CN114369458B

CN114369458B - Iodine-doped carbon quantum dot and preparation method and application thereof

Info

Publication number: CN114369458B
Application number: CN202210091180.3A
Authority: CN
Inventors: 温燕梅; 罗坤; 罗文薏; 梁志彬; 李宇彬; 康信煌; 吴育廉
Original assignee: Guangdong Ocean University
Current assignee: Guangdong Ocean University
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2022-12-06
Anticipated expiration: 2042-01-26
Also published as: LU502866B1; CN114369458A; WO2023142267A1

Abstract

The invention discloses an iodine-doped carbon quantum dot and a preparation method and application thereof, and relates to the technical field of metal ion detection. The preparation method only takes p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid as raw materials, and the iodine-doped carbon quantum dots are prepared by a one-step solvent method. The preparation method is simple, complex surface functional modification is not needed, and the prepared and synthesized iodine-doped carbon quantum dots can be used as fluorescent probes to realize the effect of Fe ³⁺ The method has low cost, is rapid and convenient for qualitative and quantitative detection, and has important practical application value in the field of metal ion detection.

Description

Iodine-doped carbon quantum dot and preparation method and application thereof

Technical Field

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

Background

Fe ³⁺ Is a trace element for maintaining human health, and plays an important role in many chemical and physiological processes, such as oxygen transportation, electron conduction, enzyme catalysis and the like. But excessive iron ion intake in human body can cause the generation of active oxygen, disturb the intracellular environment, cause hemochromatosis and the like; iron deficiency can result inAnemia, even liver cirrhosis. With rapid development of industry, fe ³⁺ The excessive discharge of the waste water is increasingly the key point of water quality environmental pollution, and serious threats are caused to the life health and the ecological environment of human beings. Therefore, the research and development of the Fe are sensitive, rapid, simple, convenient, economic and reliable ³⁺ The detection method has extremely important practical significance.

Detection of Fe at present ³⁺ Methods of ion 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 procedures. Recently, with the advent of various fluorescent probes, fluorescent methods for detecting iron ions have attracted attention with their high sensitivity and good selectivity. At present, materials for detecting iron ions are various, such as gold nanoclusters, semiconductor quantum dots, graphitic carbon polymers, and the like. Although these Fe ³⁺ However, these fluorescent materials also have some disadvantages, such as high price of metal, toxicity of semiconductor quantum dots, and complexity of graphite carbon nitrogen polymer, which are not favorable for their application. There remains a need for a synthetic route to avoid the use of toxic reagents for the preparation of Fe for qualitative analysis ³⁺ The fluorescent material of (1).

Carbon Quantum Dots (CQDs) are Carbon nanoparticles having a luminescent property composed of spheroidal particles having a particle diameter of 10nm or less. Carbon quantum dots, as a class of novel 'zero-dimensional' nanomaterials, have many excellent unique properties, such as adjustable photoluminescence, low toxicity, chemical inertness, good biocompatibility and the like, compared with traditional organic fluorescent dye molecules, fluorescent proteins and semiconductor quantum dots, and have been successfully applied to various applications, such as biological imaging, sensors, photocatalysis and detection. At present, the common preparation methods of CQDs include an arc discharge method, a laser ablation method, an ultrasonic method, chemical oxidation, an electrochemical method, a microwave method, a hydrothermal method, a solvent method and the like, wherein the one-step hydrothermal method and the one-step solvent method are the best methods for preparing carbon quantum dots simply, cheaply and with low toxicity.

In order to improve the fluorescence intensity and various performances of the carbon quantum dots, surface passivation modification or heteroatom doping is required. Generally, nitrogen, phosphorus and oxygen doping is frequently reported, fluorine and chlorine doping is rarely reported, and iodine doping is not reported. At present, most of heteroatom doping is selected from elements such as nitrogen, phosphorus, sulfur, silicon, boron and the like. 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 and can be used for bioimaging. Gao et al use glycerol and silane molecules (N- [3- (trimethoxysilyl) propyl)]Ethylenediamine, DAMO) Si-CQDs were prepared by a one-pot solvothermal method. ZHao et al use m-carboxyphenylboronic acid (CPAB) to dope B into CQDs for high-sensitivity detection of Co ²⁺ . The cases of doping halogen elements are few, and Ning et al report that N/Cl-CQDs are prepared by using a choline chloride/glycerol liquid eutectic mixture as a solvent. Zhang et al prepared iodine doped carbon quantum dots using Iodixanol and glycine and used for bioimaging. Ding et al synthesized F/N-CQDs using 3-fluoroaniline and revealed their potential as fluorescent sensors for temperature and solid state light emitting devices that are adaptable to a variety of temperatures.

In the researches, the preparation of the doped carbon quantum dots is subjected to complex surface functionalization modification, the preparation process is complicated and is not beneficial to practical application, and related reports aiming at the fluorescent probe without the modifier are few at present.

Disclosure of Invention

The invention aims to provide an iodine-doped carbon quantum dot and a preparation method and application thereof, which aim to solve the problems in the prior art, so that the iodine-doped carbon quantum dot for metal ion detection is prepared by a simple preparation method without surface functional modification.

In order to achieve the purpose, the invention provides the following scheme:

the invention aims to provide a preparation method of an iodine-doped carbon quantum dot, which is prepared by taking p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid as raw materials through a one-step solvent method.

Further, the preparation method comprises the following steps:

mixing p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid with an organic solvent, reacting at 200 ℃, cooling the system to room temperature after the reaction is finished, centrifuging to obtain a supernatant, removing the organic solvent, filtering, dialyzing, and freeze-drying to obtain the iodine-doped carbon quantum dot.

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

The second purpose of the invention is to provide the iodine-doped carbon quantum dot prepared by the preparation method.

The invention also aims to provide application of the iodine-doped carbon quantum dot in the field of metal ion detection.

The fourth purpose of the invention is to provide the iodine-doped carbon quantum dots as fluorescent probes on Fe ³⁺ Application in the field of detection.

The invention discloses the following technical effects:

the invention takes 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 takes the I-CQDs as a fluorescent probe, thereby realizing the purpose of Fe-P ³⁺ The method has the advantages of low cost, rapidness, convenience, qualitative and quantitative detection.

The preparation method is simple, does not need to be subjected to complex surface functional modification, and has important practical application value.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a surface morphology diagram of I-CQDs prepared in example 1; (A) is a transmission electron microscope picture of I-CQDs, (B) is a lattice spacing picture of I-CQDs, and (C) is a particle size distribution picture of I-CQDs;

FIG. 2 is a graph showing the fluorescence characteristics of I-CQDs prepared in example 1; (A) Ultraviolet absorption curves, maximum fluorescence excitation spectra (EX) and maximum fluorescence emission spectra (EM) of I-CQDs; (B) Fluorescence emission spectra for I-CQDs at different excitation wavelengths;

FIG. 3 is an infrared and XPS spectra of I-CQDs prepared in example 1 and narrow spectra of the various elements: (A) is an infrared spectrum of I-CQDs, (B) is an XPS spectrum of I-CQDs, (C) is a C1s spectrum of I-CQDs, (D) is an O1s spectrum of I-CQDs, and (E) is an I3D spectrum of I-CQDs;

FIG. 4 is a graph showing the sensitivity and selectivity of I-CQDs for detection of different metal ions; (A) The influence of different metal ions on the fluorescence intensity of the I-CQDs, and (B) the influence of the I-CQDs on Fe ³⁺ Is (C) Fe ³⁺ Influence of concentration on fluorescence intensity of I-CQDs, and (D) is Fe ³⁺ Concentration and [ (F) ₀ -F)/F]The exponential relationship of (c).

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated 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 in 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 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 herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

A method for preparing iodine doped carbon quantum dots (I-CQDs) comprises the following steps:

0.5g of p-iodobenzoic acid is weighed, 40mL of absolute ethyl alcohol is added, the mixture is placed in a magnetic stirrer to be uniformly dispersed, and the mixture is poured into a 100mL reaction kettle with a polytetrafluoroethylene lining and is subjected to heat preservation for 6 hours at the temperature of 200 ℃ at the speed of 1000 r/min.

After the reaction is finished, cooling to room temperature, centrifuging at 10000r/min for 15min, taking supernatant, evaporating ethanol at 50 ℃ by a rotary evaporator, filtering the obtained solution by a microporous filter membrane with the pore diameter of 0.22um, dialyzing for 3h by a dialysis bag (with the molecular weight of 12000), changing deionized water every 1h, and freeze-drying to obtain a light yellow solid.

Characterization of 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). FIG. 1 is a surface morphology of I-CQDs. FIG. 1 (A) is a transmission electron microscope image of I-CQDs, which can be observed that the prepared I-CQDs are uniform in size and distribution and are shaped like spherical particles. The I-CQDs are analyzed by high resolution transmission electron microscopy, and the calculated lattice spacing of the carbon dots is 0.32nm, as shown in FIG. 1 (B). The particle size of arbitrarily selected I-CQDs particles was counted using Image J software and then a histogram was made, as shown in FIG. 1 (C), and the average size of the particles was calculated to be 6.42. + -. 1.50nm.

(2) Fluorescent characteristics

FIG. 2 is a graph showing the fluorescence characteristics of I-CQDs.

And measuring the ultraviolet absorption spectrum, the serial fluorescence emission spectrum and the fluorescence excitation spectrum of the I-CQDs, and further analyzing the optical characteristics of the I-CQDs.

The ultraviolet absorption curve, the maximum fluorescence excitation light (EX) spectrum and the maximum fluorescence emission spectrum (EM) of I-CQDs are shown in FIG. 2 (A). As can be seen from FIG. 2 (A), the ultraviolet absorption spectrum of I-CQDs has obvious strong absorption at about 220nm, and comparing the fluorescence excitation spectrum with the fluorescence emission spectrum, the I-CQDs has obvious Stokes phenomenon.

Fluorescence emission spectra of I-CQDs at different excitation wavelengths are shown in FIG. 2 (B), and it can be seen that the emission wavelength (. Lamda.em) is red-shifted from 350nm to 430nm when the excitation wavelength (. Lamda.ex) is changed from 290nm to 350 nm. At an excitation wavelength of 330nm, there is a maximum emission wavelength of 408nm. At a molar ratio of 0.1mol/L H ₂ SO ₄ Quinine sulfate was used as a reference, and the fluorescence quantum yield of I-CQDs was 36.2%.

FIG. 3 shows the IR and XPS spectra of I-CQDs and the narrow spectra of each element, specifically: FIG. A is an infrared spectrum of I-CQDs, FIG. B is an XPS spectrum of I-CQDs, FIG. C is a C1s spectrum of I-CQDs, FIG. D is an O1s spectrum of I-CQDs, and FIG. E is an I3D spectrum of I-CQDs.

Example 2

The preparation process is the same as example 1 with m-iodobenzoic acid as the raw material.

Example 3

The preparation process is the same as example 1 with o-iodobenzoic acid as the raw material.

Example 4 sensitivity and selectivity of I-CQDs for Metal ion detection

In order to explore the application prospect of the I-CQDs in the field of metal ion detection, the I-CQDs solution with certain concentration is respectively added into 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⁺ In the solution (2), the metal cation concentration of the system is 0.01mol/L and is 330nmAnd measuring fluorescence emission spectra of the quantum dot solution containing different metal ions under excitation light, and judging the selectivity and sensitivity of the I-CQDs to the quenching effects of different metal ions according to different fluorescence intensities.

The sensitivity and selectivity of I-CQDs for detection of different metal ions is shown in FIG. 4.

FIG. 4 (A) is a graph showing the effect of different metal ions on the fluorescence intensity of I-CQDs, and it can be seen that Fe is present in comparison with other metal ions ³⁺ Can obviously quench the fluorescence of the carbon quantum dots, and other substances have no obvious influence on the fluorescence intensity of the carbon quantum dots. Therefore, the I-CQDs can be applied to the detection of Fe ³⁺ 。

To further study Fe ³⁺ In the presence of other metal cations, I-CQDs are paired with Fe ³⁺ Detecting the influence of Fe ³⁺ The mixed solution with other metal cations was mixed with I-CQDs and then measured for fluorescence intensity, respectively, as shown in FIG. 4 (B). It can be seen that, in the coexistence of other metal cations, I-CQDs are responsible for Fe ³⁺ Also has obvious fluorescence quenching effect, and the fluorescence intensity after quenching is hardly influenced by coexisting ions, which indicates that the I-CQDs have Fe ³⁺ The detection has stronger capability of resisting the interference of other metal ions.

To explore I-CQDs and Fe ³⁺ Quenching relation of concentration, namely prepared Fe ³⁺ Adding the solution into I-CQDs, and mixing Fe in the system ³⁺ The concentration of (A) is 0-200 mu M, and the Fe content is measured to contain different concentrations under the excitation wavelength of 330nm ³⁺ The fluorescence intensity of the I-CQDs solution of (1) is shown in FIG. 4 (C). As can be seen from FIG. 4 (C), it follows Fe ³⁺ The concentration is gradually increased, the fluorescence intensity is gradually weakened, and the fluorescence quenching effect is gradually enhanced.

FIG. 4 (D) shows that different concentrations of Fe ³⁺ Relative fluorescence intensity after treatment of I-CQDs [ (F) ₀ -F)/F]With Fe ³⁺ The concentrations are in good exponential correlation. In Fe ³⁺ In the concentration range of 5-200 mu M, the linear regression equation obtained by fitting is as follows: [ (F) ₀ -F)/F]＝0.442e^(0.008*x)-e^(-0.007x)，R ² ＝0.9963。R ² =0.9963 shows that the fitting curve has extremely high exponential correlation degree in the range of 0-200 μ M. Experiments show that Fe ³⁺ Can be sensitively detected at low concentration, and Fe ³⁺ The concentration and the relative fluorescence intensity are in exponential distribution, and the method is suitable for medium and low Fe ³⁺ And (4) detecting a concentration sample.

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

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. A preparation method of iodine-doped carbon quantum dots is characterized by comprising the following steps:

mixing p-iodobenzoic acid, m-iodobenzoic acid or o-iodobenzoic acid with ethanol, reacting at 200 ℃, cooling the system to room temperature after the reaction is finished, centrifuging to obtain a supernatant, removing ethanol, filtering, dialyzing, and freeze-drying to obtain the iodine-doped carbon quantum dots.

2. The method of claim 1, wherein the reaction time is 6 hours.

3. The iodine-doped carbon quantum dot prepared by the preparation method of any one of claims 1 to 2.

4. The use of the iodine-doped carbon quantum dot of claim 3 in the field of metal ion detection.

5. The iodine-doped carbon quantum dot as claimed in claim 3 as a fluorescent probe in Fe ³⁺ Application in the field of detection.