WO2023142267A1 - Iodine-doped carbon quantum dot as well as preparation method therefor and use thereof - Google Patents

Abstract

Disclosed in the present invention are an iodine-doped carbon quantum dot as well as a preparation method therefor and the use thereof, relating to the technical field of metal ion detection. The preparation method only uses p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid as a raw material to prepare the iodine-doped carbon quantum dot by means of a one-step solvent process. The preparation method in the present invention is simple and does not need complex surface functionalization modification. The prepared and synthesized iodine-doped carbon quantum dot can be used as a fluorescent probe for low-cost, rapid, simple and convenient qualitative and quantitative detection of Fe3+, thereby having important practical application value in the field of metal ion detection.

Description

A kind of iodine-doped carbon quantum dot and its preparation method and application technical field

The invention relates to the technical field of metal ion detection, in particular to an iodine-doped carbon quantum dot and its preparation method and application.

Background technique

Fe ³⁺ is a trace element to maintain human health. It plays an important role in many chemical and physiological processes, such as oxygen transport, electron conduction and enzyme catalysis. However, excessive intake of iron ions by the human body can lead to the production of active oxygen, disturb the stability of the intracellular environment, and lead to hemochromatosis; iron deficiency can lead to anemia, and even liver cirrhosis and other diseases. With the rapid development of industry, the excessive discharge of Fe ³⁺ has increasingly become the focus of water quality environmental pollution, posing a serious threat to human life and health and the ecological environment. Therefore, it is of great practical significance to research and develop a sensitive, fast, simple, economical and reliable Fe ³⁺ detection method.

Current methods for detecting Fe ³⁺ ions include inductively coupled plasma mass spectrometry, atomic absorption spectrometry, chemical methods, and electrochemical methods. However, these known detection methods have some disadvantages, such as harsh conditions, high cost, and cumbersome steps. Recently, with the emergence of various fluorescent probes, fluorescent methods for the detection of iron ions have attracted attention for their high sensitivity and good selectivity. At present, there are various materials used to detect iron ions, such as gold nanoclusters, semiconductor quantum dots, graphitic carbon polymers, etc. Although these fluorescent probe detection methods for Fe ³⁺ are relatively mature in application, however, these fluorescent materials also have some disadvantages, such as the high price of metals, the toxicity of semiconductor quantum dots, and the complexity of graphite carbon nitrogen polymers, etc., which are not conducive to their application. There is still a need to avoid synthetic routes using toxic reagents to prepare fluorescent materials for qualitative analysis of Fe ³⁺ .

Carbon quantum dots (Carbon quantum dots, abbreviated as CQDs) are carbon nanoparticles with luminescent properties composed of spherical particles with a particle size below 10nm. As a new type of "zero-dimensional" nanomaterials, carbon quantum dots have many excellent unique properties compared with traditional organic fluorescent dye molecules, fluorescent proteins and semiconductor quantum dots, such as tunable photoluminescence, low toxicity, chemical Due to the advantages of inertness and good biocompatibility, they have been successfully used in various applications such as bioimaging, sensors, photocatalysis, and detection. At present, the common preparation methods of CQDs include arc discharge method, laser ablation method, ultrasonic method, chemical oxidation, electrochemical method, microwave method, hydrothermal method and solvent method, among which one-step hydrothermal method and one-step solvent method are simple, cheap and The best way to prepare carbon quantum dots with low toxicity.

In order to improve the fluorescence intensity and various properties of carbon quantum dots, surface passivation modification or doping with heteroatoms is required. Generally, the doping of nitrogen, phosphorus and oxygen is more reported, the doping of fluorine and chlorine is rarely reported, and the doping of iodine is not reported. At present, nitrogen, phosphorus, sulfur, silicon, boron and other elements are mostly used for heteroatom doping. For example, Yang et al. prepared N-CQDs by electrochemical oxidation. Kang et al. synthesized S/N-CQDs from malic acid and L-cysteine. Yang et al. introduced P into CQDs and found that it has bright fluorescence and good biocompatibility, which can be used for bioimaging. Gao et al. prepared Si-CQDs by a one-pot solvothermal method using glycerol and silane molecules (N-[3-(trimethoxysilyl)propyl]ethylenediamine, DAMO). Zhao et al. used m-carboxyphenylboronic acid (CPAB) to incorporate B into CQDs for highly sensitive detection of Co ²⁺ . There are few cases of doping with halogen elements. Ning et al. reported that N/Cl-CQDs were prepared in choline chloride/glycerol liquid eutectic mixture as solvent. Zhang et al. prepared iodine-doped carbon quantum dots using Iodixanol and glycine for bioimaging. Ding et al. synthesized F/N-CQDs using 3-fluoroaniline and revealed their potential as temperature-based fluorescent sensors and solid-state light-emitting devices adaptable to multiple temperatures.

In the above studies, the preparation of doped carbon quantum dots has undergone complicated surface functional modification, and the preparation process is cumbersome, which is not conducive to practical application. At present, there are few related reports on fluorescent probes without modifiers.

Contents of the invention

The purpose of the present invention is to provide a kind of iodine-doped carbon quantum dots and its preparation method and application, to solve the problems in the prior art above, so as to obtain a simple preparation method that can be used for metal ion detection with a simple preparation method that does not require surface functional modification. Iodine-doped carbon quantum dots.

To achieve the above object, the present invention provides the following scheme:

One of the objectives of the present invention is to provide a method for preparing iodine-doped carbon quantum dots, using p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid as raw materials, and preparing the iodine-doped carbon quantum dots through a one-step solvent method. point.

Further, the preparation method comprises the following steps:

Mix p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid with an organic solvent, and react at 200°C. After the reaction, cool the system to room temperature, centrifuge to take the supernatant, remove the organic solvent, and filter , dialysis, and freeze-drying to obtain the iodine-doped carbon quantum dots.

Further, the organic solvent is ethanol, and the reaction time is 6h.

The second object of the present invention is to provide iodine-doped carbon quantum dots prepared by the above preparation method.

The third object of the present invention is to provide the application of the above-mentioned iodine-doped carbon quantum dots in the field of metal ion detection.

The fourth object of the present invention is to provide the application of the above-mentioned iodine-doped carbon quantum dots as fluorescent probes in the field of Fe ³⁺ detection.

The invention discloses the following technical effects:

The present invention uses p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid as raw materials, adopts a one-step solvent method to directly prepare and synthesize iodine-doped carbon quantum dots (I-CQDs), and use the I-CQDs as fluorescent probes, which can be Realize low-cost, fast and simple qualitative and quantitative detection of Fe ³⁺ .

The preparation method of the invention is simple, does not need complicated surface functional modification, and has important practical application value.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the surface morphology diagram of the I-CQDs prepared in Example 1; (A) is the transmission electron microscope diagram of I-CQDs, (B) is the lattice spacing diagram of I-CQDs, (C) is the granularity of I-CQDs Diameter distribution map;

Fig. 2 is the fluorescence characteristic diagram of the I-CQDs prepared in embodiment 1; (A) is the ultraviolet absorption curve, the maximum fluorescence excitation spectrum (EX) and the maximum fluorescence emission spectrum (EM) of I-CQDs; (B) is different excitation Fluorescence emission spectra of I-CQDs at different wavelengths;

Fig. 3 is the infrared spectrum of the I-CQDs prepared in embodiment 1, XPS spectrum and the narrow spectrum of each element: (A) is the infrared spectrum of I-CQDs, (B) is the XPS spectrum of I-CQDs, (C ) is the C 1s spectrum of I-CQDs, (D) is the O 1s spectrum of I-CQDs, (E) is the I 3d spectrum of I-CQDs;

Figure 4 shows the sensitivity and selectivity of I-CQDs to the detection of different metal ions; (A) is the effect of different metal ions on the fluorescence intensity of I-CQDs, (B) is the selectivity of I-CQDs to Fe ³⁺ , ( C) is the effect of Fe ³⁺ concentration on the fluorescence intensity of I-CQDs, (D) is the exponential relationship between Fe ³⁺ concentration and [(F ₀ -F)/F].

Detailed ways

Various exemplary embodiments of the present invention are now described in detail. The detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features and embodiments of the present invention.

It should be understood that the terminology described in the present invention is only used to describe specific embodiments, and is not used to limit the present invention. In addition, regarding the numerical ranges in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents are described. In case of conflict with any incorporated document, the contents of this specification control.

It will be apparent to those skilled in the art that various modifications and changes can be made in the specific embodiments of the present invention described herein without departing from the scope or spirit of the present invention. Other embodiments will be apparent to the skilled person from the description of the present invention. The specification and examples in this application are exemplary only.

As used herein, "comprising", "comprising", "having", "comprising" and so on are all open terms, meaning including but not limited to.

Example 1

A preparation method of iodine-doped carbon quantum dots (I-CQDs):

Weigh 0.5g of p-iodobenzoic acid, add 40mL of absolute ethanol, place it on a magnetic stirrer to disperse evenly, pour it into a 100mL polytetrafluoroethylene-lined reaction kettle and keep it at 1000r/min at 200°C for 6h.

After the reaction was finished, cool to room temperature, centrifuge at 10000r/min for 15min, get the supernatant, and steam the ethanol out with a rotary evaporator at 50°C, filter the solution obtained with a microporous membrane with a pore size of 0.22um, and use a dialysis bag (molecular weight: 12000) for 3 hours, changing the deionized water every 1 hour, and freeze-drying to obtain a light yellow solid.

Characterize the iodine-doped carbon quantum dots (I-CQDs) prepared in Example 1:

(1) Surface morphology and particle size distribution

The surface morphology and size distribution of I-CQDs were analyzed by transmission electron microscopy (TEM). Figure 1 shows the surface morphology of I-CQDs. Figure 1(A) is a transmission electron microscope image of I-CQDs. It can be observed that the prepared I-CQDs are uniform in size, uniform in distribution, and spherical in shape. The I-CQDs were analyzed by high-resolution transmission electron microscopy, and the lattice spacing of carbon dots was calculated to be 0.32nm, as shown in Figure 1(B). Using Image J software, the particle size statistics of randomly selected I-CQDs particles were made, and then the histogram was made, as shown in Figure 1(C). After calculation, the average size of the particles was 6.42±1.50nm.

(2) Fluorescent properties

Figure 2 is a graph of the fluorescence properties of I-CQDs.

Measure the ultraviolet absorption spectrum, series fluorescence emission spectrum and fluorescence excitation spectrum of I-CQDs, and then analyze the optical properties of I-CQDs.

The UV absorption curve, maximum fluorescence excitation (EX) spectrum, and maximum fluorescence emission spectrum (EM) of I-CQDs are shown in Fig. 2(A). It can be seen from Figure 2(A) that the ultraviolet absorption spectrum of I-CQDs has obvious strong absorption at around 220nm. Comparing the fluorescence excitation spectrum and fluorescence emission spectrum, it can be seen that I-CQDs have obvious Stokes phenomenon.

The fluorescence emission spectra of I-CQDs under different excitation wavelengths are shown in Fig. 2(B). It can be seen that when the excitation wavelength (λex) is changed from 290nm to 350nm, the emission wavelength (λem) is red-shifted from 350nm to 430nm. When the excitation wavelength is 330nm, there is a maximum emission wavelength of 408nm. Taking 0.1mol/L H ₂ SO ₄ quinine sulfate as a reference, the fluorescence quantum yield of I-CQDs is 36.2%.

Fig. 3 is the infrared spectrum of I-CQDs, XPS spectrogram and the narrow spectrum of each element, specifically: figure (A) is the infrared spectrogram of I-CQDs, figure (B) is the XPS spectrogram of I-CQDs, figure ( C) is the C 1s spectrum of I-CQDs, (D) is the O 1s spectrum of I-CQDs, and (E) is the I 3d spectrum of I-CQDs.

Example 2

Taking m-iodobenzoic acid as raw material, the preparation process is the same as in Example 1.

Example 3

Taking o-iodobenzoic acid as raw material, the preparation process is the same as in Example 1.

Example 4 Sensitivity and selectivity of I-CQDs to metal ion detection

In order to explore the application prospect of I-CQDs in the field of metal ion detection, a certain concentration of I-CQDs solution was added to the solution containing Fe ³⁺ , Na ⁺ , K ⁺ , Ba ²⁺ , Zn ²⁺ , Ca ²⁺ , Ni ²⁺ , Cd ²⁺ , Cu ²⁺ , Fe ²⁺ , Co ²⁺ , Al ³⁺ solution, the metal cation concentration of the system is 0.01mol/L, and the above-mentioned metal ions containing different The fluorescence emission spectrum of the quantum dot solution was used to judge the selectivity and sensitivity of I-CQDs to the quenching effect of different metal ions according to different fluorescence intensities.

The sensitivity and selectivity of I-CQDs for the detection of different metal ions are shown in Figure 4.

Figure 4(A) is the effect of different metal ions on the fluorescence intensity of I-CQDs. It can be seen that compared with other metal ions, Fe ³⁺ can significantly quench the fluorescence of carbon quantum dots, and other substances can affect the fluorescence of carbon quantum dots. Strength was not significantly affected. So I-CQDs can be applied to detect Fe ³⁺ .

In order to further study the influence of I-CQDs on the detection of Fe ³⁺ when Fe ³⁺ coexists with other metal cations, the mixed solutions of Fe ³⁺ and other metal cations were prepared respectively, and mixed with I-CQDs to test their fluorescence Strength, the test results are shown in Figure 4(B). It can be seen that when coexisting with other metal cations, I-CQDs also have a significant fluorescence quenching effect on Fe ³⁺ , and the fluorescence intensity after quenching is almost not affected by the coexisting ions, indicating that the I-CQDs on Fe ³⁺ The detection has a strong ability to resist the interference of other metal ions.

In order to explore the quenching relationship between I-CQDs and Fe ³⁺ concentration, the prepared Fe ³⁺ solution was added to I-CQDs, the concentration of Fe ³⁺ in the mixed system was 0-200 μM, and the content of The fluorescence intensities of I-CQDs solutions with different concentrations of Fe ³⁺ are shown in Fig. 4(C). It can be seen from Figure 4(C) that as the concentration of Fe ³⁺ gradually increases, the fluorescence intensity gradually decreases, and the fluorescence quenching effect gradually increases.

Figure 4(D) shows that the relative fluorescence intensity [(F ₀ -F)/F] of I-CQDs treated with different concentrations of Fe ³⁺ has a good exponential correlation with the Fe ³⁺ concentration. In the range of Fe ³⁺ concentration from 5 to 200 μM, the fitted linear regression equation is as follows: [(F ₀ -F)/F]=0.442e^(0.008*x)-e^(-0.007x), R ² = 0.9963. R ² =0.9963 indicates that the fitting curve has a very high exponential correlation within the range of 0-200 μM. Experiments show that Fe ³⁺ can be sensitively detected at low concentrations, and the Fe ³⁺ concentration and relative fluorescence intensity have an exponential distribution, which is suitable for the detection of samples with low and medium Fe ³⁺ concentrations.

In the present invention, when the iron ion concentration is in the range of 0-50 μM, the fluorescence quenching efficiency conforms to the linear equation: y=0.00636x-0.00782 (R ² =0.9922), and the detection limit is 0.47 μM.

The above-mentioned embodiments are only to describe the preferred mode of the present invention, and are not intended to limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (7)

A method for preparing iodine-doped carbon quantum dots, characterized in that the iodine-doped carbon quantum dots are prepared by a one-step solvent method using p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid as raw materials. The preparation method of iodine-doped carbon quantum dots according to claim 1, is characterized in that, comprises the following steps: Mix p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid with an organic solvent, and react at 200°C. After the reaction, cool the system to room temperature, centrifuge to take the supernatant, remove the organic solvent, and filter , dialysis, and freeze-drying to obtain the iodine-doped carbon quantum dots. The preparation method according to claim 2, wherein the organic solvent is ethanol. The preparation method according to claim 2, characterized in that, the reaction time is 6h. The iodine-doped carbon quantum dot prepared by the preparation method described in claims 1-4. Application of the iodine-doped carbon quantum dots in the field of metal ion detection as claimed in claim 5. Application of the iodine-doped carbon quantum dot as claimed in claim 5 as a fluorescent probe in the field of Fe3 ⁺ detection.

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