168 results about "Serum samples" patented technology

The invention provides a method for detecting an external vesicle marker through high-flux nano plasma exciting light immune color development, and belongs to the technical field of human extracellular vesicles. After a serum sample is subjected to centrifugal treatment, the serum sample and a CD81 capture antibody substrate are incubated, and the particle size distribution of the vesicles is monitored in real time; a zwitterionic polymer modified gold nanoparticle LAM detection probe and a polyethylene glycol modified silver nanoparticle LprG detection probe are prepared to be specifically combined with a vesicle surface antigen, a chromogenic enhancement solution is adopted to induce a plasma resonance signal, and full-hole scanning imaging is carried out; and constructing a double-layer game optimization model to cooperatively optimize the detection sensitivity and the signal stability, carrying out weighted summation on normalized signals of the particle size subgroups to obtain comprehensive detection signal intensity, comparing the comprehensive detection signal intensity with a threshold value, and outputting a final judgment result. The technical problem that quantitative accuracy is affected by signal intensity deviation caused by vesicle particle size difference in outer vesicle marker detection is solved.

The invention relates to the technical field of spectral analysis and biomedical detection, and discloses an SERS (Surface Enhanced Raman Scattering) spectrum quantitative detection method and system based on interpretable stacked ensemble learning. The method comprises the following steps: acquiring SERS spectral data of serum tumor marker standard substances with different concentration gradients; performing baseline correction and normalization preprocessing on the data, performing sparse feature selection by using an LASSO algorithm, and screening out key spectral features to construct a sample data set; constructing an interpretable stacking integration model, wherein the model adopts a base learner layer and a meta learner layer; training the model by using the training set, optimizing model hyper-parameters by using a cross validation strategy, and establishing a mapping relationship between spectral features and tumor marker concentrations; and collecting SERS spectral data of a to-be-detected serum sample, extracting key spectral features, inputting the key spectral features into the trained interpretable stacked integrated model, and outputting a concentration predicted value of the tumor marker in the to-be-detected serum sample. The method has the advantages of high precision, universality and molecular level interpretability.

This invention discloses a method and sensor for adiponectin detection using a polyaniline and polyacrylic acid-modified wire mesh carbon electrode, relating to the field of adiponectin detection technology. The method involves electrochemically activating the wire mesh carbon electrode, electropolymerizing it to form a polyaniline-polyacrylic acid composite modification layer, immobilizing adiponectin monoclonal antibody after activation with N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, blocking the antibody with bovine serum albumin, and reacting it with a serum sample. The adiponectin concentration is determined based on the peak potential shift and peak current change. This invention simultaneously achieves both conductive transport and antibody immobilization, reduces non-specific adsorption and serum interference, and improves detection sensitivity, repeatability, and quantitative accuracy.

The application relates to a centrifugal device and method for detecting animal serum samples and relates to the technical field of serum sample detection. The device comprises a body, a spline is rotationally connected to the bottom of the body cavity through a motor, a bracket is connected to the upper end of the spline in a concave-convex abutting mode, an electrically conductive slip ring is arranged on the outside of the motor output end of the bottom of the body cavity, and a stator on the outside of the electrically conductive slip ring is fixed in the cavity of the body through a connecting rod. Through cooperation of a clamping assembly, a sleeve, a clamping seat and a tube clamp, the clamping seat is driven to rotate by rotating the rotating sleeve, the tube clamp is opened and closed in an interlaced mode through meshing of the connecting plate and the gear, various sizes of serum test tubes can be clamped, special parts need not be replaced, work efficiency is improved, meanwhile, when the number of test tubes is odd, the gravity sensor senses the weight, the electric push rod pushes the connecting frame on the symmetrical position to adjust the position, the gravity center is adjusted through cooperation of the rotating structure, the bracket is balanced, sample spilling and pollution are avoided.

The application relates to an electrochemical sensor based on antibody-aptamer synergic recognition and a construction method and application thereof, and belongs to the technical field of electrochemical analysis and biomarker AZGP1 detection technology. The sensor has strong resistance to high-concentration endogenous interference, and has good selectivity when interference and AZGP1 exist. Compared with the prior art, the sensor has the advantages of high sensitivity, high selectivity, simple operation, rapid detection, low cost and the like, and successfully realizes the detection of AZGP1 in a clinical patient serum sample, and provides a new and efficient method for clinical detection of biological recognition molecules.

The invention discloses a detection method of vitamin K1, and belongs to the technical field of biological detection. The problems that a vitamin K1 detection method is tedious in operation, prone to being influenced by a matrix, low in sensitivity and the like are solved. The detection method comprises the following steps: (1) preparing a standard substance intermediate working solution, an isotope internal standard substance solution and a standard curve working solution of the vitamin K1; (2) treating a serum sample and a standard curve working solution: adding a 2-nitroso pyridine solution to carry out derivatization reaction; and (3) detecting the vitamin K1 by using a high performance liquid chromatography-tandem mass spectrometry method. According to the method, the 2-nitroso pyridine is used as a derivatization reagent, the vitamin K1 and the 2-nitroso pyridine are subjected to a Diels-Alder reaction to generate a new six-membered heterocycle containing N and O, the 2-nitroso pyridine can efficiently and completely react with the vitamin K1 in only 10 minutes at room temperature, the detection steps are simplified, the sample pretreatment time is shortened, and the detection efficiency is improved.

The invention discloses a cascade seven-core optical fiber sensor applied to folic acid detection and a preparation method of the cascade seven-core optical fiber sensor, and belongs to the technical field of optical fiber sensing and biological analysis detection. The sensor comprises a first single-mode optical fiber, a seven-core optical fiber section and a second single-mode optical fiber, a double-microsphere-cavity structure is arranged at the optical fiber connecting position to form a cascade interference optical path, and tapering is conducted on the middle portion of the seven-core optical fiber section to form a sensing area. According to the invention, mode matching is improved through the microsphere cavity, an evanescent field is enhanced through tapering, and high-sensitivity specific detection of folic acid is realized in cooperation with the folic acid binding protein biological functional layer fixed on the surface; the sensor obtains stable linear response to a folic acid standard solution in the range of 0-50 ng / mL, a clinical serum sample verifies that the detection result of the sensor is highly consistent with that of a chemiluminescence method, the sensor has good reusability, and the sensor has the advantages of being easy to prepare in structure, rapid in response, high in sensitivity, capable of being matched with a complex matrix and the like, and has good application prospects. The method has huge potential in clinical folic acid quantitative detection.

The invention discloses a blocking agent for cell immunofluorescence detection by a slide method and a use method of the blocking agent. The blocking agent is a homologous no-load cell lysis solution without transfection plasmids, and the protein concentration is greater than or equal to 30mg / mL. The blocking agent is completely the same as cell cytoplasm and cell membrane components of cells to be detected except for plasmids-expressed antigens, when in use, the blocking agent is pre-mixed with a blood cleaning sample in advance, interfering antibodies except target antibodies in serum can be purified, and meanwhile, due to the fact that no antigen protein expressed after plasmid transfection exists, the blocking agent can be used for detecting the cells to be detected. And the protein concentration is equivalent to the globulin concentration in serum, so that the target antibody cannot be lost in the serum, and the slide method CBA detection sensitivity can be greatly improved.

The invention discloses a biosensor based on an ultraviolet light triggered bio-barcode release technology (OBCA) and construction and application of the biosensor. The biosensor comprises nucleic acid functionalized silver nanoparticles, nucleic acid functionalized magnetic beads and a CRISPR (clustered regularly interspaced short palindromic repeats) / Cas12a detection system, the DNA bar code modified on the surface of the silver nanoparticle contains a light cleavable linker, a CRISPR / Cas12a activation sequence and a target capture sequence I, and a DNA capture probe containing a target capture sequence II is fixed on the surface of the magnetic bead through biotin-streptavidin action. During detection, target miRNA mediates two capture sequences to form a sandwich compound, after magnetic separation and thermal denaturation elution, 365nm ultraviolet radiation releases DNA bar code fragments, and the Cas12a trans-cleavage fluorescence quenching reporter probe is activated to generate a signal. According to the method, nucleic acid amplification and reverse transcription are not needed, the detection limits of miR-21, miR-155 and mi-210 respectively reach 158.94 aM, 763.56 aM and 197.82 aM, single-base mismatch and precursor miRNA can be distinguished, the serum sample detection result is highly consistent with that of RT-PCR, and the method is suitable for high-sensitivity quantitative detection of miRNA.

This invention relates to an IL5 / Bi2MoO6 / MXene photoactive composite material, a low-background photoelectrochemical aptamer sensor, its preparation method, and its applications. The sensor is constructed by sequentially modifying chitosan, glutaraldehyde, complementary DNA strands, and a gold nanoparticle-labeled aptamer. A fixed capture probe and APT-Au synergistically achieve dual signal quenching, constructing an extremely low detection baseline. When the target analyte MUC1 is present, its specific binding to the aptamer causes APT-Au to detach, dissolving the dual quenching and significantly restoring the photocurrent, thereby achieving quantitative detection. This invention solves the problems of low efficiency, heterojunction instability, and high baseline in single quenching modes of existing photoelectric materials, achieving highly sensitive, highly specific, rapid, and low-cost detection of the breast cancer biomarker MUC1 in human serum samples, providing a novel, industrially feasible technical solution for large-scale early screening of breast cancer.

This invention belongs to the fields of molecular biology and bioinformatics, specifically relating to a truncated bovine virus-encoded protein phage library, its construction method, and applications. This library covers all 162 known bovine viruses that host bovine subfamily viruses, containing 51,794 non-redundant peptide coding sequences of 56 amino acids each. These peptides are fused and displayed on the surface of the T7 phage capsid, with all coding sequences having a uniform total length of 200 bp. The library construction was achieved through sequence acquisition, truncation and redundancy removal, codon optimization and DNA synthesis, and in vitro ligation and packaging with T7 phage. The resulting library exhibits a positivity rate of 93% and a titer of 2.8 × 10⁻⁶. 10 PFU / mL. This invention features an optimized single-round high-throughput screening process adapted to clinical bovine serum samples, enabling efficient identification of bovine virus B-cell epitopes and providing tools and candidate targets for bovine virus vaccine development and diagnostic reagent development.

The present disclosure relates to methods, compositions, and systems for detecting whether a subject exposed to a coronavirus has developed a neutralizing antibody response. Also disclosed are methods for determining whether a patient infected by a coronavirus is likely to respond to treatment with an antibody preparation. Also disclosed are methods for detecting the level of neutralizing antibody response in a sample of serum from a subject exposed to a coronavirus or to a coronavirus vaccine.

This invention relates to the field of biotechnology, and in particular to an antigenic epitope peptide, product, and application for detecting antibodies produced by porcine deltacoronavirus infection. This invention identified short peptide epitopes in PDCoV longitudinal challenge serum samples, obtaining 12 short peptides, which were then prepared into a porcine deltacoronavirus antibody detection kit. Finally, six field serum samples were selected for antibody detection, and the effectiveness was verified using a virus neutralization experiment. The results showed that the porcine deltacoronavirus antibody detection kit provided by this invention is effective. Furthermore, the porcine deltacoronavirus antibody detection kit provided by this invention, as a novel detection method, improves sensitivity and specificity while simultaneously providing multiple detection results, namely, determining whether viral infection has occurred, identifying the stage of infection, and achieving DIVA (Differentiation, Infection, and Variability) analysis.

This invention belongs to the field of biological sample contaminant screening, specifically involving a pretreatment method for liquid chromatography-tandem mass spectrometry analysis of chemical contaminants in serum. The pretreatment method includes the following steps: (1) Preparation of Ti / Zr MOF: Zirconium source, 1,3,5-tris(4-carboxyphenyl)benzene, titanium source, and organic acid are placed in a container, dissolved in an aprotic polar solvent, heated to react, cooled, and the white powder product is collected by centrifugation and washing, which is Ti / Zr MOF, and dried for later use; (2) Extraction: The serum sample is mixed with acetonitrile, ultrasonically vortexed, centrifuged, and a portion of the supernatant is taken as the purification solution; (3) Purification: The purification solution in step (2) is mixed with the Ti / Zr MOF in step (1), ultrasonically vortexed, centrifuged, and the supernatant is taken to obtain the purified sample.

This invention discloses a method for identifying intrahepatic cholangiocarcinoma (ICC) based on serum peptide characteristics and its application. The invention collects serum samples from three groups: individuals with ICC, those with benign liver disease, and healthy controls. Peptide characteristic peaks associated with ICC are screened, and a model is constructed using a logistic regression algorithm. This model demonstrates excellent discriminative ability on both the training and independent test sets, with AUCs reaching 0.986 and 0.963, respectively, significantly outperforming traditional tumor markers CA19-9 and CEA. The peptide characteristic peak combination and the discriminative model constructed based on it can be used for early detection of ICC, differentiation between benign and malignant cases, and screening of high-risk populations. It offers advantages such as rapid detection, standardized procedures, strong early ICC identification capability, and low false positive rate, providing a highly sensitive, specific, and widely applicable non-invasive screening tool for clinical use.

The application discloses a method for detecting a plurality of alkyl imidazole ionic liquids in serum based on liquid chromatography-mass spectrometry, and comprises the following steps: preparing a matrix standard solution, and drawing a matrix standard curve; carrying out pretreatment and solid phase extraction on a human serum sample to be detected; and finally, performing quantitative analysis by using LC-MS / MS. The method can quickly and accurately detect the alkyl imidazole ionic liquids in the human serum sample, is simple, efficient and high in sensitivity, can realize the detection of 10 target alkyl imidazole ionic liquids in human exposure, is good in separation effect, can provide an effective technical means for the biological monitoring research work of ionic liquid pollutants, and in the theoretical aspect, provides a certain scientific basis for the human exposure risk and preventive measures of ionic liquids.

The invention discloses a method for analyzing serum differential expression protein characteristics of an AQP4-IgG positive NMOSD patient, and relates to the technical field of differential expression protein characteristic analysis, and the method comprises the following steps: S1, collecting a serum sample of a to-be-detected subject; s2, carrying out protein detection on the serum sample to obtain expression level data of at least one or more of PRDX2, CLU, ECM1, CFD, GPI and S100A8, wherein the expression level data is one or more of PRDX2, CLU, ECM1, CFD, GPI and S100A8; s3, carrying out comparative analysis on the expression level of the serum protein and a pre-established AQP4-IgG positive NMOSD serum protein expression characteristic reference standard; according to the method for auxiliary diagnosis of the AQP4-IgG positive neuromyelitis optica pedigree disease provided by the invention, a judgment mode capable of reflecting molecular characteristics of the AQP4-IgG positive neuromyelitis optica pedigree disease is constructed by carrying out conjoint analysis on various serum protein expression characteristics related to immunoregulation, inflammatory response, complement activation and metabolism; therefore, the problem of insufficient detection stability of a single biomarker is avoided.

The present invention relates to a method for determining whether an unknown blood sample is a serum sample, a citrated plasma sample, or an EDTA-treated plasma sample. The invention also relates to a method for the diagnosis and / or monitoring of a patient suffering from a hemostasis disorder.

This invention provides a method for simultaneously detecting free and total testosterone in serum. Free testosterone is released from a serum sample using equilibrium dialysis, followed by derivatization. An additive quencher is added to remove excess derivatizing reagent, and then a sample solution containing total testosterone is added for testing. The method provided by this invention is simple to operate, eliminating the need for complex procedures such as nitrogen blowing and liquid-liquid extraction. The quencher chosen is low-toxicity, low-cost pyruvate, which improves detection sensitivity while reducing experimental costs. Furthermore, this invention utilizes the biuret assay to determine whether protein leakage has occurred during equilibrium dialysis, providing a direct and accurate assessment.

The present invention pertains to a multiple biomarker for cancer diagnosis and a use thereof and, specifically, to a composition for cancer diagnosis, comprising an agent for measuring the protein or mRNA expression levels of IGFI, KLK2, PKCα, and TRPM8. The present inventors confirmed that rapid and accurate cancer diagnosis can be performed by detecting the unique marker combination of IGFI, KLK2, PKCα, and TRPM8 of the present invention in serum samples from actual cancer patients and one or more cancers can be simultaneously detected. Thus, the combination of IGFI, KLK2, PKCα, and TRPM8 is expected to allow for the rapid and accurate diagnosis of various cancers including prostate cancer.

The invention discloses a disease risk prediction micro-fluidic chip based on sperm motility characteristics and an experimental method thereof.The micro-fluidic chip comprises a substrate disc, a heightening layer, a sperm suspension-serum incubation layer and a sperm suspension-serum sample adding layer which are arranged in a laminated mode, and each layer is correspondingly provided with a sperm suspension channel and a plurality of serum channels; the precise co-incubation of the sperm suspension and the serum is realized; according to the invention, sperms are used as a natural high-sensitivity living body biosensor, pathological changes of a body fluid microenvironment are reflected by detecting sperm motility changes, and the problems of low specificity, high cost, complex operation and difficulty in early screening in the existing diagnosis technology are solved; the chip is high in diagnosis accuracy, high in specificity, simple and convenient to operate and low in cost, can be widely applied to early screening and risk prediction of various high-risk diseases such as malignant tumors, cardiovascular and cerebrovascular diseases and metabolic diseases, and has extremely high clinical popularization value and social significance.

This invention discloses a method for detecting adiponectin in human serum using a polydopamine-modified wire mesh carbon electrode, specifically relating to the field of adiponectin detection technology. The method involves preparing a 2 mg / mL dopamine hydrochloride solution using a 10 mM tris(hydroxymethyl)aminomethane hydrochloride buffer solution (pH=8.5) and adding it dropwise onto the surface of the working electrode. A polydopamine-modified layer is formed by electropolymerization within a range of -800 mV to 600 mV using cyclic voltammetry. A conductive layer of a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex is then coated. Adiponectin antibodies are then immobilized on the surface of the modified layer via covalent binding of amino and quinone groups. After specific binding with a serum sample, the oxidation peak current change is read out from -100 mV to 350 mV in a buffer detection medium containing 5 mM ferricyanide redox pairs, and the concentration is output from a standard curve. This method improves the density of antibody immobilization sites and inhibits non-specific serum adsorption, enhancing signal stability and sensitivity, and enabling rapid, low-cost quantitative detection of trace amounts of serum.

The application describes a method for detecting the content of multiple vitamins in blood, the multiple vitamins being vitamin A, vitamin D2, vitamin D3 and vitamin E, the detection method comprising: respectively providing a to-be-detected serum sample and a standard sample; adding an internal standard solution to the to-be-detected serum sample and the standard sample; adding a first precipitant, and mixing, wherein the first precipitant is a zinc sulfate solution with a concentration of 7.8 g / mL to 10 g / mL; adding a second precipitant, and mixing, wherein the second precipitant comprises acetonitrile and methanol; adding an extraction agent, and extracting; adding a re-dissolving solution, and re-dissolving; detecting the to-be-detected solution and the standard solution by using liquid chromatography tandem mass spectrometry; obtaining a standard curve according to the detection result of the standard solution, and obtaining the content of the multiple vitamins in the to-be-detected serum sample according to the detection result of the to-be-detected solution. According to the application, a method for detecting the content of multiple vitamins in blood with high accuracy can be provided.

The application discloses a kind of methods for constructing electrochemical immunosensor for detecting apolipoprotein A4, comprising: (1) nitrogen-doped graphene and polyethyleneimine are fully stirred in solvent Composite, then add bipyridine functionalized covalent organic framework material and fully stir Composite, obtain NG-PEI-COF composite material;With bipyridine functionalized covalent organic framework material as carrier, gold nanoparticles, apolipoprotein A4 antibody and toluidine blue are loaded in sequence, to obtain tracer probe;(2) on electrode NG-PEI-COF composite material, gold nanoparticles, apolipoprotein A4 and tracer probe are modified in sequence, to obtain the electrochemical immunosensor of the application.The electrochemical immunosensor constructed by the method shows excellent detection performance for apolipoprotein A4, the marker of depression, good reproducibility and stability, and shows good anti-interference performance for a variety of other markers of depression, can be accurately determined in 0.01~300 ng / mL linear range, detection limit is as low as 2.16 pg / mL, and can be applied to serum sample.

This invention provides a method for detecting free fatty acids in human serum. The method comprises: adding multiple fatty acid standards and a condensing agent to a solvent to obtain a fatty acid solution with activated carboxyl groups; adding an isotopic compound to the fatty acid solution, where the carboxyl groups of the fatty acids undergo a condensation reaction with the amino groups of the isotopic compound to obtain a derivatized isotopic internal standard solution; adding the condensing agent and a non-isotopic compound of the same type as the isotopic compound to a serum sample, where the carboxyl groups of the fatty acids in the serum sample undergo a condensation reaction with the amino groups of the non-isotopic compound to obtain a reacted solution; adding the isotopic internal standard solution and sending the sample to a mass spectrometer for detection to obtain the fatty acid content in the serum sample. This invention has the advantages of low detection difficulty and high accuracy.

This invention provides a method for detecting AAV antibody titers, belonging to the field of biomedical technology, comprising: S1 preparing serum-free AAV vectors with different MOI values; preparing a mixture containing different volumes of test serum samples and AAV vectors with known MOI values ​​for co-incubation; S2: adding plasmids containing the CRISPR-Cas9 gene editing system to electroporation buffer, performing electroporation on a known number of cells, adding the serum-free AAV vectors and mixture from step S1 to the electroporated cells respectively, and detecting the expression efficiency of the reporter gene after electroporation; S3: calculating the AAV antibody titer in the test serum sample based on the detection results. The main advantage of this invention is that it can display AAV antibody titers digitally and quantitatively, facilitating understanding and communication, and obtaining stable and reliable results using different cell lines and different AAV transduction doses. This method is easy to standardize and validate, saving time, effort, and detection costs compared to traditional methods, and directly reflects antibody neutralizing activity.

This invention provides a supramolecular fluorescence sensing array and its application in detecting five tyrosine kinase inhibitors, belonging to the field of analytical chemistry detection technology. The supramolecular fluorescence sensing array is composed of three supramolecular fluorescent probes: 2NR@Q[8], 2AO@Q[8], and APFG@Q[8]. This invention uses a supramolecular fluorescence sensing array composed of three supramolecular fluorescent probes: 2NR@Q[8], 2AO@Q[8], and APFG@Q[8]. By utilizing the cross-fluorescence response signals generated by this supramolecular fluorescence sensing array for five TKIs, combined with classical pattern recognition algorithms, it is possible to perform qualitative and quantitative detection of five TKIs: GEF, EH, LD, AD, and DAC. Moreover, this supramolecular fluorescence sensing array has good anti-interference properties, and serum samples have demonstrated that the supramolecular fluorescence sensing array constructed in this invention can simultaneously analyze five TKIs in complex systems. Therefore, this invention provides a new method for detecting tyrosine kinase inhibitors, which is more intuitive and convenient than traditional detection techniques.

The application belongs to the technical field of electrochemical analysis methods, and particularly relates to an aptamer electrochemical sensor for detecting homocysteine and a preparation method thereof. The preparation method of the aptamer electrochemical sensor for detecting homocysteine provided by the application comprises the following steps: preparing a single-walled carbon nanohorn modified carbon ionic liquid paste electrode, electrodepositing nano silver particles, incubating aptamers, and sealing non-specific sites that are not occupied, so as to obtain MCH / Apt / AgNPs / SWCNHs / CILPE. In the detection of Hcy, a wide linear range (0.5 nM-100 nM) and a low detection limit (0.1 nM) are exhibited, and meanwhile, good reproducibility, stability and anti-interference ability are also possessed, and the aptamer electrochemical sensor has been successfully applied to the detection of Hcy in human serum samples.

The invention provides a preparation and detection method of a liquid gate graphene transistor for detecting a colorectal cancer marker piR-54265, and the method adopts a one-step method to fix a PolyA15T5-single-stranded DNA biomolecular probe on the surface of a gold gate of the liquid gate graphene transistor to realize detection of a colorectal cancer target molecule piR-54265. The fixed probe and a target piR-54265 in an electrolyte solution can be subjected to base complementary pairing hybridization, due to the fact that a phosphoric acid framework of the piR-54265 is negatively charged and graphene has the bipolar characteristic, when the probe and the target are hybridized, the potential on the surface of a grid electrode changes, and by fixing the voltage of a drain electrode and the voltage of the grid electrode relative to a source electrode, the target piR-54265 can be obtained. The channel current can change in real time along with the change of the concentration of the added piR-54265, real-time detection without marks and amplification is realized, the lowest detection limit reaches 18.072 aM, the fastest detection time can reach 15 minutes, and the sensitivity is very high. Clinical sample detection is realized, clinical serum samples of colorectal cancer patients and healthy people can be effectively distinguished, and clinical application value is achieved.

The invention discloses an electrochemical biosensor based on a TdT-Cas12a reaction system and a HaeIII enzyme and an Alzheimer's biomarker detection method.The electrochemical biosensor comprises a TdT reaction system and a Cas12a reaction system, the TdT reaction system comprises a TdT enzyme, a TdT buffer solution, deoxyadenine triphosphate (dATP) and a marker nucleic acid conversion product, and a TdT extension product is obtained through reaction; the Cas12a reaction system comprises a reaction buffer solution, Cas12a protein, crRNA and a TdT extension product, and a Cas12a system product is obtained after incubation; the construction method of the electrochemical biosensor comprises the following steps: combining a biological probe P on the surface of a gold electrode to finish electrode surface modification; and adding a Cas12a system product to the surface of the gold electrode, and continuing incubation. The electrochemical biosensor has excellent sensitivity and specificity, can significantly improve the detection sensitivity of AD related proteins in NDE, can be used for analysis of human serum samples, and is high in recovery rate.