CN106829920A - A kind of green fluorescence carbon quantum dot material and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of green fluorescence carbon quantum dot material and preparation method thereof.Preparation method of the invention is comprised the following steps that：1) it is (1.8~2) according to volume ratio：(18~20)：1, phytic acid, distilled water and ethylenediamine are stirred 10~15 minutes under conditions of room temperature, solution is changed into turbid solution from clarifying, then high speed centrifugation removal insoluble substance, takes supernatant；2) it is carbonized in the supernatant of taking-up being added into autoclave；3) carbonization solution is taken out, high speed centrifugation, removal insoluble matter precipitation takes supernatant, carries out gel column purifying, freeze-drying and obtain green fluorescence carbon quantum dot.The inventive method operating procedure is simple, and with low cost, the fluorescent yield of the carbon quantum dot of preparation is high, can be directly used for metal Hg²⁺The detection of ion, can also be widely used in the fields such as biological detection, biological mirror image, photoelectric conversion and catalysis.

Description

A kind of green fluorescent carbon quantum dot material and preparation method thereof

technical field

The invention relates to a green fluorescent carbon quantum dot material and a preparation method thereof, belonging to the technical field of nanometer material preparation.

Background technique

Carbon quantum dots are a new fluorescent carbon nanomaterial that has emerged in recent years. It is a nearly spherical zero-dimensional semiconductor nanocrystal with a diameter of less than 10 nm and has good dispersion. This nanomaterial overcomes some shortcomings of traditional II-IV quantum dots, and has non-toxicity, high fluorescence quantum yield, good biocompatibility, high light and chemical stability, etc., and can be used for biosensing and bioimaging , environmental detection, photocatalysis and drug carriers and many other fields. Carbon dots with low toxicity have begun to replace II-IV quantum dots with high biological toxicity in the field of life sciences.

There are many methods for preparing carbon quantum dots. According to the source of carbon source, it can be divided into inorganic carbon source and organic carbon source. Generally, the fluorescence quantum yield of carbon quantum dots prepared by inorganic carbon sources is low, and the operation is complicated. However, the luminescence efficiency of carbon quantum dots prepared by organic carbon sources is better. Usually, chemical oxidation, microwave treatment, hydrothermal method and other means can be used to obtain small and dispersed carbon quantum dots, but because most of the carbon quantum dots obtained by this type of method are blue light-emitting materials, it is not conducive to the application in vivo .

Contents of the invention

The object of the present invention is to provide a green fluorescent carbon quantum dot material with non-toxicity, uniform particle size and long emission wavelength (near 520nm) and a preparation method thereof. The preparation method of the invention is simple, and the obtained green fluorescent carbon quantum dots can be directly applied to the detection of metal Hg ²⁺ ions.

The technical solution of the present invention is specifically introduced as follows.

The invention provides a green fluorescent carbon quantum dot material. Under excitation at a wavelength of 360-440nm, the emission wavelength of the green fluorescent carbon quantum dot is between 510-525nm.

The present invention also provides a preparation method of the above-mentioned green fluorescent carbon quantum dot material, the specific steps are as follows:

1) According to the volume ratio of (1.8~2):(18~20):1, stir phytic acid, distilled water and ethylenediamine at room temperature for 10~15 minutes. Centrifuge to remove insoluble matter, and take the supernatant;

2) Put the taken out supernatant into the autoclave for carbonization, the temperature is set at 175-185°C, the stirring speed is 360-400 rpm, and the reaction time is 7-9 hours;

3) Take out the carbonization solution, centrifuge at high speed to remove the insoluble precipitate, take the supernatant, perform gel column purification, and freeze-dry the eluent to obtain a green fluorescent carbon quantum dot material.

Preferably, in step 2), the temperature is set at 180-185°C.

Compared with prior art, the advantage of the present invention is:

(1) The preparation method of the present invention is simple, easy to operate, and has high reproducibility. The raw material is cheap and pure carbon quantum dot powder can be obtained.

(2) The prepared carbon quantum dots emit green fluorescence (the central emission wavelength is around 520nm), and the fluorescence emission band is higher than the emission wavelength of most traditional blue light carbon quantum dots, which can be directly used for the detection of Hg ²⁺ and is also suitable for biological application field.

(3) The fluorescence yield of the carbon quantum dots provided by the present invention is as high as 72%, which can be used in biological detection, mirror images, and applications of high photoelectric conversion efficiency in organic semiconductors.

Description of drawings

Fig. 1 is under the condition of embodiment 1, transmission electron micrograph (a) and size distribution diagram (b) of the present invention.

Fig. 2 is the fluorescence emission spectrum obtained under the excitation of 300-480nm wavelength in the present invention under the conditions of Example 1.

3 is the ultraviolet absorption and fluorescence emission spectrum of the carbon quantum dot aqueous solution sample under the conditions of Example 1. The inset (left) is a photo of the carbon quantum dot aqueous solution sample, which is colorless; the inset (right) is a fluorescent photo of carbon quantum dots irradiated by a 365nm wavelength ultraviolet lamp, which is green.

Fig. 4 is under the condition of embodiment 1, Hg ²⁺ is to the fluorescence quenching pattern of aqueous solution of carbon quantum dots. Among them, figure (a) is the quenched fluorescence spectrum of carbon quantum dots to Hg ²⁺ , figure (b) is the selectivity spectrum of carbon quantum dots to metal ions, and figure (c) is the sensitivity spectrum of carbon quantum dots to Hg ²⁺ .

detailed description

The technical solution of the present invention will be further described below in conjunction with examples.

Example 1

1) Add 20 mL of distilled water to a 100 mL beaker at room temperature, then add 2 mL of phytic acid, slowly add 1 mL of ethylenediamine under magnetic stirring, and react for 10 minutes. During this time the solution became cloudy and an insoluble salt was formed. Centrifuge after the reaction, remove the precipitate, and take the supernatant.

2) Add the supernatant taken out into the autoclave, and add the medium-sized rotor. The reaction temperature was set at 180° C. for 8 hours, and the rotation speed was 400 rpm. After the reaction, the solution was taken out and centrifuged at 8000 rpm at high speed to remove the precipitate, and the supernatant was taken.

3) Pour the above supernatant into a gel column (G-50), and the added gel is 1/2 of the column length. Before use, the gel needs to be soaked in distilled water for 24 hours. The purpose is to remove impurities in the gel and wash it thoroughly.

4) Collect the filtered solution and perform rotary evaporation to increase the concentration of the carbon quantum dot solution. Finally freeze-dried for 48 hours to obtain a solid powder. Fig. 1 is under the condition of embodiment 1, transmission electron micrograph (a) and size distribution diagram (b) of the present invention, the particle size distribution of carbon quantum dots is 2.5-7.5nm, and uniform size is 4.2nm.

The fluorescence yield of the carbon quantum dots provided in Example 1 is measured by calculation, that is, under the same excitation conditions, the fluorescence areas of the carbon quantum dots and the fluorescent reference standard are measured respectively, and are substituted into the following formula:

In the formula, Φ _sample and Φ _ref are the fluorescence quantum yields of the sample to be tested and the fluorescent reference standard, respectively, F _sample and F _ref are the fluorescence emission peak area or fluorescence intensity of the sample to be tested and the fluorescent reference standard, respectively, and A _sample , A _ref are the absorbance values of the sample to be tested and the fluorescent reference standard at the excitation wavelength, and n _sample and n _ref are the refractive indices of the solvent where the sample to be tested and the fluorescent reference standard are respectively.

Using Rhodamine B as the fluorescence reference standard, the fluorescence quantum yield of the carbon quantum dots provided in Example 1 was determined to be 0.72.

Fig. 2 is the fluorescence emission spectrum obtained under the excitation of 300-480nm wavelength in the present invention under the conditions of Example 1. The results show that the emission wavelength of the green fluorescent carbon quantum dot is between 510-525nm under the excitation of the wavelength of 360-440nm.

3 is the ultraviolet absorption and fluorescence emission spectrum of the carbon quantum dot aqueous solution sample under the conditions of Example 1. The inset (left) is a photo of a carbon quantum dot aqueous solution sample, which is colorless; the inset (right) is a fluorescent photo of carbon quantum dots irradiated by a 365nm wavelength ultraviolet lamp, which is green.

Fig. 4 is under the condition of embodiment 1, Hg ²⁺ is to the fluorescence quenching pattern of aqueous solution of carbon quantum dots. Among them, figure (a) is the quenched fluorescence spectrum of carbon quantum dots to Hg ²⁺ , figure (b) is the selectivity spectrum of carbon quantum dots to metal ions, and figure (c) is the sensitivity spectrum of carbon quantum dots to Hg ²⁺ . The results show that the carbon quantum dots of the present invention can realize the selectivity and high sensitivity detection of Hg ²⁺ .

Example 2

1) Add 18 mL of distilled water to a 100 mL beaker at room temperature, then add 1.8 mL of phytic acid, slowly add 1 mL of ethylenediamine under magnetic stirring, and react for 15 minutes. During this time the solution became cloudy and an insoluble salt was formed. Centrifuge after the reaction, remove the precipitate, and take the supernatant.

2) Add the supernatant taken out into the autoclave, and add the medium-sized rotor. The reaction temperature was set at 185°C for 8 hours and the rotation speed was 3600 rpm. After the reaction was completed, the solution was taken out and centrifuged at 8000 rpm at high speed to remove the precipitate and take the supernatant.

3) Pour the above supernatant into a gel column (G-50), and the added gel is 1/2 of the column length. Before use, the gel needs to be soaked in distilled water for 24 hours. The purpose is to remove impurities in the gel and wash it thoroughly.

4) Collect the filtered solution and perform rotary evaporation to increase the concentration of the carbon quantum dot solution. Finally freeze-dried for 48 hours to obtain a solid powder.

The particle size of the carbon quantum dots obtained in Example 2 is 2.5-7.5 nm. Under the excitation of the wavelength of 360-440nm, the emission wavelength of the green fluorescent carbon quantum dot is between 510-525nm. Fluorescence photo of carbon quantum dots illuminated by 365nm wavelength ultraviolet lamp, which is green. The fluorescence quantum yield of carbon quantum dots is 72%.

Claims (3)

1. a kind of green fluorescence carbon quantum dot material, it is characterised in that in the case where the wavelength of 360~440nm is excited, green fluorescence carbon The launch wavelength of quantum dot is between 510~525nm.

2. the preparation method of green fluorescence carbon quantum dot material as claimed in claim 1, it is characterised in that specific steps are such as Under：

1) it is (1.8~2) according to volume ratio：(18~20)：1, phytic acid, distilled water and ethylenediamine are stirred under conditions of room temperature 10~15 minutes, solution was changed into turbid solution from clarifying, then high speed centrifugation removal insoluble substance, took supernatant；

2) it is carbonized in the supernatant of taking-up being added into autoclave, temperature setting is 175~185 DEG C, mixing speed is 360~400 revs/min, the reaction time is 7~9 hours；

3) carbonization solution is taken out, high speed centrifugation, removal insoluble matter precipitation takes supernatant, carries out gel column purifying, eluent freezing It is dried to obtain green fluorescence carbon quantum dot material.

3. preparation method as claimed in claim 2, it is characterised in that step 2) in, temperature setting is 180-185 DEG C.