CN111187614B - Silicon quantum dot/cyclodextrin copper fluorescent cluster and preparation method thereof and application of fluorescent cluster in detection of sulfhydryl compound - Google Patents
Silicon quantum dot/cyclodextrin copper fluorescent cluster and preparation method thereof and application of fluorescent cluster in detection of sulfhydryl compound Download PDFInfo
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Abstract
The invention discloses a silicon quantum dot/cyclodextrin copper fluorescent cluster and a preparation method thereof and application thereof in detecting sulfhydryl compound 2 ) n Then with beta-cyclodextrin copper Cu 2 -beta-CD coordinated self-assembly to form a fluorescent cluster SiQDs- (NH) 2 /Cu 2 ‑β‑CD) n 。SiQDs‑(NH 2 /Cu 2 ‑β‑CD) n After encountering the sulfhydryl compound, the fluorescence intensity is obviously enhanced, and the increment of the fluorescence intensity is in a proportional relation with the content of the sulfhydryl compound. Therefore, based on the fluorescence cluster SiQDs- (NH) 2 /Cu 2 ‑β‑CD) n The fluorescence sensor for measuring the sulfhydryl compound can be established, has wider linear range and lower detection limit, can realize the specificity detection of the sulfhydryl compound, and other common ions and compounds hardly generate interference.
Description
Technical Field
The invention belongs to the technical field of analysis and detection, and particularly relates to a preparation method of a silicon quantum dot/cyclodextrin copper fluorescent cluster and a method for detecting a sulfhydryl compound by using the fluorescent cluster.
Background
Cysteine is an important sulfhydryl amino acid in the human body and has the ability to form disulfide bonds, which contribute to protein structure construction and protein folding. In the food industry, cysteine is a good fruit preservative and food additive. The cysteine derivative glutathione is also a sulfhydryl compound, can eliminate free radicals of a human body, can improve the immunity of the human body, maintains health and resists aging. Therefore, the method has practical significance for accurately measuring the content of the cysteine sulfhydryl active substance.
For the detection of the sulfhydryl compound, large-scale instruments such as high performance liquid chromatography, liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry and the like are often required, and the measurement is expensive and time-consuming. The fluorescence detection method is convenient to operate and has high sensitivity. At present, a fluorescence analysis method is used for detecting cysteine, wang and the like prepare phosphorus-nitrogen co-doped carbon quantum dots (Sensors and activators B-chemical,2018, 1627-1634), and after the phosphorus-nitrogen co-doped carbon quantum dots are combined with gold nanorods, fluorescence quenching is carried out, so that the content of Fe 3+ And H 2 O 2 The generated hydroxyl free radicals can induce the gold nanorods to corrode, so that the fluorescence of the carbon quantum dots is recovered, the etching progress can be inhibited by adding cysteine, and further the quantitative detection of the cysteine is realized. Borghei et al (Journal of Fluorescence,2017, 27 (2): 529-536) utilize Cys-CuNCs clusters formed by strong action force of sulfydryl and metal, and the Fluorescence intensity of the clusters is closely related to the concentration of cysteine, thereby realizing quantitative detection of cysteine; however, cysteine exhibits increased fluorescence at a low concentration, but exhibits decreased fluorescence at a high concentration, and therefore cannot be detected continuously, and is limited in application. "determination of acetylcysteine based on calcein-copper (II) fluorescence system", yang Xiaogong utilizes divalent copper ion to coordinate with calcein, so that fluorescence intensity of system is reduced, mercapto group and Cu are added 2+ The affinity of the complex is strong, and copper ions can be abstracted from the complex of the calcein-copper (II) to free the calcein, so that the fluorescence intensity of the free calcein can be recovered, and the concentration of acetylcysteine can be detected. Currently using copper (II) chlorophyllWhen the sulfhydryl compound is detected by a complex or other copper ion complex method, copper ions can directly interfere with a test result, in addition, the copper ions can also form a complex with other amino acids, and other amino acids can also interfere with the detection result of the sulfhydryl compound, so that the practical use of the sulfhydryl compound is limited.
In the fluorescence analysis method, a fluorescent probe plays a significant role. The common organic fluorescent probe has low brightness or poor light stability, the sensitivity and the stability of the fluorescent sensor are reduced, and the quantum dots of the semiconductor silicon have the characteristics of high luminous efficiency and excellent stability, so that the high-performance fluorescent sensor becomes possible. The silicon quantum dots/cyclodextrin copper are self-assembled to form the fluorescent clusters, and the fluorescence intensity of the fluorescent clusters is enhanced along with the increase of the content of the sulfhydryl compound, so that the content of the sulfhydryl compound is efficiently, conveniently and quantitatively determined.
Disclosure of Invention
The invention aims to solve the technical problem of providing a preparation method and application of a silicon quantum dot/cyclodextrin copper fluorescent cluster, wherein silicon quantum dots SiQDs- (NH) with amino-modified surfaces are utilized 2 ) n Upper amino group and beta-cyclodextrin copper Cu 2 Coordination of copper on the-beta-CD bridge, self-assembly to form SiQDs- (NH) 2 ) n /Cu 2 - β -CD fluorescence cluster, and quantitatively determining the water-soluble thiol compound using the change in fluorescence intensity of the fluorescence cluster. The method has the advantages of low cost, simple operation, environmental friendliness and wider detection limit.
The basis of the invention is that the sulfhydryl compound is added into the silicon quantum dot solution, and the fluorescence intensity of the sulfhydryl compound is consistent with that of the initial silicon quantum dot; and SiQDs- (NH) 2 ) n And Cu 2 After the fluorescent cluster is formed by the beta-CD, the sulfhydryl compound is added, the fluorescence intensity is enhanced, and the increment of the fluorescence intensity is proportional to the content of the sulfhydryl compound.
The invention provides SiQDs- (NH) 2 ) n /Cu 2 The preparation method of the-beta-CD fluorescent cluster comprises the following steps:
(1) Preparation of silicon quantum dots SiQDs- (NH) containing polyamino groups 2 ) n
Adding a proper amount of KH-550 and deionized water into a flask, magnetically stirring for hydrolysis, adding an ascorbic acid solution, continuously stirring for 30min, transferring into a polytetrafluoroethylene-lined high-pressure hydrothermal kettle, and putting into a muffle furnace at 120-180 ℃ for heat preservation for 12-24h;
(2) Preparation of beta-Cyclodextrin copper Cu 2 -β-CD
Preparing 10mL of mixed solution of sodium hydroxide and beta-cyclodextrin, adding 15mL of copper sulfate solution into the mixed solution to quickly form copper hydroxide blue precipitate, stirring the mixed solution at room temperature for 12 hours, filtering the mixed solution to remove the copper hydroxide precipitate, adding ethanol into filtrate to gradually form blue precipitate in the solution, standing the solution, filtering the solution, washing the solid with a small amount of ethanol, and drying the solid at 40 ℃ to obtain blue solid powder, namely the product;
(3)SiQDs-(NH 2 ) n /Cu 2 preparation of-beta-CD fluorescent clusters
SiQDs- (NH) at a concentration of 20g/L 2 ) n And 1X 10 -3 mol/L of Cu 2 -beta-CD is fully mixed according to the volume ratio of 1.1-1 2 ) n /Cu 2 -a solution of β -CD fluorescent clusters.
Preferably, in the step (1), the hydrolysis volume ratio of 950g/L KH550 liquid to deionized water is 2-18 to 16, the ratio of the total mixing volume to the ascorbic acid solution volume is 4:1, and the concentration of ascorbic acid is 0.05 to 0.1mol/L.
Preferably, the concentration of the sodium hydroxide in the mixed solution in the step (2) is 0.2-0.5mol/L, and the concentration of the beta-cyclodextrin is 0.01-0.02mol/L; the concentration of copper sulfate is 0.02-0.04mol/L.
SiQDs- (NH) mentioned above 2 ) n /Cu 2 the-beta-CD fluorescent cluster can be used for quantitative detection of sulfhydryl compounds, and the maximum excitation wavelength of the synthesized silicon quantum dot is preferably 360nm.
The application comprises the following steps:
in the above SiQDs- (NH) 2 ) n /Cu 2 Adding sulfhydryl compound solution (0-240 μ M) with different concentrations into the-beta-CD fluorescent cluster solution, keeping the total volume of the solution consistent, standing for 10-30min, and measuringFluorescence emission spectra of the systems. The concentration of the sulfhydryl compound is used as the abscissa, and the fluorescence enhancement rate is 10 3 And fitting a linear equation by taking the multiple as a vertical coordinate, and calculating the detection limit.
Preferably, the thiol compound is one of L-cysteine (L-Cys), D-cysteine (D-Cys) or Glutathione (GSH).
According to the technical scheme, the method comprises the following steps: firstly, KH-550 is taken as a raw material, and an amino modified silicon quantum dot SiQDs- (NH) is prepared by a hydrothermal method 2 ) n (ii) a Then self-assembling to form SiQDs- (NH) by utilizing the coordination of lone pair electrons on amino nitrogen and copper on a beta-cyclodextrin copper bridge 2 ) n /Cu 2 - β -CD fluorescent cluster. In the application process of the fluorescent cluster, the mercapto group on the mercapto compound has stronger coordination capacity with beta-cyclodextrin copper, so that the fluorescent cluster is applied to SiQDs- (NH) 2 ) n /Cu 2 After a sulfhydryl compound is added into a beta-CD fluorescent cluster solution, the original silicon quantum dot/cyclodextrin copper fluorescent cluster is disintegrated to release free SiQDs- (NH) 2 ) n Thereby causing the solution to increase in fluorescence. The increase in fluorescence intensity is proportional to the amount of the thiol compound added, and thus, fluorescence detection of the thiol compound in solution can be achieved.
The beneficial effects of the invention are:
(1) The invention provides a method for quantitatively determining a water-soluble sulfhydryl compound by a fluorescence method, which has the advantages of reliable and stable data, simple and convenient method operation, easy preparation and low cost, and is an environment-friendly determination method.
(2) The fluorescence method provided by the invention realizes the specific detection of the sulfhydryl compound, and other common ions and compounds hardly generate interference.
(3) The concentration range of the sulfhydryl compound for determination provided by the invention is 0-240 mu M, and the detection limit is 0.48 mu M.
Drawings
FIG. 1 is a graph showing the relative fluorescence intensity of fluorescent clusters at different concentrations of L-cysteine;
FIG. 2 is a linear relationship between the fluorescence enhancement rate and L-cysteine at different concentrations;
FIG. 3 is a graph showing the relative fluorescence intensity of fluorescent clusters at different concentrations of D-cysteine;
FIG. 4 is a linear relationship between D-cysteine and fluorescence enhancement rate at different concentrations;
FIG. 5 is a graph showing the relative fluorescence intensity of fluorescent clusters at different concentrations of glutathione;
FIG. 6 is a linear relationship between glutathione at different concentrations and fluorescence enhancement rate;
FIG. 7 is a graph showing the measurement of interference by a coexisting substance (300. Mu.M for both L-Cys and an unidentified interfering substance);
silicon quantum dot and Cu under condition of pH of figure 8 =6 2+ 、Cu 2+ And fluorescence spectrum in the presence of L-Cys;
figure 9pH =8 condition, silicon quantum dot and Cu 2+ 、Cu 2+ And fluorescence spectrum in the presence of L-Cys;
FIG. 10 shows SiQDs- (NH) 2 ) n /Cu 2 -AFM image of β -CD fluorescence cluster;
FIG. 11 shows SiQDs- (NH) 2 ) n AFM imaging of quantum dots.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It will be understood that these examples are intended to illustrate the invention and are not intended to limit the scope of the invention in any way.
Example 1
(1) Preparation of silicon quantum dots SiQDs- (NH) containing polyamino groups 2 ) n
Adding 950g/L KH-550 and deionized water into a flask, wherein the volume ratio is 2, and is 20mL in total, magnetically stirring for hydrolysis, adding 5mL of ascorbic acid solution with the concentration of 0.05mol/L, continuously stirring for 30min, transferring into a polytetrafluoroethylene-lined high-pressure hydrothermal kettle, and placing into a muffle furnace at 120 ℃ for heat preservation for 24h;
(2) Preparation of beta-Cyclodextrin copper Cu 2 -β-CD
Preparing 10mL of mixed solution of sodium hydroxide and beta-cyclodextrin, wherein the concentration of the sodium hydroxide in the mixed solution is 0.2mol/L, and the concentration of the beta-cyclodextrin is 0.01mol/L; then adding 15mL of 0.02mol/L copper sulfate solution into the mixture to quickly form copper hydroxide blue precipitate, stirring the mixture for 12 hours at room temperature, filtering the mixture to remove the copper hydroxide precipitate, adding ethanol into filtrate to gradually generate blue precipitate in the solution, standing the solution, filtering the solution, washing the solid with a small amount of ethanol, and drying the solid at the temperature of 40 ℃ to obtain blue solid powder, namely a product;
(3)SiQDs-(NH 2 ) n /Cu 2 preparation of-beta-CD fluorescent clusters
SiQDs- (NH) at a concentration of 20g/L (Si content) 2 ) n And 1X 10 -3 mol/L of Cu 2 Sufficiently mixing beta-CD according to the volume ratio of 1.1, and carrying out self-assembly for 10min, wherein the SiQDs- (NH) is obtained after the self-assembly is finished 2 ) n /Cu 2 -a solution of β -CD fluorescent clusters.
Example 2
(1) Preparation of silicon quantum dots SiQDs- (NH) containing polyamino groups 2 ) n
Adding KH-550 and deionized water into a flask, wherein the volume ratio is 3;
(2) Preparation of beta-Cyclodextrin copper Cu 2 -β-CD
Preparing 10mL of mixed solution of sodium hydroxide and beta-cyclodextrin, wherein the concentration of the sodium hydroxide is 0.35mol/L, and the concentration of the beta-cyclodextrin is 0.015mol/L; adding 15mL of 0.03mol/L copper sulfate solution into the solution to quickly form copper hydroxide blue precipitate, stirring the solution at room temperature for 12 hours, filtering the solution to remove the copper hydroxide precipitate, adding ethanol into the filtrate to gradually form blue precipitate in the solution, standing the solution, filtering the solution, washing the solid with a small amount of ethanol, and drying the solid at the temperature of 40 ℃ to obtain blue solid powder, namely a product;
(3)SiQDs-(NH 2 ) n /Cu 2 preparation of-beta-CD fluorescent clusters
SiQDs- (NH) at a concentration of 20g/L 2 ) n And 1X 10 -3 mol/L of Cu 2 Sufficiently mixing beta-CD according to the volume ratio of 1.2 for self-assembly for 20min, and obtaining SiQDs- (NH) after the self-assembly is finished 2 ) n /Cu 2 -a solution of β -CD fluorescent clusters.
Example 3
(1) Preparation of silicon quantum dots containing polyamino groups SiQDs- (NH) 2 ) n
Adding KH-550 and deionized water into a flask, wherein the volume ratio is 4;
(2) Preparation of beta-Cyclodextrin copper Cu 2 -β-CD
Preparing 10mL of mixed solution of sodium hydroxide and beta-cyclodextrin, wherein the concentration of the sodium hydroxide is 0.5mol/L, and the concentration of the beta-cyclodextrin is 0.02mol/L; adding 15mL of 0.04mol/L copper sulfate solution into the solution to quickly form copper hydroxide blue precipitate, stirring the solution at room temperature for 12 hours, filtering the solution to remove the copper hydroxide precipitate, adding ethanol into the filtrate to gradually form blue precipitate in the solution, standing the solution, filtering the solution, washing the solid with a small amount of ethanol, and drying the solid at the temperature of 40 ℃ to obtain blue solid powder, namely a product;
(3)SiQDs-(NH 2 ) n /Cu 2 preparation of-beta-CD fluorescent clusters
SiQDs- (NH) at a concentration of 20g/L 2 ) n And 1X 10 -3 mol/L of Cu 2 Sufficiently mixing beta-CD according to the volume ratio of 1.5 for self-assembly for 30min, and obtaining SiQDs- (NH) after the self-assembly is finished 2 ) n /Cu 2 -a solution of β -CD fluorescent clusters.
Wherein FIG. 10 shows SiQDs- (NH) 2 ) n /Cu 2 -AFM (atomic force microscopy) picture of β -CD fluorescence cluster; FIG. 11 shows SiQDs- (NH) 2 ) n AFM (atomic force microscopy) images of quantum dots. As can be seen from the figure, the fluorescent clusters are in the shape of irregular rice grains of hundreds of nanometers, siQDs- (NH) 2 ) n The average grain diameter of the quantum dots is 5.625nm.
Example 4
SiQDs-(NH 2 ) n /Cu 2 Application of-beta-CD fluorescent cluster
In example 3, the concentration of 0.0067g/m was 1.5mLSiQDs- (NH) of L (Si content) 2 ) n /Cu 2 And (3) respectively adding 1.5mL of solutions of 0-240 mu M L-Cys, D-Cys and GSH with different concentrations into the beta-CD fluorescent cluster solution, keeping the total volume of the solutions consistent, standing for 30min, exciting at 360nm, and determining the fluorescence emission spectrum of the system, wherein the diagram 1,3,5 is the relative fluorescence spectrum of L-Cys, D-Cys and GSH under the fluorescent cluster detection condition. The concentration of the thiol compound (0-240. Mu. Mol/L) is used as the abscissa, and the fluorescence enhancement rate is 10 3 The time is the ordinate (fluorescence enhancement rate = (A muM relative fluorescence intensity-0 muM relative fluorescence intensity)/0 muM relative fluorescence intensity 100%), a linear equation is fitted, the detection limit is calculated, a graph 2,4,6 is a relational graph of the concentration of L-Cys, D-Cys and GSH and the fluorescence enhancement rate, the fitted linear equations are similar, and consistent detection limit (0.48 mumol/L) is obtained, which indicates that the detection mechanism is the same. In addition, comparing fig. 2 and fig. 4, it is found that although cyclodextrin copper is the chiral host material in the fluorescent cluster, the chirality of the sulfhydryl compound does not interfere with the detection result.
Example 5
SiQDs-(NH 2 ) n /Cu 2 Fluorometric assay of L-Cys with beta-CD
SiQDs- (NH) in example 3 2 ) n /Cu 2 And (4) exciting the beta-CD fluorescent cluster solution at 360nm, and setting the peak height at the maximum fluorescence emission peak to be 1. Adding L-Cys (concentration of 0.24 μm) into the fluorescence cluster solution, standing for 10min, exciting at 360nm, and measuring the peak height of maximum fluorescence emission peak relative to SiQDs- (NH) 2 ) n /Cu 2 - β -CD is 1.19.
It is thus understood that the mercapto compound can cause SiQDs- (NH) 2 ) n /Cu 2 -fluorescence enhancement of the β -CD fluorescent cluster solution.
Comparative example 1
SiQDs-(NH 2 ) n Fluorometric assay for L-Cys
SiQDs- (NH) at a concentration of 0.02g/mL 2 ) n Excitation is carried out at 360nm, and the peak height at the maximum fluorescence emission peak is set to be 1.0; siQDs- (NH) at a concentration of 0.02g/mL 2 ) n Adding L-Cys (concentration 0.24 μ M), exciting at 360nm, and measuring the peak height of maximum fluorescence emission peak relative to SiQDs-(NH 2 ) n The system is also 1.0, indicating that the addition of L-Cys did not result in SiQDs- (NH) 2 ) n Fluorescence is enhanced, therefore, siQDs- (NH) 2 ) n Cannot be used for the fluorescence measurement of L-Cys.
Comparative example 2
(1) Preparation of silicon quantum dots SiQDs- (NH) containing polyamino groups 2 ) n The same procedure as in example 1 was repeated.
(2)SiQDs-(NH 2 ) n -preparation of Cu (ii);
SiQDs-(NH 2 ) n the pH of the solution is strong alkalinity, and SiQDs- (NH) with the concentration of 20g/L is added 2 ) n And 0.002mol/L of CuSO 4 Mixing according to the volume ratio of 2:1, and the pH value of the obtained mixed solution is between 8 and 9, and the mixed solution is Cu due to alkalescence condition 2+ Possibly with Cu (OH) 2 The Cu (II) can coordinate with lone pair electrons on amino nitrogen of the quantum dot to form SiQDs- (NH) 2 ) n -Cu(Ⅱ)；
If SiQDs- (NH) is to be substituted 2 ) n The solution was pre-adjusted to weak acidity with HCl solution, and SiQDs- (NH) was added at a concentration of 20g/L (Si content) 3 + ) n And 0.002M of CuSO 4 The volume ratio of 2:1 is mixed, the pH value of the mixed solution is between 5 and 6, because of Cu 2+ And SiQDs- (NH) 3 + ) n Are all positively charged, so SiQDs- (NH) alone 3 + ) n The quantum dot fluorescence is not quenched due to the existence of the morphology.
(3) By using SiQDs- (NH) 2 ) n Fluorometric assay of L-Cys with-Cu (II)
To SiQDs- (NH) 2 ) n Adding L-Cys into the-Cu (II) solution, wherein the concentration of L-Cys is 0.24 μ M, exciting at 360nm, and measuring SiQDs- (NH) 2 ) n -fluorescence spectrum of Cu (II).
And (3) detection results:
when copper (II) is added under the weak acid condition, the fluorescence of the quantum dots is not quenched but slightly increased, and the fluorescence is recovered after the L-Cys is added (as shown in figure 8), so that the method cannot be used for the fluorescence determination of the L-Cys.
Adding copper under alkaline condition(II), fluorescence was quenched, but no change in fluorescence was observed after addition of L-Cys (as shown in FIG. 9). Cu (OH) 2 The nano particle or micelle Cu (II) can coordinate with lone pair electrons on amino nitrogen of the quantum dot to generate energy transfer, so that fluorescence quenching is caused. However, the fluorescence is unchanged when L-Cys is added, because the bonding ability of the sulfhydryl of the cysteine L-Cys and Cu (II) is lower than that of the amino group, no fluorescence response exists. And Cu 2 The Cu (II) of the beta-CD exists in a special copper bridge bond form, the Cu (II) has stronger binding capacity with a sulfhydryl group than an amino group, so that the Cu (II) has fluorescence response to a sulfhydryl compound, and copper ions do not directly interfere with the test result.
Example 6
Interference assay for detection of sulfhydryl compounds
SiQDs- (NH) in example 3 2 ) n /Cu 2 Adding L-Cys (the concentration is 300 mu M) into the beta-CD fluorescent cluster solution, standing for 40min, exciting at 360nm, and setting the peak height at the maximum fluorescence emission peak to be 1.0; adding K into the fluorescent cluster solution added with L-Cys (with concentration of 300 μ M) + ，Na + ，Mg 2+ ， Cu 2+ ，SO 4 2- ，CO 3 2- ，Cl - Trp, phe, asp, lys, ala, glu and Thr to form a coexisting system, the concentration of each substance is 300 mu M, after the solution system is stood for 40min, the solution system is excited at 360nm, and the relative peak heights of the maximum fluorescence emission peaks are 0.9909,1.0100,1.0194,0.6133,0.9877,1.0074 and 1.0262,0.9931,1.0425,1.0295,1.0951,1.0750,1.0384,1.0503,1.0818 respectively; FIG. 7 is a graph showing that equimolar concentrations of other amino acids resulted in slight increases in fluorescence intensity, with an error of 3.8-9.5%; the ion interference of equimolar concentration is about 1.0%, but Cu 2+ The results are greatly disturbed at 300. Mu.M, but due to free Cu in human blood 2+ Concentration of (D) and Cu in food 2+ Has an extremely low concentration of Cu of 3. Mu.M 2+ During interference detection, detection error<2% therefore, cu is actually detected 2+ There is little interference with the detection.
The specific conditions are not specified in the examples and are carried out under conventional conditions. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. The methods used in the present invention are conventional in the art unless otherwise specified. The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all modifications of the above embodiments made according to the technical spirit of the present invention are included in the scope of the present invention.
Claims (8)
1. The silicon quantum dot/cyclodextrin copper fluorescent cluster is characterized in that the fluorescent cluster is composed of multi-amino silicon quantum dots SiQDs- (NH) 2 ) n And beta-cyclodextrin copper Cu 2 - β -CD composition;
wherein the cyclodextrin copper Cu 2 The preparation method of the-beta-CD comprises the following steps: preparing a mixed solution of sodium hydroxide and beta-cyclodextrin, adding a copper sulfate solution into the mixed solution to form copper hydroxide blue precipitate, stirring the mixed solution at room temperature, filtering the mixed solution to remove the copper hydroxide precipitate, adding ethanol into filtrate to gradually form blue precipitate in the solution, standing the solution, filtering the solution, washing and drying the solution to obtain blue solid powder, namely a product;
preparation of polyamino silicon quantum dots SiQDs- (NH) by adopting silane coupling agent 2 ) n Then using SiQDs- (NH) 2 ) n Upper amino group and cyclodextrin copper Cu 2 Coordination of-beta-CD by self-assembly to form SiQDs- (NH) 2 ) n /Cu 2 - β -CD fluorescent cluster.
2. The silicon quantum dot/cyclodextrin copper fluorescent cluster according to claim 1, wherein the concentration of SiQDs- (NH) is 20g/L 2 ) n And 1X 10 -3 mol/L of Cu 2 -beta-CD is fully mixed according to the volume ratio of 1.1-1 2 ) n /Cu 2 -a solution of β -CD fluorescent clusters.
3. The silicon quantum dot/cyclodextrin copper fluorescent cluster of claim 1, wherein SiQDs- (NH) 2 ) n The preparation method comprises the following steps: weighing KH-550, mixing with deionized water, and magnetically stirringHydrolyzing, adding ascorbic acid solution, stirring, transferring to high pressure hydrothermal kettle, and placing in a muffle furnace at 120-180 deg.C for 12-24h.
4. The silicon quantum dot/cyclodextrin copper fluorescent cluster according to claim 3, wherein the hydrolysis volume ratio of KH550 to deionized water is 2.
5. The silicon quantum dot/cyclodextrin copper fluorescent cluster according to claim 1, wherein the concentration of sodium hydroxide in the mixed solution is 0.2-0.5mol/L, and the concentration of β -cyclodextrin is 0.01-0.02mol/L; the concentration of copper sulfate is 0.02-0.04mol/L.
6. The method for detecting the sulfhydryl compound by using the silicon quantum dot/cyclodextrin copper fluorescent cluster according to any one of claims 1-5, characterized in that: the method comprises the following steps:
(1) Drawing of standard curve
Adding sulfhydryl compound solutions with different concentrations into the silicon quantum dot/cyclodextrin copper fluorescent cluster solution respectively, keeping the total volume of the solutions consistent, standing for a period of time, and then measuring the fluorescence emission spectrum of the system; the concentration of the sulfhydryl compound is used as the abscissa, and the fluorescence enhancement rate is 10 3 Fitting a linear equation with the times as a vertical coordinate;
(2) Actual sample detection
And (3) detecting the sample containing the sulfhydryl compound by the method, and then calculating the concentration of the sulfhydryl compound according to the linear equation.
7. The method for detecting the sulfhydryl compound by using the silicon quantum dot/cyclodextrin copper fluorescent cluster as claimed in claim 6, wherein: the sulfhydryl compound is one of L-cysteine (L-Cys), D-cysteine (D-Cys) and Glutathione (GSH).
8. The method for detecting the sulfhydryl compound by using the silicon quantum dot/cyclodextrin copper fluorescent cluster according to claim 6, wherein the detection concentration of the sulfhydryl compound solution is set to be 0-240 μ M.
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