1. A synthesis method of cadmium telluride quantum dots is characterized by comprising the following steps:

s1, preparing a potassium telluride hydride solution, placing 0.1276g of tellurium powder and 0.1618g of potassium borohydride into a 10mL colorimetric tube, introducing nitrogen into the colorimetric tube to remove air in the colorimetric tube, then adding 5mL of secondary water into the colorimetric tube, reacting the mixed solution in the colorimetric tube at the temperature of 40 ℃ under the condition of introducing nitrogen into the colorimetric tube until the solution is transparent purple, preparing the potassium telluride hydride solution, and sealing and storing the prepared potassium telluride hydride solution in a refrigerator at 4 ℃ for later use;

s2, synthesizing cadmium telluride quantum dots CdTeQDs, taking a 250mL three-necked bottle, and sequentially adding 1mL of cadmium telluride quantum dots CdTeQDs with the concentration of 0.1 mol.L^-1CdCl of (2)₂The solution, 180mL of deionized water and thioglycolic acid (TGA) were thoroughly mixed in a three-necked flask, followed by 1.0 mol. L^-1The pH value of the solution in the three-neck bottle is adjusted to 8.6-10.2 by NaOH, nitrogen is introduced into the three-neck bottle to remove oxygen for 30min, then 0.125-0.750mL of newly prepared potassium telluride hydride solution is rapidly added into the three-neck bottle, the three-neck bottle is heated and refluxed at 100 ℃ for 3.0-5.5 hours to prepare cadmium telluride quantum dot CdTeQDs solution which is prepared into 5.62 multiplied by 10^-4And (3) mol/L stock solution of cadmium telluride quantum dots CdTeQDs.

2. The method for synthesizing cadmium telluride quantum dot as claimed in claim 1 wherein the volume of thioglycolic acid (TGA) in step S2 is 13.16 μ L.

3. The method for synthesizing cadmium telluride quantum dot as claimed in claim 1, wherein 1.0 mol-L is adopted in step S2^-1NaOH adjusted the pH of the solution in the three-necked flask to 9.4.

4. The method for synthesizing cadmium telluride quantum dots as claimed in claim 1, wherein 0.25mL of newly prepared potassium telluride hydride solution is rapidly added into the three-necked flask in step S2.

5. The method for synthesizing cadmium telluride quantum dot as claimed in claim 1, wherein the heating reflux time in step S2 is 3.0 hours.

6. The application of the synthesis method of cadmium telluride quantum dots as in any one of claims 1 to 5, wherein the prepared cadmium telluride quantum dot CdTeQDs solution is applied to Cu in water²⁺The measurement of (1).

7. Use of a method of synthesis of cadmium telluride quantum dots as claimed in claim 6 wherein the Cu is specified²⁺The measuring method comprises the following steps: in a 10mL cuvetteCadmium telluride quantum dot CdTeQDs solution and copper ion solution are respectively added into the colorimetric tube, the solution in the colorimetric tube is subjected to constant volume to 5mL by using Tris-HCl reagent with the pH value of 8.2, the colorimetric tube is uniformly mixed on a vortex mixer, and after the solution in the colorimetric tube reacts for 10min, a fluorescence spectrophotometer is adopted to perform fluorescence detection on the colorimetric tube.

Background

Quantum Dots (Quantum Dots), also known as Semiconductor nanocrystals, are luminescent nanoparticles. Compared with the traditional organic fluorescent dye, the quantum dot has excellent optical characteristics such as high fluorescence quantum yield, good photochemical stability and the like, and is a fluorescent probe with great development potential.

Nowadays, quantum dots are used as fluorescent probes for research and application, and become research focus points, and the development of quantum dots in various research fields, such as chemical and biological analysis, medical diagnosis and the like, is rapidly promoted. In recent years, the water-phase quantum dots have wide application prospects in the fields of genomics, cell biology, proteomics, drug screening, targeting researches and the like as fluorescent markers due to simple synthesis method, low cost and good biocompatibility.

In the prior art, a cadmium telluride quantum dot synthesis method exists, a method for preparing a cadmium telluride quantum dot by a water phase synthesis method exists, and a step of preparing a tellurium source (a potassium telluride hydride solution) usually requires reaction of tellurium powder and sodium borohydride for more than 3 hours at room temperature, so that the time consumption is long. The traditional aqueous phase synthesis method is carried out under the condition of normal pressure reflux, the reaction time is long, the obtained quantum dot has large half-peak width and low quantum yield; meanwhile, the stability and the fluorescence performance of the synthesized cadmium telluride quantum dot are weaker.

Therefore, the present invention is directed to a method for synthesizing cadmium telluride quantum dots, so as to solve the above problems.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a synthesis method and application of cadmium telluride quantum dots, wherein thioglycolic acid is used as a modifier to synthesize the cadmium telluride quantum dots, and synthesis conditions such as the addition of a potassium telluride hydride precursor, the pH of a solution, the addition of the thioglycolic acid, heating reflux time and the like are optimized in the synthesis process, so that the synthesized cadmium telluride quantum dots have good stability and high fluorescence quantum yield; meanwhile, the synthesis reaction conditions are mild and easy to control, the reaction time is short, and high-quality cadmium telluride quantum dots are convenient to synthesize; meanwhile, the detection sensitivity of the synthesized cadmium telluride quantum dot for copper ions in water is high.

The technical purpose of the invention is realized by the following technical scheme: a synthesis method of cadmium telluride quantum dots specifically comprises the following steps:

s1, preparing a potassium telluride hydride solution, placing 0.1276g of tellurium powder and 0.1618g of potassium borohydride into a 10mL colorimetric tube, introducing nitrogen into the colorimetric tube to remove air in the colorimetric tube, then adding 5mL of secondary water into the colorimetric tube, reacting the mixed solution in the colorimetric tube at the temperature of 40 ℃ under the condition of introducing nitrogen into the colorimetric tube until the solution is transparent purple, preparing the potassium telluride hydride solution, and sealing and storing the prepared potassium telluride hydride solution in a refrigerator at 4 ℃ for later use;

s2, synthesizing cadmium telluride quantum dots CdTeQDs, taking a 250mL three-necked bottle, and sequentially adding 1mL of cadmium telluride quantum dots CdTeQDs with the concentration of 0.1 mol.L^-1CdCl of (2)₂The solution, 180mL of deionized water and thioglycolic acid (TGA) were thoroughly mixed in a three-necked flask, followed by 1.0 mol. L^-1The pH value of the solution in the three-neck bottle is adjusted to 8.6-10.2 by NaOH, nitrogen is introduced into the three-neck bottle to remove oxygen for 30min, then 0.125-0.750mL of newly prepared potassium telluride hydride solution is rapidly added into the three-neck bottle, the three-neck bottle is heated and refluxed at 100 ℃ for 3.0-5.5 hours to prepare cadmium telluride quantum dot CdTeQDs solution which is prepared into 5.62 multiplied by 10^-4And (3) mol/L stock solution of cadmium telluride quantum dots CdTeQDs.

Further, the volume of thioglycolic acid (TGA) described in step S2 was 13.16. mu.L.

Further, 1.0 mol. L is used in step S2^-1NaOH adjusted the pH of the solution in the three-necked flask to 9.4.

Further, 0.25mL of the freshly prepared potassium telluride solution was quickly added to the three-necked flask in step S2.

Further, the heating reflux time described in step S2 was 3.0 hours.

The invention also provides application of the synthesis method of the cadmium telluride quantum dots, and the prepared cadmium telluride quantum dot CdTeQDs solution is applied to Cu in water²⁺The measurement of (1).

Go toStep (2) specifically measuring Cu²⁺The method comprises the following steps: cadmium telluride quantum dot CdTeQDs solution and copper ion solution are respectively added into a 10mL colorimetric tube, the solution in the colorimetric tube is subjected to constant volume to 5mL by using a Tris-HCl reagent with the pH value of 8.2, the colorimetric tube is uniformly mixed on a vortex mixer, and after the solution in the colorimetric tube reacts for 10min, a fluorescence spectrophotometer is adopted to perform fluorescence detection on the colorimetric tube.

In conclusion, the invention has the following beneficial effects:

1. according to the invention, the cadmium telluride quantum dots are synthesized by using thioglycolic acid as a modifier, and the synthesis conditions such as the addition amount of a potassium telluride hydride precursor, the pH of a solution, the addition amount of thioglycolic acid, heating reflux time and the like are optimized in the synthesis process, so that the synthesized cadmium telluride quantum dots have good stability and high fluorescence quantum yield;

2. the synthesis method has the advantages of mild and easily controlled synthesis reaction conditions, short reaction time and convenience in synthesizing high-quality cadmium telluride quantum dots;

3. the cadmium telluride quantum dot synthesized by the method is used for detecting copper ions in water and has high sensitivity.

Drawings

FIG. 1 is a flow chart in an embodiment of the invention;

FIG. 2 is a graph of data showing the effect of KHTe addition on CdTe quantum dot fluorescence intensity in the present invention;

FIG. 3 is a graph of data showing the effect of pH on the fluorescence intensity of CdTe QDs in an embodiment of the present invention;

FIG. 4 is a graph of data showing the effect of TGA addition on CdTe QDs fluorescence intensity in an embodiment of the invention;

FIG. 5 is a graph showing the absorption spectrum of RhB and the fluorescence spectrum of CdTe in the example of the present invention (where λ ex (CdTe) ═ 365 nm; λ (RhB) ═ 553 nm);

FIG. 6 is a graph of the fluorescence spectrum of CdTe in different concentrations of RhB solution in accordance with embodiments of the invention;

FIG. 7 is a graph showing the fluorescence spectra of RhB in CdTeQDs solutions of different concentrations in the examples of the present invention;

FIG. 8 shows different pH values for CdTe-RhB and Cu in the examples of the present invention²⁺Line graph of influence of reaction System (wherein, C_CdTe＝0.28×10^-4mol/L；C_RhB＝0.47×10^-5mol/L；C_Cu ²⁺＝4.0×10^-6mol/L)；

FIG. 9 is a graph of reaction time vs. CdTe-RhB and Cu for an example of the invention²⁺The influence line graph of the reaction system;

FIG. 10 shows Cu in an example of the present invention²⁺A spectrogram of fluorescence quenching of CdTe quantum dots;

FIG. 11 shows Cu in an example of the present invention²⁺Measured working curve (wherein, C_CdTe＝0.28×10^-4mol/L；C_RhB＝0.47×10^-5mol/L；C_Cu ²⁺＝4.0×10^-6mol/L)。

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example (b): a synthesis method of cadmium telluride quantum dots is shown in FIG. 1, and specifically comprises the following steps:

s1, preparing a potassium telluride hydride solution, placing 0.1276g of tellurium powder and 0.1618g of potassium borohydride into a 10mL colorimetric tube, introducing nitrogen into the colorimetric tube to remove air in the colorimetric tube, then adding 5mL of secondary water into the colorimetric tube, reacting the mixed solution in the colorimetric tube at the temperature of 40 ℃ under the condition of introducing nitrogen into the colorimetric tube until the solution is transparent purple, preparing the potassium telluride hydride solution, and sealing and storing the prepared potassium telluride hydride solution in a refrigerator at 4 ℃ for later use.

S2, synthesizing cadmium telluride quantum dots CdTeQDs, taking a 250mL three-necked bottle, and sequentially adding 1mL of cadmium telluride quantum dots CdTeQDs with the concentration of 0.1 mol.L^-1CdCl of (2)₂The solution, 180mL of deionized water and thioglycolic acid (TGA) were thoroughly mixed in a three-necked flask, followed by 1.0 mol. L^-1The pH of the solution in the three-necked flask is adjusted to 8.6 to 10.2 by NaOH, and nitrogen is introduced into the three-necked flask to control the pHDeoxidizing for 30min, then quickly adding 0.125-0.750mL of newly prepared potassium telluride solution into the three-necked flask, and heating and refluxing the three-necked flask at the temperature of 100 ℃, wherein the reaction equation is as follows: KHTe + CdCl₂→ CdTe + HCl + KCl, and preparing into 5.62 × 10 CdTeQDs solution after heating and refluxing for 3.0-5.5 hr^-4And (3) mol/L stock solution of cadmium telluride quantum dots CdTeQDs.

Wherein the volume of the thioglycolic acid (TGA) described in step S2 is 13.16. mu.L.

Wherein, 1.0 mol. L is adopted in step S2^-1NaOH adjusted the pH of the solution in the three-necked flask to 9.4.

In step S2, 0.25mL of newly prepared potassium tellurohydride solution was quickly added to the three-necked flask.

Wherein the heating reflux time described in step S2 was 3.0 hours.

The application of the synthesis method of the cadmium telluride quantum dot provided by the invention is to apply the prepared cadmium telluride quantum dot CdTeQDs solution to Cu in water²⁺The measurement of (1).

Specific measurement of Cu²⁺The method comprises the following steps: cadmium telluride quantum dot CdTeQDs solution and copper ion solution are respectively added into a 10mL colorimetric tube, the solution in the colorimetric tube is subjected to constant volume to 5mL by using a Tris-HCl reagent with the pH value of 8.2, the colorimetric tube is uniformly mixed on a vortex mixer, and after the solution in the colorimetric tube reacts for 10min, a fluorescence spectrophotometer is adopted to perform fluorescence detection on the colorimetric tube.

In the embodiment, the cadmium telluride quantum dot is synthesized by using thioglycolic acid as a modifier, and the synthesis conditions such as the addition amount of a potassium telluride hydride precursor, the pH of a solution, the addition amount of thioglycolic acid, heating reflux time and the like are optimized in the synthesis process, so that the synthesized cadmium telluride quantum dot has good stability and high fluorescence quantum yield. Meanwhile, the synthesis reaction conditions are mild and easy to control, the reaction time is short, and the high-quality cadmium telluride quantum dots are convenient to synthesize. And the cadmium telluride quantum dot synthesized by the method is used for detecting copper ions in water, and the detection sensitivity is high.

The present embodiment will be further described below by way of experiments and experimental results.

Optimizing synthesis conditions of cadmium telluride quantum dots

1. Verifying the influence of the addition of the precursor on the fluorescence intensity of CdTe QDs:

adding the potassium telluride precursor according to the following steps: 0.125 mL, 0.25mL, 0.375 mL, 0.5 mL, 0.625 mL, 0.75mL, the experimental method was performed according to step S2, the three-necked flask was heated, refluxed and boiled at 100 ℃ and 10mL of the sample solution to be tested was taken every 0.5h, so as to examine the influence of the addition of the precursor potassium telluride hydride on the fluorescence intensity of the cadmium telluride quantum dots CdTeQDs. As shown in FIG. 3-1, in fixing Cd²⁺Comparing different Cd under the condition of constant concentration²⁺And Te^2-Influence of molar ratio on the preparation of CdTe quantum dots. Cd [ Cd ]²⁺And Te^2-The influence of the concentration on the fluorescence intensity of the CdTeQDs is obvious, and the core quantity of the CdTe depends on the Cd according to the Gibbs-Thompson equation of the classical core theory²⁺And Te^2-And (4) concentration. But too much Cd²⁺And Te^2-May cause ineffective CdTe quantum dot surface passivation defect to cause the decrease of fluorescence intensity. According to fig. 2, when the amount of the potassium telluride hydride precursor is 0.25mL, the fluorescence yield of the quantum dots is the largest, and therefore, the CdTeQDs are synthesized by using the amount, so that the cadmium telluride quantum dots with the largest fluorescence yield can be synthesized conveniently.

2. Effect of pH on the fluorescence intensity of CdTe QDs

CdTe quantum dot using mercaptoacetic acid (TGA) as stabilizer needs to control the pH value of the system within a certain range so as to ensure Cd²⁺And Te^2-And formation of TGA coordination compounds. And under the conditions that the pH value of the system is 8.6, 9.0, 9.4, 9.8 and 10.2 respectively, the influence of the pH value on the CdTe quantum dots is examined. As can be seen from FIG. 3, the CdTeQDs have the strongest fluorescence intensity at pH 9.4. The reason for this may be that the higher the pH, the greater the degree of dissociation of-SH in TGA, and Cd²⁺The more readily complexes with TGA are formed.

3. Effect of TGA addition on CdTeQDs fluorescence intensity

As can be seen from FIG. 4, the fluorescence intensity of the CdTe quantum dot gradually increases with the increase of the TGA amount, and when the TGA amount reaches 13.1Fluorescence intensity was maximal at 6. mu.L and decreased at increasing TGA, probably due to Cd²⁺Is wrapped by a large amount of TGA to block Cd²⁺And Te^2-The combination of (3) results in a decrease in the growth rate of the quantum dots.

Fluorescence resonance energy transfer between CdTe and RhB

Efficient FRET occurs and must first be such that the emission spectrum of CdTe overlaps with the absorption spectrum of the energy acceptor. Secondly, the distance between the energy donor and acceptor is close enough, and as can be seen from FIG. 5, the characteristic absorption peak of RhB is at 553 nm. The fluorescence emission peak of CdTe is at 540nm, and there is a large overlap between the emission spectrum of CdTe and the absorption spectrum of RhB.

The concentration of the quantum dots is fixed, and the concentration of rhodamine B is changed, so that the fluorescence spectrum shown in figure 6 is obtained. With the increase of the concentration of rhodamine B, the fluorescence intensity of the quantum dots is continuously reduced, and the fluorescence intensity of the rhodamine B is continuously enhanced. And the fluorescence peak position of the quantum dot has slight blue shift, which is mainly caused by the change of the microenvironment around the quantum dot in rhodamine B solutions with different concentrations. As the donor-acceptor is in the nanometer order of magnitude, the quantum dots also have huge specific surface area and are easy to agglomerate. In the alkaline range, carboxyl of rhodamine B is completely ionized and mainly takes negative charge, at the moment, the mixed solution is not turbid, and the balance of various force effects between the quantum dots and the rhodamine B can be deduced. Along with the increase of the concentration, rhodamine B molecules around the quantum dots are more and more, the probability of fluorescence resonance energy transfer is enhanced, and the comprehensive expression is that the fluorescence intensity of the quantum dots is reduced, and the fluorescence of the rhodamine B is enhanced. The fluorescence peak position of rhodamine B also has a little red shift, which is consistent with the phenomenon that the peak position red shift is along with the increase of the concentration when rhodamine B exists alone, so that the evidence that the fluorescence resonance energy transfer phenomenon exists in the solution is not sufficient from figure 6.

For this purpose, we fixed the concentration of rhodamine B and changed the concentration of quantum dots, as shown in fig. 7. We have found that the peak positions of the quantum dots do not move anymore, mainly because the change in the microenvironment around the quantum dots is very slight and not enough to disturb the movement of their peak positions. The fluorescence intensity of the quantum dots and the rhodamine B is increased simultaneously with the increase of the concentration of the quantum dots, but the concentration of the rhodamine B is not increased, which fully indicates that fluorescence resonance energy transfer exists in the mixed solution.

Third, cadmium telluride quantum dot is used for measuring copper ions

1. Measurement of Cu²⁺Condition optimization of

As shown in FIG. 8, the effect of Tris-HCl buffer solution with pH range of 7.5-8.6 on the experimental system is verified, and the results show that CdTe-RhB and Cu²⁺The reaction of (a) is more sensitive under more basic conditions. When the pH is 8.2,. DELTA.F ═ F₀The difference of-F is maximal.

The influence of the reaction time of 5, 10, 15, 20, 30, 40 and 60min on the experimental system is respectively tested. As can be seen from FIG. 9, 10min is the optimum reaction time for this system.

2. Analytical results of the Cu2+ assay

Under the above-mentioned optimum conditions, for Cu²⁺And (4) carrying out measurement. Cu²⁺For the fluorescence quenching spectrogram of CdTe quantum dot, as shown in FIG. 10, Cu is added²⁺Quenching ratio F/F before and after₀And C_Cu2+The good linear relationship is shown in FIG. 11, and the equation is: F/F₀0.463C +0.046 (correlation coefficient R: 0.9935), and the detection range is 5 × 10^-7～2.0×10^-6mol/L。

3. Coexisting ion pair Cu²⁺Interference of measurement

As shown in Table 1 below, Na when the relative error is. + -. 10%⁺(2000 times), K⁺(2000 times), Mg²⁺(1000 times), Ca²⁺(1000 times), Zn²⁺(10 times), Al³⁺(10 times), Pb²⁺(1 times) Fe³⁺(1-fold) had substantially no effect on the assay. Wherein Zn is²⁺、Al³⁺Greater interference with Fe³⁺Can be prepared by adding F^-Is masked.

TABLE 1 Effect of coexisting ions on fluorescence intensity

The experimental results are as follows: the experiment synthesizes cadmium telluride quantum dots by using thioglycollic acid as a modifier, and the experiment shows that the pH is 9.4, and the Cd²⁺And Te^2-In a molar ratio of 1:0.5, Cd²⁺The molar ratio of the cadmium telluride to the TGA is 1:2, and the reaction time is 3h, which is the optimal condition for synthesizing the cadmium telluride quantum dots. Meanwhile, fluorescence resonance energy transfer between the cadmium telluride quantum dots and the rhodamine is carried out on the basis of not adding any surfactant, and the synthesized cadmium telluride quantum dots are used for measuring copper ions in the water body, and experiments show that the concentration of the copper ions is 5 multiplied by 10^-7～2.0×10^-6When mol/L is in between, F/F₀And C_Cu ²⁺With a good linear relationship. The detection method is simple and rapid, and has good selectivity.

The above is an embodiment of the present invention. The embodiments and specific parameters in the embodiments are only for the purpose of clearly illustrating the verification process of the invention and are not intended to limit the scope of the invention, which is defined by the claims, and all equivalent structural changes made by using the contents of the specification and the drawings of the present invention should be covered by the scope of the present invention.