CN111826155B

CN111826155B - CdS quantum dot-fluorescein FRET fluorescent probe and preparation method and application thereof

Info

Publication number: CN111826155B
Application number: CN202010715885.9A
Authority: CN
Inventors: 李村; 王坤; 方敏; 朱维菊; 吴振玉
Original assignee: Anhui University
Current assignee: Anhui University
Priority date: 2020-07-23
Filing date: 2020-07-23
Publication date: 2022-06-07
Anticipated expiration: 2040-07-23
Also published as: CN111826155A

Abstract

The invention discloses a CdS quantum dot-fluorescein FRET fluorescent probe and a preparation method and application thereof, wherein the structural formula of the fluorescent probe is as follows:

the CdS quantum dot-fluorescein FRET fluorescent probe can specifically identify Cu in an aqueous solution²⁺According to fluorescence spectrum determination, Cu can be realized through change of fluorescence intensity thereof²⁺Qualitative or quantitative detection of (a); the CdS quantum dot-fluorescein FRET fluorescent probe can be applied to Cu in an actual water sample²⁺The detection limit reaches 5.8 multiplied by 10^‑8M。

Description

CdS quantum dot-fluorescein FRET fluorescent probe and preparation method and application thereof

Technical Field

The invention belongs to the technical field of metal ion detection, and particularly relates to a CdS quantum dot-fluorescein FRET fluorescent probe, and a preparation method and application thereof.

Background

As is well known, Cu²⁺Is a trace element which is extremely important in human bodies and animals, and is usually Cu²⁺Exist in forms that play an important role in biological and environmental systems. However, once Cu is present in vivo²⁺In excess, it will produce toxic effects on the human body and even damage the central nervous system, thus causing some diseases. For example, Wilson's disease, Alzheimer's disease, amyotrophic lateral sclerosis and virusesAnd (6) treating the disease. Thus, accurate determination of Cu in environmental systems and biological fluids²⁺It is very important.

Fluorescence Resonance Energy Transfer (FRET) is a non-radiative energy transfer process by which a signal is recognized to be transferred to an acceptor molecule, amplified and red-shifted to the near-infrared band. Meanwhile, the FRET method has the advantages of high sensitivity and high selectivity, and is an ideal ion detection method.

Disclosure of Invention

The invention aims to provide a CdS quantum dot-fluorescein FRET fluorescent probe and a preparation method and application thereof, and aims to solve the technical problem that Cu can be detected and identified through molecular design synthesis²⁺The fluorescent probe of (1).

The CdS quantum dot-fluorescein FRET fluorescent probe has the following structure:

the preparation method of the CdS quantum dot-fluorescein FRET fluorescent probe comprises the following steps:

step 1: adding 2.355mmol of Na₂S with 2.355mmol CdCl₂Mixing 4.67mmol of mercaptoethylamine in 50mL of deionized water for reaction to obtain CdS (mea-CdS) quantum dots modified by the surface of cysteamine;

step 2: adding 0.002mmol of fluorescein into a mixed solution of EDC (0.008mmol)/NHS (0.001mmol), and adding 1mL of meso-CdS quantum dots for reaction to obtain the quantum dot-fluorescein FRET fluorescent probe.

The structural formula of the fluorescein is as follows:

further, in the step 2, a certain amount of fluorescein is weighed and dissolved in deionized water, then carbodiimide (EDC) and N-hydroxysuccinimide (NHS) are added to react at room temperature for 20 minutes, and then mea-CdS quantum dots obtained in the step 1 are added to react at room temperature for 40 minutes under stirring, so that a target product is obtained.

The synthetic process of the invention is as follows:

the invention relates to an application of a CdS quantum dot-fluorescein FRET fluorescent probe in Cu detection²⁺The method (2) is used as a detection reagent.

Furthermore, the CdS quantum dot-fluorescein FRET fluorescent probe can specifically identify Cu²⁺By fluorescence means, Cu can be detected²⁺. Fluorescence intensity dependent on Cu²⁺The concentration increases and decreases. The fluorescent probe performs fluorescence spectrum measurement in an aqueous medium, and changes of fluorescence intensity are used for realizing Cu²⁺Qualitative or quantitative detection of (2).

The CdS quantum dot-fluorescein FRET fluorescent probe has the particle size of 2-5nm, and the core is CdS quantum dots and is modified with mercaptoethylamine (mea) and fluorescein reaction products on the surface.

The preparation condition of the invention is simple, and the fluorescent probe can be used for detecting Cu under the fluorescent condition²⁺There is a response.

The fluorescent probe can be used for Cu in an actual water sample²⁺The detection limit reaches 58nM, which is higher than that of the existing CdS quantum dot Cu²⁺Compared with the fluorescent probe, the fluorescent probe is greatly reduced.

Drawings

FIG. 1 is an infrared spectrum of CdS quantum dot, fluorescein, CdS quantum dot-fluorescein FRET fluorescent probe.

FIG. 2 is a high resolution transmission diagram of a CdS quantum dot-fluorescein FRET fluorescent probe.

FIG. 3 shows fluorescence spectra of CdS quantum dot-fluorescein FRET fluorescent probe with different metal ions added into aqueous solution.

FIG. 4 is CdS of the present inventionAdding 0-20 mu M of Cu with different concentrations into a water solution by using a quantum dot-fluorescein FRET fluorescent probe²⁺The fluorescence spectrum after the reaction was analyzed.

FIG. 5 shows the fluorescence intensity and Cu in the CdS quantum dot-fluorescein FRET fluorescent probe aqueous solution²⁺The relationship of concentration.

Detailed Description

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

Example 1: preparation and characterization of CdS quantum dot-fluorescein FRET fluorescent probe

1. Adding 2.355mmol of Na₂S with 2.355mmol CdCl₂And 4.67mmol of mercaptoethylamine is mixed and reacted in 50mL of deionized water, the reaction temperature is 70 ℃, and the reaction time is 1 hour, so that the CdS (mea-CdS) quantum dot modified by the surface of the cysteamine is obtained.

2. Weighing 0.002mmol of fluorescein, dissolving the fluorescein in 30mL of deionized water, adding 0.008mmol of carbodiimide (EDC) and 0.001mmol of N-hydroxysuccinimide (NHS) to react and activate for 20 minutes at room temperature, then adding 1mL of CdS quantum dots with cysteamine grafted on the surface, and stirring for 40 minutes at room temperature to obtain a target product.

FIG. 1 is an infrared spectrum of CdS quantum dot, fluorescein, CdS quantum dot-fluorescein FRET fluorescent probe of the present invention. -CO-NH- (1630 cm)^-1)，-COOH(1695cm^-1)。

FIG. 2 is a high resolution transmission diagram of a CdS quantum dot-fluorescein FRET fluorescent probe. The particle size is 2-5 nm.

Example 2: CdS quantum dot-fluorescein FRET fluorescent probe pair Cu²⁺Specific recognition of

For selectivity of CdS quantum dot-fluorescein FRET fluorescent probe, in Cu²⁺The method is studied under the same condition to determine the metal ion C according to the fluorescence response of other metal ions_O ²⁺，Ni²⁺，Ca²⁺，Al³⁺，Cr³⁺，Zn²⁺，Cu²⁺，Mn²⁺，Pb²⁺，Fe²⁺，Hg²⁺，Fe³⁺，Ag⁺. From FIG. 3, it can be seen that CdS quantum dot-fluorescein FRET fluorescenceProbe pair Cu²⁺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 to Cu²⁺Has high selectivity.

Example 3: CdS quantum dot-fluorescein FRET fluorescent probe fluorescence intensity and Cu²⁺Correlation of concentration

Dripping Cu with different concentrations into CdS quantum dot-fluorescein FRET fluorescent probe solution²⁺The fluorescence spectrum after the reaction is shown in FIG. 4, which is associated with Cu²⁺The fluorescence intensity of the probe gradually decreases with increasing concentration. Fluorescence intensities F and Cu were observed in the range of 4-14. mu.M²⁺The relationship between the concentrations (as shown in fig. 5). The linear coefficient R of the fluorescence intensity and the adding amount of the probe²0.99, which shows that the fluorescent probe of the invention can quantitatively detect Cu in a fluorescence spectrum²⁺. And calculating Cu by applying a formula²⁺The detection limit of the probe was 58 nM. The formula is 3 σ/k, where σ is the standard deviation of blank measurements (σ is 0.4) and k is the fluorescence intensity versus Cu²⁺Slope of the concentration plot. This limit of detection is far below the Cu of the U.S. EPA and some reported reaction-based fluorescence sensors²⁺(20. mu.M in drinking water) standard value.

Example 4: CdS quantum dot-fluorescein FRET fluorescent probe pair Cu in actual water sample²⁺Detection of (2)

Detection of Cu in tap water and lake water samples by CdS quantum dot-fluorescein FRET fluorescent probe²⁺(Table 1 below). 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 results of CdS quantum dot-fluorescein FRET fluorescent probe of the present invention on actual water samples

Claims

1. A CdS quantum dot-fluorescein FRET fluorescent probe is characterized in that the structure is as follows:

2. the method for preparing the CdS quantum dot-fluorescein FRET fluorescent probe as defined in claim 1, which comprises the following steps:

step 1: mixing Na₂S and CdCl₂Carrying out mixed reaction with mercaptoethylamine to obtain the CdS quantum dots modified by the surface of cysteamine;

step 2: adding fluorescein into the mixed solution of EDC/NHS, and adding the CdS quantum dots modified by the surface of cysteamine for reaction to obtain a quantum dot-fluorescein FRET fluorescent probe;

the structural formula of the fluorescein is as follows:

3. the application of the CdS quantum dot-fluorescein FRET fluorescent probe as claimed in claim 1 in Cu detection²⁺The method (2) is used as a detection reagent.

4. Use according to claim 3, characterized in that:

the CdS quantum dot-fluorescein FRET fluorescent probe is used as a detection reagent, fluorescence spectrum determination is carried out in an aqueous medium, and Cu is realized through the change of fluorescence intensity²⁺Qualitative or quantitative detection of (a).

5. Use according to claim 3 or 4, characterized in that:

the fluorescent probe is used for Cu in aqueous medium²⁺The detection limit of (1) reaches 58 nM.