Liquid crystal-based antimony ion detection sensor, preparation method, and detection platform

Abstract

The present invention provides a liquid crystal-based antimony ion detection sensor and its preparation method and detection platform. The liquid crystal-based antimony ion sensor includes a substrate, a liquid crystal orientation layer, a grid, a nematic liquid crystal, a cationic surfactant, and a nucleic acid aptamer. The substrate is modified with a liquid crystal orientation layer, the grid is located on the substrate modified with the liquid crystal orientation layer, the nematic liquid crystal, the cationic surfactant, and the nucleic acid aptamer are all located within the grid, and the nematic liquid crystal is located below the cationic surfactant and the nucleic acid aptamer. The cationic surfactant and the nucleic acid aptamer are combined to form a composition that induces a parallel arrangement of the surface nematic liquid crystal layer, wherein the nucleic acid aptamer is used to specifically bind to antimony ions. The antimony ion detection sensor provided by the present invention has high sensitivity, low detection limit, high detection efficiency, simple detection method, and low cost, and has broad development prospects in the fields of medicine, environment, and biological analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal detection, and in particular to a liquid crystal-based antimony ion detection sensor, a preparation method thereof, and a detection platform. Background Art

[0002] Heavy metal pollutants are considered the most hazardous of all pollutants. They are highly toxic, easily accumulate, and are difficult to degrade. They can accumulate along the food chain, causing harm to organisms and ultimately impacting biodiversity. Antimony, a toxic heavy metal, is considered one of the most dangerous pollutants in the environment. It is widely present in industry, medicine, and daily life. While monitoring and control of lead, mercury, cadmium, chromium, and arsenic are relatively mature, testing equipment for new risk control targets such as thallium and antimony is limited.

[0003] The increasing use of antimony-containing compounds has led to the release of more antimony into the air, water, or soil, causing serious environmental toxicity and health problems. The toxicity of antimony is primarily related to its valence and oxidation states. Antimony in aquatic environments generally exists in the trivalent state [Sb(III)] and the pentavalent state [Sb(V)], with Sb(III) being 10 times more toxic than Sb(V). Therefore, developing effective methods for the detection and quantitative analysis of antimony ions, particularly Sb(III), in aquatic environments is of great importance.

[0004] The detection methods currently used for antimony ions mainly include inductively coupled plasma mass spectrometry (ICP-MS), anodic stripping voltammetry, atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), spectrophotometry, electrochemical method, colorimetry and fluorescence method. However, most of the detection methods in the prior art have certain limitations. For example, ICP-MS and atomic absorption method require expensive equipment, high analysis cost, and time-consuming and labor-intensive operation process, while the sensitivity of spectrophotometry and electrochemical method is relatively low. Therefore, it is urgent to explore a sensitive, precise, simple, rapid and low-cost detection method for antimony ions in water environment. Summary of the Invention

[0005] The problem solved by the present invention is how to provide a liquid crystal-based antimony ion detection sensor with high detection sensitivity, simplicity, speed and low detection cost.

[0006] To solve at least one aspect of the above problems, the present invention provides a liquid crystal-based antimony ion detection sensor, comprising a substrate, a liquid crystal alignment layer, a grid, a nematic liquid crystal, a cationic surfactant, and a nucleic acid aptamer;

[0007] The substrate is modified with the liquid crystal alignment layer, the grid is located on the substrate modified with the liquid crystal alignment layer, the nematic liquid crystal, the cationic surfactant, and the nucleic acid aptamer are all located in the grid, and the nematic liquid crystal is located below the cationic surfactant and the nucleic acid aptamer. The cationic surfactant and the nucleic acid aptamer are combined to form a composition arranged parallel to the substrate, wherein the nucleic acid aptamer is used to specifically bind to antimony ions.

[0008] Preferably, the nucleic acid aptamer comprises poly-A, and the concentration of the nucleic acid aptamer is greater than or equal to 500 nM.

[0009] Preferably, the cationic surfactant comprises cetyltrimethylammonium bromide, and the concentration of the cationic surfactant is greater than or equal to 15 μM.

[0010] Preferably, the liquid crystal alignment layer includes N,N-dimethyl-N-octadecyl-3-aminopropyltrimethoxysilyl chloride.

[0011] Preferably, the substrate includes a glass substrate or a quartz substrate.

[0012] Preferably, a HEPES buffer is further included, and the HEPES buffer is used to dissolve the cationic surfactant and the nucleic acid aptamer, and the concentration of the HEPES buffer is less than or equal to 1 mM.

[0013] Preferably, the nematic liquid crystal comprises 4-pentyl-4'-cyanobiphenyl.

[0014] The present invention modifies a liquid crystal alignment layer on the surface of a substrate, and places a grid on the substrate modified with the modified liquid crystal alignment layer. When nematic liquid crystal is added to the grid, the nematic liquid crystal can be aligned perpendicular to the substrate under the action of the liquid crystal alignment layer. The cationic surfactant has a positive charge, and the nucleic acid aptamer has a negative charge. After the two are combined, they can induce the nematic liquid crystal located at the binding interface of the nematic liquid crystal, the cationic surfactant, and the nucleic acid aptamer to align parallel to the substrate, thereby making the polarized optical image appear bright. When antimony ions are present, the nucleic acid aptamer preferentially binds to the antimony ions and undergoes a conformational change, thereby releasing the cationic surfactant. At this time, the cationic surfactant induces the nematic liquid crystal at the binding interface to align perpendicularly to the substrate, thereby making the polarized optical image appear dark. The higher the concentration of antimony ions, the more cationic surfactant is released, and the more obvious the dark state is. Therefore, the concentration of antimony ions can be judged based on the light and dark states of the polarized optical image. Since the nucleic acid aptamer is very sensitive to the binding of antimony ions, the sensitivity of antimony ion concentration detection is higher and the detection limit is lower. The liquid crystal-based antimony ion detection sensor provided by the present invention has high sensitivity, low detection limit, high detection efficiency, simple detection method, and low cost, and has broad development prospects in the fields of medicine, environment, and biological analysis.

[0015] In another aspect, the present invention provides a method for preparing a liquid crystal-based antimony ion detection sensor, which is used to prepare the liquid crystal-based antimony ion detection sensor as described above, comprising the following steps:

[0016] Step S1, modifying a liquid crystal alignment layer on a substrate to obtain a pretreated substrate;

[0017] Step S2, placing a grid on the pretreated substrate, and then dropping nematic liquid crystals into the grid to align the nematic liquid crystals perpendicular to the substrate to form a nematic liquid crystal film;

[0018] Step S3: mixing a cationic surfactant and a nucleic acid aptamer to obtain a mixed solution, adding the mixed solution to the grid so that the mixed solution is located above the nematic liquid crystal film, and obtaining a liquid crystal-based antimony ion detection sensor.

[0019] Preferably, the step S1 comprises: cleaning the substrate, soaking it in a liquid crystal alignment layer solution, taking it out, drying it, and heating it to fix the liquid crystal alignment layer on the substrate, thereby obtaining the pretreated substrate.

[0020] The beneficial effects of the preparation method of the liquid crystal-based antimony ion detection sensor provided by the present invention relative to the prior art are the same as those of the liquid crystal-based antimony ion detection sensor, and will not be described in detail here.

[0021] On the other hand, the present invention provides an antimony ion detection platform, including a detection module, an acquisition and uploading module, an analysis module and a terminal module;

[0022] The detection module includes the liquid crystal-based antimony ion detection sensor, a light source, a polarizer, and an analyzer, wherein the light source is located below the liquid crystal-based antimony ion detection sensor, the polarizer is located between the light source and the liquid crystal-based antimony ion detection sensor, and the analyzer is located above the liquid crystal-based antimony ion detection sensor.

[0023] The detection module is used to detect the sample to be tested and generate a polarized optical image;

[0024] The acquisition and uploading module is used to acquire the polarized optical image and upload it to the analysis module;

[0025] The analysis module is used to analyze the polarized optical image and obtain the detection result of the sample to be tested;

[0026] The terminal module is used to input test conditions and is also used to display and record the test results.

[0027] The beneficial effects of the antimony ion detection platform provided by the present invention relative to the prior art are the same as those of the liquid crystal-based antimony ion detection sensor, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The chemical structure diagram of the molecules in the liquid crystal-based antimony ion detection sensor according to the embodiment of the present invention and the poly-A nucleic acid aptamer and Sb 3+ Schematic diagram of the specific binding principle, where (a) is a schematic diagram of the molecular structure of 5CB, CTAB, and DMOAP, and (b) is the base sequence of the poly-A nucleic acid aptamer and the binding of the poly-A nucleic acid aptamer to Sb 3+ Schematic diagram of the principle of specific binding;

[0029] Figure 2 The antimony ion detection sensor based on liquid crystal in the embodiment of the present invention is in the initial state and combined with Sb 3+ Schematic diagram of the structural changes and polarization optical image changes after the reaction, where (a) is a schematic diagram of the structure of the nematic liquid crystal modified with CTAB, (b) is a schematic diagram of the structure of the nematic liquid crystal modified with a mixture of CTAB and poly-A nucleic acid aptamers, and (c) is a schematic diagram of the liquid crystal-based antimony ion sensor bound to Sb after the nematic liquid crystal modified with CTAB and poly-A nucleic acid aptamers. 3+(d) is the polarization optical image of the nematic liquid crystal modified with CTAB, (e) is the polarization optical image of the nematic liquid crystal modified with CTAB and poly-A nucleic acid aptamer, (f) is the liquid crystal-based antimony ion sensor combined with Sb after the nematic liquid crystal was modified with CTAB and poly-A nucleic acid aptamer. 3+ Polarized optical image after

[0030] Figure 3 : These are polarization optical image comparison diagrams of liquid crystal-based antimony ion detection sensors under different CTAB concentration conditions in an embodiment of the present invention, wherein (a) is a polarization optical image comparison diagram of the liquid crystal-based antimony ion detection sensor under the condition of a CTAB concentration of 1 μM, (b) is a polarization optical image comparison diagram of the liquid crystal-based antimony ion detection sensor under the condition of a CTAB concentration of 5 μM, (c) is a polarization optical image comparison diagram of the liquid crystal-based antimony ion detection sensor under the condition of a CTAB concentration of 10 μM, and (d) is a polarization optical image comparison diagram of the liquid crystal-based antimony ion detection sensor under the condition of a CTAB concentration of 15 μM.

[0031] Figure 4 Figures 1 and 2 are polarization optical image comparisons of liquid crystal-based antimony ion detection sensors under different poly-A concentrations according to an embodiment of the present invention, wherein (a) is a polarization optical image comparison of the liquid crystal-based antimony ion detection sensor at different times when the poly-A concentration is 100 nM, (b) is a polarization optical image comparison of the liquid crystal-based antimony ion detection sensor at different times when the poly-A concentration is 300 nM, and (c) is a polarization optical image comparison of the liquid crystal-based antimony ion detection sensor at different times when the poly-A concentration is 500 nM.

[0032] Figure 5 The nematic liquid crystal in the embodiment of the present invention is modified with 15 μM CTAB and 500 nM Poly-A nucleic acid aptamer at different concentrations of Sb 3+ Polarization optical image comparison diagram under the following conditions, where Sb 3+ The concentrations are (a) 0 nM, (b) 20 nM, (c) 50 nM, (d) 100 nM, (e) 200 nM, (f) 500 nM, (g) 800 nM, (h) 1 μM, (i) 2 μM, (j) 3 μM, (k) 4 μM, and (l) 5 μM;

[0033] Figure 6 In the embodiment of the present invention, Sb 3+ A graph showing the relationship between concentration and the average grayscale intensity of the polarized optical image of the liquid crystal-based antimony ion detection sensor;

[0034] Figure 7 Figure 3 is a comparison of polarization optical images of nematic liquid crystals under different modifications under different pH conditions, where (a) is a comparison of polarization optical images of nematic liquid crystals modified with 15 μM CTAB, (b) is a comparison of polarization optical images of nematic liquid crystals modified with a mixture of 15 μM CTAB and 500 nM Poly-A nucleic acid aptamers; (c) is a comparison of polarization optical images of nematic liquid crystals modified with Sb in the above system. 3+ Comparison of polarized optical images after 3D scanning;

[0035] Figure 8 Figure 2 is a comparison of polarization optical images of nematic liquid crystals under different modifications at pH 2, where (a) is a comparison of polarization optical images of nematic liquid crystals modified with 20 μM and 25 μM CTAB, respectively; (b) is a comparison of polarization optical images of nematic liquid crystals modified with 25 μM CTAB and 500 nM poly-A nucleic acid aptamer, and 25 μM CTAB and 800 nM poly-A nucleic acid aptamer, respectively; (c) At pH 2, 1 μM and 2 μM Sb were added to the liquid crystal-based antimony ion detection sensor with 25 μM CTAB and 800 nM poly-A nucleic acid aptamer, respectively. 3+ Comparison of polarized optical images of nematic liquid crystal;

[0036] Figure 9 Figure 2 is a comparison of polarization optical images of nematic liquid crystals under different modifications in HEPES buffers with different concentrations, wherein (a) is a comparison of polarization optical images of nematic liquid crystals modified with 15 μM CTAB in HEPES buffers with different concentrations, and (b) is a comparison of polarization optical images of nematic liquid crystals modified with a mixture of 15 μM CTAB and 500 nM Poly-A nucleic acid aptamers in HEPES buffers with different concentrations;

[0037] Figure 10 Figure 2 is a comparison of polarization optical images of nematic liquid crystals under different modifications in 100mM HEPES buffer, where (a) is a comparison of polarization optical images of nematic liquid crystals modified with 25μM and 30μM CTAB in 100mM HEPES buffer, (b) is a comparison of polarization optical images of nematic liquid crystals modified with 30μM CTAB and 800nM poly-A nucleic acid aptamer, and 30μM CTAB and 1000nM poly-A nucleic acid aptamer in 100mM HEPES buffer, (c) is a comparison of polarization optical images of liquid crystal-based antimony ion detection sensors modified with 30μM CTAB and 1000nM poly-A nucleic acid aptamer in 100mM HEPES buffer after adding 1μM and 2μM Sb 3+Comparison of polarized optical images after 3D scanning;

[0038] Figure 11 Figures 2 and 3 show the optical response comparisons of the liquid crystal-based antimony ion detection sensor in the presence of different metal ions, where (a) shows the polarization optical image comparisons of the liquid crystal-based antimony ion detection sensor in the presence of different metal ions, and (b) shows the average grayscale intensity comparisons of the polarization optical images of the liquid crystal-based antimony ion detection sensor in response to different metal ions.

[0039] Figure 12 Schematic diagram of a process for preparing a liquid crystal-based antimony ion detection sensor according to an embodiment of the present invention;

[0040] Figure 13 Schematic diagram of the structure of the antimony ion detection platform in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0042] It should be noted that, unless otherwise specified, the features of the embodiments of the present invention may be combined with each other. The terms "comprising," "including," "containing," and "having" are non-restrictive and may include other steps and other components that do not affect the results. The above terms encompass the terms "consisting of" and "consisting essentially of." Unless otherwise specified, materials, equipment, and reagents were commercially available.

[0043] Liquid crystals, as a novel signal transducer, have been widely used in chemical and biological monitoring platforms. Their unique properties combine the fluidity of liquids with the anisotropy of crystals, resulting in long-range order in their molecular arrangement. Liquid crystals can respond to a variety of external stimuli, including temperature, electric fields, chemical surfactants, and biomolecules. The high sensitivity of liquid crystal molecules makes their orientation susceptible to tiny changes at the molecular level, which in turn affects the refraction of light. Chemical and biological interactions are amplified and converted into optical signals visible under polarized optical microscopy, causing changes in the color and brightness of the optical image.

[0044] Aptamers, as functional nucleic acids, are considered effective probes for metal ion monitoring due to their remarkable binding affinity and selectivity. The phosphates and bases in oligonucleotides provide excellent binding sites for metals. Aptamers are also structurally stable, highly programmable, and inexpensive to synthesize, making them easy to select in vitro for the development of specific metal recognition sequences.

[0045] Currently, aptamer-based heavy metal ion biosensors have been developed, utilizing signal conversion mechanisms such as electrochemistry, colorimetry, and fluorescence. However, these biosensors have limitations, such as the complex aptamer immobilization process, expensive equipment, and the need for specialized fluorophores or chemiluminescent substances for signal readout.

[0046] In addition, the existing technology uses nucleic acid aptamers conjugated to gold nanoparticles to establish a colorimetric sensor for trivalent antimony ions, but this colorimetric sensor has high requirements for chemiluminescent materials, a complex nucleic acid aptamer modification process, and a high detection limit.

[0047] The embodiment of the present invention provides a liquid crystal-based antimony ion detection sensor, comprising a substrate, a liquid crystal alignment layer, a grid, a nematic liquid crystal, a cationic surfactant, and a nucleic acid aptamer;

[0048] The substrate is modified with the liquid crystal alignment layer, the grid is located on the substrate modified with the liquid crystal alignment layer, the nematic liquid crystal, the cationic surfactant and the nucleic acid aptamer are all located in the grid, and the nematic liquid crystal is located below the cationic surfactant and the nucleic acid aptamer. The cationic surfactant and the nucleic acid aptamer are combined to form a composition that induces parallel alignment of the surface nematic liquid crystal layer, wherein the nucleic acid aptamer is used to specifically bind to antimony ions.

[0049] The substrate includes a glass substrate or a quartz substrate. For example, a glass slide can be selected as the substrate.

[0050] The liquid crystal alignment layer includes N, N-dimethyl-N-octadecyl-3-aminopropyltrimethoxysilyl chloride (DMOAP). After DMOAP is modified on the surface of the substrate, it can induce nematic liquid crystals to align perpendicularly to the substrate.

[0051] The grid comprises a metal grid with a thickness of 10-20 μm. By placing the 10-20 μm thick metal grid on the substrate that modifies the liquid crystal alignment layer, the nematic liquid crystal, cationic surfactant, and nucleic acid aptamer can be confined within the grid, thereby improving the stability of the sensor and ensuring sensor performance. For example, a TEM grid can be selected as the grid.

[0052] The nematic liquid crystal includes 4-pentyl-4'-cyanobiphenyl (5CB). The crystalline range of 5CB is 22-35° C., which is suitable for application at room temperature.

[0053] The cationic surfactant includes hexadecyltrimethylammonium bromide (CTAB), and the nucleic acid aptamer includes poly-A, wherein poly-A is polyadenylic acid, which is composed of multiple adenine nucleotides (A). For example, poly-A can be an oligonucleotide chain composed of 10 adenine nucleotides. CTAB is positively charged and poly-A is negatively charged, and the two can bind to each other through electrostatic adsorption. Wherein, the concentration of the cationic surfactant is greater than or equal to 15μM, and the concentration of the nucleic acid aptamer is greater than or equal to 500nM. When the concentration of the cationic surfactant is greater than or equal to 15μM, in the absence of the nucleic acid aptamer, the vertical orientation of the nematic liquid crystal can be maintained, and the concentration of the nucleic acid aptamer is greater than or equal to 500nM, which can ensure that the nucleic acid aptamer is fully combined with the cationic surfactant, thereby forming a composition arranged parallel to the substrate, and after the two are combined, the nematic liquid crystal at the interface between the nematic liquid crystal and the cationic surfactant can be induced to be arranged parallel to the substrate, and good stability can be maintained.

[0054] It should be noted that in the above and following contents of the embodiments of the present invention, the unit M represents mol / L, that is, mole per liter. For example, nM represents nmol / L, and μM represents μmol / L.

[0055] Metal ions are easy to bind to oligonucleotide probes, and for antimony ions, trivalent antimony ions Sb 3+ It has high affinity to oligonucleotides, and pentavalent antimony ions Sb 5+ There is no interaction with oligonucleotides. On this basis, Sb 3+ Poly-A was selected as the nucleic acid aptamer because it has a higher affinity with adenine nucleotides. 3+ The binding ability is stronger and the specificity is high, thereby improving the sensitivity of the sensor to detect antimony ions and reducing the influence of other metal ions.

[0056] It should be noted that, in the following text, unless otherwise specified, antimony ions refer to trivalent antimony ions Sb 3+ .

[0057] Figure 1 (a) is the structural formula of 5CB, CTAB and DMOAP, Figure 1 (b) is Sb 3+ Schematic diagram of the principle of specific binding to poly-A nucleic acid aptamer, Sb 3+ It specifically binds to poly-A to form a complex and changes the conformation of poly-A.

[0058] Figure 2 Schematic diagram of liquid crystal-based antimony ion detection sensor, where Figure 2(a) is a schematic diagram of the structure in which only the substrate, liquid crystal alignment layer, nematic liquid crystal 5CB and cationic surfactant CTAB exist. Figure 2 (b) is in Figure 2 The schematic diagram of the structure after adding nucleic acid aptamer poly-A on the basis of (a). Figure 2 (c) is in Figure 2 Sb is added to (b) 3+ The structural diagram after Figure 2 Middle (d), Figure 2 (e) and Figure 2 (f) corresponds to Figure 2 (a) Figure 2 (b) and Figure 2 Polarized optical image in the middle (c) state.

[0059] like Figure 2 As shown in the figure, when there are only substrate, liquid crystal alignment layer, nematic liquid crystal 5CB and cationic surfactant CTAB, the nematic liquid crystal 5CB is aligned perpendicular to the substrate under the dual action of the liquid crystal alignment layer and the cationic surfactant. At this time, the polarized optical image presents a dark state. After the poly-A nucleic acid aptamer is added, the poly-A nucleic acid aptamer and CTAB combine with each other under the action of electrostatic adsorption, inducing the nematic liquid crystal 5CB at the interface to align parallel to the substrate. At this time, the polarized optical image presents a bright state. When Sb is present, the nematic liquid crystal 5CB is aligned perpendicular to the substrate under the dual action of the liquid crystal alignment layer and the cationic surfactant. 3+ When Sb 3+ It binds to the poly-A nucleic acid aptamer and changes the conformation of the poly-A nucleic acid aptamer, releasing CTAB from the combination of the two, and re-inducing the nematic phase liquid crystal 5CB at the interface to align perpendicular to the substrate. At this time, the polarized optical image appears dark again.

[0060] Without adding nucleic acid aptamers, CTAB with concentrations of 1 μM, 5 μM, 10 μM and 15 μM was used to prepare liquid crystal-based antimony ion detection sensors, and polarization optical images of each antimony ion detection sensor were obtained, as shown in FIG. Figure 3 shown.

[0061] Figure 3 (a), (b), (c) and (d) represent the polarization optical images under the conditions of CTAB concentration of 1μM, 5μM, 10μM and 15μM, respectively. Figure 3As can be seen in the figure, the brightness of the polarized optical image gradually decreases with increasing CTAB concentration. When the CTAB concentration reaches 15 μM, the polarized optical image is completely black and remains stable, indicating that the nematic liquid crystals 5CB maintain a vertical orientation. Therefore, a cationic surfactant concentration of 15 μM or higher can maintain the vertical orientation of the nematic liquid crystals and maintain stability, thereby improving the performance of the liquid crystal-based antimony ion detection sensor.

[0062] The concentration of CTAB was set to 15 μM, and poly-A nucleic acid aptamers were added at concentrations of 100 nM, 300 nM, and 500 nM to prepare antimony ion detection sensors. Polarization optical images of each liquid crystal-based antimony ion detection sensor were obtained at 1 min, 5 min, 15 min, and 30 min, as shown in FIG. Figure 4 shown.

[0063] Figure 4 (a), (b) and (c) show the dynamic changes of polarization optical images under the conditions of poly-A concentration of 100nM, 300nM and 500nM, respectively. Figure 4 As can be seen in the figure, when the poly-A concentration is 500nM, its polarized optical image is stable and lasts for at least 30 minutes, thus improving the stability of the liquid crystal-based antimony ion detection sensor. Therefore, a poly-A nucleic acid aptamer concentration greater than or equal to 500nM can ensure the stability of the liquid crystal-based antimony ion detection sensor.

[0064] In order to verify the detection limit and detection range of the liquid crystal-based antimony ion detection sensor in the embodiment of the present invention, a liquid crystal-based antimony ion detection sensor was prepared using CTAB with a concentration of 15 μM and poly-A with a concentration of 500 nM, respectively. 3+ Solutions with concentrations of 0, 20 nM, 50 nM, 100 nM, 200 nM, 500 nM, 800 nM, 1 μM, 2 μM, 3 μM, 4 μM, and 5 μM were tested, and polarized optical images were acquired, e.g. Figure 5 shown.

[0065] According to the above, when Sb 3+ When present, Sb 3+ It can specifically bind to poly-A in liquid crystal-based antimony ion detection sensors and cause the conformation of poly-A to change, inducing the direction of the nematic phase liquid crystal to change, thereby changing the polarized optical image. 3+After adding the liquid crystal-based antimony ion detection sensor, changes in the polarized optical image were observed within 10 seconds, and a stable state was reached within 60 seconds. Therefore, the liquid crystal-based antimony ion detection sensor provided by the embodiment of the present invention can quickly and efficiently detect antimony ions.

[0066] Figure 5 (a), (b), (c), (d), (e), (f), (g), (h), (i), (j), (k) and (l) respectively represent the use of Sb 3+ Polarized optical images of solutions with concentrations of 0, 20nM, 50nM, 100nM, 200nM, 500nM, 800nM, 1μM, 2μM, 3μM, 4μM and 5μM were tested. Figure 5 It can be seen that when Sb 3+ When the concentration is 20nM, the polarization optical image of the liquid crystal-based antimony ion detection sensor begins to change, the brightness of the polarization optical image decreases, and as Sb 3+ As the concentration gradually increases, the brightness of the polarized optical image gradually decreases. At this time, the nematic phase liquid crystal molecules at the interface gradually change from a state parallel to the substrate to a state perpendicular to the substrate. 3+ When the concentration of Sb is 5μM, almost all the grids become dark, which means that the nematic liquid crystals at the interface have all formed a vertical orientation. 3+ The concentration will not continue to cause changes in the polarization optical image.

[0067] Furthermore, by using different concentrations of Sb 3+ The average gray value of the polarized optical image under Sb 3+ Quantitative analysis of Sb. Using OpenCV image processing tools, an automatic measurement system for the average grayscale value of polarized optical images was established, and the RGB image was converted into a grayscale image to obtain the average grayscale value I of the polarized optical image at different concentrations. By measuring different samples under the same conditions multiple times, the average grayscale value I of different concentrations of Sb was obtained. 3+ The standard deviation of (I0-I) / (I0) under the conditions is plotted, and a linear fitting curve is drawn, where I0 represents the standard deviation of (I0-I) / (I0) under the conditions without Sb. 3+ The initial grayscale intensity of the liquid crystal-based antimony ion detection sensor when Sb is present, I represents the ... 3+ The grayscale value after . The result is as follows Figure 6 As shown, (I0-I) / I0=0.134*C(Sb 3+ )+0.040,R 2 =0.98. Figure 6 It can be seen that the value of (I0-I) / I0 is related to Sb 3+ There is a good linear relationship between the concentrations.

[0068] Therefore, the liquid crystal-based antimony ion detection sensor provided by the embodiment of the present invention is sensitive to Sb 3+ The detection range is 20 nM-5 μM, and the limit of detection (LOD) is 20 nM. The liquid crystal-based antimony ion detection sensor provided by the embodiment of the present invention has high sensitivity and can detect antimony ions in a wide range.

[0069] The solubility of metal salts is closely related to the pH of the water environment, and the ionic strength also varies under different pH conditions. The pH of the liquid crystal-based antimony ion detection sensor was controlled to verify the antimony ion detection sensor based on liquid crystal under different pH conditions for Sb 3+ Response situation. Figure 7 As shown in FIG, the CTAB concentration in the liquid crystal-based antimony ion detection sensor is set to 15 μM, and the pH is set to 2, 3, 4, 5, 7, and 8, respectively. Figure 7 As can be seen in (a), when the pH is 7 and 8, the polarization optical image of the liquid crystal-based antimony ion detection sensor is completely dark, while under other pH conditions, there is a certain bright state. Then, a poly-A nucleic acid aptamer with a concentration of 500nM was added to each treatment. Figure 7 As can be seen in (b), the polarized optical images under all pH conditions will change from dark to bright. Among them, when the pH is 7, the difference between dark and bright is the most obvious. Then, Sb is added 3+ , the polarized optical image will change from bright to dark again. Figure 7 As can be seen in (c), the difference between the front and back lights is most obvious when the pH is 7. Therefore, controlling the pH of the liquid crystal-based antimony ion detection sensor at 7 can produce a greater contrast, which is beneficial for improving detection sensitivity and performance.

[0070] Based on the relationship between the solubility of metal salts and the pH in the aqueous environment, as well as the differences in ionic strength under different pH conditions, adjusting the concentrations of cationic surfactants and nucleic acid aptamers for different pH conditions can help ensure that the liquid crystal-based antimony ion detection sensor can achieve better detection performance under different pH conditions.

[0071] For this reason, Figure 8 As shown, in an environment with a pH of 2, the concentration of CTAB was set to 20 μM and 25 μM respectively. Figure 8 As can be seen in (a), when the CTAB concentration is 25 μM, the polarization optical image of the antimony ion detection sensor presents a completely dark state. Then, poly-A with concentrations of 500 nM and 800 nM are added, respectively. Figure 8As can be seen in (b), when the poly-A concentration is 800nM, the difference between the dark and bright states of the polarization optical image of the liquid crystal-based antimony ion detection sensor is greater. When 1μM and 2μM Sb 3+ It can be seen that the state before addition has changed. When the CTAB concentration is 25μM and the poly-A concentration is 800nM, Figure 8 As can be seen in (c), Sb 3+ The difference is even greater at a concentration of 2 μM. Therefore, when the pH changes, adjusting the concentrations of CTAB and poly-A can create better conditions to ensure the detection effect of the liquid crystal-based antimony ion detection sensor.

[0072] In one embodiment, the cationic surfactant and the nucleic acid aptamer are prepared and diluted using HEPES buffer, that is, the HEPES buffer is used to dissolve the cationic surfactant and the nucleic acid aptamer, and the concentration of the HEPES buffer is less than or equal to 1 mM.

[0073] When the concentration of HEPES buffer is different, its ionic strength is also different, which will also have a certain impact on the arrangement of nematic liquid crystals at the interface. Figure 9 As shown in FIG, the concentrations of HEPES buffer in the liquid crystal-based antimony ion detection sensor were set to 1 mM, 10 mM, 50 mM and 100 mM, and then CTAB was added at a concentration of 15 μM. Figure 9 As can be seen in (a), under all HEPES buffer concentration conditions, the polarization optical image of the liquid crystal-based antimony ion detection sensor is dark. Then, a poly-A nucleic acid aptamer with a concentration of 500 nM is added. Figure 9 As can be seen in (b), when the HEPES buffer concentration is 1 mM, the polarized optical image of the liquid crystal-based antimony ion detection sensor clearly transitions from a dark state to a bright state. However, as the HEPES buffer concentration increases, the contrast between the dark and bright states decreases. This is primarily due to the high ionic strength at high HEPES buffer concentrations, which shields the electrostatic interactions of the head group charges of the cationic surfactant CTAB, thereby forming a more densely packed cationic surfactant layer. Therefore, when the HEPES buffer concentration is less than or equal to 1 mM, the liquid crystal-based antimony ion detection sensor exhibits better performance.

[0074] Similarly, under different HEPES buffer concentration conditions, adjusting the concentrations of cationic surfactants and nucleic acid aptamers can also help ensure that the liquid crystal-based antimony ion detection sensor can achieve better detection performance under different HEPES buffer concentration conditions.

[0075] For this reason, Figure 10 As shown, under the condition that the concentration of HEPES buffer is 100mM, the concentration of CTAB is set to 20μM and 30μM respectively. Figure 10 As can be seen in (a), when the CTAB concentration is 30 μM, the polarization optical image of the liquid crystal-based antimony ion detection sensor presents a completely dark state. Then, poly-A with concentrations of 800 nM and 1000 nM is added, respectively. Figure 10 As can be seen in (b), when the poly-A concentration is 1000nM, the difference between the dark and bright states of the polarization optical image of the liquid crystal-based antimony ion detection sensor is greater. When 1μM and 2μM Sb 3+ , it can be seen that the status before joining has changed. Figure 10 As can be seen in (c), when the CTAB concentration is 30μM and the poly-A concentration is 1000nM, Sb 3+ The difference was even greater at a concentration of 2 μM. Therefore, when the HEPES buffer concentration changes, adjusting the concentrations of CTAB and poly-A can create better conditions, thereby improving the detection capability of the liquid crystal-based antimony ion detection sensor.

[0076] In summary, in the liquid crystal-based antimony ion detection sensor in the embodiment of the present invention, the cationic surfactant includes CTAB, the preferred concentration of CTAB is greater than or equal to 15 μM, the nucleic acid aptamer includes poly-A, the preferred concentration of poly-A is greater than or equal to 500 nM, the nematic phase liquid crystal includes 5CB, the pH is preferably set to 7, and HEPES buffer is preferably used to prepare and dilute the cationic surfactant and nucleic acid aptamer, and the preferred concentration of HEPES buffer is less than or equal to 1 mM.

[0077] It should be understood that when the pH conditions or HEPES buffer concentration changes, the performance of the antimony ion detection sensor can be improved by adjusting the concentrations of the cationic surfactant and the nucleic acid aptamer. Therefore, the above preferred range is not intended to limit the scope of protection of the present invention.

[0078] In order to verify the antimony ion detection sensor provided by the embodiment of the present invention for Sb 3+ To investigate the specificity of the antimony ion detection sensor based on liquid crystal (where the concentration of CTAB was 15 μM and the concentration of poly-A was 500 nM), 2 μM Sb 3 + 、Ag + 、Cd 2+ 、Cu 2+ 、Fe 3+ , K + Mg 2+ 、Mn 2+、Na + , Pb 2+ and Zn 2+ , obtain the polarization optical image of the liquid crystal-based antimony ion detection sensor and calculate the corresponding average grayscale value. The results are as follows Figure 11 shown.

[0079] like Figure 11 In (a), Initial represents the initial state of the liquid crystal-based antimony ion detection sensor, except for Sb 3+ In addition, when other metal ions exist, the brightness of the polarized optical image remains basically unchanged, while Sb 3+ When present, brightness is significantly reduced. Figure 11 (b) is a comparison of the average grayscale intensity of polarized optical images after the addition of different metal ions. Figure 11 As can be seen in (b), Sb 3+ The value is significantly lower than that of other metal ions.

[0080] Therefore, the liquid crystal-based antimony ion detection sensor provided by the embodiment of the present invention is sensitive to Sb 3+ It has good selectivity and reduces interference from other metal ions.

[0081] Another embodiment of the present invention provides a method for preparing a liquid crystal-based antimony ion detection sensor, which is used to prepare the liquid crystal-based antimony ion detection sensor as described above. Figure 12 As shown, the following steps are included:

[0082] Step S1, modifying a liquid crystal alignment layer on a substrate to obtain a pretreated substrate;

[0083] Step S2, placing a grid on the pretreated substrate, and then dropping nematic liquid crystals into the grid to align the nematic liquid crystals perpendicular to the substrate to form a nematic liquid crystal film;

[0084] Step S3: mixing a cationic surfactant and a nucleic acid aptamer to obtain a mixed solution, adding the mixed solution to the grid so that the mixed solution is located above the nematic liquid crystal film, and obtaining a liquid crystal-based antimony ion detection sensor.

[0085] In step S1, the substrate is cleaned and then immersed in a liquid crystal alignment layer solution. After being taken out, the substrate is dried and heated to fix the liquid crystal alignment layer on the substrate, thereby obtaining the pretreated substrate.

[0086] For example, the substrate is cleaned with a 5% (v / v) Decon90 solution and then rinsed with a large amount of deionized water. Next, the substrate is immersed in a 0.1% (v / v) DMOAP solution for 30 minutes and then rinsed several times with deionized water to remove excess DMOAP. The substrate is then dried under a nitrogen atmosphere and heated in an oven at 100°C for 2 hours to obtain a substrate modified with a liquid crystal alignment layer, i.e., a pretreated substrate.

[0087] In step S2, illustratively, a TEM grid is placed on the pretreated substrate, and 1 μL of 5CB nematic liquid crystal is dropped into the TEM grid, and excess nematic liquid crystal is removed with a capillary to form a nematic liquid crystal film.

[0088] In step S3, for example, a CTAB and poly-A nucleic acid aptamer aqueous solution is prepared using a HEPES buffer solution with a concentration of 1 mM and a pH of 7.4, CTAB and poly-A are diluted to appropriate concentrations, and then CTAB and poly-A are mixed to obtain a mixed solution. To ensure that the two are fully combined, the solution can be allowed to stand and incubate for 1 hour before being added dropwise to the TEM grid so that the mixed solution is located above the nematic liquid crystal film.

[0089] Yet another embodiment of the present invention provides an antimony ion detection platform, comprising a detection module, a collection and upload module, an analysis module, and a terminal module;

[0090] The detection module includes the liquid crystal-based antimony ion detection sensor, a light source, a polarizer, and an analyzer, wherein the light source is located below the liquid crystal-based antimony ion detection sensor, the polarizer is located between the light source and the liquid crystal-based antimony ion detection sensor, and the analyzer is located above the liquid crystal-based antimony ion detection sensor.

[0091] The detection module is used to detect the sample to be tested and generate a polarized optical image;

[0092] The acquisition and uploading module is used to acquire the polarized optical image and upload it to the analysis module;

[0093] The analysis module is used to analyze the polarized optical image and obtain the detection result of the sample to be tested;

[0094] The terminal module is used to input test conditions and is also used to display and record the test results.

[0095] The detection module includes the above-mentioned liquid crystal-based antimony ion detection sensor, a light source, a polarizer and an analyzer for acquiring polarized optical images.

[0096] The acquisition and uploading module can be a CCD camera or a mobile phone camera, and the collected polarization optical images can be uploaded to a cloud server for storage and analysis.

[0097] Exemplarily, the analysis module is a deep intelligent model constructed in a cloud server, which can analyze the concentration of antimony ions in a sample based on the grayscale value of a polarized optical image.

[0098] The terminal module is used to input test conditions and to display and record test results.

[0099] In one embodiment, the structural diagram of the antimony ion detection platform is as follows: Figure 13 As shown, the LED light source is located below the glass substrate of the liquid crystal-based antimony ion detection sensor, the polarizer is located between the LED light source and the glass substrate, and the analyzer is located above the liquid crystal-based antimony ion detection sensor. After the sample is added to the liquid crystal-based antimony ion detection sensor, the polarized optical image is collected by the mobile phone camera and uploaded to the analysis module for analysis and processing.

[0100] In one embodiment, the process of constructing a deep intelligent model for analyzing antimony ion concentration includes:

[0101] A large number of polarized optical images of liquid crystal-based antimony ion detection sensors were collected at different angles, different antimony ion depths, and using different LED light sources. Single grids were extracted as independent instances through image positioning and edge recognition methods, and the antimony ion concentration was mapped to the sample images to construct model training sets and test data sets. A feature extractor was selected to extract key features from the sample images, which were input into a convolutional neural network to train an antimony ion concentration recognition model, i.e., a deep intelligent model, which can be used to analyze the antimony ion concentration in unknown samples based on the polarized optical images of liquid crystal-based antimony ion detection sensors.

[0102] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A liquid crystal-based antimony ion detection sensor, characterized in that: The method comprises a substrate, a liquid crystal alignment layer, a grid, a nematic liquid crystal, a cationic surfactant and a nucleic acid aptamer; The substrate is modified with the liquid crystal alignment layer, the grid is located on the substrate modified with the liquid crystal alignment layer, the nematic liquid crystal, the cationic surfactant, and the nucleic acid aptamer are all located in the grid, and the nematic liquid crystal is located below the cationic surfactant and the nucleic acid aptamer, the cationic surfactant and the nucleic acid aptamer are combined to form a composition that induces parallel alignment of the surface nematic liquid crystal layer, wherein the nucleic acid aptamer is used to specifically bind to antimony ions; The nucleic acid aptamer includes poly-A, the concentration of the nucleic acid aptamer is greater than or equal to 500nM, the nematic phase liquid crystal includes 4-pentyl-4'-cyanobiphenyl, the cationic surfactant includes hexadecyltrimethylammonium bromide, the concentration of the cationic surfactant is greater than or equal to 15μM, and the liquid crystal alignment layer includes N,N-dimethyl-N-octadecyl-3-aminopropyltrimethoxysilyl chloride.

2. The liquid crystal-based antimony ion detection sensor according to claim 1, characterized in that: The substrate includes a glass substrate or a quartz substrate.

3. The liquid crystal-based antimony ion detection sensor according to claim 1, characterized in that: The method further comprises a HEPES buffer, which is used to dissolve the cationic surfactant and the nucleic acid aptamer. The concentration of the HEPES buffer is less than or equal to 1 mM.

4. A method for preparing a liquid crystal-based antimony ion detection sensor, for preparing the liquid crystal-based antimony ion detection sensor according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1, modifying a liquid crystal alignment layer on a substrate to obtain a pretreated substrate; Step S2, placing a grid on the pretreated substrate, and then dropping nematic liquid crystals into the grid to align the nematic liquid crystals perpendicular to the substrate to form a nematic liquid crystal film; Step S3: mixing a cationic surfactant and a nucleic acid aptamer to obtain a mixed solution, adding the mixed solution to the grid so that the mixed solution is located above the nematic liquid crystal film, and obtaining a liquid crystal-based antimony ion detection sensor.

5. The method for preparing the liquid crystal-based antimony ion detection sensor according to claim 4, characterized in that: The step S1 includes: cleaning the substrate, soaking it in a liquid crystal alignment layer solution, taking it out, drying it, and heating it to fix the liquid crystal alignment layer on the substrate, thereby obtaining the pretreated substrate.

6. An antimony ion detection platform, characterized in that: It includes detection module, collection and upload module, analysis module and terminal module; The detection module comprises the liquid crystal-based antimony ion detection sensor according to any one of claims 1 to 3, a light source, a polarizer, and an analyzer, wherein the light source is located below the liquid crystal-based antimony ion detection sensor, the polarizer is located between the light source and the liquid crystal-based antimony ion detection sensor, and the analyzer is located above the liquid crystal-based antimony ion detection sensor; The detection module is used to detect the sample to be tested and generate a polarized optical image; The acquisition and uploading module is used to acquire the polarized optical image and upload it to the analysis module; The analysis module is used to analyze the polarized optical image and obtain the detection result of the sample to be tested; The terminal module is used to input test conditions and also to display and record the test results.

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