Aluminum ion-mediated gold nanoparticle colorimetric sensor for detecting ciprofloxacin

Abstract

The present invention relates to the technical field of nanomaterial detection, and specifically discloses a method for detecting ciprofloxacin using a gold nanoparticle colorimetric sensor mediated by aluminum ions. The method comprises the following steps: 1. synthesizing catechol-modified AuNPs; 2. Al 3+ Preparation of AuNPs colorimetric sensor mediated by AuNPs; 3. AuNPs / Al 3+ Colorimetric sensor for detection of ciprofloxacin. 3+ It can cause AuNPs to aggregate and change color, and construct AuNPs / Al 3+ Colorimetric sensor. Using the AuNPs / Al 3+ The colorimetric sensor detects ciprofloxacin, and the concentration of ciprofloxacin in the sample to be tested can be determined by the intensity of ultraviolet absorption and / or the degree of color change. Compared with the direct detection of ciprofloxacin using a single nanomaterial, the AuNPs / Al 3+ The colorimetric sensor can generate more color intervals, detect ciprofloxacin of different concentrations more accurately, and improve sensitivity. The method of the invention has the characteristics of low cost, fast response speed, low detection limit, high sensitivity and selectivity.

Description

Technical Field

[0001] The invention relates to the technical field of nano material detection, and in particular to a method for detecting ciprofloxacin using a gold nanoparticle colorimetric sensor mediated by aluminum ions. Background Art

[0002] Ciprofloxacin (CIP) is a commonly used broad-spectrum antibiotic belonging to the third-generation fluoroquinolone class of drugs. It is not only active against a variety of Gram-positive and Gram-negative bacteria, but also has good therapeutic effects on a variety of infectious diseases. In addition, ciprofloxacin is also widely used as a veterinary drug. However, due to the lack of awareness of the hazards of veterinary drug residues by some livestock and poultry farmers, they abuse drugs in pursuit of economic benefits, resulting in the increasingly serious problem of ciprofloxacin residues in the environment and animal-derived foods. Long-term intake of food or Chinese medicinal materials containing ciprofloxacin residues can cause serious harm to the human body, such as liver damage, central nervous system damage, and hematuria, and may even lead to the development of drug resistance, seriously affecting the treatment of diseases. Therefore, it is necessary to detect ciprofloxacin residues in complex matrices.

[0003] At present, the main methods for detecting ciprofloxacin include high performance liquid chromatography (HPLC), enzyme-linked immunosorbent assay (ELISA) and mass spectrometry (MS). However, these methods have the disadvantages of complex pretreatment process, expensive instruments and professional operation, which makes them difficult to promote. The detection method of ELISA depends on the activity of antibodies, but the instability and lack of repeatability of antibodies limit its application. In addition, many studies have used aptamer-based sensors and electrochemical sensors to detect ciprofloxacin. However, aptamer-based sensors and electrochemical sensors have the disadvantages of complex preparation process and high cost. Therefore, it is urgent to develop a fast, simple and cost-effective method for detecting ciprofloxacin. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the object of the present invention is to provide a method for detecting ciprofloxacin by using aluminum ion-mediated gold nanoparticle colorimetric sensing, which can not only detect ciprofloxacin quickly and with high sensitivity, but also realize visual detection of real samples such as tap water, honey and milk.

[0005] To achieve the above object, the present invention provides an aluminum ion (Al 3+ )-mediated gold nanoparticle (AuNPs) colorimetric sensing method for ciprofloxacin, comprising: a solution of catechol-modified AuNPs and Al 3+ The standard solution is used as the raw material, and specific binding is carried out under a specific addition order and addition ratio to form Al-O bonds to obtain Al 3+ mediated AuNPs colorimetric sensor.

[0006] The specific steps include:

[0007] Step (1), Synthesis of Catechol-modified AuNPs Solution

[0008] Before starting the synthesis, soak all the glassware needed in aqua regia (concentrated nitric acid:concentrated hydrochloric acid=1:3, v / v) for 3 hours and wash with ultrapure water. Add catechol solution, NaOH solution and HAuCl4 solution to ultrapure water and stir vigorously at room temperature for 24 hours; then centrifuge at 14000rpm for 20min, discard the supernatant, and redisperse in ultrapure water to obtain AuNPs solution, which is stored in a refrigerator at 4°C away from light for later use;

[0009] Step (2), Al 3+ Preparation of AuNPs-mediated colorimetric sensor

[0010] The AuNPs solution obtained in step (1) and Al 3+ The standard solution (prepared by adding aluminum chloride to water) and ultrapure water are mixed, and the resulting mixed solution is the AuNPs / Al2O3 for detecting ciprofloxacin. 3+ Colorimetric sensor;

[0011] Step (3), AuNPs / Al 3+ Colorimetric sensor for detection of ciprofloxacin

[0012] The AuNPs / Al 3+ A colorimetric sensor and a ciprofloxacin solution (prepared by adding water to ciprofloxacin) are mixed to obtain a mixed solution, and different mixed solutions that interact with ciprofloxacin solutions of different concentrations are obtained by changing the concentration of the ciprofloxacin solution; the concentration of the ciprofloxacin solution and the corresponding ultraviolet absorption intensity and color change degree of the mixed solution (i.e., the concentration of the ciprofloxacin solution and the corresponding ultraviolet absorption intensity of the mixed solution) are measured. 605 with I 520 A standard curve for detecting ciprofloxacin was established, and the content of ciprofloxacin in a complex matrix system was determined based on the standard curve.

[0013] Preferably, in step (1), the concentration of the catechol solution is 80 μmol / L, the concentration of the NaOH solution is 100 mmol / L, and the concentration of the HAuCl4 solution is 8 mmol / L, and the volume ratio of the three is 20:3:6.

[0014] Preferably, in step (1), the AuNPs precipitate obtained by centrifugation is pink-purple, and the AuNPs solution obtained by redispersing in ultrapure water is pink under visible light, has a concentration of 5-7 mg / mL, has a strong ultraviolet absorption peak at 520 nm, and has a regular spherical shape under a transmission electron microscope, with a particle size of about 7.5-9.5 nm.

[0015] Preferably, in step (2), AuNPs solution, Al 3+ The volume ratio of standard solution and ultrapure water is 1:1:1.

[0016] Preferably, in step (2), Al 3+ After mixing the standard solution and ultrapure water, the solution color changes from pink to blue, and an ultraviolet absorption peak appears at 605nm. Under a transmission electron microscope, the particle morphology is no longer a regular sphere, but a dumbbell-shaped morphology: This phenomenon indicates that the addition of Al 3+ After standard solution, Al 3+ The catechol-modified AuNPs were chelated through Al-O bonds, causing the original spherical AuNPs to aggregate and present a dumbbell-shaped morphology.

[0017] Preferably, in step (2), Al 3+ The standard solution and ultrapure water were mixed and reacted for 3 minutes. 3+ The concentration of the standard solution is 80-2000 μmol / L, preferably 1000 μmol / L.

[0018] Preferably, in step (3), AuNPs / Al 3+ The volume ratio of the colorimetric sensor and the ciprofloxacin solution was 2:1.

[0019] Preferably, in step (3), in the AuNPs / Al 3+ After adding ciprofloxacin solution into the colorimetric sensor, the color of the mixed solution changed from blue to purple-red.

[0020] Preferably, in step (3), the ciprofloxacin solution and the AuNPs / Al 3+ The reaction time of the colorimetric sensor is 5 min, and the concentration range of the added ciprofloxacin is 5-1000 μmol / L, wherein the concentrations of the ciprofloxacin solution are 5, 200, 600, 700, 800, 900, and 1000 μmol / L, respectively.

[0021] Optionally, the step (3) may be to prepare the AuNPs / Al 3+A colorimetric sensor and a ciprofloxacin solution are mixed to obtain a mixed solution; different mixed solutions interacting with ciprofloxacin solutions of different concentrations are obtained by changing the concentration of the ciprofloxacin solution; image information of the mixed solution is collected by photographing with a camera and a digital matrix corresponding to RGB values ​​is obtained by using MATLAB software; finally, the RGB values ​​of pixels in the mixed solution photo are associated with the concentration of ciprofloxacin by using a PLSR model, thereby realizing the prediction of ciprofloxacin content in a complex matrix system. Preferably, the specific steps are as follows: extracting pixel information in the photographed photo with the aid of Photoshop software; then, extracting the RGB value of each pixel using MATLAB software to obtain a corresponding digital matrix; finally, combining the digital matrix with a PLSR model to construct a relationship curve between color change and ciprofloxacin concentration (i.e., constructing a relationship curve between the GRB value and its corresponding ciprofloxacin concentration). Preferably, the specific operation method is as follows: in PLSR, projecting the observed variable (X, the RGB value of the pixel in the solution photo) and the predicted variable (Y, the ciprofloxacin concentration in the real sample solution) into a new space so that the correlation between the observed variable and the predicted variable is maximized in the new space, and then gradually finding the new space through multiple iterations of the PLSR algorithm to establish a linear model, thereby realizing the prediction of the ciprofloxacin concentration. The selection of the parameters of the latent variables (LVs) in the PLSR model is based on the root mean square error (RMSE) of cross-validation, which represents the complexity of the model.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] Compared with the existing ciprofloxacin detection method, the present invention Al 3+ The AuNPs colorimetric sensor for detecting ciprofloxacin has the characteristics of low cost, fast response, low detection limit, high sensitivity and selectivity. 3+ A strong binder that can destroy Al 3+ The AuNPs aggregated and deaggregated. 3+ Compared with direct detection of a single nanomaterial, the AuNPs colorimetric sensor mediated by the present invention has a linear range of 5-1000 μmol / L, and the color range can range from pink to blue and then to purple-red, with a larger degree of color change and higher sensitivity. 3+ The colorimetric sensor detects ciprofloxacin and the concentration of ciprofloxacin in the sample to be tested can be determined by the intensity of ultraviolet absorption and / or the degree of color change. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1In the embodiment, the three stages of A are AuNPs solution (in this application, AuNPs solution refers to the AuNPs solution obtained in step (1) of the method of the present invention, wherein the AuNPs are modified with catechol), AuNPs / Al 3+ Colorimetric sensors and AuNPs / Al 3+ + Transmission electron microscopy of ciprofloxacin solution; B includes the three stages of AuNPs solution, AuNPs / Al 3+ Colorimetric sensors and AuNPs / Al 3+ + Color change diagram of ciprofloxacin solution; C is AuNPs / Al 3+ RGB colorimetric sensor detects ciprofloxacin; D is AuNPs / Al 3+ The colorimetric sensor uses RGB values ​​combined with the PLSR model to predict the concentration of ciprofloxacin in real samples; E is the selected real samples, namely honey, tap water, milk and lake water.

[0025] Figure 2 In the figure, A is a high-resolution transmission electron micrograph of the AuNPs solution of the present invention, with a scale of 50 nm; B is a particle size distribution diagram of AuNPs, which is obtained by analyzing the TEM image of Figure A with Nano Measurer; C is a UV absorption spectrum of the AuNPs solution (the inset is the color of the AuNPs solution under a fluorescent lamp: pink); D is a high-resolution transmission electron micrograph of the AuNPs solution, with a scale of 10 nm; E is the AuNPs / Al 3+ High-resolution transmission electron microscopy image of the colorimetric sensor, scale is 10nm, Al 3+ The concentration of the standard solution is 1000 μmol / L; F is the concentration of AuNPs / Al 3+ High-resolution transmission electron microscopy image of the product in the solution obtained after the reaction was completed after adding ciprofloxacin solution to the colorimetric sensor. The scale is 10 nm, Al 3+ The concentration of the standard solution was 1000 μmol / L, and the concentration of the ciprofloxacin solution was 200 μmol / L.

[0026] Figure 3 In the formula, A is Al 3+ Linear fitting curve of standard solution concentration in the range of 80-2000μmol / L (the Al 3+ The concentrations of the standard solutions from left to right are 80, 400, 600, 700, 800, 900, and 2000 μmol / L, and the ordinate is the concentration of I after adding ciprofloxacin solution. 605 with I 520 The ratio of I 605 is the absorbance of the reaction system at 605 nm, I 520A is the absorbance of the reaction system at 520 nm; B is the linear fitting curve of the ciprofloxacin solution concentration in the range of 5-1000 μmol / L (the ciprofloxacin solution concentrations corresponding to each point in the figure are 5, 200, 600, 700, 800, 900, 1000 μmol / L from left to right), and the ordinate is the I 605 with I 520 The ratio of I 605 is the absorbance of the reaction system at 605 nm, I 520 is the absorbance of the reaction system at 520 nm, and the inset in B is the AuNPs / Al 3+ Visualization results of colorimetric sensor and ciprofloxacin solutions of different concentrations (the ciprofloxacin solution concentrations corresponding to the colors in the illustration are 5, 200, 600, 700, 800, 900, and 1000 μmol / L from left to right); C is AuNPs / Al 3+ The selectivity experimental results of the colorimetric sensor reacting with ciprofloxacin, other antibiotics, and interfering substances. The ordinate is the I before and after adding various compound solutions. 605 with I 520 The ratio of represents the degree of color change, where (I 605 / I 520 )0 is AuNPs / Al 3+ The ratio when no compound solution is added to the colorimetric sensor, (I 605 / I 520 )1 is the AuNPs / Al 3+ The ratio after adding the compound solution to the colorimetric sensor. In the figure, AM is blank, ciprofloxacin, ofloxacin, gatifloxacin, chloramphenicol, erythromycin, amoxicillin, neomycin, oxytetracycline, L-phenylalanine, D-phenylalanine, D-leucine and L-serine.

[0027] Figure 4 The AuNPs / Al 3+ Visualization result diagram of colorimetric sensor detecting ciprofloxacin in real samples of lake water, tap water, milk and honey. The concentrations of ciprofloxacin in lake water, tap water, milk and honey are 0.005, 0.080, 0.200, 0.300, 0.600, 1.000 and 2.000 mmol / L, respectively.

[0028] Figure 5 The AuNPs / Al 3+ The predicted relationship curve between the actual concentration value and the predicted concentration value of ciprofloxacin in real samples of lake water (Figure A), milk (Figure B), honey (Figure C) and tap water (Figure D) detected by colorimetric sensor. DETAILED DESCRIPTION

[0029] In order to better understand the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The present invention provides an Al 3+ AuNPs-mediated colorimetric sensor for the detection of ciprofloxacin based on Al 3+ As a hard metal ion, it can form Al-O bonds with catechol modified on the surface of AuNPs, causing the AuNPs to aggregate and change color (the AuNPs solution changes from pink to blue). 3+ Colorimetric sensor; Since ciprofloxacin is Al 3+ strong binding agent in AuNPs / Al 3+ Ciprofloxacin was added to the colorimetric sensor, and ciprofloxacin could compete with AuNPs for binding to Al 3+ , so that AuNPs undergo deaggregation and color change (the solution changes from blue to purple-red). In this process, the concentration of the ciprofloxacin solution is directly related to the color change of the solution. Based on the above principle, the RGB value of the solution is extracted and combined with the PLSR model to realize the visualization concentration prediction of ciprofloxacin in a complex matrix. The Al2O3 nanostructured carbon nanotubes of the present invention are described below through specific embodiments. 3+ The method of AuNPs-mediated colorimetric sensor for detecting ciprofloxacin is described in detail.

[0031] In the following examples: 3+ The standard solution is prepared by adding aluminum chloride to ultrapure water.

[0032] The ciprofloxacin solution is prepared by adding ciprofloxacin hydrochloride monohydrate to ultrapure water.

[0033] Example 1

[0034] A kind of Al 3+ The method for detecting ciprofloxacin using a AuNPs colorimetric sensor comprises the following steps:

[0035] Step (1), Synthesis of AuNPs

[0036] Before starting the synthesis, soak all the glassware needed in aqua regia (concentrated nitric acid: concentrated hydrochloric acid = 1:3, v / v, the concentration of concentrated nitric acid is 65wt%, and the concentration of concentrated hydrochloric acid is 36.5wt%) for 3 hours, and then wash with ultrapure water. Prepare in advance a catechol solution with a concentration of 80μmol / L, a NaOH solution with a concentration of 100mmol / L, and a HAuCl4 solution with a concentration of 8mmol / L (all aqueous solutions), take 50mL, 7.5mL, and 15mL respectively and add them to ultrapure water, with a final volume of 500mL, and stir vigorously at room temperature (25°C, the same below) for 24 hours. Then, centrifuge at 14000rpm for 20min, discard the supernatant (the AuNPs precipitate obtained by centrifugation is pink-purple), and redisperse in 200mL of ultrapure water to obtain an AuNPs solution (such as Figure 2 As shown in A, C, and D, the morphology under a transmission electron microscope is a regular sphere with a particle size of 7.5-9.5 nm, an ultraviolet absorption peak at 520 nm, pink under visible light (provided by a fluorescent lamp), and a concentration of 5 mg / mL), and is stored in a refrigerator at 4°C away from light for future use.

[0037] Step (2), Al 3+ Preparation of AuNPs-mediated colorimetric sensor

[0038] Add 400 μL of the AuNPs solution obtained in step (1) and 400 μL of 1000 μmol / L Al 3+ The standard solution and 400 μL ultrapure water were added to keep the total volume of the system at 1.2 mL. After 3 min of reaction, the mixed solution obtained at room temperature and normal pressure was AuNPs / Al 3+ Colorimetric sensor.

[0039] Step (2-1), the volume of each component remains unchanged, only the Al 3+ The concentration of the standard solution was obtained with different concentrations of Al 3+ After 3 minutes of reaction, the samples of each concentration of Al 3+ The absorption spectrum data of the mixed solution corresponding to the standard solution. The results show that when Al 3+ After the standard solution, AuNPs aggregated, and a new absorption peak appeared at 605nm, and the color changed from pink to blue (such as Figure 1 B, 2E, the color of the solution changes from pink to blue after mixing, and the particle morphology under transmission electron microscopy is no longer a regular sphere, but a dumbbell-shaped morphology). 3+As the concentration of the standard solution increases, the ratio of the absorption peaks at 605nm and 520nm (I 605 / I 520 ) will gradually increase. When Al 3+ When the concentration of the standard solution is within the range of 80-2000 μmol / L (Al 3+ The concentrations of the standard solutions were 80, 400, 600, 700, 800, 900, and 2000 μmol / L, respectively. 3+ Colorimetric Sensor I 605 / I 520 Value (Y axis) and Al 3+ The concentration of the standard solution (X axis) has a good linear relationship (such as Figure 3 A).

[0040] Step (3), Al 3+ Detection of ciprofloxacin by AuNPs colorimetric sensor and prediction of ciprofloxacin concentration in real samples

[0041] Add the AuNPs / Al obtained in step (2) into the EP tube. 3+ 800 μL of the colorimetric sensor and 400 μL of a 200 μmol / L ciprofloxacin solution were mixed to obtain a mixed solution, and the total volume of the system was maintained at 1.2 mL. After reacting for 5 minutes, the ultraviolet absorption spectrum data of the mixed solution was collected at room temperature and normal pressure.

[0042] according to Figure 1 B, 2D-E, after mixing, the color of the solution changes from pink to blue. Under the transmission electron microscope, the particle morphology is no longer a regular sphere, but a dumbbell-shaped morphology. This phenomenon indicates that the addition of Al 3+ After standard solution, Al 3+ The catechol-modified AuNPs were chelated through Al-O bonds, causing the original spherical AuNPs to aggregate and present a dumbbell-shaped morphology.

[0043] The AuNPs / Al 3+ The volume of the colorimetric sensor and ciprofloxacin solution remained unchanged, and only the concentration of the added ciprofloxacin solution was changed (the concentrations of the ciprofloxacin solutions were 5, 600, 700, 800, 900, and 1000 μmol / L, respectively), to obtain a mixed solution that interacted with ciprofloxacin solutions of different concentrations. After reacting for 5 minutes, the ultraviolet absorption spectrum data of the mixed solution corresponding to each concentration of ciprofloxacin solution was collected at room temperature and normal pressure. According to the concentration of each concentration of ciprofloxacin solution and the ultraviolet absorption ratio and color change degree of the corresponding mixed solution, a standard curve for detecting ciprofloxacin was established. Figure 2As shown in F, after the addition of ciprofloxacin solution, the color of the solution changes again (from blue to purple-red). Figure 3 As shown in B, when the concentration of the added ciprofloxacin solution is in the range of 5-1000 μmol / L (the concentrations of the ciprofloxacin solution are 5, 200, 600, 700, 800, 900, and 1000 μmol / L, respectively), I 605 / I 520 There is a good linear relationship between the value (Y) and the concentration of ciprofloxacin solution (X), and the detection limit is as low as 0.13 μmol / L. As the concentration of ciprofloxacin solution added continues to increase, the color of the mixed solution gradually changes from blue to purple (such as Figure 3 (inset in B).

[0044] Verification of AuNPs and Al 3+ Binding specificity

[0045] The comparative test verified that AuNPs and Al 3+ In order to determine the specificity of the binding, different metal ion standard solutions were selected to react with the AuNPs solution, and the mixed solution after the reaction was tested. The specific process was as follows: according to the volume ratio of each raw material in step (2) of Example 1, different types of high-concentration metal ion standard solutions were added to the parallel AuNPs solution, wherein Al 3+ The concentration of the standard solution is 80 μmol / L, Ag + Standard solution (prepared by adding silver nitrate to ultrapure water), Ca 2+ Standard solution (prepared by adding anhydrous calcium chloride to ultrapure water), Cd 2+ Standard solution (prepared by adding 2.5 cadmium chloride (CdCl2·2.5H2O) to ultrapure water), Co 2+ Standard solution (prepared by adding cobalt chloride hexahydrate to ultrapure water), Sn 2+ Standard solution (prepared by adding stannous chloride dihydrate to ultrapure water), Cu 2+ Standard solution (prepared by adding cupric chloride dihydrate to ultrapure water), Fe 3+ Standard solution (prepared by adding ferric chloride hexahydrate to ultrapure water), Hg 2+ Standard solution (prepared by adding mercuric nitrate to ultrapure water), K + Standard solution (prepared by adding potassium chloride to ultrapure water), Mg 2+ Standard solution (prepared by adding magnesium chloride to ultrapure water), Mn 2+ Standard solution (prepared by adding manganese chloride tetrahydrate to ultrapure water), Ni 2+The concentration of the interfering metal ion standard solution (prepared by adding nickel chloride hexahydrate to ultrapure water) was 1000 μmol / L. The results showed that when the above interfering metal ion standard solution was added, no absorption peak appeared at 605 nm, indicating that except Al 3+ Other metal ions cannot form AuNPs / Al 3+ The colorimetric sensor is the same as the colorimetric sensor, thereby illustrating that the colorimetric sensor constructed by the present invention is effective for Al 3+ It has good selectivity. 3+ Specificity of colorimetric sensor for detecting ciprofloxacin

[0046] The AuNPs / Al 3+ The specificity of the colorimetric sensor for detecting ciprofloxacin, other antibiotics (ofloxacin, gatifloxacin, chloramphenicol, erythromycin, amoxicillin, neomycin, oxytetracycline) and other interferents (L-phenylalanine, D-phenylalanine, D-leucine and L-serine) were selected to interact with AuNPs / Al 3+ The specific process is as follows: according to the volume ratio of step (3) in Example 1, in the AuNPs / Al 3+ High concentrations of the above-mentioned other antibiotic solutions and interfering substance solutions are added to the colorimetric sensor, wherein the concentration of the ciprofloxacin solution is 100 μmol / L, the concentration of the ofloxacin, gatifloxacin, chloramphenicol, erythromycin, amoxicillin, neomycin, oxytetracycline and other antibiotic solutions is 1000 μmol / L, and the concentration of the L-phenylalanine, D-phenylalanine, D-leucine and L-serine solutions is 10000 μmol / L (the solutions of ofloxacin, gatifloxacin, chloramphenicol, erythromycin, amoxicillin, neomycin, oxytetracycline, L-phenylalanine, D-phenylalanine, D-leucine and L-serine are prepared by adding the corresponding compounds to ultrapure water). Figure 3 C, the ordinate is the I before and after adding each compound solution 605 with I 520 The ratio of represents the degree of color change, where (I 605 / I 520 )0 is AuNPs / Al 3+ The ratio when no compound solution is added to the colorimetric sensor, (I 605 / I 520 )1 is the AuNPs / Al 3+ The ratio after adding the compound solution to the colorimetric sensor. When the ciprofloxacin solution is added, (I 605 / I 520 )1 / (I 605 / I 520 )0 value is significantly reduced, while when other solutions are added, (I605 / I 520 )1 / (I 605 / I 520 )0 value is almost unchanged. The results show that AuNPs / Al 3+ The colorimetric sensor showed excellent selectivity for ciprofloxacin.

[0047] Preparation of authentic sample solutions

[0048] Lake water was obtained from Nanhu Lake (Wuhan, Hubei), and tap water was obtained from the laboratory. The lake water and tap water samples were processed as follows: large particles of impurities were removed by filtering through a microporous filter membrane with a pore size of 0.22 μm. Honey was purchased from a local pharmacy (Wuhan, Hubei), and milk was purchased from a supermarket (Wuhan, Hubei). The honey and milk samples were processed as follows: 1.0 g of sample was accurately weighed and placed in a 50 mL EP tube; 40 mL of 0.1 mol / L EDTA-Mcllvaine buffer solution was added, and the mixture was shaken for 10 min, ultrasonicated for 10 min, and then centrifuged at 10,000 rpm for 20 min to obtain the supernatant. No other treatment was required. The lake water, tap water, honey, and milk treated according to the above method were used as solvents to dissolve ciprofloxacin to obtain real sample solutions containing different concentrations of ciprofloxacin (as attached to the instruction manual). Figure 4 The concentrations of ciprofloxacin solutions using lake water, tap water, honey, and milk as solvents included 0.005, 0.080, 0.200, 0.300, 0.600, 1.000, and 2.000 mmol / L, respectively).

[0049] Preparation method of Mcllvaine buffer solution: Evenly mix 200mL of 0.1mol / L citric acid solution and 125mL of 0.2mol / L disodium hydrogen phosphate solution, and adjust the pH value to 4.00.

[0050] Preparation method of EDTA-Mcllvaine buffer solution: Add 12.1g of disodium ethylenediaminetetraacetate to 325mL of Mcllvaine buffer solution and stir to dissolve.

[0051] Visual detection of ciprofloxacin content in real sample solutions

[0052] 260 μL of the AuNPs / Al prepared in step (2) of Example 1 were added to 3+ The colorimetric sensor was mixed with 130 μL of the real sample solution containing different concentrations of ciprofloxacin prepared above. After the reaction was completed, the 96-well plate was placed on a 15W LED board to observe the color change of the solution in the wells. The color information of the actual sample solution on the 96-well plate was collected by taking a photo with a camera, such as Figure 4As shown in Figure 2, real sample solutions (tap water, lake water, honey and milk) containing different concentrations of ciprofloxacin were added to the AuNPs / Al 3+ In the colorimetric sensor, after the reaction, the solution has different degrees of color change, proving that Al 3+ The AuNPs-mediated colorimetric sensor for detecting ciprofloxacin can accurately detect ciprofloxacin in complex matrices with little interference from the matrix.

[0053] For the above-mentioned post-reaction solution, the image information of the solution is collected by taking photos with a camera and the digital matrix corresponding to the RGB value is obtained by using MATLAB software. Finally, the PLSR model is used to associate the RGB value of the pixel in the photo of the solution with the concentration of ciprofloxacin. Based on this, the prediction of ciprofloxacin content in complex matrix systems such as tap water, lake water, milk and honey is realized. The prediction results show that the PLSR model based on RGB value has a good effect and high accuracy in predicting the concentration of ciprofloxacin in 4 real sample solutions. The specific process is: with the help of Photoshop software, the pixel information in the photograph is extracted. Then, using MATLAB software, the RGB value of each pixel is extracted to obtain the corresponding digital matrix. Finally, the digital matrix is ​​combined with the PLSR chemometric model to construct a relationship curve between color change and ciprofloxacin concentration. The specific operation method is: in PLSR, by projecting the observed variable (X, the RGB value of the pixel in the solution photo) and the predicted variable (Y, the concentration of ciprofloxacin in the real sample solution) into a new space, the correlation between the observed variable and the predicted variable in this new space is maximized. Then, the new space was gradually found through multiple iterations of the PLSR algorithm, and a linear model was established to predict the concentration of ciprofloxacin.

[0054] Table 1A1 3+ The correlation results of the AuNPs colorimetric sensor using RGB values ​​combined with the PLSR model to predict the concentration of ciprofloxacin in actual samples of lake water, milk, honey, and tap water

[0055]

[0056] In Table 1, the selection of latent variables (LVs) parameters in the PLSR model is based on the root mean square error (RMSE) of cross-validation, which represents the complexity of the model. RMSE (root mean square error) measures the deviation between the predicted value and the true value and is sensitive to outliers in the data. The root mean square error of correction (RMSEC) and the root mean square error of prediction (RMSEP) are used to evaluate the accuracy of the PLSR model. RMSEC is the predicted mean square error of the calibration set, and RMSEP is the predicted mean square error of the prediction set. Generally speaking, the smaller the RMSEC and RMSEP are, the better the accuracy of the model. 2 c and R 2p is used to evaluate the correlation coefficient between the actual concentration and the predicted concentration in the training set and the prediction set, and R is the regression coefficient of the linear fit between the true value and the predicted value of the training set and the prediction set samples. 2 c. R 2 p and R 2 The closer it is to 1, the better the prediction effect of the model. The results show that there is a good linear relationship between the actual concentration and the predicted concentration of ciprofloxacin in various real sample solutions. As shown in Table 1 and Figure 5 As shown in Figure 2, the PLSR model based on RGB values ​​has a good effect on predicting the concentration of ciprofloxacin in four real sample solutions, with RSMEC≤0.02288, RSMEP≤0.0886, and R 2 ≥0.9990; it also proves that the PLSR quantitative model results have high accuracy. Taking the tap water sample solution as an example, the actual concentration is 0.6000mM, and the predicted concentration of the RGB-based PLSR model is 0.6102mM.

[0057] The above-mentioned embodiments only express the accurate implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. A method for detecting ciprofloxacin using an aluminum ion-mediated gold nanoparticle colorimetric sensor, characterized in that: The steps include: Step (1), synthesis of catechol-modified AuNPs solution, the specific process is: Before starting the synthesis, all glassware needed were soaked in aqua regia for 3 hours and washed with ultrapure water; catechol solution, NaOH solution and HAuCl4 solution were added to ultrapure water and stirred vigorously at room temperature for 24 hours; then, centrifuged at 14000 rpm for 20 min, the supernatant was discarded, and the AuNPs solution was redispersed in ultrapure water to obtain the solution, which was stored in a refrigerator at 4°C away from light for later use; The concentration of catechol solution was 80 µmol / L, the concentration of NaOH solution was 100 mmol / L, the concentration of HAuCl4 solution was 8 mmol / L, and the volume ratio of the three was 20:3:6; Step (2), Al 3+ Preparation of AuNPs-mediated colorimetric sensor The AuNPs solution obtained in step (1) and Al 3+ The standard solution and ultrapure water are mixed, and the resulting mixed solution is the AuNPs / Al required for detecting ciprofloxacin. 3+ Colorimetric sensor; Step (3), AuNPs / Al 3+ Colorimetric sensor for detection of ciprofloxacin The AuNPs / Al 3+ The colorimetric sensor and the ciprofloxacin solution are mixed to obtain a mixed solution; different mixed solutions interacting with ciprofloxacin solutions of different concentrations are obtained by changing the concentration of the ciprofloxacin solution; a standard curve for detecting ciprofloxacin is established according to the concentration of the ciprofloxacin solution and the ultraviolet absorption intensity and color change degree of the mixed solution corresponding thereto, and the determination of the ciprofloxacin content in the complex matrix system is achieved based on the standard curve, specifically: The image information of the mixed solution is collected by taking photos with a camera, and a digital matrix corresponding to the RGB value is obtained by using MATLAB software. Finally, the PLSR model is used to associate the RGB value of the pixel point in the mixed solution photo with the ciprofloxacin concentration, and the prediction of the ciprofloxacin content in the complex matrix system is realized based on this. The specific process is: with the help of Photoshop software, the pixel point information in the taken photo is extracted; then, the MATLAB software is used to extract the RGB value of each pixel point to obtain the corresponding digital matrix; finally, the digital matrix is ​​combined with the PLSR model to construct a relationship curve between color change and ciprofloxacin concentration. The specific operation method is: in the PLSR model, the RGB value of the pixel point in the solution photo is used as the observed variable X, and the ciprofloxacin concentration in the real sample solution is used as the predicted variable Y. Projected into a new space, so that in this new space, the correlation between the observed variable X and the predicted variable Y is maximized; then, the new space is gradually found through multiple iterations of the PLSR algorithm, and a linear model is established, thereby realizing the prediction of the predicted variable.

2. The method according to claim 1, characterized in that: In the step (1), the AuNPs precipitate obtained by centrifugation is pink-purple, and the AuNPs solution obtained by redispersing in ultrapure water is pink under visible light, has a concentration of 5-7 mg / mL, has a strong ultraviolet absorption peak at 520 nm, and has a regular spherical shape under a transmission electron microscope with a particle size of 7.5-9.5 nm.

3. The method according to claim 1, characterized in that In the step (2), AuNPs solution, Al 3+ The volume ratio of standard solution and ultrapure water is 1:1:

1.

4. The method according to claim 1, characterized in that: In the step (2), Al 3+ After mixing the standard solution and ultrapure water, the color of the solution changed from pink to blue, and an ultraviolet absorption peak appeared at 605 nm. Under a transmission electron microscope, the particle morphology was no longer a regular sphere, but a dumbbell-shaped morphology: Adding Al 3+ After standard solution, Al 3+ The catechol-modified AuNPs were chelated through Al-O bonds, causing the original spherical AuNPs to aggregate and present a dumbbell-shaped morphology.

5. The method according to claim 1, characterized in that In the step (2), Al 3+ The standard solution and ultrapure water were mixed and reacted for 3 min. 3+ The concentration of the standard solution is 80-2000µmol / L.

6. The method according to claim 1, characterized in that In the step (3), AuNPs / Al 3+ The volume ratio of the colorimetric sensor and the ciprofloxacin solution was 2:

1.

7. The method according to claim 1, characterized in that In the step (3), in the AuNPs / Al 3+ After adding ciprofloxacin solution into the colorimetric sensor, the color of the mixed solution changed from blue to purple-red.

8. The method according to claim 1, characterized in that In the step (3), the ciprofloxacin solution and the AuNPs / Al 3 + The reaction time of the colorimetric sensor was 5 min, and the concentration range of the added ciprofloxacin was 5-1000 µmol / L, where the concentrations of the ciprofloxacin solutions were 5, 200, 600, 700, 800, 900, and 1000 µmol / L, respectively.

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