CN114958365B - Preparation method and application of cicada slough carbon quantum dots - Google Patents
Preparation method and application of cicada slough carbon quantum dots Download PDFInfo
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Abstract
The invention relates to a preparation method and application of a cicada slough carbon quantum dot. According to the preparation method, biomass periostracum Cicadae is used as a precursor material, and a one-step hydrothermal synthesis method is combined to prepare the periostracum Cicadae carbon quantum dots (CT-CQDs). The preparation method of the cicada slough carbon quantum dot comprises the following steps: (1) pulverizing periostracum Cicadae, and dissolving in water to obtain solution; (2) heating the solution obtained in step (1); (3) And (3) cooling and centrifuging the product obtained in the step (2), collecting supernatant, filtering and dialyzing to obtain the cicada slough carbon quantum dots, namely CT-CQDs. The periostracum Cicadae carbon quantum dot synthesized by the invention can be used as a carbon quantum dot fluorescent probe, and can sensitively and selectively detect enrofloxacin in aquatic products. The invention has the advantages of no pollution, wide and low raw material sources, simple and convenient operation and the like.
Description
Technical Field
The invention belongs to the technical field of preparation of carbon quantum dot fluorescent materials, and particularly relates to a preparation method and application of a cicada slough carbon quantum dot.
Background
Enrofloxacin (ENR), also known as ethylcyclopropanafloxacin, belongs to the class of fluoroquinolone antibacterial agents (Fluoroquinolones, FQs). Because ENR has the advantages of wider antibacterial spectrum, stronger bactericidal effect, wide distribution and the like, the ENR is applied to industries such as animal husbandry, aquaculture, poultry farming and the like. However, antibiotics are double-edged swords, which have various damages to human bodies and ecological environment, and are mainly expressed as follows: bacterial resistance, adverse reactions, double infection, threat to food safety, soil microorganisms and aquatic organisms, and the like.
The current method for detecting enrofloxacin mainly comprises the following steps: fluorescence spectrophotometry, enzyme-linked chromatography, high performance liquid chromatography, mass spectrometry, and the like. Although the accuracy and the sensitivity of the methods are good, the methods have the defects of expensive instrument, time-consuming analysis, complex operation, troublesome data processing and the like. And because the animal products contain a large amount of protein and fat, the matrix is complex, and the sample is usually subjected to pretreatment such as precipitation, centrifugation, enrichment, nitrogen drying, re-dissolution and the like before detection and analysis. A large amount of toxic organic reagents are used in the treatment process, so that the safety and environmental protection performance are reduced.
In view of the numerous hazards, in many countries and regions, in order to ensure the edible safety of aquatic products, standards for the maximum residual limit of ENR in aquatic foods have been established for ENR, for example, korean regulations for maximum residual limit of ENR in crustacean aquatic products are 0.1 μg/kg, european regulations for maximum residual limit of ENR in finfish muscles are 100 μg/kg, etc. At present, enrofloxacin residue detection is mostly concentrated in livestock and poultry tissues and vegetables, and residue detection in aquatic products is not reported.
The detection method for enrofloxacin has the problems that the accuracy is low, the enrofloxacin with lower concentration can not be detected, and the like. Therefore, in order to ensure the safety of human bodies and protect the ecological environment, it is necessary to develop a simple, easy-to-operate and environment-friendly method for monitoring the antibiotic residues in the aquatic products.
Disclosure of Invention
In view of the problems existing in the prior art, the invention provides a preparation method and application of a cicada slough carbon quantum dot. The cicada slough carbon quantum dots (CT-CQDs) provided by the invention have the advantages of higher fluorescence intensity, good accuracy, high sensitivity, wide and low raw material sources and no pollution in the synthesis process. The CT-CQDs are used as fluorescent probes, and the established fluorescent analysis method can sensitively and selectively detect the ENR in the aquatic products.
The technical scheme for solving the technical problems is as follows:
the invention provides a preparation method of a cicada slough carbon quantum dot, which comprises the following steps:
(1) Pulverizing periostracum Cicadae, and dissolving in water to obtain solution;
(2) Heating the solution obtained in the step (1);
(3) And (3) cooling and centrifuging the product obtained in the step (2), collecting supernatant, filtering and dialyzing to obtain the cicada slough carbon quantum dots, namely CT-CQDs.
The beneficial effects of adopting above-mentioned scheme include: according to the preparation method provided by the invention, biomass periostracum Cicadae is used as a precursor material, and a one-step hydrothermal method is combined to synthesize the periostracum Cicadae carbon quantum dots (CT-CQDs). The cicada slough carbon quantum dot prepared by the method has the advantages of good dispersibility, uniform particle size distribution and the like.
The biomass precursor material is adopted, and the biomass precursor material has the advantages of being renewable, rich in content, easy to obtain, low in cost, capable of avoiding introducing other components in the synthesis process, and the like. The fluorescent probe can be used as a periostracum Cicadae carbon quantum dot fluorescent probe (CT-CQDs fluorescent probe) and can be used for detecting the concentration of enrofloxacin in aquatic products. The invention adopts a one-step hydrothermal method and has the advantages of low instrument cost, simple and convenient operation, environmental protection, rapidness and the like.
The cicada slough carbon quantum dot can be used as a fluorescent probe, is a novel fluorescent carbon nanomaterial, has the size of less than 20nm, and has the advantages of good accuracy, good selectivity to ENR, good linear relation, low detection limit (0.069 mu M), good water solubility, low price and the like. Compared with the traditional semiconductor quantum dots, the CQDs prepared based on biomass periostracum Cicadae have the advantages of low toxicity, environment friendliness, simplicity in synthesis, good water solubility and the like, and can be widely applied to the fields of fluorescence sensing, biological imaging, drug/gene transfer, photoelectrocatalysis, food safety and the like.
In the step (1), the feed ratio of the crushed cicada slough powder to water is 1.0 g/50 mL, and the water is purified water.
The beneficial effects of adopting above-mentioned scheme include: the adoption of the feeding ratio is beneficial to further improving the fluorescence quantum yield of CT-CQDs.
Further, in the step (2), heating is performed in a reaction kettle under the condition that the heating temperature is 180 ℃ and the heating time is 4 hours.
The beneficial effects of adopting above-mentioned scheme include: the temperature in the reaction in step (2) was 180℃and the duration was 4 hours, and the heating in the reaction vessel was aimed at selecting the optimum fluorescence intensity, too high or too low resulting in weakening of the fluorescence intensity. The heating time is 4 hours, and the higher fluorescence quantum yield of CT-CQDs can be obtained. Thus, the proper reaction temperature and time are favorable for obtaining the condition of higher fluorescence intensity, so that the CT-CQDs obtain higher fluorescence quantum yield.
Further, in the step (3), the product obtained after heating in the step (2) is cooled to room temperature and then cooled to 4500r.min -1 Centrifuging for 10min, collecting supernatant, filtering with 0.22 μm filter membrane, and dialyzing for 24 hr.
The beneficial effects of adopting above-mentioned scheme include: at 4500r·min -1 Centrifuging for 10min, filtering with 0.22 μm microporous membrane, and dialyzing to remove macromolecular impurities.
Further, the method also comprises the step of freeze-drying the carbon quantum dots of the periostracum cicadae obtained after dialysis.
The beneficial effects of adopting above-mentioned scheme include: and the freeze-dried product is convenient to store, use and the like.
The invention provides a cicada slough carbon quantum dot fluorescent probe which is prepared by the preparation method.
The beneficial effects of adopting above-mentioned scheme include: has the advantages of good dispersibility, uniform particle size, good accuracy, good selectivity to ENR, good linear relation, low detection limit (0.069 mu M), good water solubility, low cost, etc.
The invention provides a reagent or a kit for detecting enrofloxacin, which comprises the cicada slough carbon quantum dot fluorescent probe.
The beneficial effects of adopting above-mentioned scheme include: the method has the advantages of accurate detection result, good selectivity to ENR, good linear relation, low detection limit (0.069 mu M), good water solubility, low price and the like.
The invention provides application of the cicada slough carbon quantum dot prepared by the preparation method in detecting enrofloxacin.
For example: the invention provides application of the cicada slough carbon quantum dot CT-CQDs fluorescent probe prepared by the preparation method in detecting enrofloxacin content in aquatic products.
The beneficial effects of adopting above-mentioned scheme include: when the cicada slough carbon quantum dot provided by the invention is applied, the cicada slough carbon quantum dot has the advantages of low chemical cost, good stability, environmental protection, quick and accurate detection, simple operation, wide linear range, low detection limit (0.069 mu M) and the like.
The CT-CQDs provided by the invention have good selectivity on enrofloxacin in a certain range, and the influence of other antibiotics and common ions in aquatic products on the fluorescence intensity of the CT-CQDs is very small. Therefore, the effective detection of enrofloxacin in aquatic products can be realized through CT-CQDs.
The invention provides a detection method of enrofloxacin, which comprises the following steps:
s1, drawing a standard curve related to the concentration of ENR: drawing a standard curve about the concentration of enrofloxacin by taking the relative change value of the fluorescence intensity of the standard solution containing the periostracum cicadae carbon quantum dots as an ordinate and the concentration of enrofloxacin as an abscissa to obtain a standard curve;
s2, detecting the concentration of enrofloxacin in an unknown solution: mixing the cicada slough carbon quantum dot solution with the unknown solution, diluting with a buffer solution, performing fluorescence detection after reaction, detecting the fluorescence intensity of the solution to be detected, and combining a standard curve graph to obtain the concentration of enrofloxacin in the unknown solution.
Further, the sample was diluted with a buffer solution having a pH of 3.6, and fluorescence detection was performed after 5 minutes of reaction.
The beneficial effects of adopting above-mentioned scheme include: the fluorescence intensity of CT-CQDs solutions in the presence of ENR varied with pH, reaching a maximum when ph=3.6. Thus, ph=3.6 was chosen as the optimal solution pH for the test. After 5min, the fluorescence intensity of the liquid to be detected is detected, so that the better fluorescence intensity can be obtained. The detection method has the advantages of simplicity in operation, environment friendliness, no pollution, rapidness in detection, wider linear range and the like.
The CT-CQDs can be prepared by the preparation method.
The invention can adopt the method to detect the enrofloxacin content in the aquatic products.
For example: the CT-CQDs fluorescent probe is used for detecting the enrofloxacin concentration in aquatic products, and can comprise the following steps:
s1, drawing a standard curve related to the concentration of ENR: after the ENR stock solution (10 mM) was serially diluted to obtain a standard solution having an ENR concentration range of (0.13-16.67. Mu.M), 400. Mu.L of the ENR standard solution and CT-CQDs solution (0.3 mg. Multidot.mL) were each prepared -1 ) 400. Mu.L of the mixture was diluted with PBS buffer solution having a pH of 3.6, and after 5 minutes fluorescence detection was performed, and the fluorescence spectrum of each solution was recorded. Then, linearly fitting the relative change value of the fluorescence intensity of CT-CQDs at 355nm with the concentration of ENR to obtain a standard curve graph;
s2, detecting the concentration of ENR in the aquatic product: accurately weighing 5.0g of homogenate sample tissue which is evenly mixed and placing the homogenate sample tissue into a 10mL centrifuge tubeIn the method, 4.0mL of acetonitrile and 0.04mL of 1.0% acetic acid are used as extracting solution, high-speed homogenization is carried out for 1min, ultrasonic extraction is carried out for 15min, and the extracting solution is extracted at 4500r.min -1 Centrifuging for 15min, collecting supernatant, extracting residue for 1 time, and mixing the two supernatants. 400. Mu.L of CT-CQDs solution was taken, 400. Mu.L of low, medium and high concentration ENR standard solutions (0.67. Mu.M, 3.33. Mu.M, 13.33. Mu.M) and 400. Mu.L of actual sample solution were respectively taken, diluted to 3mL with PBS buffer solution having pH of 3.6 and thoroughly mixed, and transferred to a series of 4mL cuvettes. After 5min, detecting the fluorescence intensity of the solution to be detected, and combining the standard curve graph to obtain the concentration of ENR in the unknown solution.
Drawings
Fig. 1 is a schematic diagram of the detection principle of the periostracum cicada carbon quantum dot fluorescent probe for detecting enrofloxacin in aquatic products.
FIG. 2 is a perspective electron microscope image of CT-CQDs.
FIG. 3 is a histogram of CT-CQDs particle size distribution.
FIG. 4 is a graph of fluorescence emission spectra of CQDs synthesized from different precursor materials.
FIG. 5 is a graph comparing the effect of different ions and antibiotics on the fluorescence intensity of CT-CQDs.
FIG. 6 is a graph showing fluorescence emission spectra of CT-CQDs at different ENR concentrations.
FIG. 7 is a graph showing the relationship between the concentration of ENR and the relative change in fluorescence intensity of CT-CQDs.
Detailed Description
The principles and features of the present invention are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.
The invention provides a preparation method of a cicada slough carbon quantum dot fluorescent probe, which comprises the following steps:
(1) Pulverizing periostracum Cicadae, and dissolving in purified water to obtain solution;
(2) Transferring the solution obtained in the step (1) into a reaction kettle, and putting the reaction kettle into an oven for heating;
(3) And (3) cooling and centrifuging the product obtained after heating in the step (2), collecting supernatant, filtering, performing primary dialysis, dialyzing for 24 hours to obtain the cicada slough carbon quantum dots, namely CT-CQDs, and freeze-drying the sample for later use, wherein the CT-CQDs can be used as a cicada slough carbon quantum dot fluorescent probe (CT-CQDs fluorescent probe).
Further, the feed ratio of the cicada slough powder to the purified water in the step (1) is 1.0g to 50mL; specifically, the following operations may be adopted in step (1): pulverizing periostracum Cicadae, weighing 1.0g of pulverized periostracum Cicadae powder, and mixing with 50mL of purified water to obtain solution;
further, the temperature of the reaction in the step (2) was 180℃and the reaction time was 4 hours. Among them, the purpose of heating in the reaction vessel is to select the optimum fluorescence intensity, and too high or too low can cause weakening of the fluorescence intensity. The heating time is 4 hours, and the higher fluorescence quantum yield of CT-CQDs can be obtained. Thus, the proper reaction temperature and time are favorable for obtaining the condition of higher fluorescence intensity, so that the CT-CQDs obtain higher fluorescence quantum yield.
Further, in the step (3), the product obtained after heating in the step 2) is cooled to room temperature and then cooled to 4500r.min -1 Centrifuging for 10min. The supernatant was collected and filtered through a 0.22 μm filter. And (3) performing primary dialysis for 24 hours to remove macromolecular impurities in the solution.
Further, the cicada slough carbon quantum dot fluorescent probe can be prepared by the preparation method.
The cicada slough carbon quantum dot fluorescent probe can be assembled into products such as a reagent or a kit.
The CT-CQDs fluorescent probe can be applied to the measurement of enrofloxacin in aquatic products, such as the measurement of the content (concentration and the like) of enrofloxacin in the aquatic products. But are not limited to, determining enrofloxacin in an aquatic product.
The application of the periostracum Cicadae carbon quantum dot fluorescent probe can adopt the following method when being used for detecting the concentration of enrofloxacin in aquatic products, and the method comprises the following steps of:
s1, drawing a standard curve about the concentration of ENR by taking a relative change value of fluorescence intensity of a standard solution containing CT-CQDs as an ordinate and the concentration of ENR as an abscissa to obtain a standard curve;
s2, detecting the concentration of ENR in an unknown solution: mixing the CT-CQDs solution with the unknown solution, diluting with PBS buffer solution with pH of 3.6, performing fluorescence detection after 5min, detecting the fluorescence intensity of the solution to be detected, and combining a standard curve graph to obtain the concentration of ENR in the unknown solution.
For example, the following steps may be employed:
s1, drawing a standard curve related to the concentration of ENR: after the ENR stock solution (10 mM) was serially diluted to obtain a standard solution having an ENR concentration range of 0.13 to 16.67. Mu.M, 400. Mu.L of the ENR standard solution and CT-CQDs solution (concentration of 0.3 mg. Multidot.mL) were each prepared -1 ) 400. Mu.L of the mixture was diluted with PBS buffer solution having a pH of 3.6, and after 5 minutes fluorescence detection was performed, and the fluorescence spectrum of each solution was recorded. Then, linearly fitting the relative change value of the fluorescence intensity of CT-CQDs at 355nm with the concentration of ENR to obtain a standard curve graph;
s2, detecting the concentration of ENR in the aquatic product: accurately weighing 5.0g of homogenate sample tissue, placing into a 10mL centrifuge tube, adding 4.0mL acetonitrile and 0.04mL 1.0% acetic acid as extracting solution, homogenizing at high speed for 1min, ultrasonic extracting for 15min, extracting at 4500r.min -1 Centrifuging for 15min, collecting supernatant, extracting residue for 1 time, and mixing the two supernatants. 400. Mu.L of CT-CQDs solution was taken, 400. Mu.L of low, medium and high concentration ENR standard solutions (0.67, 3.33, 13.33. Mu.M) and 400. Mu.L of actual sample solution were taken respectively, diluted to 3mL with PBS buffer solution having pH of 3.6 and thoroughly mixed, and transferred to a series of 4mL cuvettes. After 5min, detecting the fluorescence intensity of the solution to be detected, and combining the standard curve graph to obtain the concentration of ENR in the unknown solution.
Because of the high fluorescence quantum yield of CT-CQDs, CT-CQDs solutions appear bluish when exposed to ultraviolet light at a wavelength of 365 nm. The invention provides a cicada slough carbon quantum dot fluorescent probe based on the characteristics, a preparation method thereof and application in the aspect of detecting the concentration of enrofloxacin, and the fluorescent probe has good selectivity and sensitivity to the enrofloxacin in a certain range, and other metal ions or antibiotics have very little interference to the detection system. Therefore, the effective detection of enrofloxacin can be realized through CT-CQDs, and the method has good application value and application prospect in the fields of food safety and the like.
Compared with the prior art, the invention has the following advantages:
(1) The carbon quantum dot fluorescent probe prepared by the invention has wide sources of raw materials, and is cheap and easy to obtain.
(2) The preparation process of the carbon quantum dot fluorescent probe is simple, convenient, easy to operate and environment-friendly.
(3) The fluorescent probe has stronger selectivity to enrofloxacin and can effectively reduce Mg 2+ ，Ca 2+ ，Na + ，K + ，Zn 2+ The interference of plasma metal ions or other antibiotics on detection leads the detection result to have higher reliability.
(4) The relative change value of the fluorescence intensity of the CT-CQDs fluorescent probe has good linear relation with the concentration of ENR in a certain range.
(5) The CT-CQDs fluorescent probe can realize effective detection of enrofloxacin in aquatic products, and has good application value and application prospect in the fields of food safety and the like.
The materials used in the examples of the present invention, unless specified, are all conventional experimental materials in the art, and may be prepared by conventional methods or commercially available.
The methods adopted in the embodiments of the present invention are all conventional experimental methods in the art unless specifically described.
In the examples, enrofloxacin (ENR), ciprofloxacin (CIP), norfloxacin (NFX), dexamethasone (DEX), gentamicin (GEN) were all purchased from bedrst biotechnology, inc, naCl solution, KCl solution, znCl 2 Solution, caCl 2 Solution, mgCl 2 Solutions were purchased from Tianjin Bairens biochemistry Co.
Example 1
The detection principle of the periostracum cicada carbon quantum dot fluorescent probe for detecting enrofloxacin in aquatic products is shown in figure 1.
Preparation of Water-solubleCT-CQDs comprising the steps of: the cicada slough is crushed, 1.0g of crushed cicada slough powder is weighed and mixed with 50mL of purified water, the mixture is transferred into a 100mL reaction kettle, and the reaction kettle is placed into a 180 ℃ oven to be heated for 4 hours. And after the reaction is finished, naturally cooling the reaction kettle to room temperature. At 4500 r.min -1 After centrifugation for 10min, CT-CQDs supernatant was collected, filtered with a 0.22 μm filter membrane, dialyzed once, and the samples were lyophilized after 24h of dialysis for subsequent further characterization and application.
The CT-CQDs are subjected to transmission electron microscope characterization, and the characterization result is as follows:
the characterization result of the transmission electron microscope is shown in fig. 2, and it can be observed from fig. 2 that CT-CQDs have better dispersibility and more uniform particle size distribution. As a result of examining the particle size distribution of CT-CQDs, the average particle size of CT-CQDs was 19.6.+ -. 0.2nm as shown in FIG. 3.
In order to obtain the carbon quantum dots with larger fluorescence intensity, the invention selects cicada slough, mosquito-repellent incense ash, a pumped filter tip, a non-pumped filter tip and ash as precursor materials, and the preparation method is operated to prepare different CQDs. 400 μl of the CQDs solution was diluted to 3mL with water and fluorescence intensity measurements were performed at λex/λem=355/436 nm, and the fluorescence spectra of each CQDs were recorded. As shown in fig. 4, the curves from top to bottom are respectively cicada slough, a pumped filter tip, a non-pumped filter tip, ash and mosquito-repellent incense ash, and the results show that the fluorescence intensity of the carbon quantum dots synthesized by taking the cicada slough biomass as a precursor material is higher, and the effect of synthesizing CT-CQDs by taking the cicada slough as the precursor material is better than that of CQDs synthesized by selecting other precursor materials.
Example 2
The effect of different ions and antibiotics on the fluorescence intensity of CT-CQDs solution was examined. The method comprises the following steps:
a blank (blank) group and a test group were set.
Test group: 400. Mu.L of standard solution or ionic solution of chloride (concentration: 10 mM) was added to a 5mL centrifuge tube, and CT-CQDs solution (0.3 mg. Multidot.mL) was added to the centrifuge tube -1 ) 400. Mu.L, diluted to 3mL with PBS buffer at pH 3.6, and transferred to a 4mL cuvette after thorough mixing. After 5min, fluorescence was detected at 355nm and the fluorescence of each solution was recordedA spectrum.
The standard substances are respectively as follows: enrofloxacin (ENR), ciprofloxacin (CIP), norfloxacin (NFX), dexamethasone (DEX), gentamicin (GEN). The ionic solutions of the chlorides were: naCl solution, KCl solution and ZnCl 2 Solution, caCl 2 Solution, mgCl 2 A solution. The concentration is 10mM, and the preparation method comprises the following steps: standard substances or chlorides are taken, precisely weighed, placed in 10mL measuring flasks respectively, dissolved by methanol, and diluted with water to a constant volume to prepare 10mM stock solution.
Blank (blank): 400. Mu.L of purified water was taken and added to a 5mL centrifuge tube, and CT-CQDs solution (0.3 mg. Multidot.mL) was added to the centrifuge tube -1 ) 400. Mu.L, diluted to 3mL with PBS buffer at pH 3.6, and transferred to a 4mL cuvette after thorough mixing. After 5min, fluorescence detection was performed at 355nm and fluorescence spectra were recorded.
As shown in FIG. 5, the fluorescence intensity of CT-CQDs added with other antibiotics or ions (10 mM) is not greatly changed compared with that of ENR fluoroquinolone antibiotics, which indicates that the influence of the common ions in other antibiotics and aquatic products on the fluorescence intensity of CT-CQDs is negligible, namely, the CT-CQDs can be used as a fluorescent probe to realize the selective detection of the ENR fluoroquinolone antibiotics in the aquatic products.
Example 3
Detecting fluorescence emission spectra of CT-CQDs under different ENR concentrations, comprising the following steps:
a plurality of 5mL centrifuge tubes were used, and the ENR stock solution (10 mM) was serially diluted to 0.13. Mu.M, 0.67. Mu.M, 1.67. Mu.M, 3.33. Mu.M, 6.67. Mu.M, 13.33. Mu.M, 16.67. Mu.M, and 400. Mu.L of each of the ENR standard solution and CT-CQDs solution (0.3 mg. Mu.M) -1 ) After 400 μl mixing, it was diluted to 3mL with PBS buffer at pH 3.6 and transferred to a series of 4mL cuvettes after thorough mixing. After 5min, fluorescence detection was performed at 355 nm.
As shown in FIG. 6, the concentration of the fluorescent light of CT-CQDs was 16.67. Mu.M, 13.33. Mu.M, 6.67. Mu.M, 3.33. Mu.M, 1.67. Mu.M, 0.67. Mu.M, 0.13. Mu.M, and 0. Mu.M, respectively, from top to bottom, and it was found that the relative change in the fluorescent light intensity of CT-CQDs increased with the increase in the concentration when the concentration of the standard solution of ENR was in the range of 0.13 to 16.67. Mu.M.
The concentration of ENR solution was linearly fitted to the relative change in fluorescence intensity, and the fitting result was shown in FIG. 7, which revealed that when the concentration of the standard solution of ENR was in the range of 0.13 to 16.67. Mu.M, there was a good linear relationship between the concentration and the relative change in fluorescence intensity (R 2 ＝0.9979)。
The limit of detection (LOD) was calculated to be 0.069. Mu.M according to the formula 3σ/s (σ is the variance of the detection data for 11 blank samples, and s is the slope of the standard curve).
Example 4
For the example of aquatic products, the ENR in the sample was detected using CT-CQDs. The feasibility and applicability of CT-CQDs to determine ENR in aquatic products was examined using the method of example 3.
ENR detection was performed on 4 kinds of aquatic products (carp, freshwater shrimp, scallop, and oyster) respectively.
(1) Pretreatment is carried out on a sample to be detected: homogenizing the sample to be detected by an electric homogenizer, accurately weighing 5.0g of homogenized sample tissue, placing into a 10mL centrifuge tube, adding 4.0mL acetonitrile and 0.04mL 1.0% acetic acid as extracting solution, homogenizing at high speed for 1min, extracting with ultrasound for 15min, extracting at 4500r.min -1 Centrifuging for 15min, collecting supernatant, extracting residue for 1 time, and mixing the two supernatants to obtain sample solution.
(2) The detection of ENR in samples using CT-CQDs comprises the steps of: CT-CQDs solution (0.3 mg.mL) -1 ) 400. Mu.L of low (0.67. Mu.M), medium (3.33. Mu.M), high (13.33. Mu.M) concentration ENR standard solution 400. Mu.L and sample solution to be detected 400. Mu.L were taken, and samples of the sample solution to be detected and the labeling solution were analyzed and the concentrations of ENR in the sample solution to be detected and the labeling solution were calculated by the same procedure and conditions as in example 3. The labeling solution sample refers to a sample solution to which ENR standard solution is added in order to further calculate the labeling recovery rate.
When a blank actual sample (namely a sample without the ENR standard solution) is added, the fluorescence intensity of the CT-CQDs is not changed significantly, which indicates that the blank actual sample does not contain or contains ENR below the detection limit.
Further calculation of the normalized recovery, as shown in table 1, the normalized recovery of ENR in the samples was in the range of 88.6% -104.7%, RSD was 5.4% (n=3). These results indicate that the method can accurately determine the ENR content in the aquatic product. Meanwhile, compared with the existing chromatographic analysis method and liquid chromatography-mass spectrometry technology, the method has wider linear range for determining the ENR parameter; the detection limit is lower compared to titration and SERS techniques. Therefore, the method has the advantages of simplicity in operation, green pollution-free performance, rapidness in detection, wider linear range and the like. Has good application value and application prospect in the fields of food safety and the like.
Table 1 results of the addition of the standard recovery of the four aquatic products ENR
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. Various modifications, equivalent arrangements, etc. to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (10)
1. The preparation method of the cicada slough carbon quantum dot is characterized by comprising the following steps of:
(1) Pulverizing periostracum Cicadae, and dissolving in water to obtain solution;
(2) Heating the solution obtained in the step (1);
(3) And (3) cooling and centrifuging the product obtained in the step (2), collecting supernatant, filtering and dialyzing to obtain the cicada slough carbon quantum dots, namely CT-CQDs.
2. The method according to claim 1, wherein in the step (1), the feed ratio of the crushed cicada slough powder to water is 1.0 g/50 ml, and the water is purified water.
3. The process of claim 1, wherein the heating is performed in the reaction vessel in step (2) at 180℃for 4 hours.
4. The process according to claim 1, wherein in step (3), the product obtained after heating in step (2) is cooled to room temperature and then cooled to 4500r.min -1 Centrifuging for 10min, collecting supernatant, filtering with 0.22 μm filter membrane, and dialyzing for 24 hr.
5. The method of any one of claims 1-4, further comprising the step of lyophilizing the carbon quantum dots of periostracum Cicadae after dialysis.
6. A periostracum cicadae carbon quantum dot fluorescent probe, which is characterized by being obtained by the preparation method of any one of claims 1-5.
7. A reagent or kit for detecting enrofloxacin comprising the periostracum Cicadae carbon quantum dot fluorescent probe of claim 6.
8. The use of the periostracum Cicadae carbon quantum dots prepared by the preparation method of any one of claims 1-5 in the detection of enrofloxacin.
9. The enrofloxacin detection method is characterized by comprising the following steps of:
s1, drawing a standard curve about enrofloxacin concentration by taking a relative change value of fluorescence intensity of a standard solution containing periostracum Cicadae carbon quantum dots as an ordinate and enrofloxacin concentration as an abscissa to obtain a standard curve;
s2, detecting the concentration of enrofloxacin in an unknown solution: mixing the cicada slough carbon quantum dot solution with an unknown solution, diluting with a buffer solution, performing fluorescence detection after reaction, detecting the fluorescence intensity of a liquid to be detected, and combining a standard curve graph to obtain the concentration of enrofloxacin in the unknown solution;
in the step S1 and the step S2, the cicada slough carbon quantum dots are prepared by the preparation method of any one of claims 1-5.
10. The method according to claim 9, wherein in S2, the pH of the buffer solution is 3.6 and the reaction time is 5min.
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| CN107490565A (en) * | 2017-06-27 | 2017-12-19 | 昆明理工大学 | A kind of method of nitrogen-doped carbon quantum dot fluorescence enhanced sensitivity detection Ciprofloxacin |
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| CN112852420A (en) * | 2021-02-04 | 2021-05-28 | 四川农业大学 | Carbon quantum dot fluorescent probe and method for detecting thiamphenicol content |
| CN113134347A (en) * | 2021-03-23 | 2021-07-20 | 西安理工大学 | Preparation method and application of heteroatom porous carbon |
| CN113721024A (en) * | 2021-09-16 | 2021-11-30 | 天津温阳生物技术有限公司 | Fluorescence immunoassay rapid detection kit and detection method for enrofloxacin carbon quantum dots in animal derived food |
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| CN107490565A (en) * | 2017-06-27 | 2017-12-19 | 昆明理工大学 | A kind of method of nitrogen-doped carbon quantum dot fluorescence enhanced sensitivity detection Ciprofloxacin |
| CN107515206A (en) * | 2017-06-27 | 2017-12-26 | 昆明理工大学 | A kind of method of sulfur doping carbon quantum dot fluorescence sensitivity detection Norfloxacin |
| CN112852420A (en) * | 2021-02-04 | 2021-05-28 | 四川农业大学 | Carbon quantum dot fluorescent probe and method for detecting thiamphenicol content |
| CN113134347A (en) * | 2021-03-23 | 2021-07-20 | 西安理工大学 | Preparation method and application of heteroatom porous carbon |
| CN113721024A (en) * | 2021-09-16 | 2021-11-30 | 天津温阳生物技术有限公司 | Fluorescence immunoassay rapid detection kit and detection method for enrofloxacin carbon quantum dots in animal derived food |
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