L-DNA and MXene composite material, preparation method thereof, gas sensor and array sensor

Abstract

The invention relates to the technical field of gas sensors, and provides a composite material of L-DNA and MXene, a preparation method of the composite material, a gas sensor and an array sensor. The composite material is prepared from MXene and L-DNA (Deoxyribose Nucleic Acid). Wherein the molecular chain of the L-DNA contains rich functional groups such as phosphate groups and basic groups, so that the L-DNA can interact with the surface of the MXene in various modes such as electrostatic interaction, hydrogen bonds and pi-pi accumulation, and the combination of the MXene and the L-DNA is realized. Therefore, the composite material disclosed by the invention has relatively good stability, meanwhile, the baseline recovery capability of the prepared gas sensor can be remarkably improved, the sensitivity of the sensor is improved, and the selective recognition capability on target gas is also improved.

Description

Technical Field

[0001] This invention relates to the field of gas sensor technology, specifically to a composite material of L-DNA and MXene, its preparation method, a gas sensor, and an array sensor. Background Technology

[0002] Gas sensors have significant applications in industrial production and medical diagnostics. In recent years, two-dimensional transition metal carbides / nitrides (MXenes) have shown great potential in gas sensing due to their excellent conductivity, large specific surface area, and abundant surface functional groups. However, standalone MXene sensors generally suffer from bottlenecks such as poor selectivity and low sensitivity. While existing composite modification strategies can improve sensitivity, the improvement in selectivity remains insignificant.

[0003] Currently, the main composite materials for MXene include MXene / Gr, MXene / MOS, MXene / TMDs, MXene / MOF, and MXene / polymer. Although sensors based on these composite materials have improved sensitivity to some extent, their limited selectivity restricts their practical applications. Some studies have used biomacromolecules (peptides) as a second phase in MXene composites, but the selectivity remains limited. Compared to proteins, DNA is more stable and possesses properties such as adjustable length, programmable sequence, and environmental friendliness, making it a potential candidate for improving MXene selectivity. Summary of the Invention

[0004] This invention aims to at least partially address one of the technical problems existing in the prior art. By combining L-DNA, which possesses anti-enzymatic properties and stereoselective recognition capabilities, with MXene, an L-DNA / MXene biocomposite material was successfully synthesized. After a series of experimental verifications, the gas sensor prepared using this composite material exhibited significant performance improvements: a substantial enhancement in baseline recovery capability, improved sensor sensitivity, and enhanced selective recognition capability for target gases.

[0005] This invention is based on the following discoveries of the inventors:

[0006] As an emerging two-dimensional material, MXene has significantly expanded its application potential in gas sensing by combining it with various functional materials. Currently researched MXene composite systems include MXene / Gr, MXene / MOS, MXene / transition metal diacids (TMDs), MXene / metal-organic frameworks (MOFs), and MXene / polymers. These composites can compensate for the performance shortcomings of single materials through synergistic effects, but each still faces unique challenges.

[0007] MXene / Gr composites, represented by Ti3C2Tx with reduced graphene oxide (rGO) or chemical vapor deposition graphene, exhibit high electrical conductivity and good mechanical properties. However, due to the easy stacking of the two-dimensional sheet structure, specific surface area is lost, and the selectivity for nonpolar gases (such as CH4) or structurally similar VOCs (such as benzene and toluene) is poor. MXene / MOS composites (such as Ti3C2Tx)... x / SnO2、Ti3C2T x MXene / ZnO is mostly prepared using hydrothermal synthesis or atomic layer deposition techniques. It utilizes the oxygen vacancies of MOS to catalyze the dissociation of gas molecules, and combines this with the high conductivity of MXene to reduce the sensor's operating temperature and shorten the response time. However, its hydrophilic surface easily adsorbs water molecules, resulting in high signal drift errors under high humidity. It also exhibits cross-sensitivity to broad-spectrum reducing gases (such as CO and ethanol), and poor specificity in target gas recognition. MXene / TMDs composites can improve NO detection sensitivity and response speed, but they have potential problems such as complex preparation processes or high costs. MXene / MOF composites can effectively improve the specific surface area and gas adsorption capacity of composite materials, but the intrinsic insulation of MOF restricts charge transport, and the weak interfacial bonding between MOF crystals and MXene leads to poor mechanical properties. MXene / polymer composites have good flexibility, and hydrophobic polymer coating can suppress humidity interference. However, the poor thermal stability of polymers limits their application in high-temperature scenarios, and non-specific adsorption results in a lack of selectivity.

[0008] Despite significant advancements in sensitivity, response speed, and environmental adaptability of the aforementioned composite materials, insufficient selectivity remains a core bottleneck hindering their practical applications. While some studies have incorporated biomolecules (peptides) as a second phase with MXene, the selectivity remains limited. In 2025, Yang et al. first revealed the superior adsorption capacity of MXene for single-stranded DNA (ssDNA), demonstrating that DNA exhibits greater stability compared to proteins and possesses advantages such as adjustable length and chemical modifiability. Therefore, programming the DNA base sequence into the MXene sensing interface will achieve high specificity and programmability for gases, thereby propelling MXene composite materials from the laboratory to real-world applications such as medical diagnostics and environmental monitoring.

[0009] The inventors discovered that L-DNA, as a mirror isoform of natural DNA (D-DNA), offers a breakthrough solution for gas detection in complex biological environments due to its resistance to enzymatic degradation and stereoselective recognition capabilities. Specifically, enzymes and receptors in organisms typically have specific recognition capabilities for D-DNA. The phosphate backbone and chiral sugar ring of L-DNA do not match the active sites of natural enzymes (such as DNase I), thus avoiding enzymatic degradation. Therefore, L-DNA exhibits excellent resistance to enzymatic degradation and biocompatibility. Furthermore, the mirror-matching effect between L-DNA and chiral gas molecules enables stereospecific binding, providing a new pathway for distinguishing gas enantiomers.

[0010] Based on this, in a first aspect, the present invention proposes a composite material. According to an embodiment of the present invention, the composite material comprises MXene and L-DNA. The L-DNA molecular chain contains abundant functional groups such as phosphate groups and bases, enabling it to interact with the MXene surface through various mechanisms such as electrostatic interactions, hydrogen bonds, and π-π stacking, thereby achieving the binding of MXene and L-DNA. Therefore, the composite material of the present invention exhibits good stability, significantly improves the baseline recovery capability of the prepared gas sensor, enhances the sensor's sensitivity, and also improves the selective recognition capability of the target gas.

[0011] According to embodiments of the present invention, the spatial configuration of L-DNA allows gas molecules to interact more easily with the L-DNA molecular chain along a specific direction when near the sensor surface. This structure can provide specific channels or binding sites, guiding gas molecules to adsorb in a specific orientation, thereby facilitating the selective recognition of specific gases. Furthermore, there may be favorable interactions between L-DNA and MXene, which can modulate the electronic structure and surface properties of L-DNA. For example, the two-dimensional structure of MXene can provide a large specific surface area, increasing the adsorption sites for gas molecules after binding with L-DNA. Simultaneously, charge transfer or electronic coupling may exist between MXene and L-DNA, making the adsorption of certain gas molecules by L-DNA more favorable. In contrast, due to the intermolecular structural characteristics, the charge transfer and electronic coupling between D-DNA and MXene may not be as pronounced as those between L-DNA and MXene. This combination results in the L-DNA / MXene composite material exhibiting relatively good adsorption and selective recognition capabilities for gas molecules during sensing, thereby improving the overall selectivity of the composite material for specific gases.

[0012] According to embodiments of the present invention, the composite material may further include at least one of the following additional technical features:

[0013] According to an embodiment of the present invention, the length of the L-DNA is 5nt-20nt. For example, it can be 5nt, 6nt, 7nt, 8nt, 9nt, 10nt, 11nt, 12nt, 13nt, 14nt, 15nt, 16nt, 17nt, 18nt, 19nt, 20nt, etc., or a range of any of the above values. According to an embodiment of the present invention, the length of the L-DNA is 10nt. This improves the sensitivity of the gas sensor to gases.

[0014] In this invention, "D-DNA" refers to right-handed deoxyribonucleic acid, the main form of naturally occurring deoxyribonucleic acid (DNA) in living organisms. Its molecular structure exhibits a right-handed helix morphology. The "L-DNA" described in this invention has a helical structure complementary to that of D-DNA.

[0015] According to embodiments of the present invention, the L-DNA sequence consists of one or two bases. It should be noted that when the L-DNA sequence consists of one base, the base is selected from any one of A (adenine), T (thymine), C (cytosine), and G (guanine); when the D-DNA sequence consists of two bases, the base is selected from any two of A (adenine), T (thymine), C (cytosine), and G (guanine).

[0016] In this invention, "DNA-A" refers to a DNA sequence consisting entirely of the base A; "DNA-C" refers to a DNA sequence consisting entirely of the base C; "DNA-G" refers to a DNA sequence consisting entirely of the base G; "DNA-T" refers to a DNA sequence consisting entirely of the base T; and "DNA-AT" refers to a DNA sequence consisting of both the base A and the base T.

[0017] According to an embodiment of the present invention, the L-DNA has any one of the sequences shown in SEQ ID NO: 1-28.

[0018] According to an embodiment of the present invention, the MXene is Ti3C2T. x .

[0019] According to an embodiment of the present invention, the molar ratio of MXene to L-DNA is (25-1000):1. For example, it can be 25:1, 50:1, 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, etc., or a range of any of the above values. Therefore, by keeping the molar ratio of MXene to L-DNA within the above range, the surface functional groups of L-DNA can interact with the surface functional groups of MXene, thereby providing more active sites and improving the sensitivity of the gas sensor when detecting gases.

[0020] According to an embodiment of the present invention, the L-DNA has a modifying group at its 5′ or 3′ end. Therefore, by chemically modifying the L-DNA, it is possible to directionally introduce specific functional groups while strengthening the DNA-MXene interface binding energy, constructing active sites for the specific adsorption of gas molecules, thereby improving the sensitivity of the gas sensor.

[0021] According to embodiments of the present invention, the modifying group includes at least one of amino, thiol, phosphate, biotin, cholesterol ester, and fluorescein. This improves the sensitivity of the gas sensor.

[0022] In a second aspect, the present invention provides a method for preparing the composite material described in the first aspect. According to an embodiment of the present invention, the method includes: mixing MXene and L-DNA to obtain the composite material. The complexation principle of L-DNA and MXene is similar to that of natural DNA and MXene, primarily based on physical and chemical interactions such as electrostatic interactions and hydrogen bonding. Since L-DNA and D-DNA have the same charge distribution and functional groups, their interactions with MXene are essentially the same. Therefore, the composite material of the present invention can be efficiently prepared from MXene and L-DNA through a simple physical mixing method.

[0023] According to embodiments of the present invention, the method for preparing the composite material may further include at least one of the following additional technical features:

[0024] According to an embodiment of the present invention, the concentration of MXene is 0.01 mg / mL to 0.1 mg / mL based on the total mass of the mixed treatment products. For example, it can be 0.01 mg / mL, 0.02 mg / mL, 0.03 mg / mL, 0.04 mg / mL, 0.05 mg / mL, 0.06 mg / mL, 0.07 mg / mL, 0.08 mg / mL, 0.09 mg / mL, 0.1 mg / mL, etc., or a range of any of the above values. According to an embodiment of the present invention, the concentration of MXene is 0.05 mg / mL based on the total mass of the mixed treatment products. According to an embodiment of the present invention, the molar concentration of L-DNA is 0.1 μM to 10 μM based on the total mass of the mixed treatment products. For example, it can be 0.1 μM, 1 μM, 2 μM, 3 μM, 4 μM, 5 μM, 6 μM, 7 μM, 8 μM, 9 μM, 10 μM, etc., or a range of any of the above values. According to an embodiment of the present invention, the molar concentration of the L-DNA is 5 μM based on the total mass of the mixed treatment products. This allows the surface functional groups of the L-DNA to interact with the surface functional groups of MXene, thereby providing more active sites and improving the sensitivity of the gas sensor in detecting gases.

[0025] In a third aspect, the present invention proposes the use of the composite material described in the first aspect or the composite material prepared by the method described in the second aspect in the fabrication of a gas sensor. The intervention of DNA provides active sites for gas adsorption, enhancing the gas adsorption process on the material surface and thus affecting the interfacial charge transfer efficiency. Consequently, the gas sensor prepared using the composite material of the present invention exhibits better baseline stability and recognition accuracy, as well as excellent sensitivity.

[0026] In a fourth aspect, the present invention provides a gas sensor. According to embodiments of the invention, the gas sensor comprises the composite material described in the first aspect or a composite material prepared using the method described in the second aspect. The intervention of DNA provides active sites for gas adsorption, enhancing the gas adsorption process on the material surface and thus affecting the interfacial charge transfer efficiency. Consequently, the gas sensor of the present invention exhibits good baseline stability and recognition accuracy, as well as excellent sensitivity.

[0027] According to an embodiment of the present invention, the composite material is coated on the surface of the interdigital electrode sheet.

[0028] In a fifth aspect, the present invention provides a method for preparing a gas sensor. According to an embodiment of the invention, the method comprises: coating the composite material described in the first aspect or the composite material prepared by the method described in the second aspect onto the surface of an interdigitated electrode sheet, and drying to obtain the gas sensor. As previously stated, the intervention of DNA provides active sites for gas adsorption, enhancing the gas adsorption process on the material surface, thereby affecting the interfacial charge transfer efficiency. Therefore, the gas sensor prepared by the method of the present invention exhibits better baseline stability and recognition accuracy, as well as excellent sensitivity.

[0029] In a sixth aspect of the invention, the invention proposes the application of the gas sensor described in the fourth aspect in the detection of gases.

[0030] According to an embodiment of the present invention, the gas is derived from at least one of ammonia, ethanol, diethyl ether, and acetone.

[0031] In a seventh aspect, the present invention provides an array sensor. According to an embodiment of the invention, the array sensor includes a plurality of gas sensors as described in the fourth aspect. Thus, by combining multiple gas sensors, the shortcomings of a single gas sensor can be overcome, improving the selectivity and accuracy of gas detection. Simultaneously, different gases can be distinguished, achieving specific detection of different odor molecules.

[0032] It should be noted that the number of gas sensors in the array sensor and the composite materials used for each gas sensor can be flexibly selected. Specifically, the composite materials used in multiple gas sensors can be completely identical, partially identical, or even completely different to meet the detection requirements of different application scenarios. Furthermore, there is no fixed limit to the number of gas sensors; it can be adjusted according to actual needs, for example, set to any number such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. Those skilled in the art can comprehensively determine the number of gas sensors and the type of composite material based on specific detection targets, environmental conditions, and cost factors to achieve optimal gas detection results.

[0033] According to embodiments of the present invention, the composite materials in the plurality of gas sensors may be the same or different.

[0034] According to embodiments of the present invention, the composite materials in the plurality of gas sensors are all different. Therefore, different sensors have different response characteristics to different gases. By combining multiple sensors into an array, the response differences of each sensor can be utilized through data processing and analysis algorithms to achieve simultaneous detection and accurate identification of multiple gases. By comprehensively analyzing the response signals of each sensor, different gases can be effectively distinguished and their concentrations accurately measured, obtaining reliable detection results even in complex environments containing interfering gases.

[0035] In an eighth aspect of the invention, the present invention proposes an application of the array sensor described in the seventh aspect, the application including at least one of the following: gas detection; cancer patient identification. According to embodiments of the present invention, the array sensor can successfully achieve accurate classification of more than ten gases. With the help of machine learning algorithms, the array sensor was applied in practical scenarios such as the exhalation of cancer patients, and the accuracy of the array sensor in identifying different gases was significantly improved, demonstrating excellent sensing performance. Therefore, the DNA interface regulation strategy proposed in this invention not only significantly improves the selectivity and sensitivity of the MXene sensor, but the constructed array sensor also shows important application prospects in fields such as food quality monitoring and non-invasive disease diagnosis.

[0036] According to embodiments of the present invention, the gas originates from at least one of ammonia, acids, alcohols, aldehydes, ketones, ethers, and esters.

[0037] According to embodiments of the present invention, the gas is derived from at least one of ammonia, ethanol, diethyl ether, acetone, formic acid, n-heptanoic acid, farnesol, 4-isopropylbenzyl alcohol, dextrorotatory carvone, dihydrojasmone, ethyl acetate, γ-caprolactone, citral, and benzaldehyde.

[0038] It should be noted that when using array sensors to identify cancer patients, neural network algorithms are required. This involves combining relevant signal processing and machine learning algorithms to form an intelligent gas sensing system. By employing algorithms such as t-Distributed Stochastic Neighborhood Embedding (t-SEN), Principal Component Analysis (PCA), Logistic Regression (LR), Linear Discriminant Analysis (LDA), K-Nearest Neighbor (KNN), Classification and Regression Trees (CART), Naive Bayes (NB), and Support Vector Machine (SVM), feature information from the sensor array can be effectively extracted, enabling accurate identification and prediction of gas types and greatly enhancing the feasibility of multi-gas differentiation.

[0039] In a ninth aspect, the present invention proposes a gas sensing system. According to an embodiment of the present invention, the gas sensing system includes: a sensing generation module, the sensing generation module including the array sensor described in the seventh aspect, for acquiring chemical signals of a gas; a data conversion and transmission module for converting the chemical signals into electrical signals; and a data visualization processing module for inputting the electrical signals into a trained machine learning model to obtain the source of the gas. Thus, the gas sensing system of the present invention can successfully achieve accurate classification of more than ten gases. With the help of machine learning algorithms, the gas sensing system has been practically applied to scenarios such as the exhalation of cancer patients, and the accuracy of the gas sensing system in identifying different gases has been significantly improved, demonstrating excellent sensing performance. Therefore, the DNA interface regulation strategy proposed in this invention not only significantly improves the selectivity and sensitivity of the MXene sensor, but the constructed gas sensing system also shows important application prospects in fields such as food quality monitoring and non-invasive disease diagnosis.

[0040] According to embodiments of the present invention, the algorithm includes, but is not limited to, at least one of t-Distributed Stochastic Neighborhood Embedding (t-SEN), Principal Component Analysis (PCA), Logistic Regression (LR), Linear Discriminant Analysis (LDA), K-Nearest Neighbor (KNN), Classification and Regression Trees (CART), Naive Bayes (NB), and Support Vector Machine (SVM).

[0041] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0043] Figure 1 This is a synthesis pathway diagram of MXene nanosheets according to an embodiment of the present invention;

[0044] Figure 2 This is the D-DNA / Ti3C2T according to an embodiment of the present invention. x Synthesis path diagram;

[0045] Figure 3 This is an example of L-DNA / Ti3C2T according to an embodiment of the present invention. x Synthesis path diagram;

[0046] Figure 4 This is an L-DNA / Ti3C2T according to an embodiment of the present invention. x The surface morphology of the material; among which,

[0047] a represents L-DNA / Ti3C2T x SEM image; b is L-DNA / Ti3C2T x TEM; c represents L-DNA / Ti3C2T x AFM image; d represents L-DNA / Ti3C2T x Data analysis of AFM images;

[0048] Figure 5 This is an L-DNA / Ti3C2T according to an embodiment of the present invention. x The crystal structure of the material; among which,

[0049] a represents L-DNA / Ti3C2T x XRD images; b is L-DNA / Ti3C2T x d is the HRTEM image; d is the SAED image corresponding to the HRTEM.

[0050] Figure 6 This is an L-DNA / Ti3C2T according to an embodiment of the present invention. x Elemental analysis of the material; among which,

[0051] a represents L-DNA / Ti3C2T x XPS spectra; b represents L-DNA / Ti3C2T x SEM images and EDS element distribution images;

[0052] Figure 7 This is the DNA / Ti3C2T according to an embodiment of the present invention. x Sensing properties of biocomposite materials; among which,

[0053] a is Ti3C2T x and low concentration DNA / Ti3C2T x Comparison of sensor response values ​​to ammonia; b represents Ti3C2T x and high concentration of DNA / Ti3C2T x Comparison of sensor response values ​​to ammonia; c represents Ti3C2T x and 16 low-concentration DNA / Ti3C2T x Analysis of the sensor's response to four gases; d represents Ti3C2T x and 16 high-concentration DNA / Ti3C2T x Analysis of sensor response to four gases; e and g low concentration DNA / Ti3C2T x Sensitivity analysis of the sensor to four gases; f and h represent high concentrations of DNA / Ti3C2T. x Sensitivity analysis of the sensor to four gases; sensor1 is sensor 1 (Ti3C2T) x Sensor2 is sensor 2 (L-DNA-A / Ti3C2T). x Sensor3 is sensor 3 (L-DNA-T / Ti3C2T). x Sensor4 is sensor 4 (L-DNA-C / Ti3C2T). xSensor5 is sensor 5 (L-DNA-G / Ti3C2T). x Ammonia, Ethanol, and Ether are all names of acetones.

[0054] Figure 8 The sensing characteristics of a five-channel sensor array according to an embodiment of the present invention; wherein,

[0055] a represents the array's sensing response to four typical gases at a concentration of 20 ppm; b represents the response value of each sensor in the array to the gas; c represents the percentage of response of each sensor in the array to a single gas; d represents the sensitivity analysis of each sensor in the array to the four typical gases; e represents the PCA image of the sensor array to the four typical gases at a concentration of 20 ppm.

[0056] Figure 9 This refers to 12 sets of dibasic DNA-AT / Ti3C2T according to embodiments of the present invention. x The sensing characteristics; among which,

[0057] a is a ball-and-stick model of 12 sets of dibasic DNA-AT sequences; b is a ball-and-stick model of 12 sets of dibasic DNA-AT / Ti3C2T sequences. x Response patterns to four gases; c represents 12 groups of dibasic DNA-AT / TTi3C2T. x Analysis of the average response values ​​for c1) acetone, c2) ammonia, c3) ethanol, c4) diethyl ether and c5);

[0058] Figure 10 L and D type DNA / Ti3C2T according to embodiments of the present invention x Response analysis and comparison of four gases; among them,

[0059] a is D-DNA / Ti3C2T x Response values ​​to four gases; b represents D-DNA / Ti3C2T x 2D PCA images of the four gases; c represents D-DNA / Ti3C2T x 3D PCA images of four gases; d represents L-DNA / Ti3C2T x Response values ​​to four gases; e represents L-DNA / Ti3C2T x 2D PCA images of four gases; f represents D-DNA / Ti3C2T x3D PCA images of four gases; sensor1 is sensor 1, sensor2 is sensor 2, sensor3 is sensor 3, sensor4 is sensor 4, sensor5 is sensor 5, sensor6 is sensor 6; Ammonia is ammonia, Ethanol is ethanol, Ether is diethyl ether; Acetone is acetone.

[0060] Figure 11 This is an example of L-DNA / Ti3C2T according to an embodiment of the present invention. x Identification of ten gases; among them,

[0061] a represents L-DNA / Ti3C2T x The sensor array's response modes to ten gases; b represents L-DNA / Ti3C2T. x t-SEN images of ten gases from a sensor array; c represents L-DNA / Ti3C2T x PCA images of ten gases;

[0062] Figure 12 This is an example of L-DNA / Ti3C2T according to an embodiment of the present invention. x Statistical analysis of exhalation from different populations using a sensor array; among which,

[0063] a is a histogram; b is a box plot; c is a PCA graph;

[0064] Figure 13 This is an L-DNA / Ti3C2T according to an embodiment of the present invention. x The sensor array identifies human odor molecules; among them,

[0065] a represents the sensor array response mode; b represents a comparison of different algorithms; c represents a scatter matrix of different sensors; d represents a confusion matrix of different human exhalations. Detailed Implementation

[0066] The embodiments of the technical solution of the present invention are described in detail below. These embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore merely examples and should not be used to limit the scope of protection of the present invention.

[0067] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0068] For the sake of brevity, this article only discloses some specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0070] In this document, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0071] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0072] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0073] The materials used in this embodiment and their sources:

[0074] Ti3AlC2 (MAX) powder (98%, 200 mesh) was purchased from Maclean's Ltd., hydrochloric acid (HCl, AR) from Tongguang Co., Ltd., lithium fluoride (LiF, 99.99%, 1-3 mm) from Zhongke Yinuo Co., Ltd. (all ground into fine powder before use), tetrabutylammonium hydroxide (TBAOH, 40%) from Aladdin Reagent (Shanghai) Co., Ltd., and N,N-dimethylformamide (DMF, SafeDry) from Adamas. Various DNA oligonucleotides were purchased from Suzhou Genewiz Biotechnology Co., Ltd.

[0075] Detection System: The real-time detection platform independently built in this invention can be divided into three modules: a sensing generation module, a data conversion and transmission module, and a data visualization and processing module. The sensing module is a gas receiving reaction chamber. During the experiment, the sensor is placed in the detection chamber where the concentration of the target gas continuously changes to achieve dynamic sensing and detection of the gas. Based on the law of conservation of mass, the number of gas molecules is controlled by adjusting the volume of the gas solution added. When the sensing material interacts with the gas molecules, electron transfer occurs. This chemical change affects the resistance of the relevant channel circuits, and the process of converting the chemical signal into an electrical signal is completed by the data conversion and transmission platform. This platform transmits the real-time resistance change signal to the data visualization and processing port (computer), and uses machine learning to complete the entire process of dynamic gas detection and recording.

[0076] The gas response value is defined as: (R0-Ri) / R0*100%, where R0 is the resistance value of the sensor in air, and Ri is the resistance value of the sensor in the gas environment to be measured.

[0077] Example 1: D-DNA / Ti3C2T x L-DNA / Ti3C2T x Synthesis

[0078] 1. Single-layer Ti3C2T x (MXene) Synthesis

[0079] This study used few-layer MXene in the experiments, and the synthesis route is as follows: Figure 1As shown. First, multilayer MXene was synthesized. In a polytetrafluoroethylene (PTFE) reactor, 40 mL of 9M hydrochloric acid solution was added, followed by the addition of 2 g of LiF for dissolution. The mixture was stirred at 35°C and 600 rpm for 30 minutes. Then, 2 g of Ti3AlC2 (MAX phase) was added, and the reaction was maintained at 35°C and 600 rpm for 24 hours until etching was complete. The resulting solution was washed with deionized water until the pH of the supernatant was 6, at which point multilayer MXene was obtained. The multilayer MXene was then freeze-dried under vacuum for 36 hours to obtain multilayer MXene powder (also known as multilayer Ti3C2T). x (Powder), store at low temperature (4℃).

[0080] Highly dispersed mono / few-layer MXenes in DMF were prepared using the microenvironmental tuning (TMM) method. 0.5 g of the obtained multilayer Ti3C2T was taken... x The powder was added to 12 mL of 25% TBAOH solution as an intercalating agent and surface modifier, and the mixture was stirred at 25°C and 500 rpm for 6 hours to perform intercalation, thereby intercalating Ti3C2T. x Transformed into Ti3C2T x -TBA powder. Excess TBAOH solution was washed out with ethanol, and the resulting precipitate was Ti3C2T. x -TBA was collected in a 50 mL centrifuge tube. 30 mL of DMF was added to the centrifuge tube, and the mixture was gently stirred or shaken to completely disperse the precipitate in the organic reagent. The 50 mL centrifuge tube was then centrifuged at 25°C and 12000 rpm for 5 minutes to collect the supernatant. After separating the solution and precipitate, an appropriate amount of DMF was added again, and the mixture was repeatedly shaken and centrifuged until the precipitate was completely dissolved and collected in a 50 mL solution. This yielded 10 mg / mL low / monolayer Ti3C2T. x MXene stock solution, stored at low temperature (4°C).

[0081] 2. D-DNA / Ti3C2T x Synthesis of (D-DNA / MXene)

[0082] This study used adsorbent solution self-assembly technology to prepare D-DNA / Ti3C2T x Complexes, such as Figure 2 As shown. The initial DNA concentration used in the experiment was 10 μM for DNA-A, DNA-T, DNA-C, and DNA-G stock solutions. Taking DNA-A as an example, 10 μL of the stock solution was added to a 1.5 mL centrifuge tube containing 90 mL of DMF and diluted 10-fold to obtain a 1 μM DNA daughter solution. 10 mg / mL of low / monolayer Ti3C2T was used... x10 μL of MXene solution was added to a 1.5 mL centrifuge tube, and 990 μL of DMF solution was added for a 100% dilution to obtain 0.1 mg / mL low / monolayer Ti3C2T. x MXene solution. Then, 0.1 mg / mL of low / monolayer Ti3C2T was taken. x 40 μL of MXene solution was added to two separate 0.5 mL centrifuge tubes, followed by 40 μL, 1 μM, and 10 μM DNA solutions, respectively. The mixtures were thoroughly mixed by pipetting repeatedly to obtain oligo / monolayer Ti3C2T solutions. x Composite solutions with a final concentration of 0.05 mg / mL and final DNA concentrations of 0.5 μM and 5 μM were prepared and labeled as low-concentration and high-concentration groups, respectively. The absence of a reagent reaction upon pipetting indicated successful synthesis of the target composite material. The resulting product was designated DNA-A / Ti3C2T. x (DNA-A / MXene). DNA-T / Ti3C2T was synthesized using the same method. x (DNA-T / MXene), DNA-C / Ti3C2T x (DNA-C / MXene) and DNA-G / Ti3C2T x (DNA-G / MXene) composite material.

[0083] 3. L-DNA / Ti3C2T x synthesis

[0084] This study used adsorption self-assembly technology to prepare L-DNA / Ti3C2T x complex ( Figure 3 Prepare an L-DNA solution with an initial concentration of 10 μM. Take 0.1 mg / mL of low / monolayer Ti3C2T... x Add 80 μL of MXene solution to a 1 mL centrifuge tube, then add 80 μL of 10 μM DNA solution to initiate self-assembly. The mixture is pipetted for 30 seconds to obtain a homogeneous gray solution; no obvious reagent reaction indicates successful assembly.

[0085] Example 2: L-DNA / MXene characterization

[0086] 1. Surface morphology

[0087] L-DNA / Ti3C2T was observed using SEM, AFM, and TEM. x Surface morphology of the material, L-DNA / Ti3C2T x The surface morphology of the composite material is illustrated using DNA-A (SEQ ID NO: 5) as an example. In the SEM image ( Figure 4 a) It was observed that the prepared material structure was a layered nanosheet. (In the TEM image) Figure 4 b) indicates that L-DNA / Ti3C2T x It has a relatively thin thickness. AFM results ( Figure 4 c, Figure 4 d) shows that the thickness of the prepared composite nanosheets is 0-7 nm. Figure 4 d), namely, the prepared Ti3C2T x The nanosheets have few layers. Due to the presence of water molecules and other surface adsorbents within the MXene nanosheets, the thickness varies slightly. This overall indicates the successful preparation of the composite nanosheets.

[0088] 2. Crystal Structure

[0089] To investigate L-DNA / Ti3C2T x The surface nanostructure was analyzed, and XRD patterns were used to examine the prepared material. It is known that Ti3AlC2 crystals exhibit a diffraction peak (002) at 9.517°, while in L-DNA / Ti3C2T... x In the sample, the Ti3AlC2 peak disappeared, and the (002) peak underwent a negative shift, that is, there was a distinct sharp peak at around 7.6°. Figure 5 a) This indicates that after selective etching, the Al layer achieved a certain degree of exfoliation, and the material was transformed into Ti3C2T. x And this peak is the crystal surface of (002).

[0090] To further investigate the crystal structure of the composite nanosheets, observation was performed using HRTEM. HRTEM image ( Figure 5 b) indicates that the composite nanosheets have a lattice spacing of 0.28 nm, corresponding to Ti3C2T x The (002) plane. The corresponding SAED region ( Figure 5 c) Shows bright crystal spots consistent with the lattice spacing, reflecting the typical lattice characteristics and crystal structure of nanosheets.

[0091] 3. Elemental Analysis

[0092] To investigate L-DNA / Ti3C2T x The chemical composition and bonding state of the composite nanosheets were analyzed using XPS. The spectra revealed L-DNA / Ti3C2T x The nanocomposite material contains Ti, C, N, O and P elements ( Figure 6 a) The C1s spectrum showed four characteristic peaks at 281.95, 284.75, 286.35, and 287.1 eV, corresponding to C-Ti-T, respectively. xCC, CO, and COO. The high-resolution spectrum of Ti 2p shows three characteristic peaks at 455.45, 459.45, and 461.65 eV, corresponding to Ti 2p, respectively. 3 / 2 Ti-O and Ti 2p 1 / 2 Among them, Ti 2p 3 / 2 The doublets at 455.35 eV and 456.75 eV correspond to Ti-Ti and Ti-C, respectively. The high-resolution N1s spectrum shows two components, NC and NH, at 399.45 and 401.1 eV, respectively, indicating the presence of bases. The P 2p spectrum exhibits a strong doublet at 133.9 eV, indicating the presence of phosphorus (P) on the material surface, while a singlet centered at 133.45 eV in the P 2p spectrum can be attributed to the PO group in the DNA phosphate groups.

[0093] Observation of the sample surface elements using SEM and its built-in EDS confirmed the presence of L-DNA / Ti3C2T. x Sample composition. EDS spectrum ( Figure 6 b) It can be observed that Ti, C, O, N and P elements are uniformly dispersed on the surface of the composite nanosheets, indicating that L-DNA / Ti3C2T has been successfully prepared. x Nanosheets. XPS and EDS results show L-DNA / Ti3C2T x The successful synthesis of biocomposite materials provides strong evidence and reveals key information about the chemical composition and bonding state of the materials.

[0094] Example 3: The Influence of Base Length and Sequence on Sensing Properties

[0095] D-DNA / Ti3C2T x or L-DNA / Ti3C2T x Fabrication of the gas sensor: The D-DNA / Ti3C2T gas sensor prepared in Example 1 was used... x or L-DNA / Ti3C2T x The composite material was drop-coated onto the interdigitated electrode sheet, ensuring complete coverage of the electrode surface. The interdigitated electrode containing the composite material was then carefully transferred to a 55°C oven and dried for 30 minutes to form a gas-sensitive membrane, yielding D-DNA / Ti3C2T. x or L-DNA / Ti3C2T x Gas sensor.

[0096] 1. The inventors further investigated the effect of DNA base length on Ti3C2T x In response to the influence of sensing properties, the inventors used D-DNA / MXene as the research object and prepared 16 different lengths of pure base D-DNA / Ti3C2T.x A bio-composite sensor was developed, in which the DNA sequence is shown in Table 1. Four standard gases—acetone, ammonia, ethanol, and diethyl ether—were detected in the range of 1 ppm to 100 ppm. The results showed that the DNA / Ti3C2T... x The bio-composite sensor generally achieved good gas response and baseline stability. To comprehensively analyze four different lengths and two different concentrations of pure DNA / Ti3C2T... x The overall response characteristics of the bio-composite sensor are presented by taking the average value of each response value and presenting the results in the form of a heatmap. Figure 7 c shows pure Ti3C2T x and low concentration of 16 pure base DNA / Ti3C2T x The sensor's response to four gases, Figure 7 d shows pure Ti3C2T x and high concentration of 16 pure base DNA / Ti3C2T x The biosensor responded to four gases. Results showed that high concentrations of DNA / Ti3C2T... x The bio-composite sensor exhibits superior overall response to multiple gases compared to low-concentration DNA / Ti3C2T. x Biocomposite sensor. By comparing DNA / Ti3C2T of different lengths... x A bio-composite sensor was discovered at two DNA concentrations in DNA / Ti3C2T. x Among sensors, those with a DNA length of 10 nt exhibit relatively high sensitivity to gases. Figure 7 e and Figure 7 f). Simultaneously, low concentrations of DNA / Ti3C2T x DNA-G / Ti3C2T x The sensor is highly sensitive to four gases, while high concentrations of DNA / Ti3C2T... x The sensitivity of the bio-composite sensor to four gases is generally ( Figure 7 g and Figure 7 h). This may be due to the high concentration of DNA with Ti3C2T. x The interaction of functional groups on the surface leads to the exposure of more active sites in the nanocomposite material. Studies have shown that for certain bases, DNA / Ti3C2T x The sensitivity of the composite sensor can be improved by increasing the DNA concentration. In summary, the study indicates that high concentrations of DNA are effective as a Ti3C2T... x The second phase of the sensor has broad application prospects and potential in the practical detection of low-concentration target gases. Furthermore, when fabricating sensor arrays that mimic the animal olfactory system, DNA / Ti3C2T with a length of 10 nt should be considered first. xBio-composite sensor.

[0097] Table 1

[0098]

[0099]

[0100] 2. In order to investigate which sensor contributes most to the sensitivity and selectivity of the array sensor, the inventors used a high concentration of 10nt DNA / Ti3C2T. x The bio-composite sensor serves as the main component of the sensor array. The array used here consists of five sensors, namely sensor 1: Ti3C2T. x Sensor 2: DNA-A / Ti3C2T x Sensor 3: DNA-T / Ti3C2T x Sensor 4: DNA-C / Ti3C2T x Sensor 5: DNA-G / Ti3C2T x .

[0101] Sensors 1-5 were attached to interdigitated electrodes to construct a sensor array. The interdigitated electrode substrate was alumina ceramic with external dimensions of 10mm × 10mm. The electrode line spacing was 50μm, the line width was 100μm, and the finger length of the 15 interdigitated pairs was 7.7mm. The electrodes were composed of Ti / Cu / Ni / Aud surface metal layers with thicknesses of 0.1μm, 5μm, 4μm, and 1μm, respectively. During sensor array construction, 20μl of the above-mentioned synthetic material solution was first pipetted and evenly added to the electrodes. The electrodes were then dried in a 55℃ oven for 30 minutes to form a gas-sensitive film. Finally, the electrodes carrying the gas-sensitive film were fixed onto the polyethylene terephthalate (PET) substrate of the test kit as the sensor array framework. At this point, the sensor array was completed, and the thin film attached to the interdigitated electrodes was DNA / Ti3C2T. x Composite materials.

[0102] The aforementioned 5-channel sensor array was used with an Arduino platform to detect four typical gases: acetone, ammonia, ethanol, and diethyl ether. First, the array was placed inside a detection chamber. When the gas concentration inside the chamber reached 20 ppm, the gas response signal of the sensor was detected. The overall response of the sensor array to acetone and ethanol was significantly better than that to ammonia and diethyl ether, indicating that the sensor array has good selectivity for acetone and ethanol. Figure 8 a). This could be due to the presence of the biological composite material DNA / Ti3C2T in the array. x The resulting surface structure and functional groups are more conducive to the adsorption of acetone and ethanol gas molecules.

[0103] The sensing performance of different sensors in the array varied for four typical gases at a concentration of 20 ppm. Sensors 2-5 in the array all showed better gas responses than sensor 1. However, the sensing performance differed significantly when detecting acetone, ethanol, and diethyl ether, while the sensing performance remained almost unchanged when detecting ammonia. Figure 8 b). This indicates that the sensor plays a major role in detecting acetone, ethanol, and diethyl ether, meaning that the addition of DNA significantly improves the sensing performance of the sensor array. Furthermore, in the sensor array, sensors 2 and 3 show significantly better responses to single gases than the other sensors. Figure 8 b, Figure 8 c). Analysis of the sensitivity of the five sensors in the array shows that sensors 2 and 3 generally have high sensitivity to the four gases. Figure 8 d). In summary, DNA / Ti3C2T x The addition of sensors enhances the selectivity of the array and improves its sensing performance. Furthermore, DNA-A and DNA-T bases play crucial roles in the array, dominating the enhancement of the sensor array's selectivity.

[0104] 3. Based on the above experimental results, the composite material DNA-A / Ti3C2T x and DNA-T / Ti3C2T x This contributes significantly to the high sensitivity and selectivity of the array, exhibiting superior sensing performance compared to biocomposite materials containing other bases. Here, we further explore the interaction between DNA and Ti3C2T based on the DNA-A and DNA-T dibase DNA-AT. x Impact on sensing performance. Considering the differences in the number of bases and their positional arrangement in dibasic DNA sequences, the inventors generated 12 sets of dibasic DNA-AT sequences using SPSS (as shown in Table 2), and then compared them with Ti3C2T... x The composite material DNA-AT / Ti3C2T was synthesized and prepared. x Investigating the dual-base DNA-AT / Ti3C2T x The sensing characteristics of the sensor.

[0105] Table 2

[0106]

[0107]

[0108] 12 sets of DAN-AT / Ti3C2T xDue to their unique molecular structure, the detection of gases varies considerably. To more intuitively observe the molecular conformation of DNA-AT sequences, the two-dimensional and three-dimensional structures of 12 DNA-AT sequences with the lowest energy were calculated and plotted using ChemDraw and Chem3D. The 12 DNA-AT structures are shown below. Figure 9 As shown in a. Figure 9 b showcased 12 sets of DAN-AT / Ti3C2T x The sensor's overall sensing modes for four gases were analyzed. By comparing and analyzing the DNA-AT sequences and their corresponding sensor response modes, it was found that when the DNA-AT sequence is in a relatively stable conformation, although some base sequences have a certain degree of structural similarity, they exhibit significant differences in gas detection. For example, sequences DNA-AT3 and DNA-AT4, and DNA-AT9 and DNA-AT10 are very similar in base composition, arrangement, and two-dimensional structure; however, the DNA-AT / Ti3C2T sensor synthesized from these sequences shows different results. x The composite biosensor exhibits the opposite effect in gas detection. Figure 9 b3-b4, Figure 9 (b9-b10). This may be attributed to the dibase DAN-AT / Ti3C2T. x The unique molecular structure affects the adsorption and desorption of gases by the composite biosensor.

[0109] To facilitate comparison with pure Ti3C2T x Sensor with 12 DNA-AT / Ti3C2T x The sensing characteristics of a composite biosensor when detecting a certain gas were analyzed. Bar charts of the response values ​​for four different gases were plotted, and the average values ​​of each gas were analyzed. Figure 9 c). The results showed that 12 groups of DNA-AT / Ti3C2T x The composite sensor performs better than pure Ti3C2T in gas detection. x Sensor, and DNA-AT1 / Ti3C2T x DNA-AT3 / Ti3C2T x DNA-AT7 / Ti3C2T x The composite biosensor exhibits high stability. Furthermore, the sensor DNA-AT3 / Ti3C2T... x In other words, the overall detection performance of the dibase DNA-AT3 sequence is superior to that of other DNA-AT sequences for the four typical gases. Figure 9 c5). This indicates that the composite biosensor DNA-AT3 / Ti3C2T x As a core component, it can be used to construct multidimensional sensor arrays for the detection of real gases.

[0110] Example 4: Performance Analysis of L-DNA / MXene Gas Sensing

[0111] 1. Sensor Sensing Performance

[0112] The inventors used an Arduino circuit to achieve the sensor's dynamic response performance to gases. The gas response performance is evaluated by calculating the sensor's resistance change in the target gas environment. Specifically, this is expressed as: (R0-Ri) / R0*100%, where R0 is the sensor's resistance in air, and Ri is the sensor's resistance in the target gas environment. Within the gas detection chamber, the dynamic concentration change of the gas is adjusted by calculating and controlling the volume of the target gas solution.

[0113] First, a comparison was made between D-DNA / Ti3C2T. x and L-DNA / Ti3C2T x The response of the array sensor and the aggregation of gas.

[0114] Preparation of six types of D-DNA / Ti3C2T x and its corresponding L-DNA / Ti3C2T x The six D-DNA sensors are: D-DNA-AT1 / Ti3C2T x (Sensor 1), D-DNA-AT3 / Ti3C2T x (Sensor 2), D-DNA-A / Ti3C2T x (Sensor 3), D-DNA-C / Ti3C2T x (Sensor 4), D-DNA-G / Ti3C2T x (Sensor 5), D-DNA-T / Ti3C2T x (Sensor 6);

[0115] The six L-DNA sensors are L-DNA-AT3 / Ti3C2T x (Sensor 1), L-DNA-AT1 / Ti3C2T x (Sensor 2), L-DNA-A / Ti3C2T x (Sensor 3), L-DNA-C / Ti3C2T x (Sensor 4), L-DNA-G / Ti3C2T x (Sensor 5), L-DNA-T / Ti3C2T x (Sensor 6). Among them, DNA-A, DNA-T, DNA-C, and DNA-G are all high-concentration 10nt DNA.

[0116] The sequence of DNA-AT1 is shown in SEQ ID NO: 17; the sequence of DNA-AT3 is shown in SEQ ID NO: 19; the sequence of DNA-A is shown in SEQ ID NO: 5; the sequence of DNA-T is shown in SEQ ID NO: 6; the sequence of DNA-C is shown in SEQ ID NO: 7; and the sequence of DNA-G is shown in SEQ ID NO: 8.

[0117] By detecting ammonia, ethanol, diethyl ether, and acetone, six types of D-DNA / Ti3C2T were identified. x The sensor response values ​​showed no significant difference and remained relatively stable. Figure 10 a). However, the response values ​​of sensor 1 (L-DNA-AT3) and sensor 4 (L-DNA-C) in the L-type sensor were significantly lower than those of other sensor types. Figure 10 d). Dimensionality reduction of data from both types of sensors using PCA was used to observe gas aggregation. When two eigenvalues ​​were retained (i.e., reduced to two dimensions), the D-type sensor showed overlap between ethanol and acetone gases, while the L-type sensor showed overlap between ethanol and ammonia gases. Figure 10 b and Figure 10 e). While this indicates that the spatial distance between the two gas detection data remains relatively close after preserving their main characteristics, resulting in a less significant classification effect, the relatively greater distance between the four gases in the L-type suggests better gas aggregation. Further observation of D-DNA / Ti3C2T... x and L-DNA / Ti3C2T x To differentiate their gas classification abilities, PCA was used to analyze the distribution of four gases in three-dimensional space, and the gases were projected in the x, y, and z directions. D-DNA / Ti3C2T x The sensor only shows good aggregation of the four gases in the x-axis direction, while L-DNA / Ti3C2T x When the sensor is positioned in the x, y, and z directions, the gas can effectively accumulate, with a much lower degree of cross-contamination compared to D-DNA / Ti3C2T. x sensor( Figure 10 c and Figure 10 f). This indicates that L-DNA / Ti3C2T x The sensor exhibits strong gas identification and aggregation capabilities, indicating greater potential. This may be due to the specific molecular structure of L-type DNA, which influences its adsorption of different gases.

[0118] 2. Sensor array sensing performance

[0119] The above experiments show that L-DNA / Ti3C2T x It exhibits stronger classification ability for four gases and better gas aggregation. This L-DNA / Ti3C2T was selected. xA sensor array was fabricated to further verify its performance. This array consists of six sensors, including sensor 1: L-DNA-A / Ti3C2T. x Sensor 2: L-DNA-T / Ti3C2T x Sensor 3: L-DNA-C / Ti3C2T x Sensor 4: L-DNA-G / Ti3C2T x Sensor 5: L-DNA-AT3 / Ti3C2T x Sensor 6: L-DNA-AT1 / Ti3C2T x Among them, DNA-A, DNA-T, DNA-C, and DNA-G are all high-concentration 10nt DNA sequences.

[0120] The sequence of DNA-AT1 is shown in SEQ ID NO: 17; the sequence of DNA-AT3 is shown in SEQ ID NO: 19; the sequence of DNA-A is shown in SEQ ID NO: 5; the sequence of DNA-T is shown in SEQ ID NO: 6; the sequence of DNA-C is shown in SEQ ID NO: 7; and the sequence of DNA-G is shown in SEQ ID NO: 8.

[0121] To test L-DNA / Ti3C2T x The sensor array's ability to recognize other gases was tested using 10 odor molecules (Table 3) as experimental subjects. These 10 odor molecules can be classified into 5 categories: acids, alcohols, aldehydes, ketones, and esters. In the experiment, the gas concentration was set to 5 ppm, and L-DNA / Ti3C2T... x The sensor array was subjected to five repeated experiments. The detection results are presented in the form of a heatmap. Figure 11 a) It can be seen that each sensor responds differently to each gas, demonstrating the array's gas selectivity. The results are then processed using PCA for dimensionality reduction, such as... Figure 11 c. It can be seen that ketones and alcohols overlap, and the clustering characteristics are not obvious enough, indicating that PCA dimensionality reduction is not suitable for processing this type of data. The t-SEN algorithm is used to distinguish these 10 gases. After data processing, a t-SEN plot is generated, as shown below. Figure 11 b. The results show that each gas molecule aggregates in its corresponding region, indicating that with the assistance of the t-SNE algorithm, the gas sensor array has excellent sensitivity and selectivity, and can accurately identify 10 gas molecules, demonstrating its ability to be applied to practical classification.

[0122] Table 3: For L-DNA / Ti3C2T x Ten odor molecules from the sensor array

[0123]

[0124]

[0125] Example 5: Application of Sensor Arrays

[0126] Using L-DNA / Ti3C2T from Example 4 x A sensor array was used to detect and identify odor molecules in the exhaled breath of individuals with colorectal cancer (A), stomach cancer (B), pancreatic cancer (C), and healthy individuals (D). Before the experiment, exhaled breath samples were collected from cancer patients using a 1L aluminum gas collection bag. To control the influence of foreign objects on the gas, patients were required to rinse their mouths and avoid eating for a certain period before gas collection. During the experiment, the piston was opened and the gas collection bag was squeezed, allowing the gas to flow evenly and steadily towards the sensor at a distance of two centimeters for 20 seconds, ensuring complete contact between the gas and the sensing material. The change in resistance was recorded in real time by a computer. During this period, each test was paused for 20 seconds to allow the sensor resistance to return to baseline. Ten tests were performed on each individual's exhaled breath, generating a total of 400 data sets. When human odor molecules came into contact with the array, L-DNA / Ti3C2T... x Electron transfer occurs on the surface, converting chemical signals into electrical signals, which are then received by a computer. With the help of machine learning algorithms, the electrical signals from different human bodies were processed, and the corresponding human odors were successfully detected using an array.

[0127] Perform statistical analysis on the data, using histograms ( Figure 12 a) and box plot ( Figure 12 b) The displayed response differences revealed that the sensor generates different electrical signals in response to the exhalations of different individuals, indicating that differences in odor molecules between individuals can be detected. The response results are processed using PCA (…). Figure 12 c) The four groups showed clear clustering, indicating that the expiratory data of these patients were very similar, and the distinction between them and other groups indicated group specificity. This suggests that L-DNA / Ti3C2T x The sensor array can distinguish and identify the exhaled breaths of different groups of people.

[0128] By introducing six computer algorithms to process the data—LR (Logistic Regression), LDA (Linear Discriminant Analysis), KNN (K-Nearest Neighbors), CART (Classification and Regression Tree), NB (Naive Bayes), and SVM (Support Vector Machine)—the identification of different groups of people was achieved. From the scatter matrix diagram ( Figure 13c) This shows the correlation between pairs of sensors in the sensor array regarding breath detection in different populations. For example, the coefficients between sensors 2 and 3, and sensors 4 and 6, for the breaths of gastric cancer patients and colorectal cancer patients, reached 0.613 and 0.598, respectively, indicating a moderate correlation between them. This suggests that each sensor in the array has a significant impact on the breath detection of different populations. Figure 13 a showed that based on L-DNA / Ti3C2T x The sensor array's response patterns to different population groups demonstrate that differences in exhaled breath between individuals can be detected by the sensors. When introducing machine learning algorithms for population classification and identification, the data is first labeled into 100*4 groups, with 90% of the data set as the training group and the remaining 10% as the test group. The model is trained using algorithms such as CART. Finally, the aforementioned six machine learning algorithms are introduced for identification. The confusion matrix shows that the gas detection platform achieves an accuracy rate of over 83% for all four human odor molecules. Specifically, the accuracy rates for odor molecules from colorectal cancer patients and healthy individuals reach 94.1% and 90.5%, respectively. Figure 13 d). After 10 cross-validations, the algorithm accuracy was compared, and the CART algorithm achieved an accuracy of 0.921, performing best, while LR only achieved 0.332, proving that the CART algorithm is not suitable for this sample recognition. Figure 13 b). In summary, L-DNA / Ti3C2T x The sensor array achieved an accuracy of up to 94.1% in recognizing human exhalation.

[0129] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0130] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A composite material, characterized in that, include: MXene and L-DNA.

2. The composite material according to claim 1, characterized in that, The length of the L-DNA is 5nt-20nt; Optionally, the sequence of the L-DNA consists of one or two bases; Optionally, the L-DNA has any one of the sequences shown in SEQ ID NO: 1-28; Optionally, the MXene is Ti3C2T x ; Optionally, the molar ratio of MXene to L-DNA is (25-1000):

1.

3. The composite material according to claim 2, characterized in that, The L-DNA has a modifying group at its 5′ or 3′ end; Optionally, the modifying group includes at least one of amino, thiol, phosphate, biotin, cholesterol ester, and fluorescein.

4. A method for preparing the composite material according to any one of claims 1-3, characterized in that, include: The composite material was obtained by mixing MXene and L-DNA. Optionally, the concentration of MXene is 0.01 mg / mL to 0.1 mg / mL based on the total mass of the mixed treatment products; preferably, it is 0.05 mg / mL. Optionally, the molar concentration of the L-DNA is 0.1 μM to 10 μM based on the total mass of the mixed treatment products; preferably, it is 5 μM.

5. Use of the composite material according to any one of claims 1-3 or the composite material prepared by the method of claim 4 in the preparation of a gas sensor.

6. A gas sensor, characterized in that, Includes the composite material according to any one of claims 1-3 or the composite material prepared by the method according to claim 4; Optionally, the composite material is coated on the surface of the interdigitated electrode sheet.

7. The application of the gas sensor according to claim 6 in gas detection.

8. An array sensor, characterized in that, Includes several gas sensors as described in claim 6.

9. The array sensor according to claim 8, characterized in that, The composite materials used in the multiple gas sensors may be the same or different.

10. An application of the array sensor according to any one of claims 8-9, wherein the application includes at least one of the following: Detecting gases; Identify individuals with cancer.

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