Preparation method and application of sensor array based on luminous carbon dots

Abstract

The invention discloses a preparation method and application of a sensor array based on luminous carbon dots, and relates to the technical field of sensors, the preparation method comprises the following steps: preparing a carbon source which comprises a precursor containing a targeting functional group or a biomolecule derived carbon source, preparing the luminous carbon dots through a chemical synthesis or physical method, modifying the surfaces of the carbon dots, and preparing the sensor array based on the luminous carbon dots. A core-shell structure is added on the surface of a carbon dot by using an in-situ growth method or a layer-by-layer self-assembly method, the carbon dot with the added core-shell structure is fixed on a substrate of a sensor array, and a performance test is carried out. By synthesizing the carbon dots with a targeted recognition function, the selectivity and the sensitivity of the sensor to a target substance can be remarkably improved, and in the synthesis process, the carbon dots can generate specific interaction with the target substance by adjusting factors such as the structure, the shape, the size and the surface chemical property of the carbon dots; therefore, accurate identification of the target substance is realized, and detection of the marker is realized.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, in particular to a method for preparing a sensor array based on luminescent carbon dots and applications thereof. Background Art

[0002] The preparation of luminescent carbon dot sensor arrays mainly utilizes the optical properties of luminescent carbon dots and combines them with specific recognition elements to achieve the detection of target molecules. This sensor array has the advantages of high sensitivity, good selectivity, and fast response speed, and can achieve the detection of a variety of substances. However, the current luminescent carbon dot sensor arrays have poor selectivity and sensitivity to target substances during preparation, and have certain defects.

[0003] The defects of existing sensors are:

[0004] 1. In patent document CN108375611B, N-MAL-CDs are used to construct ultra-sensitive biosensors, which broadens the application scope of pesticide detection systems. However, the problem that the existing luminescent carbon dot sensor arrays have poor selectivity and sensitivity to target substances during preparation is not taken into account;

[0005] 2. In the patent document CN108645903B, the main consideration is how to improve the sensitivity of sensor detection, but it does not take into account that the existing luminescent carbon dot sensor array is easily interfered by other substances during detection, and the detection accuracy is poor;

[0006] 3. In the patent document CN111504969B, the main consideration is how to prepare a nano fluorescent sensor with high sensitivity and high specificity for silver ions, and the problem of low accuracy of the existing luminescent carbon dot sensor array for different detection targets is not taken into account;

[0007] 4. In the patent document CN113218923B, the main consideration is how to improve the sensor's anti-interference ability and copper ion detection specificity, but it does not take into account that the fluorescence properties of carbon dots in the existing luminescent carbon dot sensor array cannot be protected. Summary of the invention

[0008] The purpose of the present invention is to provide a method for preparing a sensor array based on luminescent carbon dots and its application, so as to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a method for preparing a sensor array based on luminescent carbon dots, the preparation method is as follows:

[0010] S1. preparing a carbon source, wherein the carbon source includes a precursor containing a targeted functional group or a biomolecule-derived carbon source;

[0011] S2, preparing luminescent carbon dots by chemical synthesis or physical methods;

[0012] S3, modifying the surface of carbon dots;

[0013] S4, using in situ growth method or layer-by-layer self-assembly method to add core-shell structure on the surface of carbon dots;

[0014] S5, fixing the carbon dots with added core-shell structure on the substrate of the sensor array;

[0015] S6. Perform performance testing.

[0016] Preferably, in S2, metal ions or non-metal ions are doped into the structure of the carbon dots during the process of preparing the luminescent carbon dots.

[0017] Preferably, in S2, it also includes using a template method to synthesize carbon dots with specific size and shape or with multiple binding sites.

[0018] Preferably, in S3, the surface of the carbon dots is functionalized by non-covalent adsorption or covalent bonding to introduce various functional groups and biomolecules. The functionalization modification includes polymer modification and organic molecule modification. The polymer modification includes grafting a stimulus-responsive polymer on the surface of the carbon dots. The organic molecule modification connects organic molecules with specific structures and functions to the surface of the carbon dots through chemical reactions.

[0019] Preferably, in S4, the materials for generating the core-shell structure include silicon dioxide, polymethyl methacrylate, polystyrene and metal organic framework materials.

[0020] Preferably, in S5, the carbon dots are fixed on the substrate of the sensor by direct coating, doping or chemical bonding. Direct coating is to directly coat the luminescent carbon dots on the surface of the sensor, doping is to mix the luminescent carbon dots with other materials and fix them through the interaction of the materials, and chemical bonding is to connect the luminescent carbon dots to the substrate surface through chemical bonds to form a stable fluorescent probe.

[0021] Preferably, in S6, the particle size, particle size distribution and fluorescence performance of the carbon dots are measured by characterization analysis, and the sensitivity, stability, selectivity and repeatability of the prepared sensor are evaluated.

[0022] Preferably, the template method includes a molecular template method and a hard template method. The molecular template method uses the target substance or its analogue as a template molecule, and makes the carbon dots grow around the template molecule during the carbon dot synthesis process, thereby forming carbon dots with cavities or binding sites matching the template molecule;

[0023] The hard template rule uses a hard template with a specific structure to limit the growth space of carbon dots, so that the carbon dots form a structure with a specific size and shape.

[0024] Preferably, the stimulus-responsive polymer includes one or more of polyacrylic acid, polydimethylaminoethyl methacrylate, polyhistidine, poly(N-isopropylacrylamide), poly(2-ethyl-2-oxazoline), polyether polymers, azobenzene polymers, spiropyran polymers, cinnamaldehyde-thioacetal polymers, polydisulfide, selenium-containing polymers, carbon dioxide responsive polymers, polyelectrolytes, and magnetic nanoparticle composite polymers.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention can significantly improve the selectivity and sensitivity of the sensor to the target substance by synthesizing carbon dots with targeted recognition function. During the synthesis process, the structure, shape, size and surface chemical properties of the carbon dots can be adjusted to make them interact with the target substance in a specific way, thereby achieving accurate recognition of the target substance and detecting the marker.

[0027] 2. The present invention utilizes the target substance or the analogue to be detected as a template molecule, and makes the carbon dots grow around the template molecule during the carbon dot synthesis, thereby forming carbon dots with holes or binding sites that match the template molecules, so that the sensor array prepared in this way has a high degree of specific recognition ability for the target object, can accurately distinguish and bind, reduce interference from other substances, and thus improve the accuracy and selectivity of detection.

[0028] 3. The present invention modifies the surface of carbon dots to increase their affinity and selectivity for target molecules, and dopes metal ions into the structure of carbon dots, which can change the electronic structure and optical properties of carbon dots, while giving carbon dots the ability to selectively recognize specific target substances or doping non-metallic elements into carbon dots, thereby improving the affinity of carbon dots for acidic substances or substances containing specific functional groups, which can improve the selectivity of carbon dots for these target substances to a certain extent, and thus improve the accuracy of sensor detection.

[0029] 4. In the process of preparing the luminescent carbon dot sensor array of the present invention, the substrate can be converted into a product with fluorescent properties by using an enzyme catalytic reaction, or nanomaterials can be introduced into the carbon dots to enhance the intensity of the fluorescent signal, thereby realizing sensitive detection of the target substance and improving the detection sensitivity to a certain extent.

[0030] 5. The core-shell structure of the present invention can effectively prevent the carbon dots from reacting with the chemical substances in the external environment, thereby protecting the fluorescence properties of the carbon dots. Similarly, for the carbon dots in the aqueous solution, the core-shell structure can prevent the excessive interaction between water molecules and the carbon dots, avoiding the reduction of fluorescence intensity or the change of emission wavelength due to the influence of water. At the same time, the core-shell structure can reduce the non-radiative transition pathway by covering the defects on the surface of the carbon dots, thereby improving the fluorescence quantum yield, and the fluorescence quantum yield is 2.89*10 5 . DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] An embodiment provided by the present invention is a method for preparing a sensor array based on luminescent carbon dots. The preparation method is as follows:

[0033] S1. preparing a carbon source, wherein the carbon source includes a precursor containing a targeted functional group or a biomolecule-derived carbon source;

[0034] S2, preparing luminescent carbon dots by chemical synthesis or physical methods;

[0035] S3, modifying the surface of carbon dots;

[0036] S4, using in situ growth method or layer-by-layer self-assembly method to add core-shell structure on the surface of carbon dots;

[0037] S5, fixing the carbon dots with added core-shell structure on the substrate of the sensor array;

[0038] S6. Perform performance testing.

[0039] In S5, the carbon dots are fixed on the substrate of the sensor by direct coating, doping or chemical bonding. Direct coating is to directly coat the luminescent carbon dots on the sensor surface, doping is to mix the luminescent carbon dots with other materials and fix them through the interaction of the materials, and chemical bonding is to connect the luminescent carbon dots to the substrate surface through chemical bonds to form a stable fluorescent probe.

[0040] Furthermore, the selection of carbon source is based on analyzing the properties of the target substance and determining the functional groups that can specifically bind to it. For example, if the target is to detect heavy metal ions, organic molecules containing amino, carboxyl or thiol functional groups that can form coordination bonds with heavy metal ions can be selected as carbon sources. These functional groups may remain on the surface of carbon dots during the synthesis of carbon dots. For example, if thioglycolic acid is used as a carbon source, its thiol group has a strong affinity for mercury ions. In the subsequently synthesized carbon dots, the targeting of mercury ions will be retained, which helps to improve the selectivity of the sensor for mercury ion detection.

[0041] The luminescent carbon dots are prepared by chemical synthesis or physical methods, including hydrothermal / solvothermal synthesis, microwave-assisted synthesis, arc discharge method or laser ablation method to synthesize carbon dots, and organic molecules with specific functions are selected according to the target analytes and the application requirements of the sensor. For example, if the active oxygen species in the organism are to be detected, organic molecules containing antioxidant functional groups such as phenolic hydroxyl groups can be selected to modify the surface of the carbon dots. These phenolic hydroxyl groups can react with active oxygen, thereby changing the fluorescence properties of the carbon dots and realizing the detection of active oxygen. After the carbon dots are modified, a core-shell structure is added to the surface of the carbon dots by using an in-situ growth method or a layer-by-layer self-assembly method, and then the carbon dots with the added core-shell structure are fixed on the substrate of the sensor array. The fixing methods include physical adsorption method and chemical bonding method, wherein the physical adsorption method includes drop coating method and spin coating method, and the chemical bonding method includes surface functional group reaction and the use of a cross-linking agent;

[0042] Drop coating method: slowly drop a solution containing core-shell carbon dots onto the surface of the sensor array substrate, and then dry it naturally or in a vacuum environment under appropriate temperature and humidity conditions. For example, for a sensor array on a glass substrate, the carbon dot solution can be dropped onto the substrate to form a uniform adsorption layer of the carbon dots on the substrate surface.

[0043] Spin coating method: drop the carbon dot solution on the center of the substrate, and then rotate the substrate to make the solution evenly spread on the substrate surface under the action of centrifugal force;

[0044] Surface functional group reaction: If the substrate surface contains active functional groups, such as hydroxyl groups on the surface of silicon wafers, the functional groups on the surface of carbon dots can be connected with the functional groups on the substrate through chemical reactions. For example, the carboxyl groups on the surface of carbon dots can undergo esterification reaction with the hydroxyl groups on the surface of the substrate under the action of certain catalysts, thereby firmly fixing the carbon dots on the substrate.

[0045] Use cross-linking agents: introduce cross-linking agents to connect the carbon dots and the substrate. For example, use a cross-linking agent containing bifunctional groups, one of which can react with the groups on the surface of the carbon dots, and the other can react with the groups on the substrate. Commonly used cross-linking agents include glutaraldehyde, which can react with the amino groups on the surface of the carbon dots and the amino groups on the surface of the substrate to achieve the fixation of the carbon dots on the substrate.

[0046] Precursors containing targeting functional groups use substances that have affinity or reactive groups for the target substance as carbon sources. If the target substance is a certain metal ion, organic molecules containing functional groups that can form coordination bonds with the metal ion, such as amino, carboxyl or thiol, can be selected as carbon sources. In this way, during the synthesis of carbon dots, these functional groups may be retained on the surface of the carbon dots, giving the carbon dots the ability to target and recognize specific metal ions.

[0047] Biomolecule-derived carbon sources use biomolecules such as amino acids, proteins or nucleic acids as carbon sources. Biomolecules have natural specific recognition capabilities, and carbon dots prepared with them as carbon sources may inherit this property. For example, carbon dots synthesized with specific amino acids as carbon sources can target substances that interact with the amino acids.

[0048] Certain amino acid sequences have specific binding ability to specific proteins or cell receptors. The carbon dots synthesized with these amino acids as carbon sources can be used for targeted identification of related biological molecules in the field of biological detection. For example, carbon dots synthesized with carbon sources modified with the arginine-glycine-aspartic acid (RGD) tripeptide sequence have specific binding ability to integrin receptors on the surface of certain tumor cells. Such carbon dots have potential value in sensor applications for tumor diagnosis and treatment.

[0049] An embodiment provided by the present invention is a method for preparing a sensor array based on luminescent carbon dots. In S2, metal ions or non-metal ions are doped into the structure of the carbon dots during the preparation of the luminescent carbon dots.

[0050] Furthermore, doping metal ions into the structure of carbon dots can change the electronic structure and optical properties of carbon dots, while giving carbon dots the ability to selectively recognize specific target substances. For example, carbon dots doped with iron ions may be sensitive to target substances containing redox activity, and carbon dots doped with copper ions have a good binding ability to nitrogen- or sulfur-containing compounds. Nitrogen doping in non-metallic element doping can increase the electron density on the surface of carbon dots and improve the affinity for acidic substances or substances containing specific functional groups. Sulfur doping can make carbon dots have a stronger binding ability to heavy metal ions, thereby improving the selectivity for heavy metal ion target substances.

[0051] An embodiment provided by the present invention: a method for preparing a sensor array based on luminescent carbon dots, in S2, also includes using a template method to synthesize carbon dots with a specific size and shape or with multiple binding sites, the template method includes a molecular template method and a hard template method, the molecular template method uses a target substance or its analogues as a template molecule, and during the carbon dot synthesis process, the carbon dots grow around the template molecules, thereby forming carbon dots with holes or binding sites that match the template molecules; the hard template method uses a hard template with a specific structure to limit the growth space of the carbon dots, so that the carbon dots form a structure with a specific size and shape.

[0052] Furthermore, the target substance or its analogue is used as a template molecule, and the carbon dots are grown around the template molecule during the carbon dot synthesis process, thereby forming carbon dots with cavities or binding sites that match the template molecule. After the synthesis is completed, the template molecule is removed, and the obtained carbon dots have the specific recognition ability for the target substance. For example, the carbon dots synthesized with a certain protein as a template will have targeting to the protein or proteins with similar structures to the protein.

[0053] The hard template rule uses hard templates with specific structures, such as porous silicon and molecular sieves, to limit the growth space of carbon dots, so that the carbon dots form a structure with a specific size and shape. This structure can selectively identify and adsorb target substances. For example, carbon dots synthesized using molecular sieves with nanopores as templates can selectively identify target substances with molecules of matching size and pores.

[0054] An embodiment provided by the present invention: a method for preparing a sensor array based on luminescent carbon dots, in S3, the surface of the carbon dots is functionally modified by non-covalent adsorption or covalent bonding, and various functional groups and biological molecules are introduced, the functional modification includes polymer modification and organic molecule modification, the polymer modification includes grafting a polymer with stimulus responsiveness on the surface of the carbon dots, and the organic molecule modification connects organic molecules with specific structures and functions to the surface of the carbon dots through chemical reactions, and the polymer with stimulus responsiveness includes one or more of polyacrylic acid, polydimethylaminoethyl methacrylate, polyhistidine, poly(N-isopropylacrylamide), poly(2-ethyl-2-oxazoline), polyether polymers, azobenzene polymers, spiropyran polymers, cinnamaldehyde-thioacetal polymers, polydisulfide, selenium-containing polymers, carbon dioxide responsive polymers, polyelectrolytes, and magnetic nanoparticle composite polymers.

[0055] Furthermore, in the process of synthesizing carbon dots, organic molecules with specific structures and functions are selected and connected to the surface of carbon dots through chemical reactions. For example, carbon dots are modified with silane coupling agents with targeting groups so that they can specifically recognize certain receptors on the cell surface, or carbon dots are modified with organic molecules with boric acid groups so that they have selective recognition ability for biological molecules containing cis-diol structures, such as sugars.

[0056] Polymer modification is to graft polymers onto the surface of carbon dots to increase the stability and water solubility of carbon dots. It can also introduce targeted recognition functions for target substances. For example, grafting polyethylene glycol can improve the biocompatibility of carbon dots, and further functionalize polyethylene glycol to make it targeted to specific biological molecules, or grafting stimuli-responsive polymers to enable carbon dots to selectively recognize target substances under specific environmental stimuli such as pH, temperature, and light.

[0057] Polyacrylic acid (PAA): Under acidic conditions, the carboxyl groups on PAA basically do not dissociate, and the molecular chain is in a contracted state. When the pH value of the environment rises to a certain level, the carboxyl groups begin to dissociate into carboxylate anions. Due to the mutual repulsion between charges of the same kind, the molecular chain gradually stretches, resulting in significant changes in the physical and chemical properties of the polymer, such as solubility and swelling.

[0058] Polydimethylaminoethyl methacrylate (PDMAEMA): Under alkaline conditions, the dimethylamino groups on its molecular chain will be protonated, making the polymer molecular chain positively charged, increasing the electrostatic repulsion between molecules, and changing the solubility, fluid dynamics volume and other properties of the polymer. In an acidic environment, the protonation degree decreases and the conformation of the molecular chain returns to its original state.

[0059] Polyhistidine: The imidazole group on the polyhistidine residue has a certain acid-base buffering capacity and can be protonated or deprotonated at different pH values. When the pH changes, the conformation, solubility and other properties of polyhistidine will change accordingly;

[0060] Poly(N-isopropylacrylamide) (PNIPAM): It has a low critical solution temperature of about 32°C. When the temperature is lower than the critical solution temperature, the hydrogen bonding between the PNIPAM molecular chain and water is strong, and the polymer has good solubility in water to form a uniform solution. When the temperature rises above the critical solution temperature, the hydrogen bonding weakens, the polymer molecular chain dehydrates and aggregates, and precipitates from the solution to form a precipitate.

[0061] Poly(2-ethyl-2-oxazoline) (PEOz): Its critical solution temperature can be adjusted by changing the molecular weight and structure of the polymer. When the temperature is below the critical solution temperature, PEOz is soluble in water, but when the temperature rises above the critical solution temperature, a phase transition occurs and it separates from water.

[0062] Polyether polymers: such as block copolymers of polyethylene glycol (PEG) and polypropylene glycol (PPG) (PEG-b-PPG). At low temperatures, the interaction between the PEG chain segments and water is strong, and the polymer has good solubility in water; as the temperature rises, the hydrophobicity of the PPG chain segments increases, causing the polymer to phase separate;

[0063] Azobenzene polymer: Azobenzene molecules undergo reversible cis-trans isomerization under the irradiation of ultraviolet light and visible light. When azobenzene is in the trans structure, the molecule is linear, and the structure and performance of the polymer are relatively stable. Under ultraviolet light, azobenzene will transform into a cis structure, and the shape and steric hindrance of the molecule will change, thus causing changes in the physical and chemical properties of the polymer, such as refractive index, solubility, and film morphology;

[0064] Spiropyran polymer: Spiropyran is in a closed-loop structure in the absence of light or darkness. At this time, the color of the polymer is light or colorless. Under light conditions, spiropyran undergoes a ring-opening reaction to form a merocyanine structure with color, accompanied by changes in the optical and electrical properties of the polymer.

[0065] Cinnamaldehyde-thioacetal (TA) polymer: Endogenous reactive oxygen species are used as triggers to cause the cleavage of TA chains in the polymer and release cinnamaldehyde. The released cinnamaldehyde then produces more reactive oxygen species through mitochondrial dysfunction, causing self-amplifying degradation of the polymer.

[0066] Polydisulfide (PDS): The polymer main chain or side chain contains disulfide bonds (-SS-). In a reducing environment, the disulfide bonds will be reduced to thiol groups (-SH), causing the structure of the polymer to change, thus affecting its physical and chemical properties;

[0067] Selenium-containing polymers: Selenium is similar to sulfur, and the selenoether bond (-Se-Se-) in selenium-containing polymers can also undergo a reversible reaction of breaking and forming under redox conditions;

[0068] Carbon dioxide responsive polymers: such as poly (N,N-dimethylaminoethyl methacrylate), which undergo reversible chemical reactions under the action of carbon dioxide, resulting in changes in the solubility, phase behavior and other properties of the polymer;

[0069] Polyelectrolyte: Under the action of electric field, the charged groups on the polyelectrolyte molecular chain will be affected by the electric field force and move in a directional manner, thus causing the morphology, structure and properties of the polymer to change;

[0070] Magnetic field responsive polymers:

[0071] Magnetic nanoparticle composite polymer: Magnetic nanoparticles (such as ferroferric oxide nanoparticles) are composited with polymers to obtain magnetic nanoparticle composite polymers that are responsive to magnetic fields. Under the action of a magnetic field, magnetic nanoparticles will produce a magnetocaloric effect or be affected by a magnetic force, thereby increasing the temperature of the polymer or causing a morphological change.

[0072] An embodiment provided by the present invention: a method for preparing a sensor array based on luminescent carbon dots, in S4, the materials for generating a core-shell structure include silicon dioxide, polymethyl methacrylate, polystyrene and metal organic framework materials.

[0073] Furthermore, the carbon dots are first dispersed in a mixed solution of ethanol and water, and an appropriate amount of 3-aminopropyltriethoxysilane (APTES) is added as a surfactant and coupling agent. The amino group of APTES can react with functional groups on the surface of the carbon dots, such as hydroxyl and carboxyl groups, and its ethoxy part can be hydrolyzed to form silanol groups. Then, tetraethyl orthosilicate (TEOS) is added dropwise, and ammonia water is added to adjust the pH value to alkaline, so that the silicic acid generated by the hydrolysis of TEOS condenses on the surface of the carbon dots to form a silica shell. By controlling factors such as the reaction time and the amount of TEOS added, the thickness of the silica shell can be adjusted, and it can resist the erosion of various chemical substances, such as acid and alkali solutions, oxidants and reducing agents, etc. In a complex chemical environment, the silica shell can effectively prevent the carbon dots from contacting these harmful chemicals, thereby protecting the fluorescence properties of the carbon dots. For example, during the fluorescence detection process, the excitation light and the emission light can pass through the silica shell smoothly, ensuring the normal transmission of the fluorescence signal of the carbon dots.

[0074] Polymethyl methacrylate (PMMA): The core-shell structure of PMMA-wrapped carbon dots is prepared by emulsion polymerization. The carbon dots are dispersed in an aqueous solution containing a surfactant such as sodium dodecyl sulfate and SDS to form an aqueous phase. At the same time, methyl methacrylate (MMA) monomer and initiator such as potassium persulfate and KPS are dissolved in an organic solvent such as benzene to form an oil phase. Under stirring conditions, the oil phase is slowly added dropwise to the aqueous phase to form an emulsion system, which is then heated to a certain temperature to initiate the polymerization reaction of MMA. As the polymerization reaction proceeds, PMMA gradually forms a shell on the surface of the carbon dots. After the reaction is completed, the PMMA-carbon dot core-shell structure material is obtained by centrifugation, washing and other operations. It can reduce the interference of external factors on the fluorescence of the carbon dots. For example, when the ambient humidity is high, the PMMA shell can prevent water molecules from contacting the carbon dots and avoid the fluorescence quenching phenomenon caused by water molecules.

[0075] Polystyrene (PS): Taking the free radical polymerization method as an example, the carbon dots are first dispersed in the styrene monomer, and an appropriate amount of initiator such as azobisisobutyronitrile, AIBN, is added. Under conditions of heating or light, the styrene monomer undergoes a free radical polymerization reaction. During the polymerization process, the carbon dots are gradually wrapped by polystyrene as the core. After the reaction, the PS-carbon dot core-shell structure material is separated by precipitation, filtration and other methods. It can reduce the scattering and reflection of light at the core-shell interface, which is beneficial to the normal emission and propagation of carbon dot fluorescence. At the same time, the PS-carbon dot core-shell structure can maintain the fluorescence properties of the carbon dots in a complex detection environment, enabling it to detect the target substance more accurately.

[0076] Metal-organic framework (MOFs) materials: Taking ZIF-8-encapsulated carbon dots as an example, the carbon dots are first dispersed in a solution containing zinc salts such as zinc nitrate and organic ligands such as 2-methylimidazole. Under appropriate temperature and stirring conditions, the zinc salts react with 2-methylimidazole to self-assemble into a ZIF-8 framework structure, while encapsulating the carbon dots therein. After the reaction, the ZIF-8-carbon dot core-shell structure material is obtained by centrifugation, washing and other operations. This core-shell structure can utilize the porosity and chemical stability of ZIF-8 to protect the fluorescent properties of the carbon dots. The pores of MOFs can prevent some macromolecules from contacting the carbon dots. At the same time, the metal ions and organic ligands inside them can interact with the functional groups on the surface of the carbon dots to enhance the stability of the core-shell structure.

[0077] When carbon dots are wrapped with a polymer shell, the polymer can fill the tiny defects on the surface of the carbon dots, so that the transition of electrons between the excited state and the ground state is more likely to occur through radiation transition, thereby enhancing the fluorescence properties of the carbon dots and playing a protective role.

[0078] An embodiment provided by the present invention: a method for preparing a sensor array based on luminescent carbon dots, in S6, also includes measuring the particle size, particle size distribution and fluorescence properties of the carbon dots through characterization analysis, and performing sensitivity evaluation, stability evaluation, selectivity evaluation and repeatability evaluation on the prepared sensor.

[0079] Furthermore, in terms of sensitivity evaluation, the response speed and maximum response value of the sensor array to the target analyte are mainly investigated;

[0080] Sensitivity test: prepare a series of target analyte standard solutions with different concentrations, detect them respectively with carbon dot sensors, measure the change of the sensor's fluorescence signal or other output signal with the concentration of the target analyte, and determine that the detection limit of the sensor is 0.064~0.15mmol / L.

[0081] Comparative experiment: The prepared carbon dot sensor was compared with other existing similar sensors. Under the same detection conditions, their sensitivity to the target analyte was compared. The sensor prepared by the present application can identify a variety of metal ions, including but not limited to Cu2+, Fe3+, Cr6+, Fe2+, Co2+ and Ni2+, etc. The detection accuracy is 99.98%, the detection distance is 1㎜~1000㎜, the detection response time is 7.65mss, and the detection resolution is 0.01mg / L.

[0082] The stability evaluation focuses on the performance of the sensor array during long-term use. Compared with ordinary sensors, the sensor array prepared by the present application has little fluctuation in the accuracy of detection results of the same target substance under various environments under different ambient temperatures, humidity, and electromagnetic interference, and has higher stability.

[0083] Selectivity evaluation examines the selectivity of the sensor array for the target analyte, that is, the ability to exclude interfering substances.

[0084] Repeatability evaluation is to evaluate the repeatability of the sensor array when measuring the same target analyte multiple times. When evaluating repeatability, it is necessary to compare the data of multiple measurements of the same target analyte to evaluate the quality of its repeatability. The repeatability is ≤1.57%.

[0085] An embodiment provided by the present invention: the use of a sensor array preparation method based on luminescent carbon dots in the fields of environmental monitoring, food safety, and medical diagnosis.

[0086] Furthermore, in water environment monitoring, the detection of heavy metal ions such as mercury, lead, and cadmium is of great significance. For example, when luminescent carbon dots containing thiol groups are used as sensors, when mercury is present, the thiol groups combine with mercury to quench the fluorescence of the carbon dots, which can quickly and sensitively detect the content of mercury ions in water, and the detection limit can reach the nanomolar or even picomolar level.

[0087] Organic pollutant detection: In soil and atmospheric environmental monitoring, polycyclic aromatic hydrocarbons (PAHs) are detected. P-luminescent carbon dot sensors can produce fluorescence signal changes through π-π stacking with PAHs. For example, in atmospheric particulate matter monitoring, carbon dot sensor arrays are used to enrich and detect PAHs in the air, which can monitor the concentration changes of PAHs in the atmosphere in real time, providing data support for air quality assessment and pollution control.

[0088] Gas pollutant detection: Sensors based on luminescent carbon dots can change the fluorescence intensity of carbon dots through chemical reactions with nitrogen dioxide, such as redox reactions. By placing sensor arrays around industrial plants or in indoor environments, the concentration of nitrogen dioxide can be monitored in real time.

[0089] Pesticide residue detection: The hydroxyl groups on the surface of luminescent carbon dots can undergo nucleophilic substitution reaction with the phosphoryl groups in organophosphorus pesticides, quenching the fluorescence of the carbon dots;

[0090] Food additive detection: Luminescent carbon dots can combine with sweetener molecules through hydrogen bonds or electrostatic interactions, causing changes in fluorescence intensity;

[0091] Microbial detection: Taking the detection of E. coli as an example, when E. coli is present, its metabolites such as organic acids and enzymes will react with the luminescent carbon dots, resulting in changes in fluorescence intensity;

[0092] Biomarker detection: In the early diagnosis of cancer, tumor markers such as alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) are detected by connecting luminescent carbon dots with antibodies against these markers. When tumor markers are present in blood or tissue samples, the antibody-antigen binding causes the fluorescence of the carbon dots to change.

[0093] Cell imaging and detection: The luminescent carbon dots are labeled on specific receptors on the surface of cancer cells, or enter the interior of cancer cells through endocytosis. The fluorescence of the carbon dots is observed under a fluorescence microscope to track the migration and proliferation of cancer cells. For example, in tumor metastasis research, by observing the distribution of cancer cells labeled with luminescent carbon dots in the body, the metastasis pathway of tumor cells can be understood, providing a basis for cancer treatment.

[0094] Drug delivery monitoring: In drug controlled release systems, drugs are encapsulated inside luminescent carbon dots or combined with carbon dots. When the drugs are delivered to target tissues or cells, the drugs begin to be released due to changes in environmental factors such as pH value and enzyme concentration. At the same time, the fluorescence signal of the carbon dots changes. By monitoring the fluorescence changes of the luminescent carbon dots, we can understand the release of drugs in tumor tissues, optimize drug delivery strategies, and improve the effectiveness of drug treatment.

[0095] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a sensor array based on luminescent carbon dots, characterized in that: The preparation method is as follows: S1. preparing a carbon source, wherein the carbon source includes a precursor containing a targeted functional group or a biomolecule-derived carbon source; S2, preparing luminescent carbon dots by chemical synthesis or physical methods; S3, modifying the surface of carbon dots; S4, using in situ growth method or layer-by-layer self-assembly method to add core-shell structure on the surface of carbon dots; S5, fixing the carbon dots with added core-shell structure on the substrate of the sensor array; S6. Perform performance testing.

2. The method for preparing a sensor array based on luminescent carbon dots according to claim 1, characterized in that: In S2, metal ions or non-metal ions are doped into the structure of carbon dots during the process of preparing luminescent carbon dots.

3. The method for preparing a sensor array based on luminescent carbon dots according to claim 1, characterized in that: In S2, the use of template methods to synthesize carbon dots with specific sizes and shapes or with multiple binding sites is also included.

4. The method for preparing a sensor array based on luminescent carbon dots according to claim 1, characterized in that: In S3, the surface of carbon dots is functionalized by non-covalent adsorption or covalent bonding to introduce various functional groups and biomolecules. Functionalization modification includes polymer modification and organic molecule modification. Polymer modification includes grafting stimulus-responsive polymers on the surface of carbon dots, and organic molecule modification connects organic molecules with specific structures and functions to the surface of carbon dots through chemical reactions.

5. The method for preparing a sensor array based on luminescent carbon dots according to claim 1, characterized in that: In S4, the materials used to generate the core-shell structure include silicon dioxide, polymethyl methacrylate, polystyrene, and metal-organic framework materials.

6. The method for preparing a sensor array based on luminescent carbon dots according to claim 1, characterized in that: In S5, the carbon dots are fixed on the substrate of the sensor by direct coating, doping or chemical bonding. Direct coating is to directly coat the luminescent carbon dots on the sensor surface, doping is to mix the luminescent carbon dots with other materials and fix them through the interaction of the materials, and chemical bonding is to connect the luminescent carbon dots to the substrate surface through chemical bonds to form a stable fluorescent probe.

7. The method for preparing a sensor array based on luminescent carbon dots according to claim 1, characterized in that: In S6, it also includes measuring the particle size, particle size distribution and fluorescence performance of the carbon dots through characterization analysis, and conducting sensitivity evaluation, stability evaluation, selectivity evaluation and repeatability evaluation on the prepared sensor.

8. The method for preparing a sensor array based on luminescent carbon dots according to claim 3, characterized in that: The template method includes a molecular template method and a hard template method. The molecular template method uses a target substance or its analogue as a template molecule, and during the carbon dot synthesis process, the carbon dots grow around the template molecule, thereby forming carbon dots with cavities or binding sites that match the template molecule; The hard template rule uses a hard template with a specific structure to limit the growth space of carbon dots, so that the carbon dots form a structure with a specific size and shape.

9. The method for preparing a sensor array based on luminescent carbon dots according to claim 4, characterized in that: The stimulus-responsive polymer includes one or more of polyacrylic acid, polydimethylaminoethyl methacrylate, polyhistidine, poly(N-isopropylacrylamide), poly(2-ethyl-2-oxazoline), polyether polymers, azobenzene polymers, spiropyran polymers, cinnamaldehyde-thioacetal polymers, polydisulfide, selenium-containing polymers, carbon dioxide responsive polymers, polyelectrolytes, and magnetic nanoparticle composite polymers.

10. Use of the method for preparing a sensor array based on luminescent carbon dots according to any one of claims 1 to 9 in the fields of environmental monitoring, food safety, and medical diagnosis.