ions. For this reason, the doping amount of rare earth elements on the surface of the two-dimensional material carbon nitride is increased, thereby improving the antibacterial performance of the material.

[0026] The mesoporous rare earth composite antibacterial material of the present invention has a high efficiency in disinfection and sterilization performance against Staphylococcus aureus after rare earth is loaded on the surface of porous carbon nitride. Compared with gC 3 N 4 and La 2 O3 The disinfection effect was improved by 1.88 and 1.1 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a Fourier infrared spectrum of the mesoporous rare earth composite antibacterial material described in Example 1 of the present invention;

[0028] Figure 2 This is the picture of the antibacterial test on a blank agar plate;

[0029] Figure 3 gC 3 N 4 Agar plate antibacterial test diagram;

[0030] Figure 4 For La 2 O 3 Agar plate antibacterial test diagram;

[0031] Figure 5 This is the antibacterial test picture of CN@La agar plate;

[0032] Figure 6 A statistical graph of bacterial survival rate of the mesoporous rare earth composite antibacterial material described in Example 1 of the present invention;

[0033] Figure 7 This is a scanning electron microscope spectrum of the mesoporous rare earth composite antibacterial material described in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0035] C 3 N 4 , hereinafter referred to as CN.

[0036] dicyandiamide, guanidine hydrochloride and sulfuric acid (H 2 SO 4 ) was purchased from Beijing Solebow Technology Co., Ltd., lanthanum sulfate hexahydrate was purchased from Shanghai MacLean Biochemical Technology Co., Ltd., sodium chloride, peptone, and yeast extract were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. All chemicals were used without further treatment, and distilled water (ρ=18.2 MΩ•cm, 25℃) was from Millipore milli-Q water purification system. In addition, 10.0 mM MES-NaOH buffer with pH=6.0 was prepared with distilled water using 10.0 mM MES and NaOH as raw materials. Gram-negative bacteria E. coliand Staphylococcus aureus S. aureus From Beijing Sihuan Biopharmaceutical Co., Ltd.

[0037] The present invention will be described in detail below with reference to the embodiments.

[0038] Example 1

[0039] A method for preparing a mesoporous rare earth composite antibacterial material comprises the following steps:

[0040] Dissolve 30 g of lanthanum sulfate hexahydrate in 20 mL of distilled water, add 10 g of dicyandiamide and 30 g of guanidine hydrochloride, stir evenly at room temperature, then add 10 mL of 60% sulfuric acid, stir at 90 ° C, cool to room temperature, put the mixture into a polytetrafluoroethylene liner, and then put it into an autoclave, react at 180 ° C for 3 hours to obtain an intermediate, dry the intermediate, and then place it in a crucible, put it into a muffle furnace, and calcine it at 550 ° C for 2 hours with a heating rate of 10 ° C / min to obtain a mesoporous rare earth composite antibacterial material.

[0041] Comparative Example 1

[0042] A method for preparing a two-dimensional CN comprises the following steps:

[0043] Dissolve 10 g of dicyandiamide and 30 g of guanidine hydrochloride in 20 mL of distilled water, add 10 mL of 60% sulfuric acid, stir at 90 °C, cool to room temperature, dry directly in the air, then place in a crucible, put in a muffle furnace and calcine at 550 °C for 2 h with a heating rate of 10 °C / min to obtain two-dimensional CN.

[0044] Comparative Example 2

[0045] A La 2 O 3 The preparation method comprises the following steps:

[0046] 10 g of lanthanum sulfate hexahydrate was dissolved in 20 mL of distilled water, 10 mL of 60% sulfuric acid was added, stirred at 90 °C, cooled to room temperature, dried directly in the air, then placed in a crucible, and calcined in a muffle furnace at 550 °C for 2 hours at a heating rate of 10 °C / min to obtain La 2 O 3 .

[0047] The CN@La prepared in Example 1 was tested by Fourier transform infrared spectroscopy. The results are as follows: Figure 1 As shown in the figure, it can be observed that after the introduction of rare earth lanthanum, the stretching vibration intensity of the terminal amino group inside the carbon nitride (3000-3500cm -1 ) weakened, and located at 1250-2000cm -1The absorption intensity of the carbon nitride increases, which indicates that the CNC bonds and C=N bonds of the heptazine ring in the carbon nitride increase. Therefore, it can be inferred that the rare earth lanthanum ions are connected to the nitrogen atoms at the end of the heptazine ring in the CN and hinder the formation of some heptazine rings, making the lanthanum element stable on the CN surface.

[0048] The mesoporous rare earth composite antibacterial material in Example 1 was tested by scanning electron microscopy. Figure 7 As shown, it can be found from the scanning spectrum (Mag 20.0kx, FoV 14.0μm, WD 5.48mm) that CN@La has a rough surface and is in a state of agglomeration of small particles (particle size is about 500nm), and a large number of void structures are distributed in the small particles. Therefore, the scanning electron microscope spectrum can fully prove that CN@La has a certain porosity, which is consistent with the mechanism of Example 1.

[0049] Preparation of Luria-Bertani (LB) agar medium: Add 10 g of peptone, 5 g of yeast extract and 10 g of sodium chloride to 1 L of water, stir evenly, put it in a high-temperature sterilizer for sterilization, let it stand and cool to room temperature, then seal the outer opening with a sealing film and put it in a 4°C insulated refrigerator for use.

[0050] Culture of Gram-negative Staphylococcus aureus S. aureus: A single MRSA colony was inoculated into LB agar medium and cultured at 37°C and 180 rpm for 14-16 h to obtain suspensions of different types of bacteria with an optical density at 600 nm (OD 600 ) is used to evaluate the UV absorption value of S. aureus The invention controls the OD 600 =0.4-0.6.

[0051] Agar plate antibacterial test: the raw materials CN and La 2 O 3 and CN@La were respectively reacted with S. aureus Suspension (OD 600 = 0.2) and mixed. After incubation at 37°C for 3 h, 0.2 mL of the diluted bacterial suspension was spread on LB agar and incubated at 37°C for 18 h. The survival rate of bacteria was determined by the standard plate count method and photos were taken.

[0052] Antibacterial test of CN@La agar plates with different concentrations: Raw materials CN@La (0.5 μM), CN@La (1 μM), CN@La (2 μM), CN@La (4 μM) and CN@La (8 μM) were respectively incubated with S. aureus suspension (OD 600=0.2) mixed. After incubation at 37℃ for 3 h, 0.2 mL of the diluted bacterial suspension was spread on LB agar and incubated at 37℃ for 18 h. The survival rate of bacteria was determined by the standard plate count method and photos were taken. It can be observed from the photos that when CN@La (4 μM) was selected, the disinfection effect was the best, so CN@La (4 μM) was selected as the control group for the agar plate antibacterial test.

[0053] For Staphylococcus aureus S. aureus The results of the agar plate antibacterial test are as follows Figure 2-Figure 6 As shown, it was clearly observed that Staphylococcus aureus was isolated from the single CN and La 2 O 3 The survival rates of CN and La were 47% and 10%, respectively. 2 O 3 for S. aureus The two-dimensional CN structure has different inhibitory effects on the growth of Staphylococcus aureus. When the lanthanum element is loaded into the two-dimensional CN structure, the antibacterial effect is significantly improved, and the survival rate of Staphylococcus aureus reaches 0%.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a mesoporous rare earth composite antibacterial material, characterized in that: The steps include: Step 1 is to mix dicyandiamide, guanidine hydrochloride and rare earth salt uniformly, add sulfuric acid thereto, stir under heating conditions, and cool to room temperature after the reaction is complete to obtain a mixture; Step 2 is to put the mixture into the liner and react in an autoclave to obtain an intermediate after the reaction is completed; Step 3 is drying and calcining the intermediate to obtain the mesoporous rare earth composite antibacterial material; The solid-to-liquid ratio of dicyandiamide, guanidine hydrochloride, rare earth salt and sulfuric acid in step 1 is 1-3 g: 1-4 g: 2-4 g: 1 mL; The calcination step in step 3 is carried out at a temperature of 500-600°C, for a time of 1-4 hours, and at a heating rate of 5-10°C / min; The rare earth salt in step 1 is a rare earth nitrate and / or a rare earth halide; the rare earth element in the rare earth salt in step 1 is at least one of lanthanum, cerium, gadolinium, yttrium or samarium; The material of the lining in step 2 is polytetrafluoroethylene.

2. The method for preparing the mesoporous rare earth composite antibacterial material according to claim 1, characterized in that: The rare earth salt in step 1 is at least one of La(NO3)3•6H2O, Ce(NO3)3•6H2O, Y(NO3)3•6H2O, Gd(NO3)3•6H2O, Sm(NO3)3•6H2O, LaCl3•7H2O, CeCl3•6H2O, YCl3•6H2O, GdCl3•6H2O or SmCl3•6H2O.

3. The method for preparing the mesoporous rare earth composite antibacterial material according to claim 1, characterized in that: The mass concentration of the sulfuric acid is 40-70%.

4. The method for preparing the mesoporous rare earth composite antibacterial material according to claim 1, characterized in that: The temperature of the heating step in step 1 is 70-100°C.

5. The method for preparing the mesoporous rare earth composite antibacterial material according to claim 1, characterized in that: The reaction temperature in step 2 is 150-200° C. and the reaction time is 1-4 hours.

6. A mesoporous rare earth composite antibacterial material prepared by the preparation method according to any one of claims 1 to 5.

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