Boron-doped silane functionalized carbon dots with dual-mode emission and preparation method and application of boron-doped silane functionalized carbon dots

Abstract

The invention discloses a dual-mode emission boron-doped silane functionalized carbon dot as well as a preparation method and application thereof, and relates to the field of food safety research. The preparation method comprises the following steps: mixing and dissolving a nitrogen source material, 3-aminopropyltriethoxysilane and a carbon source material, heating for reaction, cooling and dialyzing to obtain the silane functionalized carbon dots; adding boric acid, rhodamine B and water into the silane functionalized carbon dots obtained in the step (1), heating for reaction, cooling and drying; the nitrogen source material is m-phenylenediamine; the molar ratio of the carbon source material to the nitrogen source material to the 3-aminopropyltriethoxysilane in the step (1) is (1.5-2): 1: 1.5. The boron-doped silane functionalized carbon dots have good stability, fluorescence and phosphorescence dual emission signals are achieved, raw materials are easy to obtain, the stability is high, and the boron-doped silane functionalized carbon dots have great application potential in the field of food safety detection.

Description

Technical Field

[0001] The present invention relates to the technical field of food safety detection, and in particular to a dual-mode emission boron-doped silane functionalized carbon dot and a preparation method and application thereof. Background Art

[0002] As a new type of carbon nanomaterial, carbon dots have the characteristics of low cost, simple preparation, low toxicity and excellent optical properties. These characteristics make carbon dots have great application potential in the field of optical sensing. However, most carbon dots used in multi-channel detection platforms rely on single-wavelength fluorescence emission, which has defects in practical applications and is easily interfered by biological autofluorescence and scattered light in environmental samples, thus affecting the accuracy and sensitivity of detection.

[0003] In the study of material properties, it was found that the performance of carbon dots can be further optimized by embedding them into a specific matrix. For example, embedding silane-functionalized carbon dots into a boric acid matrix can not only provide a stable environment for the carbon dots, but also change their optical properties and achieve the regulation of their fluorescence and phosphorescence properties. In the field of chemical detection technology, materials based on fluorescence and phosphorescence properties have the advantages of high sensitivity and high selectivity in analytical detection. The ratio method uses dual signal readings of two emission wavelengths of carbon dots to reduce background interference, but the relevant technology still needs to be improved.

[0004] Studies have shown that introducing energy acceptors, such as rhodamine B, into this composite material system can construct an effective energy transfer system. Based on the principle of fluorescence resonance energy transfer, efficient energy transfer can be achieved when the emission spectrum of the donor has sufficient spectral overlap with the absorption spectrum of the acceptor and the distance between the donor and the acceptor is within a certain range, usually less than 10nm. This energy transfer process can affect the fluorescence and phosphorescence emission characteristics of the material, providing a theoretical basis for constructing a dual-signal ratiometric detection system.

[0005] Chinese patent CN114644924A discloses a new green synthesis method of biomass carbon dots and its application in pesticide detection. This patent uses biomass orange peel and o-phenylenediamine as raw materials, and quickly synthesizes nitrogen-doped blue-light carbon dots (N-CDs) through a one-step microwave method; uses gold nanoparticles as light absorbers to quench the fluorescence of N-CDs through the inner filter effect; and restores the fluorescence of N-CDs by combining the Au-S bond between the sulfur-containing pesticide thiram and gold nanoparticles to establish a method for rapid detection of thiram pesticide residues. However, it only has fluorescence but no phosphorescence, and the signal is single. And there is no research on the selectivity and anti-interference ability of carbon dots.

[0006] The existing literature (doi.org / 10.1016 / j.snb.2021.130898) describes a multi-stage fluorescent biosensor based on boric acid embedded in carbon dots for detecting intracellular and serum glucose. The document was developed by dispersing rhodamine B carbon dots (R-CDs) in a boric acid (BA) matrix, and can be used as a simple and inexpensive visual agent for intracellular and serum glucose concentrations. However, it only has fluorescence but no phosphorescence, and the signal is single. It is not targeted at food safety testing, and there is no research on the selectivity and anti-interference ability of carbon dots.

[0007] In the detection of thiram, although traditional detection methods such as gas chromatography (GC), high performance liquid chromatography (HPLC) and mass spectrometry (MS) have high sensitivity, they are complex, time-consuming and costly. Therefore, it is necessary to develop a rapid, sensitive and highly selective thiram detection method to meet actual detection needs, which is of great significance in the fields of food safety detection. Summary of the invention

[0008] In response to the problems in the prior art, the present invention provides a dual-mode emission boron-doped silane functionalized carbon dot and a preparation method and application thereof. The raw material of the boron-doped silane functionalized carbon dot with dual emission of fluorescence and phosphorescence signals is easy to obtain, has strong stability, and has dual emission peaks of fluorescence and phosphorescence signals, which effectively solves the problem of single signal of traditional optical sensing materials and has great application potential in the field of food safety detection.

[0009] To achieve the above object, the technical solution adopted by the present invention includes:

[0010] In a first aspect, the present invention provides a method for preparing boron-doped silane functionalized carbon dots having dual emission of fluorescence and phosphorescence, comprising the following steps:

[0011] (1) mixing and dissolving a nitrogen source material, 3-aminopropyltriethoxysilane and citric acid, heating for reaction, cooling and dialyzing to obtain silane-functionalized carbon dots;

[0012] (2) adding boric acid, rhodamine B and water to the silane-functionalized carbon dots obtained in step (1), heating for reaction, cooling and drying; the nitrogen source material is m-phenylenediamine.

[0013] Preferably, the preparation method further comprises grinding and sieving.

[0014] Preferably, the sieving is through a 200 mesh sieve.

[0015] Preferably, the nitrogen source material is m-phenylenediamine.

[0016] The molar ratio of the carbon source material, the nitrogen source material and 3-aminopropyltriethoxysilane in step (1) is (1.5-2):1:1.5.

[0017] Preferably, the molar ratio of the carbon source material to the nitrogen source material is 3:2.

[0018] Furthermore, the carbon source material is at least one of citric acid and glucose.

[0019] Preferably, the carbon source material is citric acid.

[0020] Furthermore, in the dissolving step (1), the solvent is a mixed solution of ethanol and water.

[0021] Preferably, in the mixed solution, the volume ratio of ethanol to water is 1:1.

[0022] Furthermore, the heating reaction temperature in step (1) is 180-220° C. and the time is 10-40 min.

[0023] Furthermore, the dialysis time in step (1) is 24 hours, and the dialysis bag cutoff capacity of the dialysis is 1000Da.

[0024] Furthermore, the mass ratio of the silane functionalized carbon dots, boric acid and rhodamine B in step (2) is: 0.5: (1.5-3): (0.001-0.005).

[0025] Preferably, the mass ratio of the silane functionalized carbon dots, boric acid and rhodamine B is: 0.5: (1.5-3): 0.003.

[0026] Furthermore, the heating reaction in step (2) is carried out at a temperature of 180-220° C. and for a time of 2-4 hours.

[0027] Preferably, the temperature is 220° C. and the time is 2.5 hours.

[0028] In a second aspect, the present invention provides a boron-doped silane functionalized carbon dots prepared by the above preparation method.

[0029] In a third aspect, the present invention provides an application of boron-doped silane functionalized carbon dots in detecting food safety.

[0030] Furthermore, the food safety detection is the detection of thiram.

[0031] Furthermore, the detection of thiram includes a phosphorescence ratio detection method and a fluorescence ratio detection method.

[0032] Preferably, the step of detecting thiram is:

[0033] S1. Phosphorescence detection of thiram: Mix 600 μL of 200 μM copper chloride acetonitrile solution with 600 μL of standard working solution of thiram of different concentrations, ranging from 0.1 to 120 μM. After incubation for 20 minutes, add 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot acetonitrile solution, and incubate for another 10 minutes before performing a phosphorescence test.

[0034] S2. Fluorescence detection of thiram: 600 μL of 200 μM copper chloride methanol solution was fully mixed with 600 μL of standard working solution of thiram of different concentrations, ranging from 0.1 to 120 μM. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot methanol solution was added, and then incubated for another 15 minutes before fluorescence testing.

[0035] S3. Selectivity and interference of phosphorescence detection of thiram:

[0036] 600 μL of 200 μM copper chloride acetonitrile solution and 500 μM acetonitrile solutions of different pesticides were mixed and added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot acetonitrile solution was added to the centrifuge tubes. After incubation for 10 minutes, the phosphorescence spectrum of the system was measured.

[0037] Preparation of common ions (such as K + 、Na + Mg 2+ , Mn 2+ 、Ni 2+ 、Zn 2+ 、Al 3+ Cr 3+ 300 μL of 200 μM thiram, 300 μL of 400 μM copper chloride and 600 μL of interfering substance standard solution were added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot acetonitrile solution was added. After incubation for 10 minutes, the phosphorescence spectrum of the system was measured.

[0038] S4. Selectivity and interference of phosphorescence detection of thiram:

[0039] Selective experiment: 600 μL of 200 μM copper chloride methanol solution and 500 μM methanol solutions of different pesticides were mixed and added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot methanol solution was added to the centrifuge tubes. After incubation for 15 minutes, the fluorescence spectrum of the system was measured.

[0040] Preparation of common ions (such as K + 、Na + Mg 2+ , Mn 2+ 、Ni 2+ 、Zn 2+ 、Al 3+ Cr 3+ 300 μL of 200 μM thiram, 300 μL of 400 μM copper chloride and 600 μL of interfering substance standard solution were added into different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot methanol solution was added. After incubation for 15 minutes, the fluorescence spectrum of the system was measured.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The boron-doped silane-functionalized carbon dots prepared by adjusting the amount relationship of the carbon source material, the nitrogen source material, 3-aminopropyltriethoxysilane, boric acid and rhodamine B have good fluorescence and phosphorescence dual emission characteristics. The silane-functionalized carbon dots are uniformly distributed in the boric acid matrix in the form of silica microspheres and have excellent stability. Effective fluorescence resonance energy transfer is achieved between the silane-functionalized carbon dots and rhodamine B, so that the boron-doped silane-functionalized carbon dots have fluorescence and phosphorescence dual emission signals, which effectively solves the problem of single signal of traditional optical sensing materials.

[0043] (2) The boron-doped silane functionalized carbon dots of the present invention have high sensitivity and selectivity for the detection of thiram. They can accurately identify thiram in the presence of a variety of common pesticides (such as mancozeb, fipronil, carbendazim, fipronil, cartap, thiophanate-methyl and cypermethrin), and can also detect common anions in environmental samples (such as Cl - 、SO4 2- etc.), cations (such as K + 、Na + Mg 2+ , Mn 2+ 、Ni 2+ 、Zn 2+ 、Al 3+ Cr 3+ It has good anti-interference performance against interfering substances in actual samples, such as glucose in fruits and vegetables.

[0044] (3) The boron-doped silane functionalized carbon dots of the present invention have a good linear relationship for the fluorescence-phosphorescence dual signal ratio detection of thiram, thus avoiding the possibility of autofluorescence interference signal in complex matrices and improving the accuracy of detection;

[0045] (4) The boron-doped silane functionalized carbon dots of the present invention use a fluorescence-phosphorescence dual signal ratiometric method to detect thiram, with a linear detection concentration range of 0.1-120 μM and a detection limit as low as 0.056 μM, indicating that thiram can be detected quickly and efficiently.

[0046] (5) The preparation method of the present invention is simple, efficient and easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Part of the characterization diagram of Example 1; wherein A is a scanning electron microscope image, B is a transmission electron microscope image, C is an XRD spectrum, and D is a thermogravimetric analysis spectrum.

[0048] Figure 2 It is a partial characterization diagram of Example 1; wherein, the high-resolution XPS peaks of Example 1: A is C1s; B is Si 2p; C is O1s; D is B1s; and E is the infrared spectrum of boron-doped silane functionalized carbon dots (Example 1).

[0049] Figure 3 It is the fluorescence and phosphorescence two-dimensional excitation emission spectrum diagram of Example 1; wherein A is the fluorescence two-dimensional excitation emission spectrum diagram, and B is the phosphorescence two-dimensional excitation emission spectrum diagram.

[0050] Figure 4 1 is a linear relationship diagram between the fluorescence and phosphorescence signals and the concentration of thiram of Example 1; wherein A is the fluorescence response spectrum of Example 1 to different concentrations of thiram, and the lines from top to bottom represent concentrations from 120 μM to 0.1 μM (120 μM, 100 μ, 80 μM, 60 μM, 40 μM, 30 μM, 20 μM, 10 μM, 2 μM, 0.5 μM and 0.1 μM); B is the established relationship between the concentration of thiram and the concentration of Example 1. 1 is the linear relationship of the change in fluorescence intensity of Example 1; C is the phosphorescence response spectrum of Example 1 to different concentrations of thiram, and the lines from top to bottom represent concentrations from 120 μM to 0.1 μM (120 μM, 100 μ, 80 μM, 60 μM, 40 μM, 30 μM, 20 μM, 10 μM, 2 μM, 0.5 μM and 0.1 μM); D is the established linear relationship between the concentration of thiram and the change in phosphorescence intensity of Example 1.

[0051] Figure 5 It is the selectivity, competitiveness and anti-interference of the phosphorescence detection of thiram in Example 1; wherein, A is the phosphorescence response spectrum of Example 1 to thiram and other pesticides, B is the effect of other pesticides (500μM, 1000μM, 1500μM) on the phosphorescence signal after thiram (100μM) is combined with Example 1, and C is the effect of Example 1 on the phosphorescence response of thiram in the presence of various interferents.

[0052] Figure 6It is the selectivity, competitiveness and anti-interference of the fluorescent detection of thiram in Example 1; wherein, A is the fluorescence response spectrum of Example 1 to thiram and other pesticides, B is the effect of other pesticides (500μM, 1000μM, 1500μM) on the fluorescence signal after thiram (100μM) is combined with Example 1, and C is the effect of Example 1 on the fluorescence response of thiram in the presence of various interferences.

[0053] Figure 7 are the phosphorescence stability and reproducibility of Example 1; A is the phosphorescence temperature stability, B is the phosphorescence stability under continuous irradiation of a 254 nm ultraviolet lamp, and C is the phosphorescence reproducibility of thiram detected in Example 1.

[0054] Figure 8 are the fluorescence stability and reproducibility of Example 1; A is the fluorescence temperature stability, B is the fluorescence stability under continuous irradiation of a 365nm ultraviolet lamp, and C is the fluorescence reproducibility of detecting thiram in Example 1. DETAILED DESCRIPTION

[0055] The present invention is described below through specific embodiments to make the technical solution of the present invention easier to understand and grasp, but the present invention is not limited thereto, and the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0056] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0057] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention. The experimental methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0058] Example 1

[0059] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0060] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0061] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0062] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0063] Example 2

[0064] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0065] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 at a ratio of 2:1:1.5, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0066] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0067] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 3 g boric acid, 5 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 180 °C for 2 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0068] Comparative Example 1

[0069] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0070] The amounts of citric acid, o-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0071] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0072] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0073] Comparative Example 2

[0074] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0075] The amounts of citric acid, p-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0076] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0077] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0078] Comparative Example 3

[0079] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0080] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 at a ratio of 1:1:1.5, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0081] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0082] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0083] Comparative Example 4

[0084] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0085] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 at a ratio of 0.5:1:1.5, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0086] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0087] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0088] Comparative Example 5

[0089] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0090] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 at a ratio of 0.2:1:1.5, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0091] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0092] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0093] Comparative Example 6

[0094] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0095] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0096] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0097] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system, ultrasonically dissolved for 5 minutes, the beaker was sealed with tin foil and transferred to a muffle furnace, heated to 220 °C for reaction for 2.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0098] Comparative Example 7

[0099] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0100] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0101] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0102] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system and ultrasonically dissolved for 5 minutes. The beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 3 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0103] Comparative Example 8

[0104] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0105] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0106] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0107] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system and ultrasonically dissolved for 5 minutes. The beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 3.5 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0108] Comparative Example 9

[0109] 1. Preparation of silane functionalized carbon dots, comprising the following steps:

[0110] The amounts of citric acid, m-phenylenediamine and 3-aminopropyltriethoxysilane were dissolved in a mixed solution of 30 mL of ethanol and water in a volume ratio of 1:1 in a ratio of 3:2:3, and then 1.12 mL of APTES was added to the mixed solution beaker, ultrasonically dissolved for 5 minutes, heated to 200°C in a high-temperature drying oven for reaction for 30 minutes, cooled to room temperature after the reaction, and dialyzed for 24 hours to obtain silane-functionalized carbon dots.

[0111] 2. Preparation of Boron-doped Silane-functionalized Carbon Dots:

[0112] On the basis of synthesizing silane functionalized carbon dots, 0.5 g silane functionalized carbon dots, 2 g boric acid, 3 mg rhodamine B dye and 20 mL ultrapure water were then added to the system and ultrasonically dissolved for 5 minutes. The beaker was sealed with tin foil and transferred to a muffle furnace, heated to 200 °C for reaction for 4 hours, cooled to room temperature, dried and ground through a 200 mesh sieve to obtain boron-doped silane functionalized phosphorescent carbon dots with dual signals and dual emissions.

[0113] Test Example 1 Luminous Intensity Test

[0114] Take 1.8 mL of the test system solution and put it into the cuvette of Hitachi FL-7100 fluorescence spectrophotometer, set the photomultiplier tube voltage to 950 V, the excitation slit to 10 nm, the emission slit to 20 nm, and the excitation wavelength to 270.0 nm to test the phosphorescence intensity.

[0115] The test results are shown in Table 1.

[0116] Table 1

[0117] Luminous intensity (au) Example 1 2737.3 Example 2 2271.7 Comparative Example 1 203.5 Comparative Example 2 81.1 Comparative Example 3 1496.7 Comparative Example 4 1198.0 Comparative Example 5 1188.7 Comparative Example 6 484.2 Comparative Example 7 1272.6 Comparative Example 8 682.1 Comparative Example 9 211.3

[0118] Test Example 2 Linear Relationship between Phosphorescence and Substance Concentration

[0119] 1. Detection experiment of Thiram

[0120] Test Materials: Example 1.

[0121] 600 μL of 200 μM copper chloride acetonitrile solution was mixed with 600 μL of different concentrations of thiram standard working solution, the concentration range was 0.1-120 μM (0.1 μM, 0.5 μM, 2 μM, 10 μM, 20 μM, 30 μM, 40 μM, 60 μM, 80 μM, 100 μM and 120 μM), incubated for 20 minutes, and then 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot acetonitrile solution was added, and then incubated for another 10 minutes before phosphorescence testing. According to the Stern-Volmer formula: (PL 490 / PL 590 )0 / (PL 490 / PL590 )=K[C]+B, where K is the phosphorescence quenching constant, [C] is the concentration of thiram, (PL 490 / PL 590 )0 and (PL 490 / PL 590 ) are the ratios of the phosphorescence intensities at 490 nm and 590 nm in the absence and presence of thiram, respectively. With the concentration of the standard working solution as the horizontal axis, the phosphorescence intensity ratio (PL 490 / PL 590 )0 / (PL 490 / PL 590 ) as the ordinate, and establish a linear relationship between phosphorescence and substance concentration. The results are as follows Figure 4 As shown, the linear regression equation is (PL 490 / PL 590 )0 / (PL 490 / PL 590 )=1.01514+0.00723X,R 2 =0.997, LOD is 0.056 μM, the boron-doped silane functionalized carbon dots in Example 1 can sensitively and accurately indicate the content of thiram through phosphorescence signals. The parameters of the spectrophotometer are set as follows: the excitation wavelength is set to 260 nm, and the emission wavelength range is 400-650 nm.

[0122] Selective experiment: 600 μL of 200 μM copper chloride acetonitrile solution and 500 μM acetonitrile solutions of different pesticides were mixed and added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot acetonitrile solution was added to the centrifuge tubes. After incubation for 10 minutes, the phosphorescence spectrum of the system was measured.

[0123] Interference experiment: Preparation of common ions (such as K + 、Na + Mg 2+ , Mn 2+ 、Ni 2+ 、Zn 2+ 、Al 3+ Cr 3+ 300 μL of 200 μM thiram, 300 μL of 400 μM copper chloride and 600 μL of interfering substance standard solution were added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot acetonitrile solution was added. After incubation for 10 minutes, the phosphorescence spectrum of the system was measured. The results are shown in Figure 2. Figure 5 As shown, it has good selectivity and anti-interference ability.

[0124] 2. Stability and reproducibility experiments

[0125] Test Materials: Example 1.

[0126] The phosphorescence intensity of the boron-doped silane functionalized carbon dots was measured once a week for 5 weeks. The material was exposed to 254nm UV light for 120 minutes and the phosphorescence intensity was measured every 20 minutes. The phosphorescence intensity of the boron-doped silane functionalized carbon dots was measured at different temperatures. The phosphorescence detection experiment was performed on 0.1μM and 100μM thiram double standard solutions for three consecutive days to evaluate the reproducibility of the experiment. The results are shown in Figure 7 As shown, it has good stability and reproducibility.

[0127] Test Example 3: Linear Relationship between Fluorescence and Substance Concentration

[0128] 1. Detection experiment of Thiram

[0129] Test Materials: Example 1.

[0130] 600 μL of 200 μM copper chloride methanol solution was mixed with 600 μL of different concentrations of thiram standard working solution, ranging from 0.1 to 120 μM (0.1 μM, 0.5 μM, 2 μM, 10 μM, 20 μM, 30 μM, 40 μM, 60 μM, 80 μM, 100 μM and 120 μM), and after incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot methanol solution was added, and then incubated for another 15 minutes before fluorescence testing. According to the Stern-Volmer formula: FL 440 / FL 570 =K[C]+B, where K is the phosphorescence quenching constant, [C] is the concentration of thiram, FL 440 / FL 570 are the fluorescence intensities of the system at 440nm and 570nm respectively. With the concentration of the standard working solution as the horizontal axis, the fluorescence intensity ratio FL 440 / FL 570 As the vertical axis, a linear relationship between fluorescence and substance concentration was established. The results are shown in Figure 4 As shown, the linear regression equation is FL 440 / FL 570 =1.79365+0.00467X, linear regression coefficient R 2 =0.993, LOD is 0.052 μM. The boron-doped silane functionalized carbon dots in Example 1 can sensitively and accurately indicate the content of thiram through fluorescence signals. The parameters of the microplate reader are set as follows: the excitation wavelength is set to 360 nm, and the emission wavelength range is 400-650 nm.

[0131] Selective experiment: 600 μL of 200 μM copper chloride methanol solution and 500 μM methanol solutions of different pesticides were mixed and added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot methanol solution was added to the centrifuge tubes. After incubation for 15 minutes, the fluorescence spectrum of the system was measured.

[0132] Interference experiment: Preparation of common ions (such as K + 、Na + Mg 2+ , Mn 2+ 、Ni 2+ 、Zn 2+ 、Al 3+ Cr 3+ 300 μL of 200 μM thiram, 300 μL of 400 μM copper chloride and 600 μL of interfering substance standard solution were added to different 2 mL centrifuge tubes. After incubation for 20 minutes, 600 μL of 4 mg / mL boron-doped silane functionalized carbon dot methanol solution was added. After incubation for 15 minutes, the fluorescence spectrum of the system was measured. The results are shown in Figure 2. Figure 6 As shown, it has good selectivity and anti-interference ability.

[0133] 2. Stability and reproducibility experiments

[0134] Test Materials: Example 1.

[0135] The fluorescence intensity of the boron-doped silane functionalized carbon dots was measured once a week for 5 weeks. At the same time, the material was exposed to 365nm UV light for 120 minutes, and the fluorescence intensity was measured every 20 minutes. The fluorescence intensity of the boron-doped silane functionalized carbon dots at different temperatures was also measured. Fluorescence detection experiments were performed on 0.1μM and 100μM thiram standard solutions for three consecutive days to evaluate the reproducibility of the experiment. The results are shown in Figure 8 As shown, it has good stability and reproducibility.

[0136] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing dual-mode emission boron-doped silane functionalized carbon dots, characterized in that: The steps include: (1) mixing and dissolving a nitrogen source material, 3-aminopropyltriethoxysilane and a carbon source material, heating for reaction, cooling and dialyzing to obtain silane-functionalized carbon dots; (2) adding boric acid, rhodamine B and water to the silane-functionalized carbon dots obtained in step (1), heating for reaction, cooling and drying; The nitrogen source material is m-phenylenediamine; The molar ratio of the carbon source material, the nitrogen source material and 3-aminopropyltriethoxysilane in step (1) is (1.5-2):1:1.

5.

2. The preparation method according to claim 1, characterized in that: The carbon source material is at least one of citric acid and glucose.

3. The preparation method according to claim 1, characterized in that: In step (1), the solvent for dissolving is a mixed solution of ethanol and water.

4. The preparation method according to claim 1, characterized in that: The heating reaction temperature in step (1) is 180-200° C. and the time is 10-40 min.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the silane functionalized carbon dots, boric acid and rhodamine B in step (2) is: 0.5：(1.5-3)：(0.001-0.005)。 6. The preparation method according to claim 1, characterized in that: The heating reaction temperature in step (2) is 180-200° C. and the time is 2-2.5 hours.

7. The dual-mode emitting boron-doped silane functionalized carbon dots prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the boron-doped silane-functionalized carbon dots prepared by the preparation method according to any one of claims 1 to 6 or the boron-doped silane-functionalized carbon dots according to claim 7 in detecting food safety.

9. The use according to claim 8, characterized in that: The food safety detection is the detection of thiram.

10. The use according to claim 9, characterized in that: The detection of thiram includes a phosphorescence ratio detection method and a fluorescence ratio detection method.

Images