Liquid crystal microcavity array-based alanine aminotransferase detection device and detection method

Abstract

The invention discloses an alanine aminotransferase detection device and method based on a liquid crystal microcavity array, and belongs to the field of optical sensing. The device comprises a functional liquid crystal microcavity array, an excitation optical fiber and a collection optical fiber, the microcavity array is composed of liquid crystal microcavities doped with fluorescent dye and stearic acid, and the multiple microcavities are independently distributed and serve as optical sensing units; the excitation optical fiber is used for synchronously exciting the microcavity to generate an echo wall mode, and the acquisition optical fiber acquires resonance spectrum signals of each channel in real time; the functionalized liquid crystal microcavity is converted into a bipolar configuration from a radial configuration in an enzymatic reaction, echo wall mode spectrum red shift is caused, spectrum shift time is in negative correlation with enzyme concentration, and dual-channel detection is realized by matching with conversion time of a polarized light pattern. According to the detection structure based on the liquid crystal microcavity array provided by the invention, high-flux, real-time and label-free rapid detection on the concentration of alanine aminotransferase can be realized.

Description

Technical Field

[0001] The present invention belongs to the field of optical sensing, and in particular relates to an alanine aminotransferase detection device and a detection method based on a liquid crystal microcavity array. Background Art

[0002] Liquid crystal materials are a type of soft matter that combines the fluidity of liquids with the ordered crystal orientation. Their optical anisotropy, interfacial sensitivity, and responsiveness to environmental changes give them broad potential for application in biological detection. In typical nematic liquid crystals, the orientation of the molecular long axis is extremely sensitive to the external microenvironment (such as pH, electric field, temperature, etc.). When the orientation state changes, its internal refractive index changes accordingly, causing the system to significantly regulate the propagation characteristics of incident light. This characteristic allows it to be observed through polarized light microscopy, intuitively reflecting changes in molecular orientation, making it an ideal material foundation for building highly sensitive, biocompatible, and label-free microscopic sensing platforms.

[0003] Whispering gallery modes are resonant modes with high quality factors, resulting from total internal reflection of light along the tangential direction at a dielectric interface. They possess strong optical field confinement and are sensitive to refractive index perturbations in the surrounding medium. In particular, whispering gallery modes can be stably excited in spherical cavities, and their resonant wavelength is closely related to the cavity geometry and the effective refractive index within the cavity. Therefore, they can be used as a high-resolution, non-invasive sensing mechanism for environmental monitoring and molecular recognition. Introducing liquid crystal materials into microcavity structures not only preserves the optical properties of whispering gallery modes but also leverages the conformability and surface anchoring of liquid crystals to manipulate their internal molecular orientation, achieving dynamic modulation of the structural optical properties. Through molecular modification, doping, or interface design, liquid crystal microcavities can achieve controllable transitions from radial to bipolar states under specific stimuli, thereby causing changes in the cavity's effective refractive index and, in turn, shifting the resonant wavelength of the whispering gallery modes. Furthermore, liquid crystal microcavities offer advantages such as ease of sphering, ease of array construction, fast response, and low cost, making them particularly suitable for the development of multi-channel, visualized bioassay systems.

[0004] Alanine aminotransferase is a transaminase widely present in the cytoplasm of hepatocytes. Its activity level directly reflects the functional status of hepatocytes and is one of the most commonly used clinical biochemical indicators in the detection of liver function damage. At present, the main clinical methods for alanine aminotransferase detection are ultraviolet spectrophotometry, coupled enzyme method, dry chemical method, and immunochromatography. These methods have a certain degree of sensitivity and standardization basis, but usually rely on large-scale analytical equipment, have complex operating procedures, and have long detection times. They are difficult to meet the needs of portable, instant, and dynamic detection, limiting their application in primary care and resource-constrained areas or portable diagnosis and rapid screening scenarios. Therefore, the development of an alanine aminotransferase detection technology that does not require complex labeling, can respond in real time, and can output quickly and conveniently has important scientific significance and application value. The alanine aminotransferase detection method using liquid crystal microcavity arrays combines functionalized liquid crystal microcavities with the optical properties of whispering gallery modes to construct an array-type microcavity detection platform. The liquid crystal microcavities are used to respond to local pH changes caused by enzymatic reactions, leading to the reconstruction of the liquid crystal molecular structure, thereby achieving synchronous response and dual output of the whispering gallery mode spectrum and polarization pattern, providing a new technical path for early, dynamic, and high-throughput monitoring of liver function damage. Summary of the Invention

[0005] The purpose of the present invention is to provide an alanine aminotransferase detection device and detection method based on a liquid crystal microcavity array, aiming to achieve high-sensitivity and high-precision detection of alanine aminotransferase concentration and solve technical problems existing in existing traditional detection methods such as low response efficiency, insufficient throughput, lack of reference standards and complex test equipment.

[0006] The present invention provides an alanine aminotransferase detection device based on a liquid crystal microcavity array, comprising: splitting a single excitation light source to a liquid crystal microcavity sensing unit to achieve multi-channel parallel excitation operation; the liquid crystal microcavity sensing unit comprises an array structure composed of multiple array units; the array unit internally comprises a weakly alkaline substrate buffer solution and a liquid crystal microcavity; the liquid crystal microcavity is a spherical structure, the liquid crystal material surface is modified with stearic acid and doped with a fluorescent dye; and an acquisition and analysis unit comprises a polarizing microscope module, a spectrum acquisition module and a data analysis computer, and is used for real-time monitoring of the polarization pattern of molecular arrangement changes in the liquid crystal microcavity, acquiring whispering gallery mode spectra, and recording, processing and analyzing signal data.

[0007] Furthermore, the excitation unit includes a laser, a fiber beam splitter and a multi-channel excitation fiber; the laser outputs a green light excitation signal with a central wavelength of 532nm, which is transmitted to the fiber beam splitter through a multimode fiber. After splitting, the signal is introduced into the channel where each liquid crystal microcavity in the array structure is located through the excitation fiber. Each liquid crystal microcavity is coupled with the laser through the excitation fiber in the excitation unit to excite and generate an optical whispering gallery mode.

[0008] Furthermore, the pH of the weak alkaline substrate buffer solution is 7.6-8.0; the array unit includes a control unit and multiple test units; the weak alkaline substrate buffer solution added to the array unit includes 0.1mM α-ketoglutarate and 0.167mM L-alanine.

[0009] Furthermore, the liquid crystal microcavity is prepared in the array unit by microinjection, specifically: the liquid crystal material is mixed with 0.08wt% stearic acid and 0.1wt% DCM fluorescent dye to obtain a precursor solution by oscillation or ultrasound, and the precursor solution is injected into the substrate buffer solution by microinjection; the diameter of the liquid crystal microcavity is 30 to 60μm.

[0010] Furthermore, the array unit is made of highly transparent acrylic material and has a cubic structure; the ratio of the side length of the array unit to the diameter of the liquid crystal microcavity is 1.5 to 2:1; and each array unit is equipped with a set of excitation optical fibers and collection optical fibers.

[0011] Furthermore, the polarizing microscopy module includes a polarizing microscope, and the acquisition module includes an acquisition fiber and a spectrometer; the polarizing microscope acquires in real time the optical anisotropy change image generated by the liquid crystal microcavity array during the response process, and transmits the polarization pattern information to a data analysis computer through an image acquisition device to record the liquid crystal arrangement state transition process and its corresponding time node; the acquisition fiber is connected to the corresponding sensor unit in the liquid crystal microcavity array to collect the whispering gallery mode emission spectrum generated after excitation, and synchronously transmits the spectral data to the data analysis computer for analysis and processing of the spectral drift and its time evolution characteristics.

[0012] The present invention also provides a method for detecting alanine aminotransferase based on a liquid crystal microcavity array, wherein the alanine aminotransferase solution to be tested is added to the detection unit respectively; in the detection unit, during the alanine aminotransferase catalytic reaction, L-alanine and α-ketoglutarate generate pyruvate and L-glutamate under the catalytic action of the enzyme, wherein the generated pyruvate further dissociates to release hydrogen ions (H + ), resulting in a decrease in the pH value of the local microenvironment; this pH change affects the protonation state of the stearic acid molecules on the surface of the liquid crystal microcavity, which in turn causes changes in the orientation of the liquid crystal molecules, and obtains the evolution of the polarization pattern and spectral response caused by the orientation change; the higher the concentration of alanine aminotransferase as a catalytic enzyme, the shorter the time required to complete the equal amount of reaction under the condition of constant substrate concentration. According to the known alanine aminotransferase concentration grading standard, the change time of the liquid crystal molecular orientation response is used to achieve quantitative analysis of the enzyme concentration.

[0013] Furthermore, the liquid crystal molecular orientation changes from a radial state to a bipolar state, and the polarization pattern in a polarizing microscope changes from a radial state to a bipolar state, and the polarization pattern transition time is recorded. During the structural transition of the liquid crystal molecular configuration from a radial state to a bipolar state, the effective refractive index of the liquid crystal microcavity changes, causing the resonant wavelength of the whispering gallery mode to redshift, and the spectral shift time is recorded. Based on the spectral shift time and the polarization pattern transition time, combined with the reaction rate characteristics of different enzyme concentrations, a time-concentration response relationship is established to achieve highly sensitive quantitative detection of alanine aminotransferase concentration.

[0014] Furthermore, the whispering gallery mode effective refractive index n eff The relationship with the resonant wavelength λ is as follows:

[0015] λ=(2πRn eff ) / m

[0016] Where R is the radius of the microcavity; m is the mode order; as the liquid crystal molecular configuration changes from the radial state to the bipolar state, the effective refractive index n of the whispering gallery mode is excited. eff The normal refractive index in the vertical direction changes to the extraordinary refractive index along the long axis of the molecule.

[0017] Furthermore, during the detection process, the temperature of the liquid crystal microcavity (6) array is controlled to be 36-37°C.

[0018] The beneficial effects of the present invention are:

[0019] 1. The liquid crystal microcavity array-based alanine aminotransferase detection method of the present invention combines the changes in liquid crystal molecular orientation with the spectral drift characteristics of the whispering gallery mode to effectively enhance the detection signal. Compared with traditional liquid crystal color observation or a single signal channel, the present invention constructs a dual-channel response mechanism, significantly improving the sensitivity and accuracy of alanine aminotransferase detection.

[0020] 2. The liquid crystal microcavity array-based alanine aminotransferase detection method of the present invention realizes dynamic monitoring of the entire alanine aminotransferase reaction process by introducing the response time parameters T1 (polarization pattern transition time) and T2 (movement time to achieve wavelength stability). This time domain characteristic indicator not only improves detection efficiency, but also can output preliminary detection results within 10 minutes, making it suitable for real-time detection scenarios.

[0021] 3. The present invention's liquid crystal microcavity array-based alanine aminotransferase detection method utilizes an arrayed liquid crystal microcavity structure to enable parallel detection of multiple samples, significantly improving detection throughput. The system's modules eliminate the need for expensive custom components, resulting in a significantly lower overall construction cost than traditional fluorescent enzyme-labeled systems or mass spectrometry platforms.

[0022] 4. The liquid crystal microcavity array-based alanine aminotransferase detection method of the present invention does not require labeling, elution steps, or complex chemical modifications. The sample simply needs to come into contact with the liquid crystal microcavity to complete the signal reading, resulting in a simple operation and high reproducibility. Furthermore, the system is highly adaptable to environmental conditions (such as temperature and humidity) and can be adapted to various laboratory conditions, including mobile detection platforms, making it suitable for basic research and preclinical testing applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of an alanine aminotransferase detection device based on a liquid crystal microcavity array;

[0024] Figure 2 A top view of the liquid crystal microcavity array structure and a schematic diagram of the internal structure of the liquid crystal microcavity;

[0025] Figure 3 This is a schematic diagram of the spectrum detection and polarization pattern detection based on time sampling;

[0026] Figure 4 This is the corresponding relationship diagram of alanine aminotransferase concentration and reaction time. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the implementation process of the present invention, the following description is given in conjunction with the accompanying drawings, but it should be understood that these descriptions are only for exemplary explanations and do not constitute a limitation on the scope of protection of the present invention.

[0028] The present invention discloses an alanine aminotransferase detection device based on a liquid crystal microcavity array, see Figure 1 The device comprises an excitation unit, a liquid crystal microcavity sensing unit, and an acquisition and analysis unit. The excitation unit includes an Nd:YAG laser 1, a fiber beam splitter 2, and multi-channel excitation fibers 3. This splits a single excitation light source into multiple detection channels, ensuring equivalent excitation for each channel, enabling multi-channel parallel excitation operation, and providing a stable and controllable excitation light source. The liquid crystal microcavity sensing unit consists of an array structure 5 and multiple independently functionalized liquid crystal microcavities 6, designed to respond to local environmental changes triggered by the enzyme reaction being tested. The liquid crystal microcavities 601-606 are spherical structures, their surfaces modified with stearic acid and doped with fluorescent dyes to enhance the optical response signal. The array structure 5 is divided into a control unit 501 and test units 502-506. Each unit is equipped with a set of excitation fibers 301-306 and collection fibers 701-706, enabling independent detection channel configuration. The acquisition and analysis unit consists of a polarizing microscope 4, an acquisition optical fiber 7, a spectrometer 8, and a data analysis computer 9, which are used to monitor the polarization pattern of the molecular arrangement changes in the liquid crystal microcavity in real time, collect the whispering gallery mode spectrum, and record, process, and analyze the signal data. The image recording and spectral analysis of the liquid crystal response process are now performed.

[0029] The Nd:YAG laser 1 in the excitation unit outputs a green light excitation signal with a central wavelength of 532nm. This is transmitted via a multimode optical fiber to a fiber beam splitter 2. After splitting, the signals are directed as equal-intensity signals through excitation fibers 301-306 into the channels of each liquid crystal microcavity 6 in the array structure 5, thereby near-field exciting the whispering gallery mode within the functionalized liquid crystal cavity. Each excitation fiber is connected to a corresponding liquid crystal microcavity sensing unit, directing the laser excitation signal to the target microcavity for precise excitation. Each excitation fiber has independent control capabilities, supporting synchronous or asynchronous excitation modes to meet the needs of multi-channel parallel detection. The excitation light is injected into the liquid crystal microcavity via near-field coupling or end-face coupling, effectively exciting the whispering gallery mode, thereby generating a laser emission signal with a high quality factor and high sensitivity.

[0030] See also Figure 2 The liquid crystal microcavity sensing unit adopts an array structure. The array structure 5 consists of a control unit 501 and multiple test units 502-506. An input port and an output port are respectively provided on both sides of the array structure 5, which are connected to an excitation optical fiber and a collection optical fiber. When the excitation optical fiber introduces laser light to the liquid crystal microcavity, the spherical geometric characteristics of the liquid crystal microcavity and the gain effect of the internal fluorescent dye are used to excite the whispering gallery mode to emit laser light. The emission signal is collected by the collection optical fiber for subsequent spectral analysis.

[0031] Each assay cell contains 0.5 mL of substrate buffer solution (pH 7.7 to ensure enzyme activity). The substrate components specifically include 0.1 mM α-ketoglutarate and 0.167 mM L-alanine for the enzymatic reaction catalyzed by alanine aminotransferase. The volume of the substrate buffer is equal to or slightly smaller than the volume of the assay cell.

[0032] Liquid crystal microcavities 6 are prepared in array units by microinjection. Liquid crystal microcavities 6 are formed by liquid crystal materials doped with two functional materials, the fluorescent dye DCM (4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran) and stearic acid, to form an optically responsive liquid crystal mixture. Doping with 0.1 wt% DCM can generate a stable excitation fluorescence signal under laser pumping, improving the excitation efficiency and spectral signal-to-noise ratio of the WGM mode. This concentration is within the optimal range for ensuring high fluorescence intensity while avoiding aggregation quenching. Doping with 0.08 wt% stearic acid can regulate the interaction force between liquid crystal molecules, improve the stability of the molecular arrangement on the surface of the liquid crystal sphere, enhance the environmental responsiveness and configuration controllability of the liquid crystal, and facilitate liquid crystal reconstruction caused by external stimuli (such as pH changes caused by enzymatic reactions). In addition, the precursor mixed solution in the early stage of the preparation of the liquid crystal microcavity 6 needs to be shaken or ultrasonically to ensure the uniform distribution of each component in the liquid crystal matrix to prevent phase separation or uneven doping during the cavity formation process.

[0033] The liquid crystal microcavity 6 is preferably a spherical structure with a diameter of 45μm. This size range can effectively support the excitation of optical whispering gallery modes (WGMs) with high quality factors, ensuring the sensitivity and resolution of optical detection, while being conducive to array arrangement and achieving high-throughput detection requirements. Within this range, the mode spacing of the liquid crystal microcavity is sufficiently separated, which is conducive to accurately identifying changes in resonant wavelengths; the array unit 5 is preferably a cubic structure with a side length of 1.5 to 2 times the diameter of the liquid crystal microcavity 6, which contributes to the stability of the array, arrangement regularity and detection consistency. In the initial state, the liquid crystal molecules are arranged radially, and the microcavity presents a typical cross pattern under a polarizing microscope;

[0034] In the initial state, the substrate buffer added to the array unit is in a weakly alkaline environment, and the surface of the liquid crystal microcavity 6 is functionalized with stearic acid molecules. The stearic acid, as a response layer, is directly exposed to the substrate solution loaded in the array cubic lattice. The stearic acid molecules are partially deprotonated, achieving the structural anchoring of the radial configuration of the liquid crystal molecules in the liquid crystal microcavity. The surface of the liquid crystal microcavity is functionalized with stearic acid molecules. The stearic acid molecules have an amphiphilic structure. Their carboxyl ends are deprotonated in the initial weakly alkaline environment to form -COO- groups, and a stable vertical anchoring field is constructed at the liquid crystal-water interface, inducing the liquid crystal molecules in the cavity to adopt a radial state structure. As the enzymatic reaction proceeds, the generation of pyruvic acid causes the local pH to drop, causing the -COO- groups to be gradually protonated to -COOH, destroying the orderliness of the interface arrangement and the vertical anchoring ability, thereby triggering the structural transformation of the liquid crystal molecules from the radial state to the bipolar state.

[0035] 0.02 mL of the alanine aminotransferase solution to be tested was added to each of the detection units 502-506 in the liquid crystal microcavity sensor array, while an equal volume of blank buffer was added to the control unit 501. During the enzyme-catalyzed reaction, L-alanine and α-ketoglutarate react to produce pyruvate and glutamate under the action of the enzyme. The generated pyruvate further dissociates into hydrogen ions (H + ), resulting in a decrease in the local microenvironmental pH. This pH change affects the protonation state of the stearic acid molecules on the surface of the liquid crystal microcavity, which in turn causes changes in the arrangement of the liquid crystal molecules. Furthermore, by comparing the changes in the molecular arrangement and whispering gallery mode spectral response within the liquid crystal microcavity between the control and test groups during the reaction process, background interference can be effectively eliminated, improving detection accuracy.

[0036] In the acquisition and analysis unit, the polarizing microscope 4 is used to record the polarization pattern presented by the liquid crystal microcavity in real time (the transition from the radial state to the bipolar state). This change process is time-dependent, and the time required for the complete transition from the initial radial state to the stable bipolar state is defined as the transition time T1, which is related to the catalytic rate of alanine aminotransferase. The higher the enzyme concentration, the faster the product is generated and the shorter the time to trigger liquid crystal reconstruction, that is, the smaller the T1 value. By statistically analyzing the T1 change trend under different enzyme concentration conditions, the enzyme activity and concentration determination index can be realized.

[0037] Excitation fibers 301 to 306 are drawn out from the fiber beam splitter 2, corresponding to each array channel, to achieve parallel excitation; collection fibers 701 to 706 are connected to the spectrometer 8 to synchronously collect signals from different channels. The multimode optical fiber in the acquisition and analysis unit serves as the collection fiber 701-706 for each array channel, which is used to collect the whispering gallery mode optical signal in the liquid crystal microcavity and transmit it to the spectrometer 8 to obtain the change in resonant wavelength. Since the liquid crystal material itself has obvious anisotropy, the change in its molecular orientation will directly affect the equivalent refractive index inside the microcavity. Its abnormal refractive index n along the long axis of the molecule is 1 / 4 of the refractive index. e ≈1.71, normal refractive index n in the vertical direction o ≈1.54; In the process of liquid crystal microcavity structure transforming from radial state to bipolar state, the excitation of whispering gallery mode is

[0038] Effective refractive index n eff Also by n o Transformed into n e , according to the relationship between the effective refractive index and the resonant wavelength λ in the whispering gallery mode:

[0039] λ=(2πRn eff ) / m

[0040] Where R is the microcavity radius and m is the mode order, which can be seen to cause the resonance wavelength of the whispering gallery mode to redshift. Recording the time when the redshift stops, that is, the spectrum movement time T2, and extracting the peak wavelength offset can further reflect the level of alanine aminotransferase concentration.

[0041] The data analysis computer 9 in the acquisition and analysis unit is used to synchronously receive and process the dual response signals generated by the liquid crystal microcavity during the detection process, including the transition time T1 corresponding to the transition of the polarization pattern from the radial state to the bipolar state and the wavelength shift time T2 corresponding to the red shift and stabilization of the echo gallery mode resonant wavelength. Among them, T2 can be collected using a timed interval sampling method to improve detection efficiency and simplify operation. Based on the response time parameters T1 and T2, a functional relationship between the alanine aminotransferase concentration and the response time is constructed to achieve rapid estimation and high-precision quantitative analysis of the alanine aminotransferase concentration.

[0042] To ensure the stability of alanine aminotransferase activity and reaction rate, the entire liquid crystal microcavity array is maintained in a constant temperature environment during the detection process, with a temperature control range of 36°C to 37°C, close to physiological body temperature conditions.

[0043] A method for detecting alanine aminotransferase based on a liquid crystal microcavity array. The liquid crystal microcavity is placed in a substrate solution containing L-alanine and α-ketoglutarate, maintaining its initial radial configuration. When a sample containing alanine aminotransferase is added, the enzymatic reaction begins, producing pyruvate and L-glutamate, causing a pH change in the system, which in turn induces the reorientation of the liquid crystal molecules. The microcavity pattern changes from radial to bipolar, exhibiting "elliptical spots" or "double dots" characteristics. The time required for this transition is recorded as T1. Figure 3 . At the same time, the effective refractive index of the liquid crystal cavity changes, causing the resonant wavelength of the whispering gallery mode it supports to redshift. The time interval required to record the cessation of the spectrum redshift is T2. To improve detection efficiency, T2 can be characterized by a fixed time interval sampling method, that is, the time period during which the whispering gallery mode signal drift stops. According to the known alanine aminotransferase concentration grading standard, the obtained liquid crystal microcavity polarization pattern transition time T1 and the whispering gallery mode spectral drift time interval T2 are matched with the grading standard to analyze the alanine aminotransferase concentration; when the spectral drift time interval is the same, the alanine aminotransferase concentration is judged based on the wavelength change in the T2 interval.

[0044] See also Figure 4, experimental verification was carried out based on the commonly used clinical alanine aminotransferase concentration grading standard. For the diagnosis of early liver damage, the concentration range of 40-240 U / L was analyzed in particular. The results showed that the alanine aminotransferase concentration was significantly negatively correlated with the reaction time. Specifically, as the enzyme concentration increased, the liquid crystal microcavity polarization pattern transition time T1 and the whispering gallery mode spectral drift time interval T2 were significantly shortened, and the two were highly consistent. When the T2 interval was similar, further comparison of the wavelength drift amplitude could achieve more precise concentration discrimination: the smaller the drift amount, the earlier the whispering gallery mode spectral response tended to saturation, reflecting a higher alanine aminotransferase concentration. Combined with the above analysis parameters, it is possible to achieve highly sensitive, graded, and high-precision detection of alanine aminotransferase concentration, significantly improving the system's quantitative capability and clinical reference value.

[0045] It should be noted that the array structure, size, arrangement, number of microcavities, and microcavity size of the liquid crystal microcavity array described in the present invention can be adjusted or optimized based on actual application requirements without affecting the principles and methods of the invention. All improvements, modifications, and substitutions based on the principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. An alanine aminotransferase detection device based on a liquid crystal microcavity array, characterized in that: include: The excitation unit splits the single excitation light source to the liquid crystal microcavity sensing unit to achieve multi-channel parallel excitation operation; A liquid crystal microcavity sensing unit comprises an array structure (5) composed of a plurality of array units; the array unit comprises a weakly alkaline substrate buffer solution and a liquid crystal microcavity (6); the liquid crystal microcavity is a spherical structure, and the surface of the liquid crystal material is modified with stearic acid and doped with a fluorescent dye; The acquisition and analysis unit includes a polarization microscope module, a spectrum acquisition module and a data analysis computer (9), and is used for real-time monitoring of polarization patterns of molecular arrangement changes in the liquid crystal microcavity, collecting whispering gallery mode spectra, and recording, processing and analyzing signal data.

2. The alanine aminotransferase detection device based on liquid crystal microcavity array according to claim 1, characterized in that: The excitation unit comprises a laser (1), an optical fiber beam splitter (2) and a multi-channel excitation optical fiber (3); the laser (1) outputs a green light excitation signal with a central wavelength of 532 nm, which is transmitted to the optical fiber beam splitter (2) via a multimode optical fiber. After beam splitting, the signals are respectively introduced into the channels of each liquid crystal microcavity (6) in the array structure (5) via the excitation optical fiber. Each liquid crystal microcavity (6) is coupled with laser light via the excitation optical fiber in the excitation unit to generate an optical whispering gallery mode.

3. The alanine aminotransferase detection device based on liquid crystal microcavity array according to claim 1, characterized in that: The pH value of the weak alkaline substrate buffer solution is 7.6-8.0; the array unit includes a control unit and multiple test units; the weak alkaline substrate buffer solution added to the array unit includes 0.1 mM α-ketoglutaric acid and 0.167 mM L-alanine.

4. The alanine aminotransferase detection device based on liquid crystal microcavity array according to claim 1, characterized in that: The liquid crystal microcavity (6) is prepared in an array unit by a microinjection method, specifically: a liquid crystal material is mixed with 0.08 wt% of stearic acid and 0.1 wt% of DCM fluorescent dye to obtain a precursor solution by oscillation or ultrasound, and the precursor solution is injected into a substrate buffer solution by microinjection; the diameter of the liquid crystal microcavity (6) is 30 to 60 μm.

5. The alanine aminotransferase detection device based on liquid crystal microcavity array according to claim 1, characterized in that: The array unit is made of highly transparent acrylic material and has a cubic structure; the ratio of the side length of the array unit to the diameter of the liquid crystal microcavity is 1.5 to 2:

1.

6. The alanine aminotransferase detection device based on liquid crystal microcavity array according to claim 1, characterized in that: The polarizing microscope module includes a polarizing microscope (4), and the acquisition module includes an acquisition optical fiber (7) and a spectrometer (8); the polarizing microscope (4) acquires in real time an image of optical anisotropy changes generated by the liquid crystal microcavity array during a response process, and transmits polarization pattern information to a data analysis computer (9) through an image acquisition device to record the liquid crystal arrangement state transition process and its corresponding time node; the acquisition optical fiber (7) is correspondingly connected to each array unit in the liquid crystal microcavity sensing unit, and is used to acquire the whispering gallery mode emission spectrum generated by the array unit after excitation, and synchronously transmits the spectrum data to the data analysis computer (9) to analyze and process the spectrum drift and its time evolution characteristics.

7. A method for detecting alanine aminotransferase based on a liquid crystal microcavity array according to any one of claims 1 to 6, characterized in that: The alanine aminotransferase solution to be tested is added to the detection unit respectively; in the detection unit, during the alanine aminotransferase catalytic reaction, L-alanine and α-ketoglutarate generate pyruvate and L-glutamate under the catalytic action of the enzyme, wherein the generated pyruvate further dissociates into hydrogen ions (H + ), resulting in a decrease in the pH value of the local microenvironment; this pH change affects the protonation state of the stearic acid molecules on the surface of the liquid crystal microcavity, which in turn causes changes in the orientation of the liquid crystal molecules, and obtains the evolution of the polarization pattern and spectral response caused by the orientation change; the higher the concentration of alanine aminotransferase as a catalytic enzyme, the shorter the time required to complete the equal amount of reaction under the condition of constant substrate concentration. According to the known alanine aminotransferase concentration grading standard, the change time of the liquid crystal molecular orientation response is used to achieve quantitative analysis of the enzyme concentration.

8. The method for detecting alanine aminotransferase based on liquid crystal microcavity array according to claim 7, characterized in that: The liquid crystal molecule orientation changes from a radial state to a bipolar state, and the polarization pattern in the polarizing microscope (4) changes from a radial state to a bipolar state, and the polarization pattern transition time is recorded; during the structural transition of the liquid crystal molecule configuration from a radial state to a bipolar state, the effective refractive index of the liquid crystal microcavity (6) changes, causing the whispering gallery mode resonance wavelength to redshift, and the spectrum shift time is recorded; based on the spectrum shift time and the polarization pattern transition time, combined with the reaction rate characteristics of different enzyme concentrations, a time-concentration response relationship is established to achieve highly sensitive quantitative detection of alanine aminotransferase concentration.

9. The method for detecting alanine aminotransferase based on liquid crystal microcavity array according to claim 8, characterized in that: The whispering gallery mode effective refractive index n eff The relationship with the resonant wavelength λ is as follows: λ=(2πRn eff ) / m Where R is the radius of the microcavity; m is the mode order; as the liquid crystal molecular configuration changes from the radial state to the bipolar state, the effective refractive index n of the whispering gallery mode is excited. eff The normal refractive index in the vertical direction changes to the extraordinary refractive index along the long axis of the molecule.

10. The method for detecting alanine aminotransferase based on liquid crystal microcavity array according to claim 7, characterized in that: During the detection process, the temperature of the liquid crystal microcavity (6) array is controlled at 36-37°C.

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