Fluorescence Lifetime Detection System and Detection Method

Abstract

A fluorescence lifetime detection system and a detection method. The fluorescence lifetime detection system includes: a labeling unit for providing quantum dots and for labeling a detection object with the quantum dots; a light emitting unit for providing excitation light, the excitation light being projected onto the detection object labeled with the quantum dots, and the quantum dots being capable of generating fluorescence; a photodetector for detecting the fluorescence generated by the quantum dots and collecting fluorescence signals; and a time-correlated single photon counting unit for obtaining time-based fluorescence lifetime data based on the fluorescence signals. The quantum dots can exhibit different fluorescence lifetimes according to the different microenvironments of the detection object itself. Thus, by detecting the fluorescence generated by the quantum dots, the microenvironment of the detection object can be detected according to the fluorescence lifetime of the quantum dots. Moreover, compared with the autofluorescence of the detection object, the fluorescence lifetime of the fluorescence generated by the quantum dots is longer, and the fluorescence signal obtained by detecting the fluorescence generated by the quantum dots is stronger, which can reduce the detection difficulty and improve the detection accuracy.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of optical detection, and in particular to a fluorescence lifetime detection system and a detection method. Background Art

[0002] Optical methods are often used to detect whether human organs are diseased, and fluorescence lifetime is one of the optical parameters used to detect diseases.

[0003] When a substance is excited and transitions to an excited state, and then returns to the ground state in the form of radiative transition, the average residence time in the upper energy level is the fluorescence lifetime. Refer to Figure 1 , which shows the fluorescence lifetime principle diagram. The abscissa of the principle diagram is time, and the ordinate is fluorescence intensity. As shown in the principle diagram, the time required for the fluorescence intensity of the molecule to drop to 1 / e of the maximum value J max is used as the fluorescence lifetime.

[0004] The fluorescence lifetime can be described by a single e-exponential formula:

[0005] I(t) = I max exp(-t / τ)

[0006] where τ is the fluorescence lifetime, I max is the maximum fluorescence intensity value emitted, and I(t) is the fluorescence intensity at time t.

[0007] The fluorescence lifetime of a fluorescent substance is related to its own structure, the polarity, viscosity, pH, etc. of the microenvironment it is in. Therefore, the measurement of the fluorescence lifetime can reflect the changes occurring in the system. The fluorescence lifetime is mostly at the nanosecond level, and various complex intermolecular interaction processes can be observed through fluorescence technology.

[0008] When a human organ is diseased, the metabolism of the microenvironment in which human cells or tissues are located is abnormal, thus affecting the fluorescence lifetime of certain molecules in human cells or tissues. By detecting the indicators corresponding to the fluorescence lifetime, it can be judged whether the metabolism in the human body is abnormal, and further whether the organ is diseased.

[0009] However, the accuracy and sensitivity of existing optical detection systems or detection methods are insufficient, and there is a certain misdiagnosis rate. Summary of the Invention

[0010] The problem solved by the embodiments of the present invention is to provide a fluorescence lifetime detection system and a detection method, which can reduce the detection difficulty and improve the detection accuracy.

[0011] To solve the above problems, an embodiment of the present invention provides a fluorescence lifetime detection system, including: a labeling unit for providing quantum dots and labeling a detection object with the quantum dots; a light emitting unit for providing excitation light, which is projected onto the detection object labeled with the quantum dots, and the quantum dots can generate fluorescence; a photodetector for detecting the fluorescence generated by the quantum dots and collecting fluorescence signals; a time-correlated single photon counting unit for obtaining time-based fluorescence lifetime data based on the fluorescence signals.

[0012] Optionally, the time-correlated single photon counting unit includes: a processor for processing the fluorescence signals collected by the photodetector to obtain the fluorescence lifetime; the detection system further includes: a control module connected to the light emitting unit for controlling the pulse frequency of the excitation light provided by the light emitting unit; the control module is also connected to the processor for triggering the processor to process the signals collected by the photodetector.

[0013] Optionally, the time-correlated single photon counting unit further includes: a driver for providing a reference pulse clock signal; the control module includes: a pulse signal delay generator for outputting a first pulse signal and a second pulse signal based on the reference pulse clock signal, both the first pulse signal and the second pulse signal include a first level and a second level, the first level is used to turn on the light emitting unit to emit the excitation light, the second level is used to turn off the light emitting unit, and the first levels in the first pulse signal and the second pulse signal do not overlap; a first light source power controller connected to the light emitting unit and the pulse signal delay generator for controlling the pulse frequency of the excitation light emitted by the light emitting unit based on the first pulse signal and outputting a corresponding third pulse signal; a second light source power controller connected to the pulse signal delay generator for receiving the second pulse signal; a synchronous pulse signal generator connected to the second light source power controller for outputting a fourth pulse signal corresponding to the time period when the light emitting unit does not emit excitation light, having the same pulse frequency as and synchronized with the excitation light based on the second pulse signal provided by the second light source power controller; an electrical signal synthesizer connected to the first light source power controller and the synchronous pulse signal generator for synthesizing the third pulse signal and the fourth pulse signal to obtain a fifth pulse signal and outputting the fifth pulse signal to the processor; the processor is used to process the signals collected by the photodetector based on the fifth pulse signal.

[0014] Optionally, the first pulse signal and the second pulse signal are inverse signals to each other.

[0015] Optionally, the electrical signal synthesizer is used to perform an OR operation on the third pulse signal and the fifth pulse signal.

[0016] Optionally, the quantum dots provided by the marking unit include quantum dots with a core-shell structure.

[0017] Optionally, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide, and the shell of the core is zinc sulfide.

[0018] Optionally, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide, and the shell of the core is zinc sulfide; the light-emitting unit is used to emit picosecond laser light with a wavelength of 350 nanometers to 450 nanometers or femtosecond laser light with a wavelength of 700 nanometers to 900 nanometers.

[0019] Optionally, the detection system further includes: a scanning unit, which is used to scan the detection object with the excitation light, or which is used to control the excitation light to detect a preset position of the detection object.

[0020] Optionally, a dichroic mirror is further provided on the optical path between the light-emitting unit and the detection object, which is used to distinguish the excitation light and the fluorescence.

[0021] Optionally, the detection system further includes: a stage, which is used to place the detection object, or the detection system further includes: an optical fiber, which is used to transmit the excitation light to the detection object and is also used to transmit the fluorescence.

[0022] Correspondingly, an embodiment of the present invention further provides a method for detecting fluorescence lifetime, including: providing quantum dots; using the quantum dots to mark a detection object; providing excitation light; making the excitation light project onto the detection object marked with the quantum dots to cause the quantum dots to generate fluorescence; detecting the fluorescence generated by the quantum dots and collecting fluorescence signals; obtaining time-based fluorescence lifetime data according to the fluorescence signals.

[0023] Optionally, the step of providing quantum dots includes: preparing a quantum dot solution; the step of using the quantum dots to mark a detection object includes: soaking the detection object in the quantum dot solution.

[0024] Optionally, the concentration of the quantum dot solution is 0.1 milligram per milliliter to 10 milligrams per milliliter; the time for soaking the detection object in the quantum dot solution is 2 hours to 8 hours.

[0025] Optionally, in the step of providing quantum dots, the fluorescence lifetime of the quantum dots is 100 nanoseconds to 1000 nanoseconds.

[0026] Optionally, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide, and the shell of the core is zinc sulfide.

[0027] Optionally, the step of projecting the excitation light onto the analyte labeled with quantum dots to cause the quantum dots to generate fluorescence includes: scanning the excitation light on the analyte labeled with quantum dots, or controlling the excitation light to detect a preset position of the analyte labeled with quantum dots.

[0028] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0029] In the fluorescence lifetime detection system provided by the embodiment of the present invention, the labeling unit is used to label the analyte with the quantum dots. The excitation light provided by the light emitting unit is projected onto the analyte labeled with the quantum dots, and the quantum dots can generate fluorescence. The photodetector correspondingly detects the fluorescence generated by the quantum dots and collects the fluorescence signal. Quantum dots can exhibit different fluorescence lifetimes according to the different microenvironments of the analyte itself. Therefore, by detecting the fluorescence generated by the quantum dots, the microenvironment of the analyte can be detected according to the fluorescence lifetime of the quantum dots. Moreover, compared with the autofluorescence of the analyte, the fluorescence lifetime of the quantum dots is longer, and the fluorescence signal obtained by detecting the fluorescence generated by the quantum dots is stronger, which can reduce the detection difficulty and improve the detection accuracy.

[0030] In the fluorescence lifetime detection method provided by the embodiment of the present invention, the analyte is labeled with the quantum dots, the excitation light is projected onto the analyte labeled with the quantum dots to cause the quantum dots to generate fluorescence, and the fluorescence generated by the quantum dots is detected and the fluorescence signal is collected. Quantum dots can exhibit different fluorescence lifetimes according to the different microenvironments of the analyte itself. Therefore, by detecting the fluorescence generated by the quantum dots, the microenvironment of the analyte can be detected according to the fluorescence lifetime of the quantum dots. Moreover, compared with the autofluorescence of the analyte, the fluorescence lifetime of the quantum dots is longer, and the fluorescence signal obtained by detecting the fluorescence generated by the quantum dots is stronger, which can reduce the detection difficulty and improve the detection accuracy. Description of the Drawings

[0031] Figure 1 is a schematic diagram of fluorescence lifetime;

[0032] Figure 2 is a functional block diagram of an embodiment of the fluorescence lifetime detection system of the present invention;

[0033] Figure 3 is a schematic structural diagram of an embodiment of the fluorescence lifetime detection system of the present invention;

[0034] Figure 4 shows the pulse waveforms of a reference pulse clock signal, a first pulse signal, a second pulse signal, a third pulse signal, a fourth pulse signal, and a fifth pulse signal;

[0035] Figure 5 The fluorescence lifetime distribution curve and histogram of the quantum dots corresponding to the analyte are shown;

[0036] Figure 6 It is a schematic flowchart of an embodiment of the method for detecting the fluorescence lifetime of the present invention. Detailed implementation manners

[0037] As can be seen from the background art, the accuracy of existing optical detection systems or detection methods still needs to be improved.

[0038] Analysis of the reasons for the above technical problems reveals that: currently, autofluorescence of cells or tissues is usually collected to obtain the fluorescence lifetime information of the detection sample. However, the autofluorescence signal of the sample is weak and difficult to detect, and the autofluorescence lifetime of the sample is short with low discrimination, resulting in the need to improve the detection accuracy.

[0039] Currently, there is also a method called HE staining method (hematoxylin-eosin staining method), which stains the cell nucleus and cytoplasm with hematoxylin and eosin respectively, takes pictures with an ordinary microscope, and manually judges the detection results according to the nuclear morphology, size, nuclear occupancy ratio, etc.

[0040] However, when using the HE staining method for detection, manual discrimination is not accurate and objective enough, and it is easy to cause certain false negative or false positive results due to sample quality problems, personnel level problems, etc., thereby reducing the detection accuracy.

[0041] To solve the above technical problems, an embodiment of the present invention provides a fluorescence lifetime detection system, including: a labeling unit for providing quantum dots and for labeling an analyte with the quantum dots; a light emitting unit for providing excitation light, the excitation light being projected onto the analyte labeled with the quantum dots, and the quantum dots being capable of generating fluorescence; a photodetector for detecting the fluorescence generated by the quantum dots and collecting fluorescence signals; a time-correlated single photon counting unit for obtaining time-based fluorescence lifetime data according to the fluorescence signals.

[0042] In the fluorescence lifetime detection system provided by the embodiments of the present invention, the labeling unit is used to label the analyte with the quantum dots. The excitation light provided by the light emitting unit is projected onto the analyte labeled with the quantum dots. The quantum dots can generate fluorescence, and the photodetector correspondingly detects the fluorescence generated by the quantum dots and collects the fluorescence signal. The quantum dots can exhibit different fluorescence lifetimes according to the microenvironment of the analyte itself. Therefore, by detecting the fluorescence generated by the quantum dots, the microenvironment of the analyte can be detected based on the fluorescence lifetime of the quantum dots. Moreover, compared with the autofluorescence of the analyte, the fluorescence lifetime of the quantum dots is longer, and the fluorescence signal obtained by detecting the fluorescence generated by the quantum dots is stronger, which can reduce the detection difficulty and improve the detection accuracy.

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0044] Reference Figure 2 , which shows a functional block diagram of an embodiment of the fluorescence lifetime detection system of the present invention. The fluorescence lifetime detection system according to the embodiment of the present invention includes: a labeling unit, a light emitting unit, a photodetector, and a time-correlated single photon counting unit. Among them:

[0045] The labeling unit 100 is used to provide quantum dots and also to label the analyte with the quantum dots;

[0046] The light emitting unit 110 is used to provide excitation light. The excitation light is projected onto the analyte labeled with the quantum dots, and the quantum dots can generate fluorescence;

[0047] The photodetector 120 is used to detect the fluorescence generated by the quantum dots and collect the fluorescence signal;

[0048] The time-correlated single photon counting unit 130 is used to obtain time-based fluorescence lifetime data based on the fluorescence signal.

[0049] Using the fluorescence lifetime detection system of the above embodiment, the labeling unit 100 is used to label the analyte with the quantum dots. The excitation light provided by the light emitting unit 110 is projected onto the analyte labeled with the quantum dots. The quantum dots can generate fluorescence, and the photodetector 120 correspondingly detects the fluorescence generated by the quantum dots and collects the fluorescence signal. The quantum dots can exhibit different fluorescence lifetimes according to the different microenvironments of the analyte itself. Therefore, by detecting the fluorescence generated by the quantum dots, the microenvironment of the analyte can be detected according to the fluorescence lifetime of the quantum dots. Moreover, compared with the autofluorescence of the analyte, the fluorescence lifetime of the quantum dots is longer, and the fluorescence signal obtained by detecting the fluorescence generated by the quantum dots is stronger, which can reduce the detection difficulty and improve the detection accuracy.

[0050] Specifically, in this embodiment, the labeling unit 100 is used to provide quantum dots with pH sensitivity and a relatively long fluorescence lifetime to label the analyte. Thus, by measuring the fluorescence lifetime of the quantum dots, the pH environment of the analyte itself can be detected, and then it can be determined whether it is abnormal.

[0051] It should be noted that the fluorescence lifetime of the quantum dots should not be too short, otherwise it is easy to increase the detection difficulty. For this reason, in this embodiment, the fluorescence lifetime of the quantum dots is at least 100 nanoseconds.

[0052] The fluorescence lifetime of the quantum dots should not be too long either, otherwise it is easy to increase the detection time and cause unnecessary time waste. As an example, the fluorescence lifetime of the quantum dots is from 100 nanoseconds to 1000 nanoseconds.

[0053] As an embodiment, the quantum dots provided by the labeling unit 100 include quantum dots with a core-shell structure.

[0054] The quantum dots with a core-shell structure are coated with a shell layer (i.e., a cladding) on the surface of the quantum dots. The cladding can isolate the core from the external environment, thereby reducing the probability of the core being affected by the external environment. For example, it can prevent the core from being oxidized by the external environment and prevent the core substances from overflowing, etc., and then improve the structural stability of the quantum dots.

[0055] In other embodiments, based on actual requirements, the quantum dots can also be other types of quantum dots.

[0056] As an example, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide (AgInS2, AIS), and the cladding of the core is zinc sulfide (ZnS). The AIS / ZnS quantum dots have a relatively long fluorescence lifetime, generate a strong fluorescence signal, and have good sensitivity to acidity and alkalinity, which is beneficial to reducing the detection difficulty and further improving the measurement accuracy.

[0057] In other embodiments, based on actual requirements, the quantum dots provided by the labeling unit may also be other quantum dots with a core-shell structure.

[0058] In this embodiment, the labeling unit 100 includes: a quantum dot preparation module (not shown in the figure), which is used to prepare the quantum dots; and a staining and labeling module (not shown in the figure), which is used to label the analyte with the quantum dots.

[0059] Specifically, the quantum dot preparation module is used to prepare a quantum dot solution, and the staining and labeling module is used to soak the analyte in the quantum dot solution, thereby realizing the labeling of the analyte.

[0060] It should be noted that the above method of labeling the analyte with quantum dots is only an example. In other embodiments, other methods may also be used to label the analyte.

[0061] Specifically, as an example, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide (AgInS2, AIS), and the shell of the core is zinc sulfide (ZnS).

[0062] Correspondingly, as an embodiment, the quantum dot preparation module is used to provide an indium source solution; adjust the pH value of the indium source solution; after adjusting the pH value of the indium source solution, add a silver source solution and a sulfur source solution to the indium source solution; and perform a chemical synthesis process on the mixed solution of the silver source solution, the sulfur source solution, and the indium source solution to obtain a core solution of the quantum dots.

[0063] More specifically, as an embodiment, the quantum dot preparation module is used to mix glutathione, ammonium citrate, and InCl3·4H2O under stirring to obtain a mixed solution; adjust the pH value of the mixed solution; after adjusting the pH value of the mixed solution, add AgNO3 and Na2S·9H2O to the mixed solution; and perform a microwave chemical reaction process on the mixed solution to obtain a core solution of the quantum dots.

[0064] Among them, as an example, the quantum dot preparation module is used to mix glutathione (0.5 - 10 mmol), ammonium citrate (1 - 20 mmol), and InCl3·4H2O (0.5 - 10 mmol) under stirring to obtain a mixed solution.

[0065] As an example, the quantum dot preparation module is used to add NH4OH to the mixed solution to adjust the pH value of the mixed solution to 6.5 - 10.5.

[0066] As an example, the quantum dot preparation module is used to add 0.05 - 0.5 mmol of AgNO3 and 0.5 - 10 mmol of Na2S·9H2O into a mixed solution.

[0067] As an example, the quantum dot preparation module is used to keep the microwave chemical reaction system at 60 - 99 °C for 50 - 150 minutes to perform microwave chemical reaction treatment on the mixed solution.

[0068] Specifically, as an example, the quantum dots include quantum dots with a core-shell structure; the shell of the core is zinc sulfide (ZnS).

[0069] Correspondingly, as an embodiment, the quantum dot preparation module is used to add a zinc source solution into the core solution of the quantum dots, then add a sulfur source solution into the mixed solution of the zinc source solution and the core solution, and perform chemical synthesis treatment on the mixed solution of the sulfur source solution, the zinc source solution and the core solution to obtain AIS / ZnS core / shell quantum dots.

[0070] More specifically, as an embodiment, the quantum dot preparation module is used to add a solution containing ZnCl2 and glutathione into the core solution of the quantum dots, then add Na2S·9H2O into the mixed solution, and perform heating treatment on the mixed solution to obtain AIS / ZnS core / shell quantum dots; then, perform purification treatment and drying treatment on the prepared AIS / ZnS in sequence, and perform dilution treatment and pH value adjustment treatment to obtain a neutral AIS / ZnS quantum dot solution.

[0071] As an example, the quantum dot preparation module adds 1 - 30 mL of a solution containing 0.5 - 5 mmol of ZnCl2 and 0.5 - 5 mmol of glutathione into the core solution of the quantum dots, then adds 1 - 30 mL of Na2S·9H2O (0.5 - 5 mmol) into the mixed solution, and heats the mixture to 60 - 99 °C, and the heating treatment time is 1 - 30 minutes; then, perform 1 - 5 times of purification treatment on the prepared AIS / ZnS with ethanol, perform vacuum drying treatment at 70 - 110 °C, dilute it to 0.1 - 30 mg / mL, and adjust the pH value to 7.0.

[0072] Among them, the concentration of the quantum dot solution should not be too low or too high. If the concentration of the quantum dot solution is too low, the staining and labeling module will take too long to label the analyte; if the concentration of the quantum dot solution is too high, it is easy for some quantum dots that have not entered the analyte cells to adhere to the cell membrane or the culture dish, resulting in difficult cleaning, and these adhered quantum dots will affect the imaging quality. In addition, too high a concentration of the quantum dot solution will also cause waste of materials. Therefore, in this embodiment, the concentration of the quantum dot solution is 0.1-30 mg / mL.

[0073] Specifically, the staining and labeling module is used to immerse the analyte in the quantum dot solution to achieve labeling of the analyte.

[0074] It should be noted that the time for immersing the analyte in the quantum dot solution should not be too short or too long. If the time for immersing the analyte in the quantum dot solution is too short, it is easy for the quantum dots not to fully enter the cells of the analyte; if the time for immersing the analyte in the quantum dot solution is too long, it is easy to affect the cell morphology of the analyte and cause unnecessary time waste. Therefore, in this embodiment, the time for immersing the analyte in the quantum dot solution is 1 hour to 8 hours.

[0075] Continue to refer to Figure 2 Furthermore, in this embodiment, the time-correlated single-photon counting unit 130 includes: a processor 31, configured to perform data processing on the fluorescence signals collected by the photodetector 120 to obtain the fluorescence lifetime.

[0076] More specifically, the processor 31 is configured to detect and count photons, so as to measure the lifetime of the fluorescence generated by the quantum dots.

[0077] As an example, the processor 31 is a time-correlated single-photon counting (Time-correlated singlephoton counting) data acquisition card.

[0078] Refer to Figure 3 which shows Figure 2 the structural schematic diagram of the detection system shown.

[0079] Specifically, the detection system includes:

[0080] A labeling unit 100, configured to provide quantum dots and also to label an analyte with the quantum dots. As an example, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide (AgInS2, AIS), and the shell of the core is zinc sulfide (ZnS).

[0081] The light-emitting unit 110 is configured to emit picosecond laser light with a wavelength ranging from 350 nm to 450 nm or femtosecond laser light with a wavelength ranging from 700 nm to 900 nm. The laser light is used to excite quantum dots labeled on a detection object to reach an excited state, and then the quantum dots emit fluorescence. Specifically, the laser light is used to excite AIS / ZnS quantum dots to reach an excited state and then emit fluorescence.

[0082] In other embodiments, the excitation light emitted by the light-emitting unit may also be laser light of other wavelength bands that can enable quantum dots to reach an excited state.

[0083] In this embodiment, the light-emitting unit 110 is a laser. Specifically, the light-emitting unit 110 is a femtosecond laser; or the light-emitting unit 110 is a picosecond laser.

[0084] Continuing to refer to Figure 2 , further, in this embodiment, the time-correlated single-photon counting unit 130 further includes: a driver 32 configured to provide a reference pulse clock signal.

[0085] In this embodiment, the driver 32 is an external board.

[0086] More specifically, in this embodiment, the time-correlated single-photon counting unit 130 further includes: a computer 33 connected to the driver 32 and configured to control the driver 32 to continuously generate the reference pulse clock signal.

[0087] In this embodiment, the detection system further includes: a scanning unit 150 configured to scan the detection object with the excitation light, or configured to control the excitation light to detect a preset position of the detection object.

[0088] Specifically, the scanning unit 150 is a galvanometer drive system including an x-galvanometer and a y-galvanometer, and is configured to perform area scanning on the detection object.

[0089] In addition to performing area scanning, the scanning unit 150 can also control the excitation light to scan a preset position of the detection object, so as to enable the excitation light to detect a specific position of the detection object.

[0090] In this embodiment, the scanning unit 150 is also connected to the driver 32, so that the scanning unit 150 can scan the detection object with the excitation light based on the reference pulse clock signal provided by the driver 32, or control the excitation light to detect a preset position of the detection object.

[0091] Specifically, the scanning unit 150 is a galvanometer drive system, and the reference pulse clock signal is used to control the x-galvanometer and the y-galvanometer of the galvanometer drive system respectively.

[0092] In this embodiment, an objective lens group 160 is further disposed between the scanning unit 150 and the detection object, which is used to magnify the image of the detection object and also to allow the fluorescence to pass through.

[0093] The objective lens group 160 is used to magnify the image of the detection object, so that an enlarged image of the detection object can be obtained for determining the detection position of the detection object, thereby further improving the detection accuracy.

[0094] The objective lens group 160 is also used to allow the fluorescence to pass through, so that the fluorescence can be transmitted to the photodetector 120 in the subsequent optical path for detection.

[0095] Specifically, the objective lens group 160 is an objective lens of a laser confocal microscope or can also be an objective lens of an ordinary microscope.

[0096] It should be noted that in other embodiments, by setting a self-focusing motor and an objective lens adjustment focus screw, continuous scanning acquisition of the detection object in the z direction can be achieved, so that the detection object can be detected in one more dimension, and similar detection accuracies can be obtained for detection objects at different depths.

[0097] As Figure 3 shown, the detection system further includes a stage 170 for placing the detection object.

[0098] In other embodiments, the detection system may not be provided with the stage, but includes an optical fiber for transmitting the excitation light to the detection object and also for transmitting the fluorescence, so that the detection of the detection object is realized through the optical fiber. The material of the optical fiber is relatively soft, and the probe at the end of the optical fiber can be used to detect some parts or areas that are not conducive to detection.

[0099] When the excitation light reaches the detection object, it can excite the quantum dots labeled on the detection object to the excited state, and then return to the ground state in the form of radiative transition. By detecting the fluorescence generated by the quantum dots, the fluorescence lifetime of the quantum dots can be obtained, so as to detect the microenvironment of the detection object and then determine whether it is abnormal.

[0100] Taking the detection object as cervical exfoliated cells as an example, the principle of judging whether the cervix has cancer by judging the fluorescence lifetime of quantum dots is as follows: The fluorescence lifetime of a fluorescent substance is related to its own structure, the polarity, viscosity, pH and other conditions of the microenvironment it is in. Therefore, the measurement of the fluorescence lifetime can reflect the changes occurring in the system. The most significant sign in cancer is that the pH value in cancer cells is quite different from that in normal cells. For example, the pH value in cancer cells is relatively high (about 7.3 - 7.6), while the pH value in normal cells is about 7.2. Thus, cancer detection is achieved by using the fact that quantum dots exhibit different fluorescence lifetimes at different pH values.

[0101] Continue to refer toFigure 3 , in this embodiment, a dichroic mirror 180 is further disposed on the optical path between the light emitting unit 110 and the analyte for distinguishing the excitation light and the fluorescence.

[0102] To measure the fluorescence lifetime, in this embodiment, the excitation light causes the quantum dots labeled on the analyte to generate fluorescence. The fluorescence reaches the dichroic mirror 180 through the objective lens group 160 and the scanning unit 150. The dichroic mirror 180 reflects the fluorescence, so that the fluorescence is separated from the excitation light on the optical path, and then the subsequent optical path can detect the fluorescence.

[0103] As Figure 3 shown, in this embodiment, a color filter 210 is further disposed on the optical path between the dichroic mirror 180 and the photodetector 120 for allowing light of a preset wavelength band in the fluorescence to pass through, so as to screen the information of the required wavelength band and further reduce the stray light of the excitation light.

[0104] In this embodiment, the color filter 210 is a band-pass filter with a wavelength range of 500nm - 700nm, which allows the fluorescence generated after the quantum dots are excited and fall back to the ground state to pass through, and obtains the data for detecting the fluorescence lifetime of the quantum dots.

[0105] It should be noted that in other embodiments, for quantum dots, the color filter only needs to allow the light within the emission spectrum band of the quantum dots to pass through.

[0106] It should be noted that in this embodiment, as Figure 3 shown, a first reflecting mirror 206 and a second reflecting mirror 208 are further disposed on the optical path between the dichroic mirror 180 and the color filter 210. The first reflecting mirror 206 and the second reflecting mirror 208 are used to change the direction of light propagation and improve the compactness of the detection system. In other embodiments, the first reflecting mirror and the second reflecting mirror may not be provided.

[0107] It should be noted that in this embodiment, as Figure 3 shown, a first conjugate aperture 201 is further disposed on the optical path between the light emitting unit 110 and the analyte for filtering out stray light and improving the detection accuracy and resolution.

[0108] In addition, in this embodiment, a second conjugate aperture 202 is further disposed on the optical path between the first reflecting mirror 206 and the second reflecting mirror 208 for filtering out the fluorescence of the non-focal plane and improving the detection accuracy and resolution.

[0109] In other embodiments, the first conjugate aperture and the second conjugate aperture may not be provided.

[0110] Continue to refer to Figure 3, the photodetector 120 is configured to detect the fluorescence generated by the quantum dots, and convert the optical signal into an electrical signal to form a fluorescence signal.

[0111] Specifically, the photodetector 120 is a photomultiplier tube (PMT), which can convert relatively weak light into an electrical signal with a large gain, improving the detection sensitivity.

[0112] In other embodiments, the photodetector may also be other types of photodetectors, such as a phototube, a Charge Couple Device (CCD), an avalanche photodiode (APD), etc.

[0113] The time-correlated single-photon counting unit 130 is configured to obtain time-based fluorescence lifetime data according to the fluorescence signal.

[0114] Specifically, the time-correlated single-photon counting unit 130 processes the fluorescence signal (the electrical signal corresponding to the fluorescence) collected by the photodetector 120, so as to obtain a fluorescence lifetime curve, and further determine whether there is an abnormal change in the fluorescence lifetime of the quantum dots.

[0115] In this embodiment, the time-correlated single-photon counting unit 130 includes: a processor 31, configured to perform data processing on the fluorescence signal collected by the photodetector 120 to obtain the fluorescence lifetime; a driver 32, configured to provide a reference pulse clock signal; and a computer 33, connected to the driver 32, configured to control the driver 32 to continuously generate the reference pulse clock signal.

[0116] It should be noted that the fluorescence lifetime can be described by the single e-exponential formula

[0117] I(t) = I0exp(-t / τ)

[0118] where τ is the fluorescence lifetime, I0 is the maximum fluorescence intensity value radiated, and I(t) is the fluorescence intensity at time t.

[0119] Continuing to refer to Figure 2 , further, in this embodiment, the detection system further includes: a control module 140, connected to the light-emitting unit 110, configured to control the excitation light pulse frequency provided by the light-emitting unit 110; the control module 140 is also connected to the processor 31, configured to trigger the processor 31 to perform data processing on the signal collected by the photodetector 120.

[0120] The control module 140 controls the pulse frequency of the excitation light provided by the light-emitting unit 110, so that the excitation light excites the analyte (with controlled timing), thereby controlling the frequency of the fluorescence generated by the quantum dots to facilitate the acquisition of the fluorescence signal by the photodetector 120 and the data processing of the fluorescence signal by the processor 31.

[0121] The control module 140 is further configured to trigger the processor 31 to perform data processing on the fluorescence signal collected by the photodetector 120, thereby controlling the processor 31 to perform photon acquisition detection within a preset period to prevent the processor 31 from missing the processing of the fluorescence signal, so as to achieve accurate measurement of the fluorescence signal.

[0122] More specifically, the control module 140 is configured to provide a pulse trigger signal to the processor 31, so that the processor 31 detects and counts photons based on the pulse trigger signal, and further realizes the measurement of the fluorescence lifetime of the quantum dots.

[0123] Combined with reference Figure 3 and combined with reference Figure 4 respectively show the pulse waveform diagrams of the reference pulse clock signal, the first pulse signal, the second pulse signal, the third pulse signal, the fourth pulse signal, and the fifth pulse signal.

[0124] In this embodiment, the control module 140 includes:

[0125] A pulse signal delay generator 41, configured to output a first pulse signal and a second pulse signal based on the reference pulse clock signal. Both the first pulse signal and the second pulse signal include a first level and a second level. The first level is used to turn on the light-emitting unit 110 to emit the excitation light (i.e., laser on), and the second level is used to turn off the light-emitting unit 110 (i.e., laser off), and the first levels in the first pulse signal and the second pulse signal do not overlap;

[0126] A first light source power controller 42, connected to the light-emitting unit 110 and the pulse signal delay generator 41, configured to control the pulse frequency of the excitation light emitted by the light-emitting unit 110 based on the first pulse signal and output a corresponding third pulse signal;

[0127] A second light source power controller 43, connected to the pulse signal delay generator 41, configured to receive the second pulse signal;

[0128] A synchronization pulse signal generator 44, connected to the second light-emitting power supply controller 43, is configured to output a fourth pulse signal that corresponds to the time period when the light-emitting unit 110 does not emit excitation light, has the same pulse frequency as the excitation light, and is synchronous, based on the second pulse signal provided by the second light-emitting power supply controller 43;

[0129] An electrical signal synthesizer 45, connected to the first light-emitting power supply controller 42 and the synchronization pulse signal generator 44, is configured to synthesize the third pulse signal and the fourth pulse signal to obtain a fifth pulse signal as a pulse trigger signal, and output the fifth pulse signal to the processor;

[0130] The processor 31 performs data processing on the signal collected by the photodetector 120 based on the fifth pulse signal.

[0131] In this embodiment, the pulse signal delay generator 41 is connected to the driver 32, so that it can output a first pulse signal and a second pulse signal based on the reference clock signal provided by the driver 32, and the pulse signal delay generator 41 can also be synchronized with the reference clock signal.

[0132] In this embodiment, the fluorescence generated by the quantum dots is detected, so as to detect the microenvironment of the analyte according to the fluorescence lifetime of the quantum dots.

[0133] Among them, the fluorescence lifetime of the quantum dots is relatively long. The pulse signal delay generator 41 outputs a first pulse signal and a second pulse signal both including a first level and a second level. The first level is used to turn on the light-emitting unit 110 to emit the excitation light (i.e., laser on), and the second level is used to turn off the light-emitting unit 110 (i.e., laser off). Moreover, the first levels in the first pulse signal and the second pulse signal do not overlap each other. Thus, the first light-emitting power supply controller 42 can control the light-emitting unit 110 to emit excitation light in a first preset time period based on the first pulse signal. The first preset time period of the pulsed laser output is the excitation light on (laser on), so as to increase the time interval between the emitted laser pulses of the excitation light to match the fluorescence lifetime of the quantum dots, so that the photodetector 120 and the processor 31 can detect the speed of the fluorescence decay of the quantum dots.

[0134] Among them, the second pulse signal is output to the second laser power controller 43. The second laser power controller 43 receives the second pulse signal. Thus, the synchronization pulse signal generator 44 outputs a fourth pulse signal that corresponds to the time period when the light emitting unit 110 does not emit excitation light, has the same pulse frequency as the excitation light, and is synchronous, based on the second pulse signal provided by the second light emitting power controller 43. The fourth pulse signal is correspondingly a pulse signal corresponding to the laser off of the excitation light. Thus, the electrical signal synthesizer 45 synthesizes the third pulse signal and the fourth pulse signal, that is, synthesizes the signals in the two time periods of laser off and laser on of the excitation light. Furthermore, the fifth pulse signal output by the electrical signal synthesizer 45 to the processor is used as a pulse trigger signal, which can continuously trigger the processor to detect and count photons in both the time period when the light emitting unit 110 emits excitation light and the time period when it does not emit excitation light, and correspondingly can achieve accurate measurement of long fluorescence lifetimes.

[0135] Combined with reference Figure 4 , in this embodiment, the first pulse signal and the second pulse signal are anti-phase signals to each other. Thus, when the electrical signal synthesizer 45 synthesizes the third pulse signal and the fourth pulse signal to obtain the fifth pulse signal, the fifth pulse signal is a complete pulse signal that has the same pulse frequency as the excitation light and is synchronous. In other embodiments, the first pulse signal and the second pulse signal may not be anti-phase signals to each other.

[0136] Combined with reference Figure 4 , in this embodiment, the electrical signal synthesizer 45 is used to perform an OR operation on the third pulse signal and the fourth pulse signal. Specifically, in this embodiment, the first pulse signal and the second pulse signal are anti-phase signals to each other. Thus, the fifth pulse signal obtained by performing an OR operation on the third pulse signal and the fourth pulse signal is a complete pulse signal that has the same pulse frequency as the excitation light and is synchronous.

[0137] Combined with reference Figure 5 , taking the detection object as cervical exfoliated cells as an example, Figure 5 in Figure 5 , the curves A1, A2, A3, and A4 in (a) are respectively the fluorescence lifetime distribution curves of quantum dots corresponding to cervical exfoliated cells of four typical cases of normal, benign lesions, precancerous lesions (cervical intraepithelial neoplasia), and cervical cancer. Figure 5 (b) shows Figure 5 the bar charts of the fluorescence lifetime distributions of different cases in groups A1, A2, A3, and A4 in (a) (where Figure 5 each bar in (b) represents a patient, and each small circle represents the analysis data of a fluorescence lifetime image).

[0138] FromFigure 5 It can be seen that the difference in the fluorescence lifetimes of the quantum dots corresponding to the cervical exfoliated cells in the normal group and the benign lesion group is small. The fluorescence lifetime of the quantum dots corresponding to the cervical exfoliated cells in the cervical cancer group is significantly lower than that of the quantum dots corresponding to the cervical exfoliated cells in the normal group and the benign lesion group. The fluorescence lifetime of the quantum dots corresponding to the cervical exfoliated cells in the precancerous lesion group is between that of the quantum dots corresponding to the cervical exfoliated cells in the normal group and the benign lesion group and that of the quantum dots corresponding to the cervical exfoliated cells in the cervical cancer group.

[0139] To solve the above technical problem, the present invention also provides a method for detecting fluorescence lifetime. Figure 6 It is a schematic flowchart of an embodiment of the method for detecting fluorescence lifetime of the present invention.

[0140] S1. Provide quantum dots.

[0141] S2. Label the analyte with the quantum dots.

[0142] S3. Provide excitation light.

[0143] S4. Project the excitation light onto the analyte labeled with the quantum dots to cause the quantum dots to emit fluorescence.

[0144] S5. Detect the fluorescence emitted by the quantum dots and collect the fluorescence signal.

[0145] S6. Obtain time-based fluorescence lifetime data based on the fluorescence signal.

[0146] Using the detection method of the above embodiment, the analyte is labeled with the quantum dots, the excitation light is projected onto the analyte labeled with the quantum dots to cause the quantum dots to emit fluorescence, and the fluorescence emitted by the quantum dots is detected and the fluorescence signal is collected. Quantum dots can exhibit different fluorescence lifetimes according to the microenvironment of the analyte itself. Therefore, by detecting the fluorescence emitted by the quantum dots, the microenvironment of the analyte can be detected according to the fluorescence lifetime of the quantum dots. Moreover, compared with the autofluorescence of the analyte, the fluorescence lifetime of the quantum dots is longer, and the fluorescence signal obtained by detecting the fluorescence emitted by the quantum dots is stronger, which can reduce the detection difficulty and improve the detection accuracy.

[0147] The following Figure 3 detection system is used to elaborate on each step of the detection method of this embodiment. It should be noted that this embodiment is described by taking the detection of a cervical tissue section (i.e., the analyte is a cervical tissue section) as an example. In other embodiments, the analyte can also be other analytes.

[0148] Step S1 is executed: Provide quantum dots.

[0149] Specifically, in this embodiment, quantum dots with pH sensitivity and a relatively long fluorescence lifetime are provided to label the analyte. By measuring the fluorescence lifetime of the quantum dots, the pH environment of the analyte itself can be detected, and then it can be determined whether it is abnormal.

[0150] It should be noted that the fluorescence lifetime of the quantum dots should not be too short, otherwise it is easy to increase the difficulty of detection. Therefore, in this embodiment, the fluorescence lifetime of the quantum dots is at least 100 nanoseconds.

[0151] The fluorescence lifetime of the quantum dots should not be too long either, otherwise it is easy to increase the detection time and cause unnecessary time waste. As an example, the fluorescence lifetime of the quantum dots is from 100 nanoseconds to 1000 nanoseconds.

[0152] As an embodiment, the quantum dots include quantum dots with a core-shell structure.

[0153] The quantum dots with a core-shell structure are coated with a shell layer (i.e., cladding) on the surface of the quantum dots. The cladding can isolate the core from the external environment, thereby reducing the probability of the core being affected by the external environment. For example, it can prevent the core from being oxidized by the external environment and prevent the overflow of core substances, etc., and then improve the structural stability of the quantum dots.

[0154] In other embodiments, based on actual needs, the quantum dots can also be other types of quantum dots.

[0155] As an example, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide (AgInS2, AIS), and the cladding of the core is zinc sulfide (ZnS). The AIS / ZnS quantum dots have a relatively long fluorescence lifetime, produce strong fluorescence signals, and have good sensitivity to acidity and alkalinity, which is conducive to reducing the difficulty of detection and further improving the measurement accuracy.

[0156] In other embodiments, based on actual needs, the provided quantum dots can also be other quantum dots with a core-shell structure.

[0157] Specifically, the step of providing the quantum dots includes: preparing a quantum dot solution.

[0158] Specifically, as an example, the quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide (AgInS2, AIS), and the cladding of the core is zinc sulfide (ZnS).

[0159] Correspondingly, as an embodiment, the quantum dot preparation module is configured to provide an indium source solution; adjust the pH value of the indium source solution; after adjusting the pH value of the indium source solution, add a silver source solution and a sulfur source solution to the indium source solution; perform chemical synthesis on the mixed solution of the silver source solution, the sulfur source solution and the indium source solution to obtain a nuclear solution of quantum dots.

[0160] More specifically, as an embodiment, the steps of preparing the quantum dot solution include: mixing glutathione, ammonium citrate and InCl3·4H2O under stirring to obtain a mixed solution; adjusting the pH value of the mixed solution; after adjusting the pH value of the mixed solution, adding AgNO3 and Na2S·9H2O to the mixed solution; performing microwave chemical reaction treatment on the mixed solution to obtain a nuclear solution of quantum dots.

[0161] Among them, as an example, glutathione (0.5 - 10 mmol), ammonium citrate (1 - 20 mmol) and InCl3·4H2O (0.5 - 10 mmol) are mixed under stirring to obtain a mixed solution.

[0162] As an example, NH4OH is added to the mixed solution to adjust the pH value of the mixed solution to 6.5 - 10.5.

[0163] As an example, 0.05 - 0.5 mmol AgNO3 and 0.5 - 10 mmol Na2S·9H2O are added to the mixed solution.

[0164] As an example, the microwave chemical reaction system is maintained at 60 - 99 °C for 50 - 150 minutes to perform microwave chemical reaction treatment on the mixed solution.

[0165] Specifically, as an example, the quantum dots include quantum dots with a core-shell structure; the shell of the core is zinc sulfide (ZnS).

[0166] Correspondingly, as an embodiment, the quantum dot preparation module is configured to add a zinc source solution to the nuclear solution of the quantum dots, then add a sulfur source solution to the mixed solution of the zinc source solution and the nuclear solution, and perform chemical synthesis on the mixed solution of the sulfur source solution, the zinc source solution and the nuclear solution to obtain AIS / ZnS core / shell quantum dots.

[0167] More specifically, as an embodiment, the step of preparing the quantum dot solution further includes: adding a solution containing ZnCl2 and glutathione to the core solution of the quantum dots, then adding Na2S·9H2O to the mixed solution, and subjecting the mixed solution to a heat treatment to obtain AIS / ZnS core / shell quantum dots; thereafter, the prepared AIS / ZnS is subjected to purification treatment and drying treatment in sequence, and then dilution treatment and pH value adjustment treatment are carried out to obtain a neutral AIS / ZnS quantum dot solution.

[0168] As an example, 1 to 30 mL of a solution containing 0.5 to 5 mmol of ZnCl2 and 0.5 to 5 mmol of glutathione is added to the core solution of the quantum dots, then 1 to 30 mL of Na2S·9H2O (0.5 to 5 mmol) is added to the mixed solution, and the mixture is heated to 60 to 99 °C for 1 to 30 minutes; thereafter, the prepared AIS / ZnS is purified 1 to 5 times with ethanol, dried under vacuum at 70 to 110 °C, diluted to 0.1 to 30 mg / mL, and the pH value is adjusted to 7.0.

[0169] Among them, the concentration of the quantum dot solution should not be too low or too high. If the concentration of the quantum dot solution is too low, the staining and labeling module will take too long to label the analyte; if the concentration of the quantum dot solution is too high, it is easy to cause some quantum dots that have not entered the analyte cells to adhere to the cell membrane or culture dish, resulting in difficult cleaning, and these adhered quantum dots will affect the imaging quality. In addition, too high a concentration of the quantum dot solution will also cause waste of materials. Therefore, in this embodiment, the concentration of the quantum dot solution is 0.1 to 30 mg / mL.

[0170] Correspondingly, step S2: The step of labeling the analyte with the quantum dots includes: immersing the analyte in the quantum dot solution.

[0171] The analyte is immersed in the quantum dot solution, thereby realizing the labeling of the analyte.

[0172] It should be noted that the above method of labeling the analyte with quantum dots is only an example. In other embodiments, other methods can also be used to label the analyte.

[0173] It should be noted that the time for immersing the test object in the quantum dot solution should not be too short or too long. If the immersion time is too short, it is likely that the quantum dots cannot fully enter the cells of the test object; if the immersion time is too long, it is likely to affect the cell morphology of the test object and cause unnecessary time waste. Therefore, in this embodiment, the time for immersing the test object in the quantum dot solution is 1 hour to 8 hours.

[0174] Perform step S3: Provide excitation light.

[0175] Specifically, the excitation light is picosecond laser with a wavelength of 350 nm to 450 nm or femtosecond laser with a wavelength of 700 nm to 900 nm. The laser is used to excite the quantum dots on the test object labeled with quantum dots to reach the excited state, and then the quantum dots emit fluorescence. Specifically, the laser is used to excite AIS / ZnS quantum dots to reach the excited state and then emit fluorescence.

[0176] In other embodiments, the provided excitation light can also be laser of other wavelength bands that can make the quantum dots reach the excited state.

[0177] Specifically, the light emitting unit 110 is used to provide excitation light. In this embodiment, the light emitting unit 110 is a laser. Specifically, the light emitting unit 110 is a femtosecond laser; or, the light emitting unit 110 is a picosecond laser.

[0178] It should be noted that in this embodiment, the fluorescence lifetime of the quantum dots is relatively long. Therefore, control the light emitting unit 110 to emit excitation light in the first preset time period. The first preset time period of the pulsed laser output is the laser on, so as to increase the time interval of the emitted laser pulses of the excitation light to match the fluorescence lifetime of the quantum dots, so as to facilitate detecting the speed of fluorescence decay of the quantum dots.

[0179] Perform step S4: The step of making the excitation light project onto the test object labeled with quantum dots to make the quantum dots generate fluorescence includes: scanning the test object labeled with quantum dots with the excitation light, or controlling the excitation light to detect a preset position of the test object labeled with quantum dots.

[0180] Specifically, use the scanning unit 150 to scan the test object labeled with quantum dots with the excitation light, or control the excitation light to detect a preset position of the test object labeled with quantum dots.

[0181] In this embodiment, the scanning unit 150 is a galvanometer drive system, including an x-galvanometer and a y-galvanometer, for realizing surface scanning of the test object.

[0182] In addition to implementing area scanning, the scanning unit 150 can also control the excitation light to scan a preset position of the detection object, so that the excitation light can detect a specific position of the detection object.

[0183] Execute step S6: Obtain time-based fluorescence lifetime data according to the fluorescence signal.

[0184] When the excitation light reaches the detection object, it can excite the quantum dots labeled on the detection object to the excited state, and then return to the ground state in the form of radiative transition. By detecting the fluorescence generated by the quantum dots, the fluorescence lifetime of the quantum dots can be obtained, so as to detect the microenvironment of the detection object and then determine whether it is abnormal.

[0185] Taking the detection object as exfoliated cervical cells as an example, the principle of judging whether the cervix has cancer by judging the fluorescence lifetime of quantum dots is as follows: The fluorescence lifetime of a fluorescent substance is related to its own structure, the polarity, viscosity, pH, etc. of the microenvironment it is in. Therefore, the measurement of the fluorescence lifetime can reflect the changes occurring in the system. The most significant hallmark of cancer is that the pH value in cancer cells is significantly different from that in normal cells. For example, the pH value in cancer cells is relatively high (about 7.3 - 7.6), while the intracellular pH value in normal cells is about 7.2. Thus, cancer detection is achieved by using the fact that quantum dots exhibit different fluorescence lifetimes at different pH values.

[0186] It should be noted that the fluorescence lifetime can be described by the single exponential formula

[0187] I(t) = I0 exp(-t / τ)

[0188] where τ is the fluorescence lifetime, I0 is the maximum fluorescence intensity value emitted, and I(t) is the fluorescence intensity at time t.

[0189] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A fluorescence lifetime detection system, characterized in that, Comprising: A labeling unit, configured to provide quantum dots and further configured to label a detection object with the quantum dots; the quantum dots provided by the labeling unit include quantum dots with a core-shell structure; A light-emitting unit, configured to provide excitation light, the excitation light being projected onto the detection object labeled with the quantum dots, and the quantum dots being capable of generating fluorescence; A photodetector, configured to detect the fluorescence generated by the quantum dots and collect fluorescence signals; A time-correlated single-photon counting unit, configured to obtain time-based fluorescence lifetime data according to the fluorescence signals; The time-correlated single-photon counting unit further includes: a driver, configured to provide a reference pulse clock signal; The detection system further includes: a control module, connected to the light-emitting unit, configured to control the pulse frequency of the excitation light provided by the light-emitting unit; the control module includes: A pulse signal delay generator, configured to output a first pulse signal and a second pulse signal based on the reference pulse clock signal, both the first pulse signal and the second pulse signal including a first level and a second level, the first level being used to turn on the light-emitting unit to emit the excitation light, the second level being used to turn off the light-emitting unit, and the first levels in the first pulse signal and the second pulse signal do not overlap; A first light-emitting power controller, connected to the light-emitting unit and the pulse signal delay generator, configured to control the pulse frequency of the excitation light emitted by the light-emitting unit based on the first pulse signal and output a corresponding third pulse signal; A second light-emitting power controller, connected to the pulse signal delay generator, configured to receive the second pulse signal; A synchronous pulse signal generator, connected to the second light-emitting power controller, configured to output a fourth pulse signal corresponding to the time period when the light-emitting unit does not emit excitation light, having the same pulse frequency as and being synchronous with the excitation light based on the second pulse signal provided by the second light-emitting power controller; An electrical signal synthesizer, connected to the first light-emitting power controller and the synchronous pulse signal generator, configured to synthesize the third pulse signal and the fourth pulse signal to obtain a fifth pulse signal.

2. The fluorescence lifetime detection system according to claim 1, wherein The time-correlated single-photon counting unit includes: a processor, configured to perform data processing on the fluorescence signals collected by the photodetector to obtain the fluorescence lifetime; The control module is further connected to the processor, configured to trigger the processor to perform data processing on the signals collected by the photodetector.

3. The fluorescence lifetime detection system according to claim 2, wherein The processor is configured to perform data processing on the signals collected by the photodetector based on the fifth pulse signal.

4. The fluorescence lifetime detection system according to claim 1, wherein The first pulse signal and the second pulse signal are inverse signals to each other.

5. The fluorescence lifetime detection system according to claim 1, wherein The electrical signal synthesizer is configured to perform an OR operation on the third pulse signal and the fourth pulse signal.

6. The fluorescence lifetime detection system according to claim 1, characterized in that, The quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide, and the shell of the core is zinc sulfide.

7. The fluorescence lifetime detection system according to claim 1, characterized in that, The quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide, and the shell of the core is zinc sulfide; the light-emitting unit is configured to emit picosecond laser light with a wavelength of 350 nm to 450 nm or femtosecond laser light with a wavelength of 700 nm to 900 nm.

8. The fluorescence lifetime detection system according to claim 1, wherein The detection system further includes: a scanning unit for scanning the analyte with the excitation light, or for controlling the excitation light to detect a preset position of the analyte.

9. The fluorescence lifetime detection system according to claim 1, wherein, A dichroic mirror is further provided on the optical path between the light emitting unit and the analyte for distinguishing the excitation light and the fluorescence.

10. The fluorescence lifetime detection system according to claim 1, wherein The detection system further includes: a stage for placing the analyte, or the detection system further includes: an optical fiber for transmitting the excitation light to the analyte and also for transmitting the fluorescence.

11. A method for detecting the fluorescence lifetime of a fluorescence lifetime detection system according to any one of claims 1-10, characterized in that, Comprising: Providing quantum dots; Labeling the analyte with the quantum dots; Providing excitation light; Projecting the excitation light onto the analyte labeled with the quantum dots to cause the quantum dots to generate fluorescence; Detecting the fluorescence generated by the quantum dots and collecting fluorescence signals; Obtaining time-based fluorescence lifetime data based on the fluorescence signals.

12. The detection method according to claim 11, characterized in that, The step of providing the quantum dots includes: preparing a quantum dot solution; The step of labeling the analyte with the quantum dots includes: immersing the analyte in the quantum dot solution.

13. The detection method according to claim 12, wherein The concentration of the quantum dot solution is 0.1 mg / ml to 10 mg / ml; the time for immersing the analyte in the quantum dot solution is 2 hours to 8 hours.

14. The detection method according to claim 11, wherein In the step of providing the quantum dots, the fluorescence lifetime of the quantum dots is 100 nanoseconds to 1000 nanoseconds.

15. The detection method according to claim 11, characterized in that The quantum dots include quantum dots with a core-shell structure; the core of the quantum dots is silver indium sulfide, and the shell of the core is zinc sulfide.

16. The detection method according to claim 11, characterized in that, The step of projecting the excitation light onto the analyte labeled with the quantum dots to cause the quantum dots to generate fluorescence includes: scanning the analyte labeled with the quantum dots with the excitation light, or controlling the excitation light to detect a preset position of the analyte labeled with the quantum dots.

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