CN102517024A - Method for water-phase microwave preparation of CdSeS quantum dots - Google Patents

Abstract

The invention discloses a water-phase microwave preparation method of CdSeS quantum dots. The steps are: A. Preparation of sodium selenosulfate solution: prepared by reacting selenium powder and sodium sulfite solution; B. Weighing cadmium chloride crystals and using deionized Dissolve in water to a constant volume to obtain a cadmium chloride solution; C, add a certain amount of mercaptopropionic acid in the cadmium chloride solution; D, adjust the solution to a specific pH value with sodium hydroxide solution; E, pass inert gas to remove After oxygenation, add sodium selenosulfate solution; E. Dispense the mixed solution into a polytetrafluoroethylene digestion tank, heat and react in a microwave digestion furnace; G. After cooling to room temperature, add isopropanol for purification, and dry in a freeze dryer Obtain CdSeS quantum dot solid powder. The process is fast and simple, the process parameters are easy to control, and the price is low. The synthesized quantum dots have a small particle size and a relatively uniform particle size distribution. for the detection of metal ions.

Description

A water-phase microwave preparation method of CdSeS quantum dots

technical field

The present invention relates to the synthesis of fluorescent nanomaterials, more specifically to a water-phase microwave preparation method of CdSeS quantum dots, the synthesized quantum dots have a small particle size (2-4nm) and uniform particle size distribution, and the fluorescence quantum efficiency is relatively high. Finally, it can be used as a bioluminescent labeling material, and can also be used for the detection of metal ions.

Background technique

CdSe quantum dots have the characteristics of tunable luminescence characteristics (the luminescence range covers the entire visible region from blue to red light), wide excitation range, relatively narrow emission full width at half maximum, and high luminescence quantum yield. One of the most studied quantum dots. However, the high-quality CdSe quantum dots currently synthesized are all synthesized from the organic phase, and the quantum dots directly synthesized in the aqueous phase not only have a wide half-peak width, but also have a low quantum yield, which cannot be applied to biomarkers. Therefore, how to synthesize high-quality CdSe quantum dots in aqueous phase has become a research hotspot.

Contents of the invention

The object of the present invention is to provide a microwave-assisted preparation method of CdSeS alloy quantum dots. The powder is dissolved in PBS solution or deionized water before use to obtain a CdSeS quantum dot solution. The quantum dot preparation process is fast and simple, the process parameters are easy to control, no post-treatment process is required, the required raw materials are cheap, the synthesized quantum dots have a small particle size (2-4nm) and a relatively uniform particle size distribution, and the fluorescence quantum yield is high ( ≈30%), it can be used as a bioluminescence labeling material after being coupled with biomolecules, and can also be used for the detection of metal ions.

In order to achieve the above object, the present invention adopts the following technical measures:

Its technical concept is: a CdSeS alloy quantum dot, which is composed of: Selenium powder (Se, Tianjin Kemiou Chemical Reagent Development Center), cadmium chloride (CdCl ₂ 2.5H ₂ O, Sinopharm Chemical Reagent Co., Ltd. ), mercaptopropionic acid (MPA, Japan), and the rest are aqueous solutions. In the present invention, mercaptopropionic acid is used as a stabilizer and a sulfur source, sodium selenosulfate is used as a selenium source, and CdSeS alloy quantum dots are prepared by microwave heating. Uniformity, high fluorescence quantum efficiency (30%-40%, 25% as reported in relevant literature). This method overcomes the limitations of long reaction time, wide particle size distribution and low quantum yield of CdSeS quantum dots synthesized by hydrothermal method.

In the CdSeS alloy quantum dot, the molar ratio of selenium powder (Se), cadmium chloride (CdCl ₂ ·2.5H ₂ O), and mercaptopropionic acid (MPA) is 1/5～1/10:1:1.7～ 2.4, heat at 120-150°C for 20-40 minutes.

The pH of the solution is 8-10.

A water-phase microwave preparation method of CdSeS quantum dots, the steps are:

1. Prepare sodium selenosulfate solution by reacting selenium powder (Se) with sodium sulfite (Na ₂ SO ₃ ): weigh 0.7890-2.3670g selenium powder and 2.5208-7.5624g sodium sulfite respectively in a 250mL three-necked flask, and add 60-80mL Deionized water, reflux in a water bath (80-95°C) and react for 8-10 hours until the solution turns into a light yellow transparent liquid, then stop heating. Naturally cool to room temperature (20-25°C, the same below), then transfer to a 100mL volumetric flask and use deionized water to set the volume to the mark, which is a 0.10-0.30mol/L sodium selenosulfate solution. The reaction equation is as follows:

Se+ _{Na2SO3 = Na2SeSO3 ;}

2. Weigh 0.2284-2.2835g cadmium chloride (CdCl ₂ 2.5H ₂ O) crystals, dissolve in deionized water and set the volume to 100mL to obtain 0.01-0.10mol/L cadmium chloride solution;

3. Weigh 0.1061~1.0614g of mercaptopropionic acid (MPA), dilute with deionized water to 100mL to obtain 0.01~0.10mol/L mercaptopropionic acid solution;

4. Take 95-200mL of deionized water, add 0.520-31.2mL of 0.01-0.10mol/L cadmium chloride solution and 0.884-74.88mL of 0.01-0.10mol/L mercaptopropionic acid solution in sequence, and use 1- 5mol/L sodium hydroxide solution to adjust the pH value to 8-10, add 0.104mL0.10～0.30mol/L sodium selenosulfate solution after aeration of nitrogen for 10-30min, and continue aeration reaction for 4-6min;

5. Pack the mixed solution in step 4 into polytetrafluoroethylene digestion tanks with 50ml per tank, and heat in microwave at 120-150°C for 20-40min to obtain water-soluble CdSeS quantum dots, sodium selenosulfate, The molar ratios of cadmium chloride and mercaptopropionic acid are 1/5～1/10:1:1.7～2.4 respectively;

6. Add isopropanol for purification, freeze in a refrigerator at -20°C and then dry in a freeze dryer to obtain CdSeS quantum dot solid powder. The powder was redissolved in water, and the ethanol solution of rhodamine 6G was used as a reference, and the ultraviolet absorption was measured at 354nm, and the peak area of the fluorescence emission peak was measured by excitation at 354nm. The fluorescence quantum yield was measured to be about 30%, which was higher than that in the literature reported value. Observing its morphology and particle size under a JEM-2100 high-resolution transmission electron microscope, the average particle size is 2-3nm, which is obviously smaller than the value reported in the literature (12nm).

Compared with the prior art, the present invention has the following advantages and effects:

1. The main raw materials of the quantum dots are rich in sources, low in price, and low in synthesis cost.

2. The traditional selenium sources (sodium selenide or hydrogen selenide, etc.) have harsh reaction conditions when synthesizing quantum dots, requiring the precursor solution to be absolutely oxygen-free, so sodium selenide or hydrogen selenide must be freshly prepared. And the selenium source in the method is sodium selenosulfate solution, is mixed with the stock solution of certain concentration after hydrothermal synthesis, is placed in the brown bottle and is refrigerated in the refrigerator, and the stability is high (can not go bad within a few months) , can be used and taken at any time, simplifying the synthesis steps.

3. The quantum dots are prepared by the microbiometry method, which is different from conventional heating methods. The heating speed is fast, the synthesis time is short, and the synthesized quantum dots have uniform particle size distribution and high crystallinity.

4. The preparation process is simple, and the process parameters are easy to control (the molar ratio of selenium powder, cadmium chloride and mercaptopropionic acid is 1/5～1/10: 1: 1.7～2.4, the pH value is 8～10, and the heating time is 20-40min, heating temperature is 120-150℃).

5. The quantum dot has small particle size (2-4nm), uniform particle size distribution, and high fluorescence quantum yield (up to 30%), and can be directly used for cell labeling.

Detailed ways

Example 1:

Below by embodiment, further illustrate outstanding feature of the present invention, only in order to illustrate the present invention and in no way limit the present invention.

A CdSeS alloy quantum dot, which consists of: selenium powder (Se, Tianjin Kemiou Chemical Reagent Development Center), cadmium chloride (CdCl ₂ 2.5H ₂ 0, Sinopharm Chemical Reagent Co., Ltd.), mercaptopropionic acid (MPA, Japan), and the rest are aqueous solutions.

In the CdSeS alloy quantum dots, the molar ratio of selenium powder (Se), cadmium chloride (CdCl ₂ ·2.5H ₂ O), and mercaptopropionic acid (MPA) is 0.2:1:2.0, under the condition of 120-150°C Heat for 20-40min.

The pH of the solution is 8-10.

A microwave-assisted synthesis method of CdSeS alloy quantum dots, the steps are:

1. Prepare sodium selenosulfate solution by reacting selenium powder (Se) with sodium sulfite (Na ₂ SO ₃ ): Weigh 2.3670g selenium powder and 7.5624g sodium sulfite respectively in a 250mL three-necked flask, add 80mL deionized water to it, and bathe in 80 Reflux at ~95°C for 8 or 9 or 10 hours until the solution turns into a light yellow transparent liquid, then stop heating. Naturally cool to room temperature (20-25°C, the same below), then transfer to a 100mL volumetric flask and use deionized water to set the volume to the mark, which is a 0.30mol/L sodium selenosulfate solution. The reaction equation is as follows:

Se+ _{Na2SO3 = Na2SeSO3 ;}

2. Weigh 0.2284g of cadmium chloride (CdCl ₂ 2.5H ₂ O) crystal, dissolve it in deionized water to 100mL, and obtain a 0.01mol/L cadmium chloride solution;

3. Weigh 0.1061g of mercaptopropionic acid (MPA), dilute to 100mL with deionized water to obtain 0.01mol/L mercaptopropionic acid solution;

4. Take 140 mL of deionized water, add 20 mL of 0.01 mol/L cadmium chloride solution and 40 mL of 0.01 mol/L mercaptopropionic acid solution in turn, and adjust the pH value to 8 or 8.5 with 1 mol/L sodium hydroxide solution. Add 0.667 mL of 0.30 mol/L sodium selenosulfate solution after 30 minutes of nitrogen gas flow, and continue the ventilation reaction for 5 minutes;

5. The above mixed solution was divided into polytetrafluoroethylene digestion tanks with 50ml per tank, and microwaved at 120°C for 40min to prepare CdSeS quantum dots with a concentration of 1.0mmol/L, sodium selenosulfate (Na ₂ SeSO ₃ ), the molar ratio of cadmium chloride (CdCl ₂ ·2.5H ₂ O) and mercaptopropionic acid (MPA) is 0.2:1:2.0, and the fluorescence quantum yield of the obtained quantum dots is 11.7-13.4%.

Example 2:

A CdSeS alloy quantum dot, which consists of: selenium powder (Se, Tianjin Kemiou Chemical Reagent Development Center), cadmium chloride (CdCl ₂ 2.5H ₂ O, Sinopharm Chemical Reagent Co., Ltd.), mercaptopropionic acid (MPA, Japan), and the rest are aqueous solutions.

In the CdSeS alloy quantum dot, the molar ratio of sodium selenosulfate (Na ₂ SeSO ₃ ), cadmium chloride (CdCl ₂ ·2.5H ₂ O), and mercaptopropionic acid (MPA) is 0.125:1:2.4, 130 Heating at ℃ for 30-40min.

The pH of the solution is 9-9.5.

A microwave-assisted synthesis method of CdSeS alloy quantum dots, the steps are:

1. Weigh 1.1835g of selenium powder and 3.7812g of sodium sulfite into a 250mL three-neck flask, add 85mL of deionized water, and reflux in a water bath at 95°C for 8 or 9 or 10 hours until the solution is clear and transparent. Remove the heat source and stop heating. After naturally cooling to room temperature (20-25°C), transfer it to a 100mL volumetric flask and dilute it to the mark with deionized water. It is a 0.15mol/L sodium selenosulfate solution. The reaction equation is as follows:

Se+ _{Na2SO3 = Na2SeSO3 ;}

2. Take 200 mL of anaerobic deionized water, add 2.5 mL of 0.10 mol/L cadmium chloride solution and 6 mL of 0.10 mol/L mercaptopropionic acid solution in turn, and adjust the pH value to 9 with 5 mol/L sodium hydroxide solution Or 9.5, add 0.208mL of 0.15mol/L sodium selenosulfate solution after blowing nitrogen for 30 minutes, and continue blowing and reacting for 5 minutes;

3. The above mixed liquid was divided into polytetrafluoroethylene digestion tanks with 50ml per tank, and microwaved at 130°C for 30-40min to prepare CdSeS quantum dots with a concentration of 1.25mmol/L, cadmium chloride, selenium The molar ratios of sodium sulfate and mercaptopropionic acid are 1:0.125:2.4 respectively, and the fluorescence quantum yield of the obtained quantum dots is 27.3-30.8%.

Other implementation steps are the same as in Example 1.

Example 3:

1. Weigh 2.3670g of selenium powder and 7.5624g of sodium sulfite in a 250mL three-neck flask, add 80mL of deionized water to it, and reflux in a water bath at 90°C for 8 or 9 or 10 hours until the solution is clear and transparent, and the black selenium powder disappears completely. The heat source stops heating. After naturally cooling to room temperature (20-25°C), transfer it to a 100mL volumetric flask and dilute it to the mark with deionized water, which is a 0.30mol/L sodium selenosulfate solution. The reaction equation is as follows:

Se+ _{Na2SO3 = Na2SeSO3 ;}

2. Take 200 mL of anaerobic deionized water, add 2.5 mL of 0.10 mol/L cadmium chloride solution, 6 mL of 0.10 mol/L mercaptopropionic acid solution, and adjust the pH value to 8 with 5 mol/L sodium hydroxide solution. Or 9 or 10, add 0.166mL0.30mol/L sodium selenosulfate solution after 30min of nitrogen gas, and continue to ventilate for 5min;

3. The above mixed liquid was divided into polytetrafluoroethylene digestion tanks with 50ml per tank, and microwaved at 140°C for 20-25min to prepare CdSeS quantum dots with a concentration of 1.25mmol/L, cadmium chloride, selenium The molar ratios of sodium sulfate and mercaptopropionic acid are 1:0.2:2.4 respectively, and the fluorescence quantum yield of the obtained quantum dots is 20.3-24.6%.

Other implementation steps are the same as in Example 1.

Claims (1)

1. A water-phase microwave preparation method of CdSeS quantum dots, the steps are: A. Reaction of selenium powder and sodium sulfite to prepare sodium selenosulfate solution: Weigh 0.7890~2.3670g selenium powder and 2.5208~7.5624g sodium sulfite respectively in a 250mL three-necked flask, add 80mL deionized water to it, and reflux the water bath for 8~10h to The solution turns into light yellow transparent liquid, stop heating, naturally cool to normal temperature, then transfer to a 100mL volumetric flask and dilute to the mark with deionized water, it is 0.10～0.30mol/L sodium selenosulfate solution, the reaction equation is as follows: Se+ _{Na2SO3 = Na2SeSO3 ;} B. Weigh 0.2284-2.2835g of cadmium chloride crystals, dissolve and set the volume to 100mL with deionized water to obtain 0.01-0.10mol/L cadmium chloride solution; C. Weigh 0.1061-1.0614g of mercaptopropionic acid, dilute to 100mL with deionized water to obtain 0.01-0.10mol/L mercaptopropionic acid solution; D. Take 95~200mL of deionized water, add 0.520~31.2mL of 0.01~0.10mol/L cadmium chloride solution and 0.884~74.88mL of 0.01~0.10mol/L mercaptopropionic acid solution in turn, and use 1~ 5mol/L sodium hydroxide solution to adjust the pH value to 8-10, add 0.104mL0.10～0.30mol/L sodium selenosulfate solution after aeration of nitrogen gas for 10-30 minutes, and continue aeration reaction for 4-6 minutes; E. The mixed solution in step D is divided into polytetrafluoroethylene digestion tanks with 50ml per tank, and microwaved at 120-150°C for 20-40min to obtain water-soluble CdSeS quantum dots, sodium selenosulfate, The molar ratios of cadmium chloride and mercaptopropionic acid are 1/5~1/10:1:1.7~2.4 respectively; F. Add isopropanol to purify and freeze-dry to obtain CdSeS quantum dot solid powder.