CN115684127A - Activated carbon quantum dot composite nano-silver Raman-enhanced substrate, preparation method thereof and application thereof in detection of microcystins - Google Patents
Activated carbon quantum dot composite nano-silver Raman-enhanced substrate, preparation method thereof and application thereof in detection of microcystins Download PDFInfo
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Abstract
The invention belongs to the technical field of microcystin detection, and discloses an active carbon quantum dot composite nano silver Raman enhanced substrate, a preparation method thereof and application thereof in microcystin detection. The active carbon quantum dot composite nano silver Raman enhancement substrate comprises a nano silver particle inner core and an attached carbon quantum dot shell layer; the nano silver particle inner core is prepared by an optimized seed growth method, nano silver liquid with the particle size of about 20-30 nm is used as a crystallization center, a carbon quantum dot solution and a noble metal salt solution are added to generate the SERS enhanced substrate through reaction, the synthetic method is simple, and the nano silver particles cannot be aggregated due to the existence of the carbon quantum dots, so that the nano silver particle inner core has better stability and good enhancement performance. Can be applied to the detection of microcystin MC-LR in water environment.
Description
Technical Field
The invention belongs to the technical field of microcystin detection, and particularly relates to an active carbon quantum dot composite nano silver Raman enhanced substrate, a preparation method thereof and application thereof in detection of microcystin.
Background
Surface-enhanced Raman spectroscopy (SERS) has become a powerful fingerprint identification method, and can rapidly identify different chemical and biological analytes without labels and damage, and SERS has been widely developed and applied in various fields through more than forty years of research. How to produce a SERS substrate having high specificity and high sensitivity by a simple processing and preparation method at low cost is one of the important issues of current interest to researchers.
Microcystins (MC) are biotoxins with hepatotoxicity produced by algae widely distributed in water and have multiple isomers, wherein microcystins (LR) is the most common and most harmful microcystins (MC-LR). Because the water body is complex during detection, the interference components are more, and the concentration of MC-LR is often lower than 10 mug/L, in the detection process of MC-LR, although the detection method of a large instrument has high sensitivity and accurate result, the detection method also has the problems of expensive equipment, low precision, instability, need of experienced operators, poor applicability and the like.
Therefore, the preparation of the specific surface enhanced Raman substrate for detecting the microcystin LR is necessary for improving the detection sensitivity and accuracy of the residual microcystin LR in the water environment. Therefore, the invention provides a preparation method of a novel active carbon quantum dot composite nano silver Raman substrate for detecting microcystin LR in water environment by adopting surface imprinting and surface enhanced Raman technology.
Specific for detecting microcystin LR at presentThe sexual surface enhanced Raman substrate is provided with a solid porous array electromagnetic field enhanced SERS device (CN201710317198. X), and a film layer exposed out of the device and a metal layer on the film layer are respectively provided with an upper through hole and a lower through hole which are arranged in an array mode and used for enhancement; CN201110343901.7 prepares magnetic particles connected with monoclonal antibodies of microcystins, and the magnetic particles are used for SERS signal amplification; the invention uses the novel quantum dot material doped with nano-silver as a reinforced substrate, and can obtain the quantum dot material with the thickness of up to 10 4 Compared with the prior art, the signal intensity of the order of magnitude can obtain higher signal intensity, and the stability of the particle is better compared with that of a monoclonal antibody (CN 201110343901.7), so that the detection of trace microcystins in a water environment is facilitated.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention mainly aims to provide a preparation method of an activated carbon quantum dot composite nano silver Raman enhanced substrate (AgNPs @ CQDs).
The invention also aims to provide the activated carbon quantum dot composite nano silver Raman enhancement substrate prepared by the preparation method.
The invention also aims to provide an application of the activated carbon quantum dot composite nano silver Raman-enhanced substrate in detecting microcystin in water environment, in particular an application in detecting microcystin LR (MC-LR) in water environment.
The purpose of the invention is realized by the following technical scheme:
a preparation method of an activated carbon quantum dot composite nano silver Raman enhanced substrate comprises the following operation steps:
a. preparing carbon quantum dot powder (CQDs);
b. preparing 20-30 nm nano silver (AgNPs);
c. and (3) preparing an activated carbon quantum dot composite nano silver Raman enhanced substrate (AgNPs @ CQDs).
Preferably, the carbon quantum dot powder (CQDs) in step a is obtained by performing a hydrothermal reaction on activated carbon and a nitric acid solution, and is specifically prepared according to the following steps: heating and refluxing the activated carbon and a nitric acid solution under the condition of magnetic stirring, collecting a suspension after the reaction is finished, cooling the suspension to room temperature, filtering by using a 0.45-micron filter membrane, carrying out multiple centrifugal cleaning by using first-grade water until the pH value is 7, carrying out centrifugal concentration, drying by reduced pressure distillation, crushing, and sieving by using a 150-250-mesh sieve to obtain the activated carbon quantum dot powder.
The concentration of the nitric acid solution is 8mol/L; the dosage of the active carbon and the nitric acid solution is as follows according to the mass volume ratio (10 g-50 g): 1L, preferably (30 g to 35 g): 1L; the temperature of the heating reflux reaction is 80-140 ℃, and preferably 110-130 ℃; the reaction time is 10 to 60min, preferably 30min.
The activated carbon may be carbon source using other organic materials.
Preferably, the nano silver with the particle size of 20-30 nm in the step b is prepared by growing Ag @ NPs seed solution as seeds, and specifically comprises the following steps: to a small beaker containing magnetons, 1.5mL of a 2.5X 10 concentration solution was added -3 mol/L silver nitrate solution, 10mLAg @ NPs seed solution and 1mL PVP solution with the concentration of 1mol/L are added into the ice-water bath after being stirred uniformly, 1.5mL PVP solution with the concentration of 2.5 multiplied by 10 is added -3 A sodium citrate solution of mol/L; and then 0.4mL of 0.1mol/L sodium borohydride solution is dropwise added, stirring reaction is continuously carried out during the dropwise addition, after the reaction is finished, the reaction solution is transferred to a centrifuge tube and placed into a centrifuge chamber for centrifugation at room temperature, supernatant is removed after the centrifugation, and the nano silver with the particle size of 20-30 nm is obtained after repeated washing for 2-3 times by deionized water. The glass instrument used in the step must be washed clean after being soaked in aqua regia.
More preferably, the Ag @ NPs liquid is prepared according to the following preparation method: to a small beaker containing magnetons was added 1mL of a 2.5X 10 concentration solution -3 Adding 1.5mL of 2.5X 10 concentration PVP solution after stirring uniformly in ice-water bath -3 A sodium citrate solution of mol/L; and then dropwise adding 0.16mL of 0.1mol/L sodium borohydride solution, continuously stirring and reacting during dropwise adding, transferring the reaction solution to a centrifuge tube after the reaction is finished, centrifuging the reaction solution at room temperature in the centrifuge tube, removing supernatant after centrifuging, and repeatedly washing the reaction solution for 2 to 3 times by using deionized water to obtain 8 to 12nm silver nanoparticle liquid, namely Ag @ NPs liquid. Book (I)The glassware used in the step must be washed clean after being soaked in aqua regia.
Preferably, the activated carbon quantum dot composite nano silver raman enhanced substrate in the step c is prepared by taking nano silver with the diameter of 20-30 nm obtained in the step b as a crystallization center, and preparing the nano silver, the silver nitrate solution, the carbon quantum dot powder obtained in the step a and a reducing agent together through a seed growth method; the mass ratio of the carbon quantum dot powder to the silver element in the silver nitrate solution is 1:1 to 10; the reducing agent is glucose solution, sodium borohydride solution, ascorbic acid solution or hydrogen peroxide solution.
More preferably, the activated carbon quantum dot composite nano silver raman enhancement substrate is prepared by the following method: b, mixing and stirring the carbon quantum dot powder obtained in the step a and a silver nitrate solution for 5min, adjusting the pH value to 9, adding the nano silver with the particle size of 20-30 nm obtained in the step b, stirring at 120 ℃ for 15min, adding a reducing agent into the boiling solution, and boiling for 20min to reduce silver ions by the reducing agent; stopping heating, and continuing stirring to cool to room temperature; subsequently, the cooled mixture was centrifuged at 12000rmp for 10min 3 times; finally, re-dispersing the obtained precipitate into ultrapure water to obtain the activated carbon quantum dot composite nano silver Raman enhanced substrate; the mass ratio of the carbon quantum dot powder to the silver element in the silver nitrate solution is 1:8 to 9.
The active carbon quantum dot composite nano silver Raman enhanced substrate prepared by the preparation method. The active carbon quantum dot composite nano silver molecularly imprinted Raman-enhanced substrate provided by the invention has the structure that nano silver particles with certain particle size are taken as growth seed crystals, then carbon quantum dots are polymerized on the outer layer and the growth of the nano silver particles is regulated, and a polymer taking the nano silver particles as an inner core and the carbon quantum dots as the outer layer is formed.
The activated carbon quantum dot composite nano silver Raman-enhanced substrate is used as a surface-enhanced Raman spectrum material for detecting microcystins, and the application comprises the steps of performing solid-phase extraction pretreatment on a water body containing microcystins and detecting by adopting the activated carbon quantum dot composite nano silver Raman-enhanced substrate.
The principle of the invention is as follows:
the Surface Enhanced Raman Scattering (SERS) technology is a powerful high-speed detection technology, provides molecular fingerprint identification information through ultrahigh-sensitivity detection, and can effectively overcome the limitation of complex matrix interference by introducing a simple pretreatment technology, so that the detection sensitivity of SERS can be further improved. The Carbon Quantum Dots (CQDs) structurally represent the composition of quasi-spherical zero-dimensional nano particles with the size and the grain diameter of 1-10 nm, and the carbon-based Quantum Dots have the similar size, property and optical activity as the traditional metal-based Quantum Dots, and also have the incomparable advantages of inorganic semiconductor Quantum Dots such as non-toxicity (biocompatibility), photobleaching resistance, water solubility, low cost, simple synthesis and the like. According to the invention, a novel SERS substrate with high specificity and high sensitivity can be obtained by combining a surface enhanced Raman technology with a carbon quantum dot, so that the high response to MC-LR Raman signals is realized, and meanwhile, the Raman spectrum detection (SERS technology) is combined with a solid phase extraction pretreatment technology, so that the separation and enrichment of microcystin LR in a complex substrate are realized, the interference of the complex substrate on specific Raman signals is avoided, and the rapid detection of MC-LR in the complex substrate is realized.
Compared with the prior art, the invention has the following advantages and effects:
(1) According to the invention, the formation of the composite SERS enhanced substrate generated by nano silver is regulated and controlled by means of the carbon quantum dot nano material, and the strength of an SERS response signal can be effectively improved compared with a single enhanced substrate such as a nano gold substrate, a nano silver substrate and the like;
(2) The enhanced substrate can be more stable while enhancing SERS response signals, aggregation of nano silver particles is prevented, and the quality guarantee period of the substrate is prolonged.
(3) The method can realize rapid enrichment and separation of MC-LR in a complex matrix by combining a solid-phase extraction pretreatment technology, improve the specificity of SERS detection, and realize rapid and sensitive detection of microcystin LR.
Drawings
FIG. 1 is a scanning electron micrograph of AgNPs @ CQDs in example 1.
FIG. 2 is a scanning electron micrograph of 20-30 nm nano-silver in example 1.
FIG. 3 is the SEM image of the Ag @ NPs liquid in example 1.
FIG. 4 is a schematic diagram of preparation of AgNPs @ CQDs substrate and application of the substrate to SERS detection of microcystin-LR.
Fig. 5 is a graph of the linear relationship of SERS intensity of the present invention to different concentrations of MC-LR.
Detailed Description
The following examples are presented to further illustrate the present invention and should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.
The scanning electron microscope image of AgNPs @ CQDs obtained in the following preparation examples is shown in FIG. 1, which is a composite material particle with an outer layer coated with carbon dots and a center of Ag with a particle size of about 100 nm. The 20-30 nm nano-silver scanning electron microscope image used in the preparation of the final product AgNPs @ CQDs is shown in figure 2, and is spherical particles with the average particle size of 24.2nm, and the preparation method specifically comprises the following steps: to a small beaker containing magnetons, 1.5mL of a 2.5X 10 concentration solution was added -3 Adding silver nitrate solution of mol/L, seed solution of 10mLAg @ NPs and 1mL PVP solution of 1mol/L concentration, stirring uniformly in ice-water bath, adding 1.5mL PVP solution of 2.5 × 10 concentration -3 A sodium citrate solution of mol/L; and then 0.4mL of 0.1mol/L sodium borohydride solution is dropwise added, stirring reaction is continuously carried out during the dropwise addition, after the reaction is finished, the reaction solution is transferred to a centrifuge tube and placed into a centrifuge chamber for centrifugation at room temperature, supernatant is removed after the centrifugation, and the nano silver with the particle size of 20-30 nm is obtained after repeated washing for 2-3 times by deionized water. The glass instrument used in the step must be washed clean after being soaked in aqua regia.
The scanning electron microscope image of the Ag @ NPs liquid shows as figure 3, the Ag @ NPs liquid is spherical particles and has a relatively uniform size, the average particle size is about 9.6nm, and the Ag @ NPs liquid is prepared according to the following preparation method: to a small beaker containing magnetons was added 1mL of a 2.5X 10 concentration solution - 3 A silver nitrate solution with a concentration of 1mol/L and 1mLPVP solution is added into 1.5mL of 2.5 multiplied by 10 concentration after being evenly stirred in ice-water bath -3 A sodium citrate solution of mol/L; and then dropwise adding 0.16mL of 0.1mol/L sodium borohydride solution, continuously stirring and reacting during dropwise adding, transferring the reaction solution to a centrifuge tube after the reaction is finished, centrifuging the reaction solution at room temperature in the centrifuge tube, removing supernatant after centrifuging, and repeatedly washing the reaction solution for 2 to 3 times by using deionized water to obtain 8 to 12nm silver nanoparticle liquid, namely Ag @ NPs liquid. The glass instruments used in the preparation steps must be washed clean after being soaked in aqua regia.
The application schematic diagram in the following application embodiment is shown in fig. 4, after the preparation of the AgNPs @ CQDs substrate is completed, the liquid to be detected is pretreated through solid phase extraction, and finally SERS detection is carried out after the obtained concentrated solution reacts with the AgNPs @ CQDs substrate, and the specific steps are as follows:
Step 2, the preparation method of the MC-LR molecularly imprinted solid phase extraction column comprises the following steps: emptying a 1mL liquid-transfering injector tube, plugging absorbent cotton at the bottom of the liquid-transfering injector tube, weighing 200-500 mg of MC-LR molecularly imprinted polymer MIPs prepared in the step 1 as a filler for column packing, wherein the column packing method is wet column packing. Adding 200-500 mg of filler into the column with the lower end blocked, adding a certain volume of methanol as homogenate, finally washing with methanol, and drying with nitrogen for later use to obtain the MC-LR molecularly imprinted solid phase extraction cartridge. Preferably, the packing of the solid phase extraction column in the step 2 is 200mg.
And 3, separating and enriching the MC-LR in the water environment by using the MC-LR molecular imprinting solid phase extraction column obtained in the step 2 as an extraction column to obtain a concentrated solution. The method comprises the following steps: firstly, activating the extraction column, using water and methanol as leacheate in the leaching process, firstly leaching the extraction column by using 1-5 mL of water, then leaching by using 1-5 mL of methanol molecules, using water as equilibrium liquid in the equilibrium process, and then balancing before extraction by using 3-5 mL of water. And after the balance is finished, adding a certain volume of solution to be detected containing MC-LR into the extraction column, performing MC-LR molecular imprinting solid-phase extraction to finish the enrichment of MC-LR in the water environment, and eluting the MC-LR adsorbed in the imprinted polymer by using a preferred eluent. Collecting the eluent, concentrating by a nitrogen blowing method, diluting to 0.5-2 mL by methanol after concentration, completing corresponding concentration, collecting the concentrated solution, and storing in the dark at-20 ℃ for subsequent SERS detection. Preferably, the flow rate of the loading solution in step 3 is 1mL/min. Preferred MC-LR molecularly imprinted solid phase extraction conditions are as follows: the sample loading solution is a solution to be detected containing 5mg/L MC-LR, and the sample loading volume is 2mL; the leacheate is 3mL of water and 3mL of methanol in sequence; the eluent was a methanol acetic acid mixed solution (v/v = 4.
And 4, adopting a handheld Raman spectrometer to carry out SERS detection, adding the concentrated solution with a certain volume in the step 3 into a centrifugal tube, adding the 200-1000 mu L of AgNPs @ CQDs substrate into the centrifugal tube, mixing and shaking uniformly, and carrying out SERS test after incubating for 5-20 min. Preferably, the SERS test strip in step 4The parts are as follows: the volume ratio of the AgNPs @ CQDs substrate to the concentrated solution is 2 -1 ～2400cm -1 (preferably 600 cm) -1 ～1700cm -1 ). The aforementioned SERS assay was performed at 1457cm for MC-LR -1 Has good linear relation, so 1457cm is selected -1 The Raman shift is taken as a corresponding peak of a signal of concentration calculation, the linear detection range of the microcystin LR in the sample solution is between 0.334 and 20 mug/L, and the detection limit is 0.0407 mug/L. Preferably, in step 3, an MC-LR solid phase extraction column with other existing specifications can be selected for detection step 4.
Preparation example 1:
preparing an activated carbon quantum dot composite nano silver Raman enhanced substrate:
1. adding 5g of activated carbon and 150mL of nitric acid solution (8 mol/L) into a three-necked flask, adding a tetrafluoroethylene magnetic stirring rotor, heating to 130 ℃ under the condition of magnetic stirring for reflux reaction, collecting suspension after the reaction is finished, cooling the suspension to room temperature, filtering by using a 0.45-micrometer filter membrane, performing multiple times of centrifugal cleaning by using first-stage water until the pH value is 7, performing centrifugal concentration, drying by reduced pressure distillation, crushing, and sieving by using a 150-250-mesh sieve to obtain activated carbon quantum dot powder, namely CDs powder; 2. preparing the CDs powder obtained in the step 1 into a CDs solution with the concentration of 5mg/mL by using primary water; 300mL of the resulting CDs solution and 120mL of AgNO 3 (1 mol/L) was added to a 500mL beaker and the solution was stirred for 5min; then adjusting the pH of the solution to about 9 by using 0.1mol/L NaOH solution, and adding 10mL of nano silver solution with the particle size of 20-30 nm; subsequently, after the solution was stirred at 120 ℃ for 15min, 80mL of glucose solution (90 mg/mL) was rapidly added to the boiling solution; boiling for 20min to reduce silver ions by glucose. Stopping heating, naturally cooling the solution to room temperature, and simultaneously continuing stirring; subsequently, the cooled mixture was centrifuged at 12000rmp for 3 times at 10min; and finally, re-dispersing the AgNPs @ CQDs into 10mL of ultrapure water to obtain the activated carbon quantum dot composite nano silver Raman enhanced substrate, namely the AgNPs @ CQDs substrate, and storing at 4 ℃ for later use.
Preparation example 2:
preparing an activated carbon quantum dot composite nano silver Raman enhanced substrate:
1. adding 50g of activated carbon and 1000mL of nitric acid solution (8 mol/L) into a three-necked flask, adding a tetrafluoroethylene magnetic stirring rotor, heating to 130 ℃ under the condition of magnetic stirring for reflux reaction, collecting suspension after the reaction is finished, cooling the suspension to room temperature, filtering by using a 0.45-micrometer filter membrane, carrying out multiple centrifugal cleaning by using first-stage water until the pH value is 7, carrying out centrifugal concentration, drying by reduced pressure distillation, crushing and sieving by using a 150-250-mesh sieve to obtain activated carbon quantum dot powder, namely CDs powder; 2. preparing the CDs powder obtained in the step 1 into a CDs solution with the concentration of 5mg/mL by using primary water; 300mL of the resulting CDs solution and 120mL of AgNO 3 (1 mol/L) was added to a 500mL beaker and the solution was stirred for 5min; then adjusting the pH of the solution to about 9 by using 0.1mol/L NaOH solution, and adding 10mL of nano silver solution with the particle size of 20-30 nm; subsequently, after the solution was stirred at 120 ℃ for 15min, 80mL of glucose solution (90 mg/mL) was added rapidly to the boiling solution; boiling for 20min to reduce silver ions by glucose. Stopping heating, naturally cooling the solution to room temperature, and continuously stirring; subsequently, the cooled mixture was centrifuged at 12000rmp for 3 times at 10min; and finally, re-dispersing the AgNPs @ CQDs into 10mL of ultrapure water to obtain the activated carbon quantum dot composite nano silver Raman enhanced substrate, namely the AgNPs @ CQDs substrate, and storing at 4 ℃ for later use.
Application example 1:
the establishment steps of the SERS detection standard curve of MC-LR are as follows: 1. taking a 1.0mg MC-LR standard substance, fully dissolving with 1.0mL methanol, then preparing a 10mg/L standard stock solution with ultrapure water, and storing at 4 ℃ in a dark place; 2. mixing 200 μ L of AgNPs @ CDs substrate prepared in preparation example 1 with 800 μ L of MC-LR standard solution with different concentrations, wherein the concentrations of the MC-LR standard solution are 0 μ g/L, 0.3125 μ g/L, 0.625 μ g/L, 1.25 μ g/L, 5 μ g/L, 10 μ g/L and 20 μ g/L respectively; 3. fully mixing the uniformly mixed liquid, and incubating for 15min; 4. detecting the standing samples with a portable Raman spectrometer, performing parallel measurement for 3 times on each sample, setting the excitation power to 125mW, and the integration time to 5000ms. 5. And drawing a linear relation graph according to the obtained SERS intensity and the concentration of the corresponding standard solution, as shown in FIG. 5. Choose 1457cm -1 Raman shift at position as the corresponding peak of the signal for concentration calculation at 1457cm -1 The correction equation is y =0.0541x +0.0235.
Application example 2:
the following steps are applied to the detection of the actual sample: 1. taking tap water in a laboratory as a sampling object, and repeatedly filtering a water sample through a filter membrane of 0.22 mu m after the water is taken until the water sample is clear; 2. labeling the MC-LR standard solution with MC-LR stock solution at concentration of 10 μ g/L; 3. obtaining a concentrated solution through solid-phase extraction pretreatment; 4. 400 μ L of the AgNPs @ CQDs substrate prepared in preparation example 1 and 1600 μ L of the concentrate are added into a 2.5mL centrifuge tube, mixed and shaken uniformly, incubated for 20min and then subjected to Raman test. 5. Each water sample was assayed in 3 replicates. The test conditions comprise that the excitation wavelength is 785nm, the laser power is 200mW, the excitation time is 5000ms, and the scanning range is 600cm -1 ～1600cm -1 (ii) a 6. The concentration of microcystin-LR in the concentrated solution is calculated according to the correction equation in the application example 1, the linear detection range of MC-LR in the sample solution is 0.334-20 mug/L, and the detection limit is 0.0407 mug/L.
Application example 3:
the following procedure was applied for the detection of the actual sample: 1. taking a field lake water sample as a sampling object, and repeatedly filtering the water sample through a filter membrane of 0.22 mu m after water is taken until the water sample is clear; 2. labeling the MC-LR standard solution with MC-LR stock solution at concentration of 10 μ g/L; 3. obtaining a concentrated solution through solid-phase extraction pretreatment; 4. 400 μ L of the AgNPs @ CQDs substrate prepared in preparation example 1 and 1600 μ L of the concentrate are added into a 2.5mL centrifuge tube, mixed and shaken uniformly, incubated for 20min and then subjected to Raman test. 5. Each sample was subjected to 3 replicates. The test conditions comprise that the excitation wavelength is 785nm, the laser power is 200mW, the excitation time is 5000ms, and the scanning range is 600cm -1 ～1600cm -1 (ii) a 5. The concentration of microcystin-LR in the concentrated solution is calculated according to the correction equation in the application example 1, the linear detection range of MC-LR in the sample solution is 0.334-20 mug/L, and the detection limit is 0.0407μg/L。
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A preparation method of an activated carbon quantum dot composite nano silver Raman enhanced substrate is characterized by comprising the following operation steps:
a. preparing carbon quantum dot powder;
b. preparing 20-30 nm nano silver;
c. and (3) preparing the activated carbon quantum dot composite nano silver Raman-enhanced substrate.
2. The preparation method of the activated carbon quantum dot composite nano-silver Raman-enhanced substrate according to claim 1, characterized in that: the carbon quantum dot powder obtained in the step a is obtained by carrying out hydrothermal reaction on activated carbon and a nitric acid solution, and is specifically prepared according to the following steps: heating and refluxing the activated carbon and a nitric acid solution under the condition of magnetic stirring, collecting a suspension after the reaction is finished, cooling the suspension to room temperature, filtering by using a 0.45-micrometer filter membrane, carrying out multiple centrifugal cleaning by using primary water until the pH value is 7, carrying out centrifugal concentration, drying by reduced pressure distillation, crushing, and sieving with a 150-250-mesh sieve to obtain activated carbon quantum dot powder.
3. The preparation method of the active carbon quantum dot composite nano-silver Raman-enhanced substrate according to claim 1, characterized by comprising the following steps: the nano silver with the particle size of 20-30 nm in the step b is prepared by growing Ag @ NPs seed solution serving as seeds, and specifically comprises the following steps: to a small beaker containing magnetons, 1.5mL of a 2.5X 10 concentration solution was added -3 Adding silver nitrate solution of mol/L, seed solution of 10mLAg @ NPs and 1mL PVP solution of 1mol/L concentration, stirring uniformly in ice-water bath, adding 1.5mL PVP solution of 2.5 × 10 concentration - 3 A sodium citrate solution of mol/L; thenAnd (2) dropwise adding 0.4mL of 0.1mol/L sodium borohydride solution, continuously stirring and reacting during dropwise adding, transferring the reaction solution to a centrifuge tube after the reaction is finished, centrifuging at room temperature in the centrifuge tube, removing supernatant after centrifuging, and repeatedly washing for 2-3 times by using deionized water to obtain the nano silver with the particle size of 20-30 nm.
4. The preparation method of the active carbon quantum dot composite nano-silver Raman-enhanced substrate according to claim 1, characterized by comprising the following steps: the activated carbon quantum dot composite nano silver Raman enhancement substrate obtained in the step c is prepared by taking the nano silver with the particle size of 20-30 nm obtained in the step b as a crystallization center, and then mixing the nano silver with a silver nitrate solution, the carbon quantum dot powder obtained in the step a and a reducing agent through a seed growth method; the mass ratio of the carbon quantum dot powder to the silver element in the silver nitrate solution is 1:1 to 10; the reducing agent is glucose solution, sodium borohydride solution, ascorbic acid solution or hydrogen peroxide solution.
5. The preparation method of the activated carbon quantum dot composite nano-silver Raman-enhanced substrate according to claim 2, characterized in that: the concentration of the nitric acid solution is 8mol/L; the dosage of the active carbon and the nitric acid solution is as follows according to the mass volume ratio (10 g-50 g): 1L; the temperature of the heating reflux reaction is 80-140 ℃, and the reaction time is 10-60 min.
6. The preparation method of the active carbon quantum dot composite nano-silver Raman-enhanced substrate according to claim 5, characterized in that: the dosage of the active carbon and the nitric acid solution is as follows according to the mass volume ratio (30 g-35 g): 1L; the temperature of the heating reflux reaction is 110-130 ℃, and the reaction time is 30min.
7. The preparation method of the active carbon quantum dot composite nano-silver Raman enhanced substrate according to claim 3, characterized in that: the Ag @ NPs liquid is prepared by the following preparation method: 1mL of a 2.5X 10 concentration solution was added to a small beaker containing magnetons -3 mol/L silver nitrate solution and 1mL PVP solution with the concentration of 1mol/LAfter stirring uniformly in an ice-water bath, 1.5mL of a 2.5X 10 solution was added -3 A sodium citrate solution of mol/L; and then dropwise adding 0.16mL of 0.1mol/L sodium borohydride solution, continuously stirring and reacting during dropwise adding, transferring the reaction solution to a centrifuge tube after the reaction is finished, centrifuging the reaction solution at room temperature in the centrifuge tube, removing supernatant after centrifuging, and repeatedly washing the reaction solution for 2 to 3 times by using deionized water to obtain 8 to 12nm silver nanoparticle liquid, namely Ag @ NPs liquid.
8. The preparation method of the active carbon quantum dot composite nano-silver Raman-enhanced substrate according to claim 4, characterized in that: the active carbon quantum dot composite nano silver Raman enhancement substrate is prepared by the following method: b, mixing and stirring the carbon quantum dot powder obtained in the step a and a silver nitrate solution for 5min, adjusting the pH value to 9, adding the nano silver with the particle size of 20-30 nm obtained in the step b, stirring at 120 ℃ for 15min, adding a reducing agent into the boiling solution, and boiling for 20min to reduce silver ions by the reducing agent; stopping heating, and continuing stirring to cool to room temperature; subsequently, the cooled mixture was centrifuged at 12000rmp for 10min 3 times; finally, re-dispersing the obtained precipitate into ultrapure water to obtain the activated carbon quantum dot composite nano silver Raman enhanced substrate; the mass ratio of the carbon quantum dot powder to the silver element in the silver nitrate solution is 1:8 to 9.
9. An activated carbon quantum dot composite nanosilver Raman-enhanced substrate prepared by the preparation method of any one of claims 1-8.
10. The application of the activated carbon quantum dot composite nano silver Raman-enhanced substrate as a surface-enhanced Raman spectrum material in detecting microcystins according to claim 9 is characterized in that: the application comprises the steps of carrying out solid-phase extraction pretreatment on a water body containing microcystin, and then detecting by adopting an activated carbon quantum dot composite nano silver Raman enhanced substrate.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116465872A (en) * | 2023-05-09 | 2023-07-21 | 临沂大学 | Method for rapidly detecting microcystin |
| CN116465872B (en) * | 2023-05-09 | 2023-11-28 | 临沂大学 | Method for rapidly detecting microcystin |
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