CN111208101A

CN111208101A - Method for conveniently detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycoside and derivatives thereof

Info

Publication number: CN111208101A
Application number: CN202010041086.8A
Authority: CN
Inventors: 石星波; 魏伟; 高文丽
Original assignee: Hunan Agricultural University
Current assignee: Hunan Agricultural University
Priority date: 2020-01-15
Filing date: 2020-01-15
Publication date: 2020-05-29
Anticipated expiration: 2040-01-15
Also published as: CN111208101B

Abstract

A convenient method for detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycoside and derivatives thereof is characterized in that the flavonoid glycoside and the derivatives thereof are used as precursors to synthesize blue fluorescent carbon quantum dots with emission peaks at 400-; then, the aluminum ions induce the blue fluorescent carbon quantum dots to generate green fluorescence with an emission peak at 490-580 nm; and then under the irradiation of ultraviolet light, acquiring a carbon quantum dot color fluorescence photo induced by aluminum ions, and analyzing the photo by using an RGB method to detect the concentration of the aluminum ions. The invention provides a method for synthesizing carbon quantum dots by flavonoid glycoside and derivatives thereof, and constructing portable Al detection based on the carbon quantum dots³⁺The policy of (1). According to the change of different fluorescence colors of the carbon quantum dots under the irradiation of ultraviolet light, Al is quantified³⁺. Therefore, the fluorescent color change of samples with different concentrations under the irradiation of ultraviolet light can be analyzed only by means of the smart phone and RGB analysis software, and the rapid detection of metal ions can be realized.

Description

Method for conveniently detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycoside and derivatives thereof

Technical Field

The invention mainly relates to a method for detecting aluminum ions, in particular to a method for detecting aluminum ions in a portable manner by using carbon quantum dots synthesized based on flavonoid glycoside and derivatives thereof.

Background

Aluminum is the highest metal element in the earth's crust and is widely used for water treatment, aluminum containers and food additivesEtc. to neutralize aluminum ions (Al) in water and food³⁺) The concentration is increased. Aluminum ions accumulate slowly in the human body and may pose a hazard to human health (diseases such as alzheimer's disease and parkinson's disease). The World Health Organization (WHO) specifies that the average aluminum intake in humans is about 3-10 mg/day. The traditional methods for detecting aluminum ions mainly comprise atomic absorption spectrometry, atomic emission spectrometry, inductively coupled plasma mass spectrometry and the like. The methods require expensive instruments, have complicated sample pretreatment, long analysis time and inconvenient carrying, and are difficult to meet the requirement of on-site instant and rapid detection. Therefore, there is a need to develop a new detection strategy for detecting aluminum ions with high sensitivity, which is economical, simple, fast and portable.

Carbon quantum dots (CDs) are a novel fluorescent nanomaterial, and have been widely studied due to their characteristics of simple synthesis and excellent optical properties. Hydrothermal synthesis is the most popular method for synthesizing CDs, by directly heating a solution of carbon-rich small molecules. The hydrothermal synthesis precursor has wide source and low cost, and chemical substances such as amino acid, citric acid, ethylenediamine and the like can be used as precursors for synthesizing CDs. Because the surface functional groups of the synthesized CDs can interact with metal ions through chelation, the CDs synthesized based on different precursor substances realize sensitive detection of various metal ions.

Colorimetric-based detection methods are of great interest because of the easy readout of the detection signal and the low cost. The method is based on the change of the absorptivity, and the sensitivity and the accuracy are lower. In order to further improve the sensitivity and accuracy of the colorimetric sensor, the proportional probe is constructed by using two fluorescent nano materials with different colors, so that the influences of light source fluctuation, environmental uncertainty and the like can be effectively eliminated, and the detection sensitivity is improved. At present, a two-color fluorescent probe based on nano materials such as carbon quantum dots, semiconductor quantum dots, metal nanoclusters and the like realizes high-sensitivity detection of metal ions and small molecules. However, such a colorimetric detection technique based on fluorescence usually requires adjusting the fluorescence intensity ratio of two fluorescent nanomaterials with different colors, thereby making the detection process more complicated.

Recently, the portable detection method based on the smart phone improves the colorimetric detection technology based on fluorescence, and meets the requirement of on-site real-time detection. RGB (color pattern of three color channels of red, green and blue) analysis is carried out on the color photo of the sample by using analysis software (Image J, RGB Picker and the like) on a mobile phone, and real-time portable detection on the target can be realized based on the color intensity ratios of different color channels. The method can simply, quickly and portably detect the metal ions only by using a smart phone, analysis software and an ultraviolet lamp.

Disclosure of Invention

The invention aims to provide a method for conveniently detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycoside and derivatives thereof, which utilizes carbon quantum dots (CDs) synthesized by the flavonoid glycoside and the derivatives thereof and realizes the detection of the aluminum ions (Al) based on the CDs³⁺) Portable detection of (2).

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for conveniently detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycosides and derivatives thereof comprises the following steps:

A. taking flavonoid glycoside and derivatives thereof as precursors to synthesize blue fluorescent carbon CDs with emission peaks at 400-480 nm;

B. inducing the blue fluorescence CDs by aluminum ions to generate green fluorescence with an emission peak at 490-580 nm;

C. obtaining Al under the irradiation of ultraviolet light³⁺Color fluorescence photograph of induced CDs, which was analyzed by RGB method to detect Al³⁺The concentration of (c).

Preferably, the flavonoid glycoside and the derivatives thereof mentioned in the step a are one or more of naringin, hesperidin or hesperidin and derivatives thereof.

Preferably, the method for synthesizing the carbon quantum dots in the step a is a hydrothermal method, an ultrasonic method, a solvothermal method, a microwave digestion method or an ultrasonic oscillation method, which are conventional methods. The hydrothermal method is used for illustration, and the specific process is as follows: dissolving 0.01-0.1 g of flavonoid glycoside and derivatives thereof in 5-50 ml of absolute ethanol, dissolving by ultrasonic oscillation, and reacting at 120-200 deg.C for 1-8 h; and after the reaction is finished, separating, purifying and freeze-drying the solution after the reaction to obtain CDs powder.

Preferably, the induction in step B is performed by adding Al at different concentrations³⁺Mixing the solution with 0.01mg/ml-1mg/ml blue fluorescent CDs solution, and reacting at room temperature for 5min-30 min.

Preferably, the wavelength of the ultraviolet light in the step C is 200-; the CDs color fluorescence photographs were acquired by a smartphone, which contains all types of smartphones with camera imaging capabilities.

Analysis of CDs color fluorescent photograph by RGB method mentioned above for Al detection³⁺The course of concentration is conventional in the art.

According to the invention, the flavonoid compound is rich in carbon, hydrogen and oxygen elements and contains hydroxyl groups, and can be used as a precursor for synthesizing CDs to synthesize blue fluorescent CDs (the emission peak is positioned at 400-; and Al³⁺Can induce CDs to generate a new green fluorescence emission peak (490-580nm), and the original blue fluorescence intensity (400-480nm) of CDs is weakened; meanwhile, the intelligent mobile phone is combined with RGB analysis, so that the obvious color change of the CDs probe from blue to green under ultraviolet light can be recognized, and the Al can be simply, quickly and portably detected³⁺See fig. 1 in combination.

The invention provides a method for synthesizing CDs by flavonoid glycoside and derivatives thereof, and constructing portable detection Al based on CDs³⁺The policy of (1). According to the change of different fluorescence colors of CDs under the irradiation of ultraviolet light, Al is quantified³⁺. Therefore, the method can realize the detection of the metal ions by analyzing the fluorescent color change of the samples with different concentrations under the irradiation of ultraviolet light by using the smart phone and RGB analysis software (such as Image J software). The method is simple to operate, convenient to carry, rapid in detection, easy to popularize and suitable for various inspection departments for detecting the aluminum ions.

Drawings

FIG. 1 is a schematic diagram of the detection principle of the method of the present invention.

FIG. 2 is a basic property characterization of CDs synthesized based on naringin;

wherein A represents a spectrogram of CDs, and a and b respectively represent an ultraviolet absorption spectrum and a fluorescence emission spectrum of the CDs; b represents the fluorescence emission properties of CDs under different excitation wavelengths, and a, B, c, d, e and f respectively refer to the fluorescence emission spectrums of CDs under the excitation wavelengths of 300nm, 320nm, 340nm, 360nm, 380nm and 400 nm; c represents the change of the fluorescence intensity of the CDs at different pH values, and the fluorescence intensity ratio refers to the ratio between the fluorescence intensity of the CDs at different pH values and the fluorescence intensity of the CDs at pH 7; d represents a fourier infrared spectrum of CDs.

FIG. 3 is a graph showing Al detection by fluorescence spectroscopy³⁺The data of (2) is a graph and specificity.

Wherein A represents adding Al with different concentrations³⁺Fluorescence spectra of the CDs; b represents Al³⁺The relationship between the concentration of (D) and the I500/I420 value, the inset shows a linear relationship in the range of 23.08 μ M-769.23 μ M; c represents addition of 769.23. mu.M of a different metal ion (Ag)⁺，Al³⁺，Ca²⁺，Cd²⁺，Co²⁺，Cr³⁺，Cu²⁺，Fe²⁺，Fe³⁺，Hg²⁺，K⁺，Mg²⁺，Na⁺，Ni²⁺And Zn²⁺) Fluorescence spectra of the CDs; d represents addition of 769.23. mu.M of different metal ions (Ag)⁺，Al³⁺，Ca²⁺，Cd²⁺，Co²⁺，Cr³⁺，Cu²⁺，Fe² ⁺，Fe³⁺，Hg²⁺，K⁺，Mg²⁺，Na⁺，Ni²⁺And Zn²⁺) Thereafter, the I500/I420 value of CDs varied, and Blank was shown.

FIG. 4 is a graph showing the detection of Al based on the RGB method³⁺The data of (2) is a graph and specificity.

Wherein A represents adding Al with different concentrations³⁺Then, obtaining CDs images by using a smart phone under a 360nm ultraviolet lamp, wherein a, b and c respectively refer to fluorescence CDs images, the fluorescence CDs images are decomposed into blue channels through Image J, and the fluorescence CDs images are decomposed into green channels through Image J; b represents Al³⁺The relationship between the concentration of (a) and the ratio of the color intensity of the green channel/the blue channel, the inset shows a linear relationship in the range of 3.85. mu.M-2.31 mM; c represents addition of 307.69. mu.M of a different metal ion (Ag)⁺，Al³⁺，Ca²⁺，Cd²⁺，Co²⁺，Cr³⁺，Cu²⁺，Fe²⁺，Fe³⁺，Hg²⁺，K⁺，Mg²⁺，Na⁺，Ni²⁺And Zn²⁺) Then, obtaining CDs images by using a smart phone under a 360nm ultraviolet lamp, wherein a, b and c respectively refer to fluorescence CDs images, the fluorescence CDs images are decomposed into blue channels through Image J, and the fluorescence CDs images are decomposed into green channels through Image J; d represents addition of 307.69. mu.M of different metal ions (Ag)⁺，Al³⁺，Ca²⁺，Cd²⁺，Co²⁺，Cr³⁺，Cu²⁺，Fe²⁺，Fe³⁺，Hg²⁺，K⁺，Mg²⁺，Na⁺，Ni²⁺And Zn²⁺) The relationship between the color intensity ratios of the green channel/blue channel of CDs. Blank in the figure.

FIG. 5 is a schematic diagram based on CDs and CDs-Al³⁺(7.69mM) in a transmission electron microscope.

Wherein A represents a transmission electron microscope picture of CDs in an aqueous solution, the CDs are approximately spherical and have good monodispersity, the average diameter of the CDs is 1.17nm by selecting 100 individual CDs for statistical analysis, and an inset shows a particle size distribution histogram of the CDs; b represents the addition of 7.69mM Al³⁺Thereafter, the CDs agglomerated to some extent, as shown in the circles in the figure.

FIG. 6 is based on the addition of different concentrations of Al³⁺Fourier Infrared Spectroscopy of CDs after (0. mu.M, 7.69. mu.M, 76.9. mu.M, 769. mu.M, 7.69 mM).

Wherein A represents the Fourier transform infrared spectrum of CDs, and B-E represent the addition of 7.69. mu.M, 76.9. mu.M, 769. mu.M, and 7.69mM Al, respectively³⁺Fourier Infrared Spectroscopy of CDs when Al is added³⁺As the concentration increases, the tensile vibration of the C-O-C group increases.

Detailed Description

The present invention will be described in further detail with reference to examples.

The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

Example 1

Synthesis of blue fluorescent CDs with naringin as precursor and based on Al³⁺Inducing blue fluorescence CDs to generate new green fluorescence, recording the change condition of two color fluorescence by using a fluorescence spectrometry method and an RGB method, and combining Al³⁺The relation between the concentration and the ratio of the fluorescence of the two colors realizes the Al³⁺High sensitivity detection.

1. Synthesis of CDs

Weighing naringin (11.6 mg) as precursor of CDs, and dissolving in 5ml anhydrous ethanol; the solution is placed in a reaction kettle after being subjected to ultrasonic oscillation for 10min, and is heated for 2h at 180 ℃; the reacted solution was centrifuged (10000rpm/min, 10min), microfiltered (pore size 0.22. mu.M), dialyzed (pore size 1000D), and freeze-dried to obtain CDs powder. CDs were formulated with water as a 0.1mg/ml solution.

And analyzing ultraviolet absorption peaks, fluorescence emission properties regulated by excited wavelength and pH value and surface group types of the synthesized CDs. The uv absorption peaks of the CDs were at 270nm and 340nm (see fig. 2A), respectively due to pi-pi of the C ═ C bond^*N-pi of transition and C ═ O bond^*Transition; when the excitation wavelength is 360nm, the fluorescence emission peak of CDs is positioned at 420nm (see FIG. 2A); as the excitation wavelength increased from 320nm to 400nm, the fluorescence intensity of CDs gradually decreased and a spectral red-shift of 100nm occurred, which is probably due to the size distribution and surface state of CDs (see fig. 2B); the fluorescence of CDs is affected by pH as the pH increases from 2 to 13, but the fluorescence of CDs remains stable in the pH range 4-9 (see fig. 2C); 1385cm in the Fourier Infrared Spectrum of CDs^-1、1520cm^-1、1694cm^-1And 3034-3476cm^-1The peaks at (a) correspond to the tensile vibrations of the C-O-C, C ═ C, -C ═ O and-OH groups, respectively (see fig. 2D), indicating that the CDs surface has epoxy, hydroxyl and carboxyl groups, which improve the water solubility of the CDs (see fig. 2D)And (4) sex.

2. Detection of Al by fluorescence spectrometry³⁺

20 μ L of Al at different concentrations (0-3.08mM)³⁺The solution was mixed with 500. mu.L of 0.1mg/ml CDs solution and reacted at room temperature for 10 min. 400. mu.L of the above solution was taken and placed in a cuvette, and the fluorescence spectrum of CDs was measured at an excitation wavelength of 360nm (see FIG. 3A). Recording different concentrations of Al³⁺The change of fluorescence intensity of two fluorescence peaks of CDs is generated, and a standard curve is drawn. After nonlinear fitting, the obtained relation is that y is 0.27497x +0.71864, R²0.97023 (see FIG. 3B), the fluorescence intensity of two fluorescence peaks of CDs was dependent on Al³⁺The solution concentration increased and the detection limit was 6.15 nM.

Record the same concentration (769.23. mu.M), different metal ions (Ag)⁺,Ca²⁺,Cd²⁺,Co²⁺,Cr³⁺,Cu²⁺,Fe² ⁺,Fe³⁺,Hg²⁺,K⁺,Mg²⁺,Na⁺,Ni²⁺And Zn²⁺) The change in fluorescence intensity of the two fluorescence peaks causing CDs (see FIG. 3C) is plotted as a histogram. Detection of Al by fluorescence spectroscopy³⁺As is clear from FIG. 3D, Al was added³⁺The I500/I420 value of the CDs is obviously higher than that of the CDs added with other ions, and the CDs synthesized by the method are used for detecting Al based on the fluorescence spectroscopy³⁺The specificity of (A) is good. See FIG. 5, addition of 7.69mM Al³⁺Thereafter, some degree of agglomeration of the CDs occurs morphologically. See FIG. 6, with the addition of 7.69. mu.M, 76.9. mu.M, 769. mu.M, 7.69mM Al³⁺Then, CDs were found at 1385cm^-1The tensile vibration of the C-O-C group of (A) was gradually increased, indicating that Al is present³⁺Interact with C-O-C bonds on the surface of CDs and form CDs-Al³⁺A complex compound. These CDs in the complex are close to each other, which increases the extension of the conjugated π system and causes a red shift in the fluorescence spectrum of the CDs, so that the CDs produce green fluorescence. Thus, CDs vs Al³⁺Can be attributed to Al³⁺Complexation of ions with C-O-C bonds on the surface of CDs.

Analysis and detection of Al by RGB method³⁺

20 μ L of Al at different concentrations (0-3.08mM)³⁺The solution was mixed with 500. mu.L of 0.1mg/ml CDs solution and reacted at room temperature for 10 min. 400 mu L of the solution is put into a 1ml PE tube, and a color fluorescent photo is obtained through a smart phone after the solution is excited by a 360nm ultraviolet lamp. The color fluorescence photograph was decomposed into blue, green and red channel photographs (see FIG. 4A) using Image J software, and the ratio of the color intensities of the green and blue channels was selected for Al detection³⁺. Recording different concentrations of Al³⁺The standard curve is drawn to cause the intensity ratio of the green to blue channel in the color CDs fluorescence photograph to change. After nonlinear fitting, the obtained relation is that y is 0.25377x +1.09496, R²0.98917 (see FIG. 4B), with Al³⁺The concentration is increased, the color intensity ratio of green to blue channels in CDs fluorescent photos is gradually increased, and the Al-doped fluorescent lamp can realize the effect on Al³⁺The detection limit of the method is 6.72nM, which is not much different from the detection limit obtained by the fluorescence spectrometry detection and analysis.

Record the same concentration (307.69. mu.M), different metal ions (Ag)⁺,Ca²⁺,Cd²⁺,Co²⁺,Cr³⁺,Cu²⁺,Fe² ⁺,Fe³⁺,Hg²⁺,K⁺,Mg²⁺,Na⁺,Ni²⁺And Zn²⁺) The resulting change in the ratio of the color intensities of the green and blue channels in the color CDs fluorescence photograph is plotted in bar graph form, see fig. 4C and 4D in combination. Analysis and detection of Al by RGB method³⁺As is clear from FIG. 4D, Al was added³⁺The color intensity ratio of the CDs is obviously higher than that of the CDs added with other ions, and the CDs synthesized by the method are used for detecting Al based on an RGB method³⁺The specificity of (A) is good. Referring to FIGS. 5 and 6 in combination, CDs vs Al³⁺Can be attributed to Al³⁺Complexation of ions with C-O-C bonds on the surface of CDs.

4. Spiking recovery survey

Taking several Al with known concentration³⁺The solutions, respectively using the CDs synthesized by the present invention, were examined for spiking recovery rates based on fluorescence spectroscopy and RGB method, and the results are shown in Table 1 below. As can be seen from the data in the table, the result of the standard recovery rate obtained by the fluorescence spectrometry and the RGB method are not very different, and the RGB methodThe higher recovery rate of the obtained standard addition indicates that the method has strong feasibility and reliable result and can be used for detecting actual water samples. But the result of the fluorescence spectrometry is more accurate and is suitable for laboratory operation, and the method synthesizes CDs by flavonoid glycoside and derivatives thereof, and is more suitable for outdoor sampling detection of Al by combining a smart phone and an RGB method³⁺And is convenient and quick.

TABLE 1 data sheet for recovery ratio test with standard addition

Claims

1. A method for conveniently detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycosides and derivatives thereof is characterized by comprising the following steps:

A. taking flavonoid glycoside and derivatives thereof as precursors to synthesize blue fluorescent carbon quantum dots with emission peaks at 400-480 nm;

B. inducing the blue fluorescent carbon quantum dots to generate green fluorescence with an emission peak at 490-580nm by using aluminum ions;

C. under the irradiation of ultraviolet light, a carbon quantum dot color fluorescence photo after the induction of aluminum ions is obtained, and the photo is analyzed by an RGB method to detect the concentration of the aluminum ions.

2. The method for conveniently detecting aluminum ions based on the carbon quantum dots synthesized from the flavonoid glycoside and the derivatives thereof as claimed in claim 1, wherein the flavonoid glycoside and the derivatives thereof in the step A are one or more of naringin, hesperidin or hesperidin and the derivatives thereof.

3. The method for conveniently detecting aluminum ions based on the carbon quantum dots synthesized from flavonoid glycoside and derivatives thereof according to claim 1, wherein the method for synthesizing the carbon quantum dots in the step A is a hydrothermal method, an ultrasonic method, a solvothermal method, a microwave digestion method or an ultrasonic oscillation method.

4. The method for conveniently detecting aluminum ions based on the carbon quantum dots synthesized from flavonoid glycoside and derivatives thereof according to claim 1, wherein the induction in the step B is to mix aluminum ion solutions with different concentrations and a blue fluorescent carbon quantum dot solution of 0.01mg/ml to 1mg/ml and react at room temperature.

5. The method for conveniently detecting aluminum ions based on the carbon quantum dots synthesized from flavonoid glycoside and derivatives thereof according to claim 4, wherein the reaction time is 5-30 min.

6. The method as claimed in claim 1, wherein the UV wavelength in step C is 200-395 nm.

7. The method for conveniently detecting aluminum ions based on carbon quantum dots synthesized from flavonoid glycoside and derivatives thereof according to claim 1, wherein in the step C, a color fluorescence photograph of the carbon quantum dots is obtained by using a smart phone.