183results about How to "Achieving Sensitive Detection" patented technology

The invention discloses a method for preparing an electrochemical luminescence paper chip and a method for measuring content of signal molecule hydrogen sulfide in MCF-7 by using an electrochemical luminescence sensor. The method is characterized by preparing a hydrophobic region, a semi-hydrophobic region, a hydrophilic region and a hollow channel on paper by utilizing a wax printing technology, cutting the hollow channel by virtue of a laser cutting machine, preparing proper printing ink, printing a corresponding reference electrode and a working electrode on the paper, functionalizing the working area, dripping stock solution in a pretreatment region, and fixing cancer cells; and folding the prepared paper chip, forming a three-electrode system, dropwise adding electrolyte solution in a reaction region, connecting an electrochemical workstation, thus realizing high-sensitivity detection of the low-content signal molecules in the cancer cells.

The invention relates to a method for detecting trace ochratoxin A by adopting an electrochemical aptamer sensor, and belongs to the technical field of electrochemical sensors. The method comprises the following steps: firstly, the DNA modification is performed on a gold electrode; then an aptamer is assembled through the complementary base pairing effect so as to capture labeled DNA of gold nanoparticles; the DNA rich in G is assembled on the surfaces of the gold nanoparticles so as to capture a great quantity of methylene blue (MB) to build a signal amplification strategy; finally, a series of OTA standard solutions is detected by taking differential pulse voltammetry scanning as the detection means so as to obtain the response relation between the reductive peak current of MB and the concentration of OTA, and a standard curve is drawn. The invention aims to provide a preparation method of an aptamer sensor, which is simple in operation, high in sensitivity and strong in specificity and is used for sensitivity detection of trace OTA.

The invention relates to a magnetic graphene enzyme-mimicking property-based acetylcholine visual-detection method, belonging to the technical field of biosensing. A hydrothermal method is used for synthesizing Fe3O4 / rGO by one step, H2O2 (hydrogen peroxide) is catalyzed to oxidize a substrate TMB (tetramethylabenzidine) to generate blue by utilizing the peroxidase-like property of the Fe3O4 / rGO, and the characteristic absorption intensity of an oxidation product of the TMB at the wavelength of 652nm is detected to realize the detection of hydrogen peroxide; furthermore, the H2O2 can be catalyzed to oxidize and convert the colorless TMB into a corresponding blue product based on the Fe3O4 / rGO, and the blue product is combined with acetyl choline to decompose H2O2 in the presence of both acetylcholinesterase and choline oxidase, and a novel acetylcholine visual-sensing method is established. The invention aims to provide an acetylcholine colorimetric detection method, and according to the method, the operation is convenient and flexible, the detection cost is low, the sensitivity is high, and instruments and equipment are simple.

The invention aims at providing an electrochemical sensor for sensitively detecting heavy metal cadmium ions and a preparation method of the electrochemical sensor. The structure of the sensor is formed by an electrochemical workstation, an electrolytic cell and electrodes; the electrodes include a platinum wire counter electrode, a silver / silver chloride reference electrode and a working electrode, wherein the working electrode refers to a glassy carbon electrode adopting nitrogen-sulfur codoping and graphite porous carbon / Nafion / bismuth film modification. The electrochemical sensor can realize sensitive detection of trace heavy metal cadmium ions, the detection linear range is 4-80 micrograms / L, and the detection limit reaches 0.1 microgram / L. By combining with good properties of a bismuth film, a Nafion film and a nitrogen-sulfur codoped porous carbon material, the electrochemical sensor has the performances of high sensitivity, good selectivity, wide linear range, good reproducibility, good stability and the like and can be applied to detecting the heavy metal cadmium ions in an actual water sample.

The invention discloses a preparation of a CS / IL-GR modified bovine serum albumin molecular imprinting electrode. The preparation comprises the following steps of the preparation of a CS / IL-GR / GCE, and the preparation of MIPs / CS / IL-GR / GCE. The invention also discloses an application of the CS / IL-GR modified bovine serum albumin molecular imprinting electrode to the detection on BSA. The application is characterized in that a [Fe(CN)6]<3- / 4-> is adopted as an electrochemical probe, an electrochemical impedance (EIS) and a differential pulse voltammetry (DPV) are adopted to represent a property of the MIPs / CS / IL-GR / GCE, the imprinting electrode can express a good linear relation on the BSA within a 1.0*10<-10>-1.0*10<-4>g / L concentration range, the peak current change value deltaI can be calculated as follows: deltaI (muA)=27.42+2.21*log(CBSA)(g / L), R=0.996, and the detection limit can be up to 2.02*10<-11>g / L. The preparation method provided by the invention has the beneficial effects that an imprinting sensor can express the good selectivity, sensitivity and reproducibility based on a synergistic effect of an IL-GR compound and the interaction of a chitosan molecule and a protein molecule, and the preparation method is used for clinical analysis detection on a trace sample.

The invention relates to a method for detection of ochratoxin A (OTA) with ultralow concentration by a label-free aptamer sensor. The method comprises the following specific steps: using o-amino thiophenol functionalized graphene oxide (GO-SH) and chloroauric acid as starting materials and sodium citrate as a reducing agent to prepare gold nanoparticles modified functionalized reduction graphene oxide (Au-S-rGO) by a one pot method; loading mercapto modified single stranded DNA3 by using the Au-S-rGO as a vector to obtain DNA3-Au-S-rGO; then modifying mercapto modified single stranded DNA1 on a gold electrode surface, and modifying an aptamer (DNA2) to the electrode surface through complementary pairing of bases; and then reacting the sensor interface with OTA of different concentrations. The method for quantitative detection of OTA has the advantages of simple preparation process, high sensitivity, wide measuring range and low cost, and solves the problems of high cost, complex detection scheme, long detection time and low sensitivity in the prior art.

The invention relates to a preparation method for a Cr2O3 or NiO porous film material using WO3 as a base material and a method for manufacturing an air-sensitive sensor. A WO3-Cr2O3 or WO3-NiO sol material is prepared by using chemical pure tungstic acid H2WO4 and analytical pure Cr(NO3)3.9H2O or Ni(NO3)2.6H2O as raw materials, 2mol / L of citric acid as a complexing agent, 30 percent of hydrogen peroxide (H2O2) as a dispersing agent and urea as a pore-forming agent. A porous film type air-sensitive sensor manufactured by a sol-gel method has the characteristics of high selectivity, high sensitivity, short response-recovery time, high stability and the like. By the methods, the sensitivity of low-concentration specific gas can be detected; and the methods are particularly suitable for the fields of breath detection, food quality detection, environment detection and the like, have obvious research and application value, have the characteristics of low energy consumption, low cost, smallvolume and the like and are easy to operate.

The invention discloses a polarization-sensitive distributed perturbation sensing method and a polarization-sensitive distributed perturbation sensing system. The better embodiment of the polarization-sensitive distributed perturbation sensing system comprises a function generator (1), a pulse laser (2), a polarization controller (3), a circulator (4), a sensing optical fiber (5), a polarization beam splitter (6), a balanced amplification photoelectric converter (7), a data acquisition unit (8) and a data processing unit (9), wherein the intensity of two paths of optical signals of which the polarization directions are vertical mutually is subjected to substraction by the balanced amplification photoelectric converter so as to obtain the intensity difference reflecting the change of the polarization state of the two paths of optical signals; and data acquired by a data acquisition module is detailedly analyzed to realize the sensitive monitoring on optical perturbation signals. The method has the advantage of improving the detection sensitivity of the sensing system greatly.

The invention discloses a preparation method of a pyrene-containing conjugated polymer fluorescent sensing film, comprising the steps of tailoring a substrate, preparing lotion, preparing an activated substrate, preparing a pyrene-containing conjugated polymer, preparing a stock solution of the pyrene-containing conjugated polymer, and preparing the pyrene-containing conjugated polymer fluorescent sensing film. The fluorescent sensing film can be prepared by introducing a pyrene group into a conjugated fluorescent polymer main chain and coating the synthesized pyrene-containing conjugated polymer on the surface of the substrate; and the invention realizes the sensitive detection on solutions of nitryl aromatic explosives. The preparation method is simple and convenient for operation and has mild reaction condition. The prepared fluorescent sensing film has the advantages of favorable stability, long service life and high sensitivity, can be used for a sensor for detecting nitryl-containing aromatic compounds, or can be arranged on a detection instrument for detecting the nitryl-containing aromatic compounds by using the fluorescent principle. In addition, the fluorescent sensing films are subjected to nitryl aromatic chemical combination and are directly detected by using a fluorescent instrument.

The invention discloses a method for detecting the DNA glycosylase activity by alpha-hemolysin nanopores. According to the method, a partial complementary double-chain DNA is designed and is used as aDNA glycosylase hOGG1 substrate; then, the double-chain DNA is fixed on the surface of a streptomyces affinity magnetic bead; a double-chain DNA-magnetic bead compound is formed to be used as a probe. When the DNA glycosylase hOGG1 exists, damaged basic groups 8-methoxyguanine on the double-chain DNA substrate can be specially recognized; the damaged basic groups are cut away; the DNA framework is cut away. The alpha-hemolysin nanopores are used for detecting the output DNA; the frequency of the generated blocking signals has positive correlation to the activity of the hOGG1. Therefore the method is used for detecting the DNA glycosylase activity, and has the advantages of high sensitivity, high efficiency, labeling avoidance and amplification avoidance.

The invention belongs to the field of electrochemical luminescence detection, and particularly relates to an electrochemical luminescence aptamer sensor for detecting ractopamine, a preparation methodand an application method thereof. The electrochemical luminescence aptamer sensor provided by the invention is formed by loading an aptamer on the surface of a glassy carbon electrode modified by anano composite material HKUST-1 / PTC-PEI. According to the invention, the electrostatic interaction of PTC-PEI and HKUST-1 is fully utilized to jointly modify the surface of the glassy carbon electrode, so the flexibility and stability of electrochemical luminescence are obviously improved. The electrochemical luminescence aptamer sensor is obtained by loading the aptamer through the combination effect of the amido bond, so that the target molecule ractopamine can be specifically recognized, and the selectivity of ractopamine detection is improved.

The invention relates to a method for rapidly and sensitively detecting organophosphorus pesticide chlorpyrifos and belongs to the technical field of electrochemical detection. The method comprises the following steps: firstly, preparing a Cd0.5Zn0.5S-rGO nano composite in situ with graphite oxide, Cd(NO3)2 and Zn(NO3)2 as starting raw materials and H2S gas a sulfur source and a reducing agent; then, sequentially modifying Cd0.5Zn0.5S-rGO and acetylcholin esterase on the surface of a glassy carbon electrode by dispensing and physical absorption; and finally, constructing a photoelectrochemical sensing interface based on the good photoelectrochemical performance and the biocompatibility of the Cd0.5Zn0.5S-rGO and applying the photoelectrochemical sensing interface to rapid and sensitive detection of the organophosphorus pesticide. According to a photoelectrochemical and enzyme sensing coupling technology provided by the invention, the sensitive detection of the chlorpyrifos is realized successively; the method needs few samples, has short detection time and high sensitivity and is suitable for detection analysis of pesticide residues in agricultural products.

The invention discloses an organic fluorescent gel compound based on naphthalimide. The compound is alkyl chain carboxylic acid 4-hydroxyl-N-caproyl-1,8-naphthalimide with 4-hydroxy naphthalimide as a chromophore, and has a structural formula as below, and a molecular formula of [6-HO-C12H5NO2-(CH2)5-COOH]. The invention uses simple fatty acids to introduce the naphthalimide group with fluorescence property, and provides a novel simple gel system; at the same time, the gelator has response function to triethylamine, addition of triethylamine results in fluorescence quenching, and addition of a certain amount of acid generates fluorescence recovery, therefore the invention uses this property, to realize sensitive detection of tri ethylamine by the gel system.

The invention provides a preparation method of an electrochemical adapter sensor for detecting fumonisin B1 (FB1). The preparation method comprises the following steps of step one, preparation of an silk-printed carbon electrode (SPCE); step two, preparation of an activated FB1 aptamer solution; step three, preparation of an Au nanoparticles (AuNPs) modified SPCE; step four, preparation of an FB1 aptamer modified AuNPs-SPCE; step five, sealing of spare active sites on the surface of the electrode. According to the preparation method of the electrochemical adapter sensor for detecting the FB1, provided by the invention, the AuNPs are adopted for modifying the surface of the electrode, on one hand, the large amount of AuNPs are loaded on the surface of the electrode, so that a signal amplification function on label-free impedance method detection is obtained; on the other hand, more sulfhydrylated adapters are fixed to the surface of the electrode by utilizing Au-S bonds. An FB1 impedance detection method provided by the invention has the characteristics that the operation is more simple, convenient and flexible, instruments and equipment are simpler, the dosage of a reagent is less, the detection cost is low, and the like.

The invention relates to a selenocysteine near-infrared fluorescent probe, and a preparation method and application thereof, belonging to the field of chemical analysis and detection. The near-infrared fluorescent probe Fsec-3 for detecting selenocysteine provided by the invention has the advantages of good selectivity, high sensitivity, low detection limit (20 nM) and good biocompatibility. In aphosphate buffer, the fluorescence intensity and the concentration of selenocysteine (0-100[mu]M) are in a good linear relationship, which indicates that the probe Fsec-3 is suitable for quantitativedetection of selenocysteine. The probe Fsec-3 achieves fluorescence imaging of selenocysteine in the human breast cancer cell MCF-7; and the probe Fsec-3 also achieves sensitive detection of endogenous selenocysteine in a living body, and is fast in response and stable in fluorescence signals. Thus, the fluorescent probe Fsec-3 prepared by the invention is an effective tool for visual and quantitative detection of the content of selenocysteine in cells, living bodies and tumor tissue.

The invention provides a method for preparing a label-free portable aptamer sensor for detecting AFB1, and belongs to the field of electrochemical analysis. The method comprises the following steps: preparation of magnetic ferroferric oxide nanoparticles (Fe3O4); preparation of gold-coated ferroferric oxide core-shell magnetic nanoparticles (Fe3O4@Au); preparation of a nucleic acid aptamer-modified Fe3O4@Au nano-bioprobe; pretreatment of a screen printed electrode; construction of the label-free portable aptamer sensor; and detection of the AFB1 by electrochemical ac impedance spectroscopy. The method adopts the nucleic acid aptamer-modified magnetic core-shell material Fe3O4@Au to modify the surface of the screen printed electrode, the material is quickly modified on the surface of the electrode by the action of an external magnetic field, the operation is simple, and the use time is short; Au-S bonds can be used to fix more thiolated aptamers on the surface of the electrode more firmly, and the sensitivity of the sensor is effectively improved. The method has the advantages of simple preparation process, short time consumption, less reagent dosage and low detection cost and the like.

The invention discloses a photoelectric chemical analysis method for detection of 5-hydroxymethylcytosine based on black titanium dioxide. The method is characterized in that firstly, a photoelectricchemical biosensor for detecting 5hmC is constructed, including an electrode, black TiO2, probe DNA, the 5hmC, p-aminophenylboronic acid, PAMAM and amino-modified zinc oxide which are sequentially fixed on the surface of the electrode. The method is advantaged in that photoelectric properties of the black TiO2, the specific catalysis of glycosyltransferase for the 5-hydroxymethylcytosine, the amplification effect of a PAMAM signal and signal quenching of ZnO are utilized to achieve sensitivity detection of the 5-hydroxymethylcytosine. The method is advantaged in that operation is simple, miniaturization is facilitated, and detection of the 5-hydroxymethylcytosine can be realized through only modifying the surface of the ITO electrode.

The invention belongs to the technical field of immune analysis and biosensing detection, and particularly relates to a preparation method and an application of an electrochemical immunosensor based on Hemin-rGO (reduced graphene oxide). A Hemin-rGO (reduced graphene oxide) porous composite material separated by microporous carbon spheres loaded with silver nanoparticles is used as a detection antibody marker, and the constructed sandwich electrochemical immunosensor realizes detection of tumor marker carcinoembryonic antigens, has the advantages of high sensitivity, high specificity, low cost, low detection limit and the like, and has important scientific significance and application value for early diagnosis and disease monitoring of lung cancer.

The invention discloses a preparation method of boron-nitrogen-containing small molecules and conjugated macromolecules and application in fluorine ion sensing, and belongs to the technical field of preparation of fluorescent compounds and preparation of fluorescent probes. A boron ring compound is synthesized via BTE (boron-tin-exchange) reaction; the boron ring compound is subjected to ring-expanding reaction via azide molecules by utilizing Lewis acidity of high boron, and a series of boron-nitrogen-containing (BN-containing) small-molecular monomers are prepared; boron-nitrogen-containingconjugated macromolecules are successful prepared via Stille coupling. Both boron-nitrogen-containing small molecules and macromolecules are suitable for colorimetric selective recognition for fluorine ions. The preparation method of the boron-nitrogen-containing fluorescent compound is simple, and has mild reaction conditions; a prepared fluorescent probe has good opto-chemical stability, high sensitivity and good selectivity.

The invention discloses an organogel compound of 4-nitrophenylthiourea. The compound is 1-(2-(3,4,5-tri(dodecyl) benzamido)ethyl)-3-(4-nitrobenzene)thiourea taking (p-nitrophenyl)thiourea as a chromophore, the structural formula is as shown in the specification, and the molecular formula is respectively [4-NO2C6H4N2H2S-C2H4NHCOC6H2-(OC12H25)3]. The gel factor has the function of sensitively detecting fluorine ions and mercury ions, the color of the solution state of the gel factor is changed by adding the fluorine ions, and ring closing reaction is generated and the color of the solution state of the gel factor is changed again by adding the mercury ions; and the gel system has sensitive effects on the fluorine ions and mercury ions in a good state. By utilizing the property, the sensitive detection of the gel system on the fluorine ions and mercury ions can be realized.

The invention discloses a preparation method of a biosensor for detecting L-cysteine and an application of the biosensor in detecting yield of escherichia coli L-cysteine. Main components of the biosensor comprise a transcriptional control gene CcdR coding gene from pantoea ananatis, a promoter region and a terminator region of the transcriptional control gene CcdR coding gene, a promoter region of a gene ccdA from pantoea ananatis, a green fluorescent protein coding gene eGFP and a plasmid framework pTrc-Mob. The biosensor can have a good linear relation under the L-cysteine concentration of 0-32 mmol L<-1> and has the highest fluorescence intensity value and cysteine concentration relation under the L-cysteine concentration of 0.01-8 mmol L<-1>. Through combination with a high-throughput screening system, the biosensor performs real-time detection on the yield of escherichia coli L-cysteine, can screen out high-yield mutants of L-cysteine and mutants for key enzymes in biological synthesis of L-cysteine. Specific, quantitative and real-time detection of L-cysteine can be realized, and the sensitivity is high.

The invention discloses a method for preparing a cadmium sulfide-coated zinc oxide nano array composite material and a method for detecting multiple tumor cells and relates to a method for preparing the cadmium sulfide-coated zinc oxide nano array composite material and a method of the composite material. Preparation of a nano array material is realized according to chemical deposition, modification and assembly of a nanometer material are realized through the electrostatic interaction, and finally, the synthesized nano array material is applied to preparing a cancer cell biosensor. Moreover, the hepatoma cells are sensitively detected, and the method has the advantages of simplicity in operation, high reaction speed, good effect, high selectivity, low cost and the like. The method also can realize detection of multiple tumor cells by changing the types of the modified antibodies, can be used in aspects such as scientific research and clinical medicine and particularly has wide application prospects in the field of biological analysis and in the aspects such as tumor cell detection.

The invention provides a preparation method and application of an electrode for detecting a transgenic CaMV35S promoter. The method includes the steps of: preparation of a reduced graphene oxide / gold nanocomposite RGO / Au; preparation of a silicon @ cadmium telluride nanocomposite Si@CdTe; preparation of a probe 1 (Probe 1) on an ITO electrode; modification of a target DNA (t-DNA) CaMV 35S promoter onto the probe 1 (Probe 1); and modification of a probe 2 (Probe2) onto the target DNA (t-DNA) CaMV 35S promoter. Through dual signal amplification at both ends of rGO / Au NPs and Si@CdTe, the sensitive detection of the transgenic CaMV35S promoter is realized; and in the concentration range of 0.05-100 pM, the concentration of CaMV35S and photocurrent present good linear relationship, and the detection limit can reach 0.017 pM.

The invention relates to a nano gold array surface-enhanced Raman chip, a preparation method thereof and application of the Raman chip and belongs to the field of rapid detection of pesticide residues. According to the preparation method of the chip, a nano gold array is formed by means of the assembling of the interface of nano gold; the array is transferred to the surface of a flexible filteringmembrane, the flexible filtering membrane with the array is dried and cut into a structure of a suitable size, so that the surface-enhanced Raman chip can be obtained; a solvent is added to the surface of a fruit or vegetable to be tested, so that pesticide residues are extracted into the solvent; and the chip is attached to the surface of the fruit or vegetable and is made to wipe the solvent, so that pesticide residue molecules are transferred to the surface of the chip through coordination, and then a Raman spectrometer is used to quantitatively measure the pesticide residue molecules on the chip. The chip of the invention has high surface strengthening capacity; the surface extraction method and coordination transfer method are adopted, and therefore, the introduction of the interference of the complicated matrixes of the fruit or vegetable to be tested can be effectively avoided, operation is simple and convenient, and the surface extraction method and coordination transfer method can be conveniently used for transferring the pesticide residues on the surface of the fruit or vegetable; and the chip and the portable Raman spectrometer can be used jointly to achieve the quantitative detection of the pesticide residues on the fruit or vegetable.

The invention relates to a photo-electrochemical sensor based on NSCQDs / Bi2S3 and preparation and application thereof. A Bi2S3 nanorod serves as a photoactive material, NSCQDs synthesized through a hydrothermal method is subjected to electrostatic adsorption through PDDA; then carboxy on the surface of the NSCQDs is activated through EDC and NHS, and through an amidation reaction, Ab is modified on the electrode surface; and in the presence of AFP, through antigen-antibody recognition, and an Ab-AFP immune complex is formed on the electrode surface, so that steric hindrance on the electrode surface is increased, transmission of electronic sacrificial agent ascorbic acid (AA) to the electrode surface is hindered, and consequently, photoelectric current signals of the sensor are changed. According to the relation between the AFP concentration and the sensor photoelectric current, the AFP concentration is detected; the photo-electrochemical sensor has good selectivity, repeatability and stability; detection operation on ATP is easy, the cost is low, high efficiency and high sensitivity are achieved, and the photo-electrochemical sensor has the low detection limit and the wide detection range and is of important significance to clinical and biological analysis of proteins.

The invention relates to a preparation method and application of a photoelectrochemical aflatoxin B1 sensor based on a tungsten trioxide composite material, and belongs to the field of photoelectrochemical sensors. The preparation method comprises the following steps: synthesizing a rectangular WO3 nanoflake on a fluorine doped tin oxide FTO substrate by using a wet chemical method; then closely combining TiO2 nano-thorn with a unique structure on the WO3 nanoflake by using a chemical bath deposition method; carrying out double matching between an energy band structure and a lattice structureof WO3 and TiO2 to enhance the photoelectric response and stability of the WO3; then combining with upper p-type narrow bandgap semiconductor Ag2O nanoparticles by using an in situ growth method, thusobtaining the tungsten trioxide composite material WO3 / TiO2 / Ag2O composite material with remarkably improved photoelectric activity. The material shows excellent visible light activity in the presence of glutathione. An aflatoxin B1 antibody, bovine serum albumin and an aflatoxin B1 antigen are assembled into the WO3 / TiO2 / Ag2O composite material by using a layer-by-layer self-assembly method; ultra-sensitive detection of the aflatoxin B1 is realized by utilizing specific combination of excellent photoelectric activity of WO3 / TiO2 / Ag2O with an aflatoxin B1 antigen antibody, which is of great significance for analysis and detection of the aflatoxin B1.

The invention belongs to the technical field of immunoassay and biological sensing technologies and provides a preparation method and application of an interlayer type lung cancer marker electrochemical transducer. Graphene-loaded Cu2+ doped by functional nitrogen of dual-metal nanometer material Au@Pt of a core-shell structure is utilized as a catalytic material and serves as a marker after beinghatched with detected antibodies, and meanwhile nanometer gold particles functionalized by polydopamine are adopted as electrode modification materials, so that detection of lung cancer marks such asCEA, CA125 and SCCA is achieved. The interlayer type lung cancer marker electrochemical transducer has high sensitivity and specificity, low detection limitations and a significant scientific meaningand a high application value on early detection of lung cancer.

The invention provides a fluorescent biosensor for detecting Hg<2+>. The fluorescent biosensor comprises a composite probe Q, an annular template CP, a trigger chain T, a fuel chain F, a Klenow fragment and thioflavin T; and the trigger chain T, the composite probe Q, the fuel chain F, the annular template CP and the Klenow fragment are uniformly mixed with a mercury ion solution with a series ofconcentrations and a to-be-detected solution respectively, incubating is performed, enzyme is inactivated, the sulfur element T is added, incubating is performed, and the fluorescence intensity is detected. Target cyclic amplification and signal amplification are realized on the basis of the specific binding capacity between basic groups T and Hg<2+> and entropy-driven strand displacement amplification and rolling circle amplification reactions, and the biosensor for sensitive detection of a target object is realized. The sensor has the advantages of high detection speed, low detection limit,high sensitivity and the like, can make up the defects and deficiencies of the existing detection method of Hg<2+>, and realizes rapid and accurate quantitative detection of Hg<2+>.

The invention discloses a microRNA detection method based on Hg<2+> assistance and a double-polymerase isothermal nucleic acid amplification technology, and belongs to the technical field of optical bio-sensing. On the basis of a combined catalytic action of a polymerase Klenow fragment and terminal deoxynucleotidyl transferase, microRNA is effectively extended into a polythymine base sequence which is relatively long; Hg<2+> is added, so that a T-Hg<2+>-T double-stranded structure is formed; an SYBR Green I fluorescent dye is interpolated into the T-Hg<2+>-T double-stranded structure, so that the fluorescence of the SYBR Green I is enhanced; and a fluorescence enhancing degree is positively related to the concentration of the microRNA; therefore, the sensitive detection of the microRNA is achieved.

The invention discloses a tungsten sulfide-black titanium dioxide heterojunction-based method for detecting 5fC via photoelectrochemical analysis. According to the method, a photoelectrochemical biosensor for detecting the 5fC is firstly constructed; and the photoelectrochemical biosensor comprises an electrode, and a thin-layer tungsten sulfide nanosheet, AuNPs, 4-amino-3-hydrazino-5-sulfydryl-1,2,4-triazole, 5fC and black titanium dioxide, which are modified on the surface of the electrode in sequence. According to the method, the good photoelectric activity of WS2, the effect of the AuNPs on accelerating the electron transfer, and the specific covalent reaction of a diamine group on 4-amino-3-hydrazino-5-sulfydryl-1,2,4-triazole and an aldehyde group on the 5fC are utilized, and the black titanium dioxide is used as a signal amplification molecule, so that the sensitive detection for 5-formylcytosine is realized. The detection method provided by the invention is high in operation stability, strong in sensitivity, low in detection limit and convenient to realize miniaturization, and is capable of realizing the rapid and sensitive detection for the 5fC through only modifying the surface of the ITO electrode.