Applications of Chiral Carbon Quantum Dots

Abstract

The present invention discloses the application of chiral carbon quantum dots as imaging materials for bacteria and / or fungi, and also discloses a method for differentiating Gram-positive bacteria / fungi from Gram-negative bacteria. The chiral carbon quantum dots (left-handed chiral carbon quantum dots or right-handed chiral carbon quantum dots) in the present invention have the advantages of low toxicity, good biocompatibility, anti-photobleaching, and stable fluorescence properties. Moreover, they have chiral properties and fluorescence emission properties dependent on the excitation wavelength, and are suitable as imaging materials for bacteria and / or fungi. By using the chiral quantum dots of the present invention as imaging materials, the differentiation between Gram-positive bacteria and fungi, and the differentiation between Gram-positive bacteria and Gram-negative bacteria can be achieved.

Description

Technical Field

[0001] The present invention relates to a new use of chiral carbon quantum dots, and particularly to the application of chiral carbon quantum dots as fungal / bacterial imaging materials. Background Art

[0002] Carbon quantum dots (CQDs), also known as carbon dots (CDs) or carbon nanodots, are spherical fluorescent nanoparticles with a carbon-based framework structure, good dispersibility, and a particle size less than 10 nm. They are a new type of zero-dimensional carbon-based nanomaterial discovered after fullerenes, carbon nanotubes, and graphene. Due to their nanoscale size effect, adjustable photoluminescence properties, low toxicity, good biocompatibility, and easy surface modification, carbon quantum dots have been widely studied and applied in the fields of biological detection, fluorescence imaging, catalysis, anti-tumor, etc.

[0003] On the other hand, bacterial infection is one of the greatest challenges faced globally, and the rapid diagnosis of bacterial infection is crucial for clinical treatment. The standard method for differentiating unknown bacteria is the Gram staining method, which classifies bacterial species into two categories: Gram-positive and Gram-negative. However, this method has some drawbacks, such as a cumbersome procedure and a tendency to produce false positive results. Quantitative real-time PCR (qPCR) has been considered a highly sensitive technique for bacterial species identification, but this technique is too expensive for many places in developing countries, which greatly limits its practical application. Therefore, it is very urgent to invent rapid bacterial infection diagnosis and simple, efficient bacterial identification techniques. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a new use of chiral carbon quantum dots.

[0005] Another technical problem to be solved by the present invention is to provide a method for differentiating Gram-positive bacteria / fungi from Gram-negative bacteria.

[0006] To solve the above technical problems, the present invention provides an application of chiral carbon quantum dots as bacterial and / or fungal imaging materials.

[0007] Specifically, the inventors have found through extensive research that chiral carbon quantum dots (left-handed chiral carbon quantum dots or right-handed chiral carbon quantum dots) have good chiral properties, stable fluorescence performance, and fluorescence emission characteristics dependent on the laser wavelength. In addition, chiral carbon quantum dots have low toxicity, good biocompatibility, and anti-photobleaching. Therefore, they have good application prospects in the field of bacterial and / or fungal imaging materials.

[0008] Specifically, in one embodiment of the present invention, the preparation method of chiral carbon quantum dots is as follows: Sodium hydroxide, L-cysteine or D-cysteine, and water are mixed in a weight ratio of (0.1-1):(3-7):(120-200), and reacted at 100-140°C for 12-20 h. The obtained reaction solution is centrifuged and dialyzed to obtain chiral carbon quantum dots.

[0009] Among them, L-cysteine or D-cysteine is used as the chiral source and carbon source, sodium hydroxide is used as the catalyst for the carbonization polymerization reaction, and water is used as the dispersant. After forming a reaction system, a hydrothermal reaction is carried out. After the hydrothermal reaction, centrifugation is performed, and the supernatant is filtered through a cylindrical filter membrane with a pore size of 0.2-0.3 μm, and then dialyzed for 12-36 h using a dialysis membrane with a molecular weight cut-off of 500-1000 Da (using water as the external dialysis solution, and the external dialysis solution is changed every 4 h) to obtain an aqueous solution of chiral carbon quantum dots, and then freeze-dried under vacuum at -100°C to -50°C for 24-48 h to obtain the finished product of chiral carbon quantum dots.

[0010] The chiral carbon quantum dots prepared based on the above method are uniformly dispersed, and the average particle size is 4-5.5 nm. More specifically, the average particle size of L-chiral carbon quantum dots (L-CDs) is 5-5.5 nm, and the lattice spacing is 0.2-0.25 nm; the average particle size of D-chiral carbon quantum dots (D-CDs) is 4-5 nm, and the lattice spacing is 0.3-0.35 nm. Both have good crystal structures. Further, the chiral carbon quantum dots prepared based on the above method have stable fluorescence properties, which lays a good foundation for their use as imaging materials for bacteria and / or fungi.

[0011] It should be noted that traditional semiconductor quantum dots have high toxicity and poor photostability, and it is difficult to be used as imaging materials for bacteria and / or fungi. In addition, graphene quantum dots functionalized with chiral amino acids can selectively kill bacteria and are non-toxic to mammalian cells, and can perform bioimaging on Escherichia coli, Staphylococcus aureus, and Hela cells within 3 h. However, this kind of carbon quantum dots cannot effectively distinguish Gram-negative bacteria from Gram-positive bacteria within a short time (30 min), and cannot distinguish Gram-negative bacteria from fungi, so it cannot be used well as an imaging material for Gram-positive bacteria / fungi.

[0012] After incubating the chiral carbon quantum dots of the present invention with bacteria / fungi for about 30 min, they can stain Gram-positive bacteria and fungi well, and do not perform fluorescence imaging on Gram-negative bacteria, so as to achieve the purpose of distinguishing Gram-negative bacteria from Gram-positive bacteria / fungi. In addition, the chiral carbon quantum dots of the present invention can achieve blue, green, and red three-color fluorescence imaging.

[0013] Further, in one embodiment of the present invention, the bacterium is a Gram-positive bacterium. Specifically, the inventors found through a large number of experiments that the chiral carbon quantum dots in the present invention can achieve good staining of Gram-positive bacteria, making them show blue, green, and red fluorescence under three laser excitations, thereby achieving the purpose of identifying them. Preferably, the Gram-positive bacteria are Staphylococcus aureus (S. aureus, ATCC25923), Methicillin-resistant Staphylococcus aureus (MRSA, ATCC43300), Enterococcus faecalis (E. faecalis, ATCC29212), Bacillus subtilis (B. subtilis, CMCC(B)63501).

[0014] Further, in one embodiment of the present invention, the fungi are Candida albicans (C. albicans, ATCC10231), Candida parapsilosis (C. parapsilosis, ATCC22019), but are not limited thereto.

[0015] Correspondingly, the present invention also discloses a method for distinguishing Gram-positive bacteria / fungi from Gram-negative bacteria, which includes the steps of co-incubating the test bacteria with chiral carbon quantum dots and then performing detection.

[0016] Among them, the chiral carbon quantum dots can be left-handed chiral carbon quantum dots (L-CDs) or right-handed chiral carbon quantum dots (D-CDs).

[0017] Among them, the co-incubation time ≥ 30 min. If the incubation time < 30 min, the fluorescence observed in Gram-positive bacteria / fungi is relatively weak. Preferably, the incubation time is 30 - 40 min. Through this incubation time, the fluorescence is obvious, the detection accuracy is high, and the detection efficiency is high.

[0018] Among them, the detection is performed by flow cytometry or confocal laser scanning (CLSM) microscopy, but is not limited thereto. Preferably, confocal laser scanning (CLSM) microscopy is used for detection; its detection wavelengths are 405 nm, 488 nm, and 552 nm respectively. Further, when using confocal laser scanning (CLSM) microscopy for detection, if the test bacteria show blue, green, and red fluorescence under the excitation of three excitation wavelengths of 405 nm, 488 nm, and 552 nm, the test bacteria are Gram-positive bacteria or fungi; otherwise, the test bacteria are Gram-negative bacteria.

[0019] Preferably, in one embodiment of the present invention, the Gram-negative bacteria are Escherichia coli, Proteus mirabilis, and / or Salmonella; the Gram-positive bacteria are Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Enterococcus faecalis, and / or Bacillus subtilis.

[0020] Preferably, in one embodiment of the present invention, the fungus is Candida albicans and / or Candida parapsilosis;

[0021] The Gram-negative bacteria are Escherichia coli, Proteus mirabilis and / or Salmonella.

[0022] Implementing the present invention has the following beneficial effects:

[0023] The present invention provides an application of chiral quantum dots as imaging materials for bacteria and / or fungi. Specifically, the chiral carbon quantum dots (left-handed chiral carbon quantum dots or right-handed chiral carbon quantum dots) of the present invention have the advantages of low toxicity, good biocompatibility, anti-photobleaching, and stable fluorescence properties, and they have chiral properties and fluorescence emission dependent on the laser wavelength, and are suitable as imaging materials for bacteria and / or fungi. Using the chiral quantum dots of the present invention as imaging materials can achieve the detection of Gram-positive bacteria and fungi, as well as the distinction between Gram-positive bacteria and Gram-negative bacteria. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Structural characterization and photophysical property diagrams of chiral carbon quantum dots in Example 1 and Example 2; wherein, A is the circular dichroism spectrum diagram of chiral carbon quantum dots (D-CDs, L-CDs); B is the Zeta potential diagram of chiral carbon quantum dots (D-CDs, L-CDs); C is the transmission electron microscopy morphology diagram and particle size distribution diagram of right-handed chiral carbon quantum dots (D-CDs); D is the high-resolution transmission electron microscopy and lattice morphology diagram of right-handed chiral carbon quantum dots (D-CDs); E is the fluorescence spectrum diagram of right-handed chiral carbon quantum dots (D-CDs); F is the fluorescence spectrum diagram of right-handed chiral carbon quantum dots (D-CDs) in different ratios of tetrahydrofuran-water mixtures; G is the line graph of the change in fluorescence intensity of right-handed chiral carbon quantum dots (D-CDs) in different ratios of tetrahydrofuran-water mixtures; H is the transmission electron microscopy morphology diagram of right-handed chiral carbon quantum dots (D-CDs) in a 60% (v:v) tetrahydrofuran-water mixture;

[0025] Figure 2Structural characterization and photophysical property diagrams of chiral carbon quantum dots in Example 1 and Example 2; wherein, A is the UV-Vis absorption spectrum diagram of chiral carbon quantum dots (D-CDs, L-CDs); B is the Fourier transform infrared spectrum diagram of chiral carbon quantum dots (D-CDs, L-CDs); C is the transmission electron microscopy morphology diagram and particle size distribution diagram of L-CDs; D is the high-resolution transmission electron microscopy and lattice morphology diagram of L-CDs; E is the fluorescence spectrum diagram of L-CDs; F is the fluorescence spectrum diagram of L-CDs in tetrahydrofuran-water mixtures with different ratios; G is the line graph of the change in fluorescence intensity of L-CDs in tetrahydrofuran-water mixtures with different ratios; H is the transmission electron microscopy morphology diagram of L-CDs in a 70% (v:v) tetrahydrofuran-water mixture;

[0026] Figure 3 Laser confocal (CLSM) microscope images and flow cytometer detection results of chiral carbon quantum dots and Gram-positive bacteria; wherein, A is D-CDs, and B is L-CDs;

[0027] Figure 4 Laser confocal (CLSM) microscope images and flow cytometer detection results of chiral carbon quantum dots and Gram-negative bacteria; wherein, A is D-CDs, and B is L-CDs;

[0028] Figure 5 Laser confocal (CLSM) microscope images and flow cytometer detection results of chiral carbon quantum dots and fungi; wherein, A is D-CDs, and B is L-CDs. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Preparation and characterization of L-CDs in Example 1

[0031] This example provides a preparation method for L-CDs, which is as follows:

[0032] (1) Weigh 0.06 g of sodium hydroxide precisely into 15 mL of ultrapure water, stir and dissolve it with a glass rod, add 0.5 g of L-cysteine, stir and dissolve it, and perform ultrasonic treatment for 10 min until the sample is fully mixed;

[0033] (2) Transfer the dispersed solution to a 50 mL polytetrafluoroethylene liner and place it in the steel sleeve of a high-pressure reactor;

[0034] (3) Place the reactor in an electrothermal blast drying oven and carry out hydrothermal reaction at 120 °C for 16 h;

[0035] (4) After the reaction is completed, wait for the reactor to cool to room temperature. Centrifuge the obtained orange-red suspension at 10000 rpm for 10 min to collect the supernatant;

[0036] (5) Filter the supernatant with a 0.22 μm cylindrical filter membrane, transfer the obtained filtrate into a dialysis bag with MW = 1000 Da, place it in deionized water for dialysis for 24 h, and change the external dialysis solution every 4 h during the process;

[0037] (6) After the dialysis process is completed, collect the yellow solution in the dialysis bag to obtain a pure aqueous solution of dextral chiral carbon quantum dots;

[0038] (7) Freeze-dry the yellow carbon quantum dot solution in a vacuum freeze dryer at -60 °C for 48 h. The obtained brown powder is dextral chiral carbon quantum dots and is stored at 4 °C for standby.

[0039] Example 2 Preparation and Characterization of Dextral Chiral Carbon Quantum Dots (D-CDs)

[0040] This example provides a preparation method for dextral chiral carbon quantum dots, which is as follows:

[0041] (1) Weigh 0.06 g of sodium hydroxide precisely into 15 mL of ultrapure water, stir and dissolve it with a glass rod, add 0.5 g of dextral cysteine, stir and dissolve it, and perform ultrasonic treatment for 10 min until the sample is fully mixed;

[0042] (2) Transfer the dispersed solution to a 50 mL polytetrafluoroethylene liner and place it in the steel sleeve of a high-pressure reactor;

[0043] (3) Place the reactor in an electrothermal blast drying oven and carry out hydrothermal reaction at 120 °C for 16 h;

[0044] (4) After the reaction is completed, wait for the reactor to cool to room temperature. Centrifuge the obtained orange-red suspension at 10000 rpm for 10 min to collect the supernatant;

[0045] (5) Filter the supernatant with a 0.22 μm cylindrical filter membrane, transfer the obtained filtrate into a dialysis bag with MW = 1000 Da, place it in deionized water for dialysis for 24 h, and change the external dialysis solution every 4 h during the process;

[0046] (6) After the dialysis process is completed, collect the yellow solution in the dialysis bag to obtain a pure aqueous solution of dextral chiral carbon quantum dots;

[0047] (7) The yellow carbon quantum dot solution was freeze-dried in a vacuum freeze dryer at -60 °C for 48 h, and the resulting brown powder was the dextral chiral carbon quantum dots, which were stored at 4 °C for later use.

[0048] The left-handed carbon quantum dots (L-CDs) and right-handed carbon quantum dots (D-CDs) obtained in Examples 1 and 2 were tested. The specific test methods are as follows:

[0049] 1) Use a pipette to aspirate 2 mL of the chiral carbon quantum dot solution with a concentration of 0.01 mg / mL into a quartz cuvette, place it in a circular dichroism spectrometer to collect CD signals; place it in an ultraviolet spectrophotometer to test the ultraviolet absorption spectrum from 200 to 800 nm; test the fluorescence emission spectrum of the chiral carbon quantum dots at an excitation wavelength from 280 to 500 nm.

[0050] 2) Prepare a 0.5 mg / mL solution of the chiral carbon quantum dots with ultrapure water, perform ultrasonic dispersion treatment for 20 min, use a pipette to aspirate 1 mL of the solution and inject it into a Malvern Zeta potential cell, and perform Zeta potential testing on the chiral carbon quantum dots with a Malvern laser particle size analyzer ZS90.

[0051] 3) Prepare a 1 mg / mL solution of the chiral carbon quantum dots with ultrapure water, perform ultrasonic dispersion treatment for 20 min, use a pipette to aspirate 10 μL of the well-dispersed solution drop by drop onto a 300-mesh transmission electron microscopy (TEM) special copper grid, and allow it to dry naturally at room temperature for 24 h, and observe it under a TEM with an acceleration voltage of 200 kV and 300 kV.

[0052] 4) Accurately weigh the chiral carbon quantum dot powder and dry potassium bromide in a mass ratio of 1:100 with a balance, place them in an agate mortar and grind them finely, transfer the powder to an infrared mold, evacuate and apply pressure for 3 min, and collect Fourier transform infrared spectroscopy data after pressing into a tablet.

[0053] 5) Aggregation-induced emission effect test: Prepare a mixture of tetrahydrofuran and water with a volume ratio v:v = 0% to 100%, add chiral carbon quantum dots with a final concentration of 10 μg / mL, and test the fluorescence spectrum at an excitation wavelength of 340 nm.

[0054] The specific test results are as Figure 1 shown. Specifically, Figure 1 The circular dichroism spectrum of A shows that L-CDs and D-CDs exhibit opposite and symmetric chiral signals, indicating that the carbon quantum dots have successfully inherited the chiral properties of the left-handed / dextral cysteine raw materials; Figure 1 B shows that the chiral L / D-CDs have similar Zeta potential values; Figure 1The transmission electron microscopy (TEM) test results of C and D show that the prepared chiral carbon quantum dots are spherical and evenly dispersed, with an average particle size of 4 - 5.5 nm. The average particle size of L-CDs is 5.2 nm, and that of D-CDs is 4.3 nm. They have a good crystal structure, and the lattice spacing is 0.22 or 0.33 nm; Figure 1 E. The fluorescence spectra show that the chiral carbon quantum dots have the characteristic of fluorescence emission dependent on the excitation wavelength and have the maximum emission under the excitation of 340 nm; Figure 2 A. The ultraviolet spectra show that the chiral carbon quantum dots have two absorption peaks at 275 nm and 320 nm respectively, which are attributed to the π-π* transition of C=C and the n-π* transition of C=O; Figure 2 In the Fourier transform infrared spectrum of B, the broad peak at 3400 cm -1 and the small hump at 3207 cm -1 are attributed to the stretching vibrations of O-H and N-H. The peaks at 2975 and 2920 cm -1 originate from C-H. The peaks at 1610 cm -1 and 1135 cm -1 may be related to the stretching vibrations of C=O and C-O respectively. The peak at 1380 cm -1 may originate from C-N, N-H and COO - . Among them, the peaks at 2550 and 1190 cm -1 are related to the presence of S, and are attributed to -S-H and C-S respectively. Compared with the raw material cysteine, the peaks at these two positions of L / D-CDs are not obvious, which may be due to polymerization during the hydrothermal process. It can be seen from the infrared spectrum that the chiral carbon quantum dots have characteristic groups such as -COOH, -OH, -NH2, etc., which is related to the good water solubility characteristics of the carbon quantum dots. In the test of the aggregation-induced emission behavior of the chiral carbon quantum dots, Figure 1 F shows that within a certain range, the fluorescence intensity of the carbon quantum dots increases with the increase of the volume ratio of THF. The maximum fluorescence intensities of D-CDs and L-CDs are reached when THF:H2O = 60%, 70% (v:v) respectively. Further observation by transmission electron microscopy shows that the chiral carbon quantum dots form large aggregated particles with a diameter of 20 - 30 nm in the THF-H2O binary system, verifying that L / D-CDs have an aggregation-induced effect.

[0055] Example 3 Confocal imaging test of chiral carbon quantum dots with bacteria

[0056] Test strains used: Gram-positive bacteria: Staphylococcus aureus (S. aureus, ATCC25923), methicillin-resistant Staphylococcus aureus (MRSA, ATCC43300), Enterococcus faecalis (E. faecalis, ATCC29212), Bacillus subtilis (B. subtilis, CMCC(B)63501). Gram-negative bacteria: Escherichia coli (E. coli, ATCC25922), Proteus mirabilis (P. mirabilis, Pro10(AO250)), Salmonella typhimurium (S. typhimurium, ATCC14028). Fungi: Candida albicans (C. albicans, ATCC10231), Candida parapsilosis (C. parapsilosis, ATCC22019). Use an inoculation loop to pick single bacterial colonies into 5 mL of LB broth medium respectively, and pick a single colony of Candida albicans into Sabouraud glucose fungal medium, and incubate overnight with shaking at 37 °C and 200 rpm for 18 h. Centrifuge the bacteria and fungi at 5000 rpm for 3 min to collect, resuspend with sterile PBS buffer (10 mM, pH = 7.4), and adjust the bacterial concentration to 1×10 6 ~10 7 CFU / mL. Incubate the bacteria and fungi with L / D-CDs (final concentration 50 μg / mL) at 37 °C and 200 rpm on a shaker for 30 min. After incubation, rinse twice with sterile PBS, and finally resuspend with 1 mL of PBS and vortex to mix evenly. Pipette 10 μL and place it on a clean glass slide, carefully cover it with a coverslip using forceps, and observe under a laser confocal microscope with a 100× oil immersion objective lens.

[0057] Figure 3 Confocal images of A, 3B, 5A, and 5B show that after treatment with chiral carbon quantum dots for 30 min, the four Gram-positive bacteria and two fungi show blue, green, and red fluorescence under lasers with three excitation wavelengths of 405, 488, and 552 nm respectively. Figure 4 A and B show that no obvious fluorescence of carbon quantum dots was observed in the three tested Gram-negative bacteria, which proves that chiral carbon quantum dots enter Gram-positive bacteria / fungi within a short time, but cannot enter Gram-negative bacteria. Gram-positive bacteria / fungi can be well distinguished from Gram-negative bacteria.

[0058] Example 4 Flow cytometry test of chiral carbon quantum dots and bacteria

[0059] Use an inoculation loop to pick single colonies of the test strains into 5 mL of LB broth medium, and pick single colonies of Candida albicans into Sabouraud glucose fungal medium. Incubate with shaking at 37°C and 200 rpm for 18 h. Centrifuge the bacteria / fungi at 5000 rpm for 3 min to collect, resuspend with sterilized PBS buffer (10 mM, pH = 7.4), and adjust the bacterial concentration to 1×10 6 ~10 7 CFU / mL. Incubate the bacteria / fungi with L / D-CDs (final concentration 50 μg / mL) at 37°C with shaking at 200 rpm for 30 min, using PBS as a control. After incubation, rinse twice with sterilized PBS, finally resuspend with 1 mL of PBS, vortex to mix evenly, and quantitatively detect the fluorescence intensity of chiral carbon quantum dots in the bacteria using a flow cytometer.

[0060] The results are shown in Figure 3 、 4 、5. Compared with the control group, significantly increased fluorescence signals were detected in Gram-positive bacteria / fungi by flow cytometry, while no obvious fluorescence signals were detected in the three Gram-negative bacteria. It is proved that chiral carbon quantum dots can better distinguish Gram-positive bacteria / fungi from Gram-negative bacteria.

[0061] The above is the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A method for distinguishing Gram-positive bacteria from Gram-negative bacteria, characterized in that: The method comprises the steps of incubating the bacteria to be detected with the chiral carbon quantum dots and then performing the detection; wherein the incubation time is ≥30 minutes; After incubation, blue, green, and red fluorescence from the chiral carbon quantum dots was observed in Gram-positive bacteria at excitation wavelengths of 405 nm, 488 nm, and 552 nm, while no fluorescence was observed in Gram-negative bacteria; The preparation method of the chiral carbon quantum dots is: Sodium hydroxide, L-cysteine or D-cysteine, and water are mixed in a weight ratio of (0.1-1): (3-7): (120-200), reacted at 100-140° C. for 12-20 hours, and the resulting reaction solution is centrifuged and dialyzed to obtain chiral carbon quantum dots.

2. The method according to claim 1, wherein The Gram-negative bacteria are Escherichia coli, Proteus mirabilis and / or Salmonella; The Gram-positive bacteria are Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Enterococcus faecalis and / or Bacillus subtilis.

3. A method for distinguishing fungi from Gram-negative bacteria, characterized in that: The method comprises the steps of incubating the bacteria to be detected with the chiral carbon quantum dots and then performing the detection; wherein the incubation time is ≥30 minutes; After incubation, blue, green, and red fluorescence from the chiral carbon quantum dots was observed in fungi at excitation wavelengths of 405 nm, 488 nm, and 552 nm, while no fluorescence was observed in Gram-negative bacteria; The preparation method of the chiral carbon quantum dots is: Sodium hydroxide, L-cysteine or D-cysteine, and water are mixed in a weight ratio of (0.1-1): (3-7): (120-200), reacted at 100-140° C. for 12-20 hours, and the resulting reaction solution is centrifuged and dialyzed to obtain chiral carbon quantum dots.

4. The method according to claim 3, wherein The fungus is Candida albicans and / or Candida parapsilosis; The Gram-negative bacteria are Escherichia coli, Proteus mirabilis and / or Salmonella.

5. The method according to claim 1 or 3, wherein: include: The bacteria to be tested were resuspended in sterile PBS, where the concentration of the bacteria to be tested was 1×10 6 ~1×10 7 CFU / mL; Mix the chiral carbon quantum dots with the resuspended test bacteria and incubate in a shaker at 30-45°C and 180-250 rpm for 10-30 minutes. The concentration of the chiral carbon quantum dots is 40-70 μg / mL. The incubated product was rinsed 1 to 3 times with sterile PBS, and finally resuspended with sterile PBS. After vortexing, it was detected by flow cytometry or laser confocal microscopy.

Images