Preparation method of nanodiamond-gold-polydopamine quantum sensor

Abstract

The present invention relates to a method for preparing a nanodiamond-gold-polydopamine quantum sensor. The quantum sensor includes nanodiamonds and Au@PDA. The Au@PDA is obtained by forming PDA by self-polymerization of dopamine hydrochloride in an alkaline environment and is included on the surface of Au particles. The nanodiamond-Au@PDA quantum sensor is obtained by connecting Au@PDA to the surface of the nanodiamond through non-covalent coupling between biotin and streptavidin. By controlling the concentration of Au@PDA, the nanodiamond temperature transfer effect, energy transfer, and quantum spin signal are effectively regulated, thereby achieving improvements in the fluorescence intensity, fluorescence lifetime, optical detection magnetic resonance spectrum, and relaxation time of the nanodiamond nitrogen vacancy color center. The nanodiamond-Au@PDA quantum sensor prepared by the present invention has broad application prospects in quantum precision measurement and quantum computing.

Description

Technical Field

[0001] The present invention relates to the field of diamond NV color center precision quantum sensing, and specifically to a method for preparing a novel nanodiamond-gold-polydopamine (nanodiamond-Au@PDA) quantum sensor. Background Art

[0002] Diamond nitrogen vacancy color center (hereinafter referred to as NV color center) is the most common luminescent defect in diamond. It consists of a nitrogen atom that replaces carbon and a hole. It has attracted much attention in precision quantum measurement. The energy level structure of diamond NV color center shows that under 532nm laser excitation, NV transitions from the ground state triplet state to the excited triplet state. The process of electrons returning from the excited triplet state to the ground state triplet state will produce 670nm red light. In the absence of an external magnetic field, the magnetic quantum number m s = ±1 are in degenerate state; when an external magnetic field is applied, the two energy levels split into m due to the Zeeman effect. s = +1 and m s = -1. The quantum spin signal of the NV center is read by collecting fluorescence. The quantum spin signal of the NV center is highly dependent on changes in the external environment. Therefore, modification of the diamond surface can manipulate the NV center's quantum signal. In recent years, diamond NV centers have been widely used as high-precision quantum sensors for measuring physical quantities such as temperature, magnetic field, and stress, as well as for biomarkers and bioimaging.

[0003] While quantum sensing based on diamond NV centers has proven successful in many fields, its application in measuring the physical properties of nanomaterials remains to be improved. Key factors hindering the measurement of nanomaterial physical properties include the small size of the nanomaterials, the fidelity of NV center spin manipulation and measurement, spin coherence time, inhomogeneous broadening, fluorescence intensity, and system stability. Therefore, a method is urgently needed to combine nanomaterials with diamond NV centers to measure the physical properties of single nanoparticles.

[0004] Chinese patent application number CN202111373155.6 reports a diamond nitrogen-vacancy color center array sensor. The NV color center layer is grown using in-situ MPCVD, and diamond is etched using ICP to create a nanopillar array containing NV color centers. Chinese patent application number CN202310767313.9 reports a diamond NV color center fiber magnetic field sensor based on flux concentration enhancement. By integrating micron-sized diamonds on the end face of a tapered multimode fiber and increasing the magnetic flux density using a flux concentrator, the sensor's magnetoelectric conversion coefficient and test sensitivity are enhanced. Chinese patent application number CN201910570946.4 reports a quantum pressure sensor based on diamond nitrogen vacancy color centers and its fabrication method. By etching a cavity from the bottom of a substrate layer, a diamond film containing nitrogen vacancy color centers and two symmetrically arranged ferrites are deposited on top of an insulating layer to achieve highly sensitive pressure measurements. Summary of the Invention

[0005] Technical problem: In response to the shortcomings of the existing technology, the present invention provides a method for preparing a nanodiamond-gold-polydopamine quantum sensor, the purpose of which is to improve the quantum spin signal readout of the diamond NV color center, thereby realizing the measurement of the physical properties of nano-sized materials.

[0006] Technical solution: The preparation method of a nanodiamond-gold-polydopamine quantum sensor of the present invention adopts a technical solution comprising:

[0007] Step 1: Modify the surface of nanodiamond with streptavidin by chemical coupling reaction to form streptavidin-nanodiamond.

[0008] Step 2: Modify the surface of gold particles with polydopamine (PDA) by chemical synthesis to prepare Au@PDA.

[0009] Step 3, surface-modifying Au@PDA with biotin to prepare biotin-Au@PDA;

[0010] Step 4: Mix streptavidin-nanodiamond and biotin-Au@PDA to prepare a nanodiamond-Au@PDA quantum sensor.

[0011] The chemical synthesis method is a self-polymerization reaction.

[0012] The diameter of the Au@PDA is 30-120 nm.

[0013] The preparation process of the Au@PDA is as follows:

[0014] Step 2.1, taking a Tris-HCl buffer with a pH of 7.0-7.5, and adjusting the pH of the Tris-HCl buffer to 8.0-8.7 by adding Tris;

[0015] Step 2.2, dissolving dopamine hydrochloride in the Tris-HCl buffer adjusted to a pH of 8.0-8.7 obtained in step 2.1, and sonicating for 8-15 minutes to obtain a mixed solution A;

[0016] Step 2.3, dissolving the gold particle solution obtained in step 2.1 in a Tris-HCl buffer adjusted to a pH of 8.0-8.7, and sonicating for 8-15 minutes to obtain a mixed solution B;

[0017] Step 2.4, mixing the mixed solution A and mixed solution B obtained in steps 2.2 and 2.3 above at room temperature, and magnetically stirring for 4-20 hours;

[0018] Step 2.5, centrifuging at 6000-13000 rpm to obtain the Au@PDA.

[0019] The dopamine hydrochloride accounts for 15%-20% by mass in the mixed solution A.

[0020] The concentration of the gold particle solution is 0.05-0.1 mg / mL, and the volume of the gold particle solution in the mixed solution B accounts for 5%-10%.

[0021] The size of the nano-diamond is 80-200 nm, and the nitrogen vacancy color center concentration of the nano-diamond is 2.5-3 ppm.

[0022] The step 4 is specifically as follows:

[0023] Step 4.1, streptavidin-nanodiamond and biotin-Au@PDA were mixed, sonicated for 8-15 min, and incubated at 30-40 °C for 20-30 h;

[0024] In step 4.2, the mixture was centrifuged by differential centrifugation and washed with deionized water, and finally Au@PDA was modified on the surface of the nanodiamond to prepare a nanodiamond-Au@PDA quantum sensor.

[0025] Beneficial effects: The present invention modifies Au@PDA onto the diamond surface through the non-covalent coupling method between biotin and streptavidin, and utilizes the photothermal effect of Au@PDA to heat the nanodiamond, thereby improving the reading of the quantum spin signal of the diamond NV color center, thereby increasing the fluorescence intensity, fluorescence lifetime, relaxation time and magneto-optical detection spectrum of the NV color center, and broadening its application in the field of quantum precision measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the preparation method of nanodiamond-Au@PDA quantum sensor;

[0027] Among them are nanodiamond 1, streptavidin 2, streptavidin-nanodiamond 3, Au particles 4, Au@PDA 5, biotin 6, biotin-Au@PDA 7, and nanodiamond-Au@PDA 8. DETAILED DESCRIPTION

[0028] Example 1

[0029] The present invention provides a method for preparing a nanodiamond-gold-polydopamine quantum sensor, comprising nanodiamonds and Au@PDA. The Au@PDA consists of Au particles coated with a layer of polydopamine (PDA) with an average diameter of 50 nm. The specific preparation process is as follows:

[0030] (1) First, take 5 mL of Tris-HCl buffer (PH = 7.2) by pipetting, add Tris to the Tris-HCl buffer, stir and dissolve it completely, and adjust the pH of the solution to 8.5. Then, take 5 mg of dopamine hydrochloride and place it in the Tris-HCl buffer, ultrasonicate for 10 minutes to fully disperse the dopamine hydrochloride. Then, take 2 mL of Au particle solution by pipetting and place it in the Tris-HCl buffer containing dopamine hydrochloride; ultrasonicate for 10 minutes to fully disperse the Au particles. Finally, stir magnetically for 6 hours at room temperature, then centrifuge at 11000 rpm to obtain a black solution, which is Au@PDA, and wash it three times with deionized water. (2) First, take 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and dissolve it in deionized water, ultrasonicate for 10 minutes to fully dissolve the EDC. Then, dissolve the nanodiamond in the EDC solution, ultrasonicate for 10 minutes to fully disperse the nanoAu diamond, shake the reaction at room temperature for 12 hours, and wash it three times with deionized water. Biotin was then dissolved in deionized water and sonicated for 10 minutes to dissolve the biotin, obtaining a biotin solution. Finally, the nanodiamond solution was added to the biotin solution, shaken at room temperature for 8 hours, centrifuged at 11,000 rpm, and washed three times with deionized water.

[0031] (3) Dissolve streptavidin in deionized water and sonicate for 10 minutes to fully dissolve the streptavidin to obtain a biotin solution. Then, dissolve Au@PDA in the streptavidin solution, shake at room temperature for 12 hours, centrifuge at 11,000 rpm, and wash three times with deionized water to obtain streptavidin-modified Au@PDA.

[0032] (4) Use a pipette to take 25 μL of the biotin-nanodiamond solution and 25 μL of the streptavidin-Au@PDA solution, mix them, and sonicate for 10 minutes to ensure full and uniform dispersion. Then, shake the reaction at room temperature for 25 hours, centrifuge at 7000 rpm, and rinse three times with deionized water to finally modify the Au@PDA on the nanodiamond surface.

[0033] Example 2

[0034] The present invention provides a method for preparing a nanodiamond-gold-polydopamine quantum sensor, comprising nanodiamonds and Au@PDA. The Au@PDA consists of Au particles coated with a layer of polydopamine (PDA) with an average diameter of 80 nm. The specific preparation process is as follows:

[0035] (1) First, take 4 mL of Tris-HCl buffer (PH = 7.2) by pipetting, add Tris to the Tris-HCl buffer, stir and dissolve it completely, and adjust the pH of the solution to 8.5. Then, take 10 mg of dopamine hydrochloride and place it in the Tris-HCl buffer, ultrasonicate it for 14 minutes to fully disperse the dopamine hydrochloride. Then, take 2 mL of Au particle solution by pipetting and place it in the Tris-HCl buffer containing dopamine hydrochloride; ultrasonicate it for 10 minutes to fully disperse the Au particles. Finally, stir it magnetically at room temperature for 15 hours, then centrifuge it at 11000 rpm to obtain a black solution, which is Au@PDA, and wash it three times with deionized water.

[0036] (2) Dissolve EDC in deionized water and sonicate for 10 minutes to fully dissolve the EDC. Then dissolve the nanodiamond in the EDC solution and sonicate for 10 minutes to fully disperse the nano-Au diamond. Shake and react at room temperature for 12 hours and wash three times with deionized water. Then dissolve biotin in deionized water and sonicate for 10 minutes to dissolve the biotin to obtain a biotin solution. Finally, add the nanodiamond solution to the biotin solution, shake and react at room temperature for 8 hours, centrifuge at 11,000 rpm, and wash three times with deionized water.

[0037] (3) Dissolve streptavidin in deionized water and sonicate for 10 minutes to fully dissolve the streptavidin to obtain a biotin solution. Then, dissolve Au@PDA in the streptavidin solution, shake at room temperature for 12 hours, centrifuge at 11,000 rpm, and wash three times with deionized water to obtain streptavidin-modified Au@PDA.

[0038] (4) First, 25 μL of biotin-nanodiamond solution and 25 μL of streptavidin-Au@PDA solution were mixed using a pipette and ultrasonicated for 10 min to ensure uniform dispersion. Then, the mixture was shaken at room temperature for 25 h, centrifuged at 8000 rpm, and washed three times with deionized water. Finally, Au@PDA was modified on the nanodiamond surface.

[0039] The preparation method of the present application can improve the fluorescence quantum spin signal of the nanodiamond NV color center. The obtained Au@PDA-modified nanodiamond NV color center can realize the measurement of physical properties such as temperature and magnetic field of nanomaterials, and has broad application prospects in quantum precision measurement and quantum computing based on diamond NV color centers.

[0040] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A method for preparing a nanodiamond-gold-polydopamine quantum sensor, characterized in that: include: Step 1: Modifying the surface of nanodiamond (1) with streptavidin (2) by a chemical coupling reaction method to form streptavidin-nanodiamond (3), wherein the nitrogen vacancy color center concentration of the nanodiamond is 2.5-3 ppm; Step 2, using a chemical synthesis method to modify polydopamine (PDA) on the surface of Au particles (4) to prepare Au@PDA (5); Step 3, surface-modifying Au@PDA (5) with biotin (6) to prepare biotin-Au@PDA (7); Step 4: Mix streptavidin-nanodiamond (3) and biotin-Au@PDA (7) to prepare nanodiamond-Au@PDA (8) quantum sensor.

2. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 1, characterized in that: The chemical synthesis method is a self-polymerization reaction.

3. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 1, wherein: The Au@PDA (5) has a diameter of 30-120 nm.

4. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 1, wherein: The preparation process of the Au@PDA is as follows: Step 2.1, take a Tris-HCl buffer with a pH of 7.0-7.5, and adjust the pH of the Tris-HCl buffer to 8.0-8.7 by adding Tris; Step 2.2, dissolving dopamine hydrochloride in the Tris-HCl buffer adjusted to a pH of 8.0-8.7 obtained in step 2.1, and sonicating for 8-15 minutes to obtain a mixed solution A; Step 2.3: Dissolve the gold particle solution obtained in step 2.1 in Tris-HCl buffer adjusted to a pH of 8.0-8.7, and sonicate for 8-15 minutes to obtain a mixed solution B. Step 2.4, mix the mixed solution A and mixed solution B obtained in steps 2.2 and 2.3 above at room temperature and stir magnetically for 4-20 h; In step 2.5, the Au@PDA is obtained by centrifugation at a speed of 6000-13000 rpm.

5. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 4, characterized in that: The dopamine hydrochloride accounts for 15%-20% by mass in the mixed solution A.

6. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 4, characterized in that: The concentration of the gold particle solution is 0.05-0.1 mg / mL, and the volume of the gold particle solution in the mixed solution B accounts for 5%-10%.

7. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 1, characterized in that: The size of the nanodiamond is 80-200 nm.

8. The method for preparing the nanodiamond-gold-polydopamine quantum sensor according to claim 1, characterized in that: The step 4 is specifically as follows: Step 4.1, streptavidin-nanodiamond (3) and biotin-Au@PDA (7) were mixed, sonicated for 8-15 min, and incubated at 30-40 °C for 20-30 h; In step 4.2, the mixture was centrifuged by differential centrifugation and washed with deionized water, and finally Au@PDA was modified on the surface of the nanodiamond to prepare the nanodiamond-Au@PDA (8) quantum sensor.

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