1. A CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe is characterized in that:

the inner core of the ratiometric fluorescent probe is 2-5nmCDTE quantum dots, and the surface of the CdTe quantum dots is modified with mercaptoethylamine and a reaction product of mercaptoethylamine and benzocoumarin-3-formic acid.

2. The CdTe quantum dot-benzocoumarin-3-formate ratiometric fluorescent probe of claim 1, characterized in that the structure is as follows:

3. a method for preparing CdTe quantum dot-benzocoumarin-3-carboxylic acid ratiometric fluorescent probe according to claim 1 or 2, characterized by comprising the following steps:

step 1: reacting Te with NaBH₄Adding colorless transparent NaHTe solution obtained after reaction into CdCl₂Reacting with mercaptoethylamine mixed solution to obtain CdTe quantum dots modified by cysteamine surface;

step 2: adding benzocoumarin-3-formic acid into the mixed solution of EDC/NHS, adding a CdTe quantum dot modified by the surface of cysteamine, and reacting to obtain a quantum dot-benzocoumarin-3-formic acid ratio fluorescent probe;

the structural formula of the benzocoumarin-3-formic acid is as follows:

4. a Cd as claimed in claim 1 or 2The application of the Te quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe is characterized in that: the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe is used for preparing and detecting Hg²⁺The detection reagent of (1).

5. Use of a CdTe quantum dot-benzocoumarin-3-carboxylic acid ratiometric fluorescent probe according to claim 1 or 2, characterized in that: the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe is used for detecting Hg²⁺The method (2) is used as a detection reagent.

6. Use according to claim 5, characterized in that:

the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe is used as a detection reagent, fluorescence spectrum determination is carried out in an aqueous medium, and Hg is realized through the change of fluorescence intensity²⁺Qualitative or quantitative detection of (a).

7. Use according to claim 5 or 6, characterized in that:

the ratiometric fluorescent probe is used for Hg in an aqueous medium²⁺The detection limit of (3) is up to 0.03. mu.M.

Background

Mercury is a toxic heavy metal pollutant, and is safe to environment and humanOne of the most harmful heavy metal ions for human health. Mercury contamination is more severe than other common contaminants and certain persistent organic contaminants. Hg is a mercury vapor²⁺It damages the nervous system and long-term vital organs due to its accumulation in human cells. Therefore, it is very important to be able to detect Hg in the environment and in the living body efficiently, quickly and accurately²⁺Ions.

The ratio fluorescence-based detection method is a popular visual detection method for target reaction based on a signal probe at present, and can reduce inference errors and environmental factors to the maximum extent. The design of the ratiometric sensing system is such that one donor is responsible for the target-specific binding of the final quenching, and the other donor remains unchanged (fluorescent reference) to allow visual detection.

Disclosure of Invention

The invention aims to provide a CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe and a preparation method and application thereof, and aims to solve the technical problem that Hg can be detected and identified through molecular design synthesis²⁺The fluorescent probe of (1).

The CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe has a core of 2-5nmCdTe quantum dots, and mercaptoethylamine (Mea) and a reaction product of the mercaptoethylamine and the benzocoumarin-3-formic acid are modified on the surface of the CdTe quantum dots.

The CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe has the structural formula as follows:

the structure of the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe comprises the following parts: firstly, modifying cysteamine on the surface of CdTe quantum dots, and then reacting with benzocoumarin-3-formic acid to obtain a probe structure. The amount of the benzocoumarin-3-formic acid participating in the reaction influences the detection effect of the probe, and the detection effect is optimal when the amount of the benzocoumarin-3-formic acid participating in the reaction accounts for 15-30% of the amount of the cysteamine. The percentage is about 22% in the examples.

The preparation method of the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe comprises the following steps of:

step 1: mixing 0.4mmol Te with 1.2mmol NaBH₄The colorless and transparent NaHTe solution obtained after the reaction is added into 0.8mmol CdCl₂Reacting with 1.6mmol of mercaptoethylamine mixed solution to obtain CdTe quantum dots (Mea-CdTe) modified by cysteamine surface;

step 2: adding 0.008mmol of carbodiimide (EDC) and 0.001mmol of N-hydroxysuccinimide (NHS) into 50mL of 20-mu M benzocoumarin-3-formic acid solution, reacting and activating for 20 minutes at room temperature, then adding 2mL of 0.0028M (calculated according to selenium source) Mea-CdTe quantum dot solution, and stirring for 40 minutes at room temperature to obtain the CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescent probe.

The structural formula of the benzocoumarin-3-formic acid is as follows:

the synthetic process of the invention is as follows:

the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe is used for preparing and detecting Hg²⁺The detection reagent of (1).

The invention relates to an application of a CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe in Hg detection²⁺The method (2) is used as a detection reagent.

Furthermore, the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe can specifically identify Hg²⁺Hg can be detected by fluorescence²⁺. The fluorescence intensity of the quantum dots is along with Hg²⁺The concentration increases and decreases. The probe is used for carrying out fluorescence spectrum determination in an aqueous medium, and Hg is detected through the change of the fluorescence intensity of the quantum dots²⁺Qualitative or quantitative detection of (a).

The preparation condition of the invention is simple, and the fluorescent probe can treat Hg under the fluorescent condition²⁺In response, Hg²⁺Combining with unreacted amino groups on the surface of the CdTe quantum dots to quench the fluorescence of the CdTe quantum dots. With Hg²⁺The fluorescent color of the probe solution under the ultraviolet lamp changes from bright yellow to light purple when the concentration is increased, and the probe solution can be used for Hg²⁺Visual qualitative detection of (1).

The fluorescent probe can be used for Hg in an actual water sample²⁺The high selectivity and sensitive detection is realized, and the detection limit reaches 0.03 mu M.

Drawings

FIG. 1 is a CdTe quantum dot transmission diagram.

FIG. 2 is an infrared spectrum of the CdTe quantum dot, CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe.

FIG. 3 is the fluorescence spectrum of CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe added with different metal ions in aqueous solution.

FIG. 4 shows that the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe of the invention is added with 0-1.4 mu M Hg with different concentrations in aqueous solution²⁺The fluorescence spectrum after the reaction was analyzed.

FIG. 5 shows fluorescence intensity and Hg in the aqueous solution of the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe of the invention²⁺The relationship of concentration.

FIG. 6 shows the absence and presence of Hg in CdTe quantum dot-benzocoumarin-3-formate ratiometric fluorescent probes of the invention²⁺An infrared spectrum of (1).

Detailed Description

The invention is further illustrated by, but is not limited to, the following examples.

Example 1: preparation and characterization of CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescent probe

0.8mmol of CdCl₂And 1.6mmol of cysteamine hydrochloride was placed in a three-necked flask containing 100mL of pretreated deionized water. The pH of the solution was adjusted to 5.6 with 1M NaOH solution. Add to 40mL of deionized water0.4mmol Te and 1.2mmol NaBH₄The solution is added in N₂Stirring for 4 hours under the atmosphere to obtain a colorless transparent solution, namely a NaHTe solution. And pouring the obtained colorless transparent NaHTe solution into the Cd (II) -Mea precursor solution, and stirring for 3 hours at 95 ℃ (under the protection of nitrogen) to obtain Mea-CdTe quantum dot solution.

50mL of a 20. mu.M solution of benzocoumarin-3-carboxylic acid was activated at room temperature by EDC/NHS. Then adding 2mL of Mea-CdTe quantum dot solution and stirring for 40 minutes at room temperature to obtain the target product.

FIG. 1 is a CdTe quantum dot transmission diagram. The particle size is 2-5 nm.

FIG. 2 is an infrared spectrum of the CdTe quantum dot, CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe. -CO-NH- (1600 cm)^-1)。

Example 2: CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescence probe for Hg²⁺Specific recognition of

Selectivity of CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescence probe in Hg²⁺The fluorescence response of the method to other metal ions is studied under the same condition to determine the metal ion Mg²⁺，Al³⁺，Pb²⁺，Ag⁺，Zn²⁺，Cu²⁺，Ni²⁺，Fe²⁺，Fe³⁺，Cr³⁺. From FIG. 3, it can be seen that CdTe quantum dot-benzocoumarin-3-carboxylic acid ratio fluorescence probe is directed to Hg²⁺Has obvious fluorescence quenching efficiency, and other metal ions have no obvious fluorescence signal change under the same conditions. The results show that the fluorescent probe is directed against Hg²⁺Has high selectivity.

Example 3: CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescence detection fluorescence intensity and Hg²⁺Correlation of concentration

Dropping Hg with different concentrations into CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescent probe solution²⁺The fluorescence spectrum after the reaction is shown in FIG. 4, which is dependent on Hg²⁺The fluorescence intensity of the probe gradually decreases with increasing concentration. The fluorescence intensity ratio I was observed in the range of 0.4 to 1.2. mu.M₅₇₅/I₄₃₆(I₅₇₅Is characteristic fluorescence emission peak of Mea-CdTe quantum dot, I₄₃₆Is the characteristic fluorescence emission peak of the benzocoumarin-3-formic acid. ) And Hg²⁺The relationship between concentrations (as shown in fig. 5). The linear coefficient R of the fluorescence intensity and the adding amount of the probe²This indicates that the fluorescent probe of the present invention can quantitatively detect Hg in the fluorescence spectrum^{2 +}. And Hg is calculated by applying the formula²⁺The detection limit of the probe was 0.03. mu.M. The formula is that the detection limit is 3 σ/k, where σ is the standard deviation of the blank measurement values and k is the fluorescence intensity ratio I₅₇₅/I₄₃₆For Hg²⁺Slope of the concentration plot. This limit of detection is far below the Hg of the us EPA and some reported reaction-based fluorescence sensors²⁺(20. mu.M in drinking water) standard value.

Example 4: CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescence probe for detecting Hg²⁺Principle of (1)

In order to explore Hg²⁺According to the interaction principle with the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe, Hg is added into the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe²⁺Infrared characterization was performed after ionization, as shown in FIG. 6, in comparison to the absence of Hg²⁺Compared with the infrared spectrogram of the CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe, the surface of the quantum dot is 1635cm^-1The infrared vibration peak of the amino group is obviously weakened, and Hg can be seen²⁺The fluorescent dye is combined with amino on the surface of the CdTe quantum dot to quench the fluorescence of the CdTe quantum dot.

Example 5: CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescent probe for Hg in actual water sample²⁺Detection of (2)

CdTe quantum dot-benzocoumarin-3-formic acid ratiometric fluorescent probe for detecting Hg in tap water and lake water samples²⁺(Table 1). The detection result is substantially consistent with the actual addition. This indicates that the fluorescent probe of the present invention has application value in environmental detection.

TABLE 1 detection result of CdTe quantum dot-benzocoumarin-3-formic acid ratio fluorescence probe of the invention on actual water sample