WO2021013175A1

WO2021013175A1 - Solid quantum dot sensor and method for producing the same as well as use thereof

Info

Publication number: WO2021013175A1
Application number: PCT/CN2020/103503
Authority: WO
Inventors: Jingtang LIU; Aimetiasi AMATE
Original assignee: Xi'an Jiaotong-Liverpool University
Priority date: 2019-07-24
Filing date: 2020-07-22
Publication date: 2021-01-28
Also published as: CN110296968A; CN110296968B

Abstract

A solid quantum dot sensor and methods for producing the same as well as use thereof. The quantum dot is entrapped in polymer matrix, which is composed of perfluorosulfonic acid and polyvinyl alcohol, to form solid quantum dot sensor. Glucose oxidase is entraped into the solid quantum dot sensor produces solid quantum dot glucose sensor. In the solid quantum dot sensors, the quantum dots and the glucose oxidase are stabilized in the sensor by specifically selecting a polymer matrix. When the sensor is exposed to sample to be tested, it can respond quickly, so that the detection efficiency and sensitivity are improved.

Description

SOLID QUANTUM DOT SENSOR AND METHOD FOR PRODUCING THE SAME AS WELL AS USE THEREOF

Technical Field

The invention relates to the field of fluorescence detection, more particularly to a solid quantum dot sensor for detecting hydrogen peroxide or glucose, and methods for producing the same as well as use thereof.

Background

Quantum dots (QD) are a kind of nanoparticle which composed mainly of the elements from the II-VI, III-V or IV groups in the periodic table. The characteristic sizes of the material are comparable with the de Broglie wavelength or mean free path of electrons in three dimensions, that is, the energy of electrons is quantized in three dimensions. Quantum dots have unique optical properties such as wide absorption peak, narrow emission peak, good light stability and fluorescence intensity, which allow quantum dots to be widely used in the fields of physics, chemistry, electronics, and biology. Studies have shown that the quantum dots can be used to produce fiber-optic glucose biosensors, which are more sensitive than the traditional methods for detecting glucose. However, in the prior art, the stability, detection sensitivity, and detection response speed of the quantum dots in the sensor need to be further improved.

CN103472043A disclosed a fluorescent glucose sensor comprising substrate which has a working area made from indium tin oxide. The surface of the working area is provided with a semiconductor quantum dot modifying layer, a glucose barrier layer and an enzyme layer. Microfibers and fluorescent signal collectors are provided at the bottom of the working area. The microfibers transmit lights to the surface of the working area, and the fluorescence signal collectors collect fluorescence emitted by the semiconductor quantum dots modified on the surface of the working area. The semiconductor quantum dots are cadmium telluride quantum dots.

CN103454325A disclosed a photocatalytic glucose microelectrode sensor comprising substrate which is provided with working electrode, counter electrode and reference electrode. The working electrode is provided with a semiconductor quantum dot modifying layer and a glucose oxidase modifying layer on its working area. The substrate is provided with microfibers which vertically transmit lights through the working electrode. The semiconductor quantum dots are CdSe-CdS quantum dots.

CN105928999A disclosed a glucose oxidase enzyme membrane modified with carbon quantum dots and a method for producing the same, which relate to the field of electrochemical biosensor and production thereof. The glucose oxidase enzyme membrane modified with the carbon quantum dots has nitrocellulose membrane as matrix membrane, contains glucose oxidase as catalyst and nanomaterial carbon quantum dots, as well as benzoic acid as preservative, gentamicin as antibacterial agent, bovine serum albumin as protective agent, glycerin as softener, glutaraldehyde as cross-linking agent and other components. The method for production is as follows: Firstly, the additives such as benzoic acid and gentamicin are dissolved in the glucose oxidase solution with a certain ratio. The carbon quantum dots and glutaraldehyde are subsequently mixed with the glucose oxidase solution and crosslinked. The mixture is then dropped onto the nitrocellulose matrix. After drying the enzyme membrane of the invention will be obtained.

Although quantum dots based biosensors are very common, the stability of quantum dots in sensors, the response speed of the detection reactions, and detection sensitivity need to be further improved. Therefore, it is important to provide a quantum dot sensor with high stability and sensitivity as well as fast response.

Description of the invention

In view of the deficiencies of the prior art and of the actual demands, the present invention provides a solid quantum dot sensor and a method for producing the same and use thereof, wherein the solid quantum dot sensor is produced with a polymer matrix specifically selected in such a way that the quantum dots are stabilized in the sensor. When the sensor is exposed to the sample to be tested, it can respond quickly, so that the detection efficiency and sensitivity are improved.

To attain the above mentioned object, the present invention employs the following technical solutions.

In the first aspect, the present invention provides a solid quantum dot sensor, wherein quantum dots are entrapped in the polymer matrix which is composed of perfluorosulfonic acid and polyvinyl alcohol. The perfluorosulfonic acid component provides the mechanical strength and serves as an anion filter, which might interfere with the detection. The polyvinyl alcohol component gives the membrane its softness and enhances mass transport through rapid hydration. A composite membrane that contains suitable ratios between the two components is critical for the membrane to effectively stablilize large molecules, such as an enzyme within the membrane matrix without compromising its activity; and allows small target molecules and products to efficiently diffuse into the membrane.

In the present invention, by specifically selecting of the composition of the polymer matrix, the quantum dots are trapped in the polymer matrix to form a membrane which preserved the optical activity of the free quantum dots. The solid quantum dot sensor membrane absorbs ultraviolet and visible light of certain wavelength and emits light in visible and far infrared region. The fluorescence of the sensor membrane is sensitive to hydrogen peroxide, the concentration of which can therefore be determined by the fluorescence intensity changes. The polymer matrix composite membrane makes it possible to anchor the quantum dots and other reagents, to stabilize the reagents from leaching out to the media, to stabilize the quantum dots to increase storage time, to provide fast hydration, to allow rapid diffusion of analytes into the membrane, to facilitate absorption of light energy of certain wavelength by the quantum dots, and to facilitate the emission of light energy of certain wavelength. For specific applications, the quantum dots of the sensor of the present invention can be selected according to the intended emission wavelength, and one common excitation light source sufficient for all quantum dots can be used.

Preferably, the quantum dots comprise CdTe.

In the present invention, any quantum dots reactive with hydrogen peroxide can be used for the production of the solid quantum dot sensor, i.e., any other quantum dots can be used for the application, in which they are capped by molecules chemically reactive with hydrogen peroxide to result in destabilization of the quantum dots.

Preferably, the quantum dots are coated with mercaptopropionic acid and/or glutathione.

In the present invention, with thiol capping, the quantum dots can be oxidized by hydrogen peroxide, thereby reflecting the concentration of the analyte.

In the second aspect, the present invention provides use of the solid quantum dot sensor according to the first aspect for detecting hydrogen peroxide, glucose, cholesterol or triglycerides.

In the present invention, the solid state quantum dot sensor can be used for directly detecting hydrogen peroxide, and can also detect small biological molecules by further enzymatic modification. Said biological molecules are typically but not limited to glucose, cholesterol or triglyceride. The concentration of the corresponding small molecule in the sample to be tested can be further detected by corresponding enzymatic modification (glucose oxidase, cholesterol oxidase or triglyceride oxidase) .

Preferably, the sample to be tested is aqueous media.

Preferably, the aqueous media comprise buffer solution, saliva, plasma or urine.

In the present invention, the solid state quantum dot sensor can be used for detecting any aqueous media, in which the detection of glucose in saliva is greatly simplified in terms of the detection process which is performed in a non-invasive manner, and the detection limit is up to micromolar level with high sensitivity. The present invention can be widely applied to such as wastewater analysis (hydrogen peroxide in wastewater from paper mills and hospitals) , food industry using hydrogen peroxide for disinfection, or measurement of hydrogen peroxide used for papermaking. In the third aspect, the present invention provides a method for producing the solid quantum dot sensor for detecting hydrogen peroxide, comprising the following steps:

(1) mixing perfluorosulfonic acid with polyvinyl alcohol and then stirring the mixture;

(2) adding quantum dots into the solution obtained in the step (1) which is subsequently stirred and sonicated;

(3) adding the mixture obtained in the step (2) to the matrix material and drying it to obtain the solid quantum dot sensor for detecting hydrogen peroxide.

Preferably, the polyvinyl alcohol has a concentration of 0.5-4%in water, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, or 4%, preferably 1%.

Preferably, the polyvinyl alcohol has a molecular weight of 20-100k Da, such as 20kDa, 30kDa, 40kDa, 50kDa, 60kDa, 70kDa, 80kDa, 90kDa, or 100kDa.

Preferably, the perfluorosulfonic acid has a concentration (w/v) of 0.01-0.2%, such as 0.01%, 0.05%, 0.1%, 0.15%, or 0.2%, preferably 0.05%.

Preferably, the volume ratio of the perfluorosulfonic acid to the polyvinyl alcohol is 1: 0.5-20, such as 1: 0.5, 1: 1, 1: 2, 1: 3, 1: 4, 1: 5, 1: 6, 1: 7, 1: 8, 1: 9, 1: 10, 1: 11, 1: 12, 1: 13, 1: 14, 1: 15, 1: 16, 1: 17, 1: 18, 1: 19, 1: 20, preferably 1: 20.

Preferably, the stirring in the step (1) is carried out for 10-20 min, preferably 15 min.

Preferably, the concentration by mass of the quantum dots solution in the step (2) is 0.5-2.5 mg/mL, such as 0.5mg/mL, 0.54mg/mL, 0.6mg/mL, 0.65mg/mL, 0.7mg/mL, 0.8mg/mL, 0.9mg/mL, 1mg/mL, 1.1mg/mL, 1.2mg/mL, 1.3mg/mL, 1.4mg/mL, 1.5mg/mL, 1.6mg/mL, 1.7mg/mL, 1.8mg/mL, 1.9mg/mL, 2mg/mL, 2.1mg/mL, 2.2mg/mL, 2.3mg/mL, 2.4mg/mL, or 2.5mg/mL, preferably 0.54mg/mL.

Preferably, the stirring in the step (2) is carried out for 2-10min, such as 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, or 10min, preferably 5 min.

Preferably, the sonicating in the step (2) is carried out for 10-120s, such as 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, or 120s, preferably 30s.

Preferably, the matrix material in the step (3) comprises PET or micro cuvette.

Preferably, the drying in the step (3) is carried out at room temperature.

Preferably, the drying in the step (3) is carried out for 12-24h, such as 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h.

As a preferred embodiment of the present invention, the method includes the following steps:

(1) mixing 0.5 mL of 0.05%perfluorosulfonic acid and 0.5 mL of 1%polyvinyl alcohol to achieve a mass ratio of 1: 20, and stirring for 10-20 min to obtain a mixture;

(2) adding quantum dots to the mixture obtained in the step (1) with a final concentration of the quantum dots of 0.54 mg/mL, stirring for 3-10 min, and sonicating for 20-120s to obtain a mixture;

(3) adding the mixture obtained in the step (2) to matrix material and drying it at room temperature for 12-24 hours to obtain the solid quantum dot sensor for detecting hydrogen peroxide.

In the fourth aspect, the present invention provides a method for producing the solid quantum dot sensor for detecting glucose, comprising the following steps:

(1’) mixing perfluorosulfonic acid with polyvinyl alcohol and then stirring the mixture;

(2’) adding quantum dots into the solution obtained in the step (1’) which is subsequently stirred and sonicated;

(3’) mixing the glucose oxidase homogeneously with the solution obtained in the step (2’) ;

(4’) adding the mixture obtained in the step (3’) to the matrix material and drying to obtain the solid quantum dot sensor for detecting glucose.

Preferably, the polyvinyl alcohol has a mass fraction of 0.5%.

Preferably, the perfluorosulfonic acid has a mass fraction of 0.5-2.5%, such as 0.5%, 1%, 1.5%, 2%, or 2.5%, preferably 1%.

Preferably, the volume ratio of the perfluorosulfonic acid to the polyvinyl alcohol is 1: 0.1-20, such as 1: 0.1, 1: 0.5, 1: 1, 1: 2, 1: 3, 1: 4, 1: 5, 1: 6, 1: 7, 1: 8, 1: 9, 1: 10, 1: 11, 1: 12, 1: 13, 1: 14, 1: 15, 1: 16, 1: 17, 1: 18, 1: 19, or 1: 20.

In the present invention, by selecting the ratio between perfluorosulfonic acid and polyvinyl alcohol, the polymer composite membrane is enabled to stabilize the enzyme molecule from leaching, to preserve the activity of the enzyme and to facilitate the enzyme catalyzed reaction.

Preferably, the stirring in the step (1’) is carried out for 10-20 min, preferably 15 min.

Preferably, the concentration by mass of the quantum dots in the step (2’) is 0.5-2.5mg/mL, preferably 0.54mg/mL.

Preferably, the stirring in the step (2’) is carried out for 2-10min, preferably 5 min.

Preferably, the sonicating in the step (2’) is carried out for 10-120s, preferably 30s.

Preferably, the concentration by mass of the glucose oxidase solution in the step (3’) is 1.0-3.0 mg/mL.

Preferably, the glucose oxidase solution in the step (3’) is mixed with the solution obtained in the step (2’) with a volume ratio of 1: 16-50, such as 1: 16, 1: 17, 1: 18, 1: 19, 1: 20, 1: 25, 1: 30, 1: 35, 1: 40, 1: 45, or 1: 50, preferably 1: 50.

Preferably, the matrix material in the step (4’) comprises PET or micro cuvette.

In the present invention, the matrix material may be an opaque or transparent polymer material such as PET plastic or a commercial product, typically but not limited to micro cuvette for optical measurement.

Preferably, the drying in the step (4’) is carried out at room temperature.

Preferably, the drying in the step (4’) is carried out for 2-10h, such as 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, or 10h, preferably 3-4h.

Preferably, after the step (4’) , a post processing is carried out, consisting of storing the solid quantum dot sensor at -4℃.

The method of the present invention for producing the solid quantum dot sensors for detecting glucose can also be used for producing sensors for detecting cholesterol, triglyceride or any small molecule active substance generating hydrogen peroxide as by-product through enzymatic reaction. Multisensor configuration can be used to simultaneously or individually detect different analytes in a sample. The present invention employs kinetic data rather than absolute data for analysis, and the results are thus more reliable.

(1’) mixing 1%perfluorosulfonic acid with 0.5%polyvinyl alcohol to achieve a mass a ratio of 1: 20, and stirring for 10-20 min;

(2’) adding quantum dots to the solution obtained in the step (1’) with a final concentration of the quantum dots of 0.54 mg/mL, then stirring, and sonicating for 10-120s;

(3’) homogeneously mixing glucose oxidase with the solution obtained in the step (2’) with a volume ratio of 1: 16-50, and the glucose oxidase has a concentration by mass of 1.0-3.0mg/mL;

(4’) adding the mixture obtained in the step (3’) to the matrix material and drying it at room temperature for 2-10h to obtain the solid quantum dot sensor.

In the present invention, the quantum dots are soluble/dispersible in water and are stabilized in polymer matrix with specific formulation composed of perfluorosulfonic acid and polyvinyl alcohol with different proportions. Rapid hydration is provided when the sensor is exposed to the test sample. The polymer matrix attracts water molecules in the presence of water, and the hydrated sensor allows the analyte to diffuse rapidly into the membrane, which is transparent to incident light so that the emission of the light energy with specific wavelength is facilitated.

In the fifth aspect, the present invention provides a method of detecting glucose with a solid quantum dot sensor according to the first aspect, which includes the following steps:

activating the solid state quantum dot sensor, then

adding the sample to be tested, and then

determining the content of the glucose in the sample by comparing with the standard curve in terms of the change of the fluorescence value,

Preferably, the activating is consisted of adding buffer to the solid quantum dot sensor.

Preferably, the buffer is a phosphate buffer.

Preferably, the buffer has a pH of 7.4.

Preferably, the activating is carried out for 30-120 min.

The present invention has the following beneficial effects compared with the prior art:

(1) The solid quantum dot sensor provided by the present invention achieves high sensitivity by specifically selecting a polymer matrix, and the detection can reach a micro molar level. The polymer matrix may facilitate the diffusion of the analyte into the sensor to accelerate the detection reaction, and at the same time, the quantum dots have high stability and fast response in the sensor;

(2) The solid quantum dot sensor of the present invention can be used for detecting any object in aqueous media to be tested. The applicability is wide.

(3) The solid quantum dot sensor provided by the present invention can be simply produced and is thus suitable for industrial production.

Brief description of the figures

Fig. 1 shows the flow diagram for producing the solid state quantum dot sensor of the example 2;

Fig. 2 shows the fluorescence intensity of the quantum dots in the hydrogen peroxide solutions with different concentrations.

Fig. 3 shows the linear fit of hydrogen peroxide concentration and fluorescence intensity.

Fig. 4 shows the standard curve for the test of glucose in artificial saliva.

Fig. 5 shows the standard curve for the test of glucose in human saliva.

Detailed Description of the Invention

The technical solution of the present invention is further illustrated by following specific embodiments, in order to further describe the technical means and the effects thereof, but the present invention is not limited to the scope of the examples.

Example 1: Method for preparing solid quantum dot sensor for detecting hydrogen peroxide

0.5 ml of polyvinyl alcohol (PVA) (1%) and 0.5 ml of perfluorosulfonic acid (nafion) (0.05%) were mixed in a 10 ml cuvette and stirred at room temperature for 15 minutes. The mixing ratio of PVA-nafion is 20: 1.30 μL of QD (1.78 mg /mL) was added to 1 mL of the prepared PVA-nafion solution and stirred for 5 minutes. The obtained mixture was sonicated for 30 seconds. After mixing and sonicating, a uniform solution of nafion-PVA and QDs was obtained which is directly used for preparing the sensors. The sensors were prepared on a 96-well plate. 20 μL of PVA-nafion-QDs membrane was incorporated into a 96-well plate or a PET sheet and dried overnight in the open air at room temperature.

Perfluorosulfonic acid and polyvinyl alcohol have the structure shown as following formulae I and II respectively, and the structure of the quantum dot CdTe modified by mercaptopropionic acid is as shown in Formula III.

Example 2: Method for preparing solid quantum dot sensor for detecting glucose

An enzyme-modified sensor was prepared by adding 40 μL of QDs solution (1.87 mg /mL) to a 0.5 mL solution containing 1.0%nafion and 0.5%PVA. A glucose oxidase stock was prepared by dissolving 2 mg of solid GOx (glucose oxidase) in1.5 mL of water. 50 μL of GOx stock was added to the mixture of QD and polymer.. 25 μL of the obtained final solution was added to each micro cuvette of a commercial 96-well plate and then dried at room temperature for 3 hours. The prepared sensors were stored in a refrigerator at 4 ℃ before use for analyses. The preparation process of the enzyme-modified solid quantum dot sensor is shown in FIG. 1.

Calibration of quantum dots in hydrogen peroxide solution

Briefly, 25 mL of 0.238 g/L QDs in a 5mM potassium phosphate buffer solution was placed in a conical flask and the solution was stirred continuously. To this solution, aliquots of 5μL, 10μL, 15μL, 20μL, 30μL, 40μL, 50μL, and 60 μL of 0.1 M freshly prepared H ₂O ₂ stock solutions were added separately. The final concentration of H ₂O ₂ was 20μM, 39.9μM, 59.9μM, 79.8μM, 119.6μM, 159.2μM, 198.6μM, and 237 μM respectively, after each addition. As shown in the Fig. 2, after each addition of H ₂O ₂ the fluorescence emission intensity of the QDs solution at 596 nm was recorded, using an excitation wavelength of 420 nm with a slit width of 2 nm. As shown in the Fig. 3, the concentration of H ₂O ₂ is selected as the horizontal coordinate and the fluorescence emission intensity as the vertical coordinate for linear fitting. The Fig. 3 also shows that the concentration of H ₂O ₂ is linearly positively correlated with the fluorescence intensity, and the concentration of H ₂O ₂ in the solution to be tested can be obtained with the standard curve and the fluorescence intensity.

Detection of the glucose in saliva

1. Calibration of the solid quantum dot sensors

Artificial saliva containing 5 mM NaCl, 1 mM CaCl ₂, 15 mM KCl, 1 mM citric acid, 5 mM uric acid, 1 mM ascorbic acid, 0.2 mM lactic acid, 1.1 mM potassium thiocyanate KSCN and 4 mM NH ₄Cl was prepared with water. Measurements of glucose in artificial saliva was performed by using glucose standards of 500, 800, 1400, 2600 and 5000 μM in artificial saliva prepared from 20 mM glucose stock. The sensor obtained from the example 2 was activated for 1 hour with 100 μL of 5 mM phosphate buffer with pH 7.4 before calibrating. The measurement was carried out by adding 2 μL of the standard solution to the sensor in the 100 μL buffer. The final concentration of glucose in artificial saliva is 9.8, 25.2, 51.6, 99.8, 190.7, 369.2 μM respectively. The results were linear fitted as shown in Fig. 4.

After each addition of glucose in artificial saliva, the change in fluorescence was monitored for 600 seconds with a FluoroMax-4 spectrophotometer (Horiba scientific USA) . The excitation and emission wavelengths used were 400 and 586 nm, respectively, and the slit was 5 nm.

As shown in the Fig. 4, the measurements of the solid quantum dot sensor of the present invention covered the linear range of the glucose concentration from 10 to 370 μM which is sufficient to cover the glucose concentration in human saliva.

2. Detection of glucose in human saliva using a standard curve

5 mL of stimulated or unstimulated saliva was collected from subjects according to the standard procedures.

The saliva was collected from subjects of age 25-34 years. The donor was trained on saliva collection and a donor information sheet for saliva collection was signed by donors.

1) Non-stimulated sample collection:

· There was no intake of any drugs/medicines by the subjects.

· There was no any infective Hepatitis B or Hepatitis C and HIV, musculoskeletal or co-morbid oral disease or recent operation of the donors.

· The individuals were non-smokers with excellent oral health.

· The individual abstained from drinking, oral hygiene procedures, and eating at least 2 h prior to the collection.

· The subjects were not to cough up mucus during saliva collection, the goal is to collect saliva passively.

· All the doners rinsed their mouth with clean water prior to saliva collection.

· During saliva collection, the doner sat comfortably and bend their head down to assemble saliva in the mouth.

· The first lots of saliva expectoration were discarded to avoid any food partials and other contaminants that interfere with analysis.

· A second lot of saliva was expectorated into sterile cleaned tubes and place the tube on ice while collecting more saliva.

· The total average volume of saliva collected was 5 ml.

2) Stimulated sample collection:

· A stimulated saliva sample was collected using all the basic and initial procedure described above. Commercially available collection kit was used.

· Where the subjects were asked to chew a sterile cotton for 2 min. After that the cotton was kept in sterile test-tube and was placed in an ice bath.

· The saliva was extracted from the salivary cotton by centrifugation and filtration. The saliva was centrifuge two times at 4000 RPM followed by filtration.

· No stimulants were used in saliva collecting procedure.

· The collected saliva samples were used for analysis immediately or stored at 3-7 ℃ and used on the same day.

· The pH of saliva stimulated and unstimulated saliva was recorded.

The sensor was activated with 75μL of phosphate buffer of pH 7.4 for one hour, then 35 μL of human saliva (or 35 μL phosphate buffer of pH 7.4 as a blank) was spiked into the sensor wells with mixing. All the measurements were performed at room temperature 25 ℃. The fluorescence signal was recorded for both saliva and bank sensor wells. The glucose standard solutions were added to the sensor well to complete the calibrations. Aliquots of 3.2 μL and 2.1μL from 2560 μM glucose stock solution and 2.1 μL from 5120 μM stock solution were added into the sensor well gradually. The final concentration of the glucose without unknown saliva glucose was 69.3 μM, 114 μM, and 202 μM. after each addition of glucose stock aliquots the fluorescence emission was recorded at 591 nm excited by 400 nm with slit width of 5nm. The linear relationship between the glucose concentration in human saliva and the fluorescence intensity is represented in Fig. 5. All the measurement was repeated thrice. The unknown saliva glucose concentration was calculated from the slope of the calibration curve.

Tab1. Glucose content in the saliva of the subject

N= Normal healthy subjects;

D= Subjects with diabetes

The solid quantum dot sensor of the present invention successfully measured the concentration of glucose in human saliva and the accuracy of the measurements was confirmed by GC-MS.

The Applicant declares that the present invention is illustrated by the above described examples, but is not limited to the above detailed methods, that is, the present invention must not be implemented by the above detailed methods. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent alternatives of the various materials of the products of the present invention, addition of auxiliary components, selection of specific means, and the like, are all within the scope of protection and disclosure of the present invention.

Claims

A solid quantum dot sensor, characterized in that the quantum dots are entrapped in a polymer matrix which is composed of perfluorosulfonic acid and polyvinyl alcohol, to form the solid quantum dot sensor.
The solid quantum dot sensor according to claim 1, characterized in that the quantum dots comprise CdTe;

Preferably, the quantum dots are coated with mercaptopropionic acid and/or glutathione.
Use of the solid quantum dot sensor according to claim 1 or 2 for detecting hydrogen peroxide, glucose, cholesterol or triglyceride;

preferably, the sample to be detected is of aqueous media;

preferably, the aqueous media comprises buffer solution, saliva, plasma or urine.
A method for producing a solid quantum dot sensor for detecting hydrogen peroxide, characterized in that it comprises the following steps:

(1) mixing perfluorosulfonic acid with polyvinyl alcohol and then stirring the mixture;

(2) adding the quantum dots into the solution obtained in step (1) which is subsequently stirred and sonicated;

(3) adding the mixture obtained in the step (2) to a substrate material and drying to obtain the solid quantum dot sensor for detecting hydrogen peroxide.
The method according to claim 4, characterized in that the polyvinyl alcohol used has a concentration (w/v) of 0.5-4 %in water;

Preferably, the polyvinyl alcohol has a molecular weight of 20-100k Da;

preferably, the perfluorosulfonic acid has a concentration (w/v) of 0.01-0.2%in water, preferably 0.05%;

preferably, the volume ratio of the perfluorosulfonic acid to the polyvinyl alcohol is 1: 0.5-20, preferably 1: 20;

preferably, the stirring in the step (1) is carried out for 10-20 min, preferably 15 min;

preferably, the concentration by mass of the quantum dots in the step (2) is 0.5-2.5 mg/mL;

preferably, the stirring in the step (2) is carried out for 2-10 min, preferably 5 min;

preferably, the sonicating in the step (2) is carried out for 10-120 s, preferably 30 s;

preferably, the substrate material in the step (3) comprises PET or micro cuvette;

preferably, the drying in the step (3) is carried out at room temperature;

preferably, the drying in the step (3) is carried out for 12-24 h.
The method according to claim 4 or 5, characterized in that the method comprises the steps of:

(1) mixing 0.5 mL of 0.05%perfluorosulfonic acid and 0.5 mL of 1%polyvinyl alcohol to achieve a mass ratio of 1: 20, and stirring for 10-20 min to obtain a mixture;

(2) adding quantum dots to the mixture obtained in the step (1) , with a final concentration of the quantum dots of 0.54 mg/mL, stirring for 3-8 min, and sonicating for 20-120 s to obtain a mixture;

(3) adding the mixture obtained in the step (2) to matrix material and drying it at room temperature for 12-24 hours to obtain the solid quantum dot sensor for detecting hydrogen peroxide.
A method for producing a solid quantum dot sensor for detecting glucose, characterized in that it comprises the following steps:

(1’) mixing perfluorosulfonic acid with polyvinyl alcohol and then stirring the mixture;

(2’) adding the quantum dots into the solution obtained in the step (1’) which is subsequently stirred and sonicated;

(3’) mixing glucose oxidase homogeneously with the solution obtained in the step (2’) ;

(4’) adding the mixture obtained in the step (3’) to the matrix material and drying to obtain the solid quantum dot sensor for detecting glucose.
The method according to claim 7, characterized in that the polyvinyl alcohol has a concentration of 0.5%in water;

preferably, the perfluorosulfonic acid has a concentration (w/v) of 0.5-2.5%, preferably 1%;

preferably, the volume ratio of the perfluorosulfonic acid to the polyvinyl alcohol is 1: 0.1-20;

preferably, the stirring in step (1’) is carried out for 10-20 min, preferably 15 min;

preferably, the concentration by mass of the quantum dots in the step (2’) is 0.5-2.5 mg/mL, preferably 0.54mg/mL;

preferably, the stirring in step (2’) is carried out for 2-10 min, preferably 5 min;

preferably, the sonicating in step (2’) is carried out for 10-120 sec, preferably 30 sec;

preferably, the concentration by mass of the glucose oxidase in the step (2) is 1.0-3.0 mg/mL;

preferably, in step (3’) , the glucose oxidase solution is mixed with the solution obtained in step (2’) with a volume ratio of 1: 16-50.

preferably, the matrix material in the step (4’) comprises PET or micro cuvette;

preferably, the drying in step (4’) is carried out at room temperature;

preferably, the drying in step (4’) is carried out for 2-10 hours, preferably 3-4 hours;

preferably, after step (4’) , a post processing is carried out, consisting of storing the solid quantum dot sensor for detecting glucose at 4℃.
The method according to claim 7 or 8, characterized in that the method comprises the steps of:

(1’) mixing 1%perfluorosulfonic acid with 0.5%polyvinyl alcohol to achieve a mass ratio of 1: 20 and stirring for 10-20min;

(2’) adding quantum dots to the solution obtained in the step (1’) with final concentration of the quantum dots of 0.54 mg/mL, then stirring, and sonicating for 10-120s;

(3’) mixing the glucose oxidase homogeneously with the solution obtained in the step (2’) in a ratio of 1: 16-50, and the glucose oxidase has a concentration by mass of 1.0-3.0 mg/mL;

(4’) adding the mixture obtained in the step (3’) to the matrix material and drying it at room temperature for 2-10 h to obtain the solid quantum dot sensor.
A method for detecting glucose by a solid quantum dot sensor according to claim 1 or 2, characterized in that the said method comprises the steps of:

activating the solid state quantum dot sensor, then

adding the sample to be tested, and then

determining the content of the glucose in the sample by comparing the change of the fluorescence value with the calibration curve;

preferably, the activating is consisted of adding buffer to the solid quantum dot sensor;

preferably, the buffer is a phosphate buffer;

preferably, the buffer has a pH of 7.4;

preferably, the activating is carried out for 30-120 min.