174results about How to "Achieving Specific Detection" patented technology

The invention relates to a preparation method and application of an environmental estrogen electrochemical immunosensor, belonging to the technical field of electrochemical detection. The sensitivity of the sensor is obviously improved by adopting the characteristics that the conductivity of chitosan dispersed graphene is high, the stability is high, the specific surface area of a gold hybrid mesoporous silicon dioxide nano composite material is large, the biocompatibility is good, the catalytic efficiency is high and the like. The immunosensor is constructed by adopting the method of layer-by-layer self-assembly of the chitosan dispersed graphene, cross-linking agent, composite solution of nano materials and antibodies, and bovine serum albumin. In combination with specificities of antigens and antibodies, by virtue of an electrochemical workstation instrument, by recording current change before and after corresponding antigens modify the sensor, the environmental estrogens in water and food can be directly detected. The environmental estrogen electrochemical immunosensor prepared by adopting the preparation method has the advantages that the sensitivity is high, the specificity is good, the operation is easy to conduct and the detection limit is low, and the sensitive, rapid and accurate detection of various environmental estrogens in actual samples can be realized.

The invention discloses a device and a method for detecting glucose based on optical fiber surface plasma resonance. The device comprises a light source, a polarizer, a polarization controller, a sensor probe, a filter and a photoelectric detector which are connected with each other in turn through an optical fiber, wherein the sensor probe comprises the optical fiber engraved with inclined fiber bragg gratings; a metal film in nanometer-level thickness is plated on the outer surface of the covering of the optical fiber; the light emitted from the light source passes through the polarizer and the polarization controller and then enters into the optical fiber engraved with the inclined fiber bragg gratings on the sensor probe; a covering film generated in the optical fiber is coupled with the metal film on the outer surface of the covering of the optical fiber; the surface plasma resonance is stimulated; the light containing the plasma resonance output by the optical fiber is sent into the photoelectric detector by the sensor probe through the filter. According to the invention, glucose oxidase is added into a to-be-measured serum solution, so that a hydrogen peroxide corroded metal film is formed, and the glucose concentration in the serum solution is acquired according to a response rate of the light intensity which changes along with the time and is detected and acquired by the photoelectric detector.

The invention discloses a detection method of target molecules, which is based on manometer gold and a nucleic acid structure and comprises the sequential steps: (1), hybridizing specific DNA (Deoxyribonucleic Acid) with cDNA (Complementary Deoxyribonucleic Acid) in fluorescence labeling to form a double-stranded capture probe, wherein the specific DNA can be in specificity combination with the target molecules; (2), adding a solution to be detected for reaction; (3), adding a manometer gold solution for reaction and recording a fluorescence spectrum of the reaction solution. The detection method of the invention has commonality and wide range of application so that detection objects can be any target molecule. The invention can be utilized to conveniently realize the rapid, sensitive and selective detection of the target molecules.

The invention discloses a method and a kit for adopting a colloidal gold chromatographic technique for detecting mycoplasma pneumoniae nucleic acid and belongs to the technical field of medical biochemistry. According to the method, a colloidal gold grain is directly marked on a nucleic acid probe; the sequence for the marked nucleic acid probe is designed as a universal sequence; the nucleic acid probe also can be used for detecting other pathogens. During the design process for the kit provided by the invention, the introduced special probe A and special probe B have the functions of bridge molecular components and a gold marked probe and an MP (Mycoplasma Pneumoniae) nucleic acid amplified fragment are successively combined with each other in series by the two probes, so that the special detection for the MP nucleic acid fragment is realized. More than two probes can be designed in each set of probes; such a design is beneficial to the increasing of the sensitivity of the test strip; the advantages of the amplification technique for the depending nucleic acid sequence of MP and the colloidal gold marked detection for the products after amplification are integrated; the technical demand on the experimenter is low; no special instrument is required; the popularization of the MP nucleic acid detection in basic and faraway rural medical institutions is easily realized.

The invention discloses a SERS sensor of a sandwich structure for detecting tyrosinase, and a preparation and detection method thereof. The SERS sensor utilizes the specific recognition principle of the tyrosinase antigen antibody, and a solid phase antibody-to-be-detected antigen-labelled antibody sandwich structure is formed through the combination of the solid-phase antibody on a substrate andthe labelled antibody with the antigen through the adsorption of the magnetic substrate and the enhancement effect of the surface-enhanced Raman probe, the content of the tyrosinase is analyzed by recognizing a labelled molecular SERS signal, and then a surface-enhanced Raman analysis method for detecting the tyrosinase is established. The detection method disclosed by the invention has the advantages of being quick, sensitive, simple and less in sample consumption. Furthermore, the sensor for detecting the tyrosinase has good linearity, the detection limit is low, and can reach 1ng / mL. And meanwhile, the adding standard recovery rate of the tyrosinase in the human serum sample is in the range of 96.0%-136.0%. Therefore, the SERS sensor is expected to be an effective method for clinicallydetecting tyrosinase.

The invention discloses a molecularly-imprinted electrochemical sensor for detecting sunset yellow. According to the imprinted electrochemical sensor, through the electrode surface modification technology, the surface of a glassy carbon electrode is covered with prepared oxidized graphene / magnetic carbon dots / gold nano particle compounds, and then the purposes of enhancing electric signals and improving the detection sensitivity of the sensor are achieved. By means of an electric polymerization mode, molecularly-imprinted polymers with pyrrole serving as a functional monomer and sunset yellow serving as template molecules are modified to the surface of the electrode, after elution of the template molecules, holes are formed in the surface of the sensor, and the holes and the structure of sunset yellow can achieve specificity matching. The successfully-prepared electrochemical sensor is a working electrode, through specific binding of the template molecules on the surface of the electrode and the holes, the current change is generated, and specificity detection of sunset yellow can be achieved through the current change. The prepared molecularly-imprinted electrochemical sensor is high in selectivity, high in sensitivity, easy and quick to operate and suitable for detection of sunset yellow in food.

The invention relates to a preparing method and a detecting method of a liquid grid type grapheme field-effect tube based on polyimide (PI). The methods are characterized in that an aluminum layer is deposited on a silicon substrate to be used as a sacrificial layer, PI photoresist is coated on the aluminum layer in a spin mode to be used as a substrate of a flexible field-effect tube, a commercialized grapheme / polymethyl methacrylate thin film is transferred to a titanium / gold electrode which is deposited on the PI substrate in advance to form good ohmic contact, AZ 4620 photoresist is used as a mask layer for grapheme patterning, grapheme is etched through oxygen plasma, and an insulating layer is manufactured on the surface of the patterned grapheme through the PI photoresist to form a liquid grid type structure. The field-effect tube is in the liquid grid type structure, so that machining steps can be reduced, further surface decoration on the surface of the grapheme is convenient, and accordingly specific detection on various biological signals is achieved.

The invention discloses a fluorescent probe having aggregation-induced luminescent property and a preparation method and application of the fluorescent probe. The fluorescent probe is formed by connection of polypeptide capable of specifically recognizing SIRT1 protein and aggregation-induced luminescent molecules, wherein the amino acid sequence of the polypeptide is glycine-acetylated lysine-tyrosine-aspartic acid-aspartic acid, and the aggregation-induced luminescent molecules are connected with the glycine of the polypeptide; as the polypeptide contains the acetylated lysine at the specific position, the polypeptide in the fluorescent probe can be recognized specifically by SIRT1 protein, the SIRT1 protein can perform deacetylation modification on the polypeptide; the fluorescent probe has no fluorescence absorption basically, but when the fluorescent probe loses the acetyl on the lysine, the fluorescent probe has remarkable fluorescence absorption; and furthermore, when the polypeptide is cut off at the position of the lysine by incision enzyme, the fluorescence absorption strength of the fluorescent probe is further enhanced and the activity of the SIRT1 protein can be detected specifically in real time.

The invention relates to a target molecule detection method based on nanometer-gold and nucleic acid structure and a kit thereof. The target molecule detection method comprises the following steps of: (1) reacting specific DNA which can be specifically combined with the target molecules with a solution to be detected; (2) mixing the reaction solution obtained in the step (1) with a nanometer-gold solution for reaction; and (3) observing the fluorescence spectrum of the reaction solution finished in the step (2). The detection method has generality, the detected object can be an arbitrary target molecule, and the application range is wide. By utilizing the invention, the target molecules can be fast, sensitively and selectively detected.

The invention discloses a colorimetric detection method based on a nanometer-gold and nucleic acid structure and a kit thereof. The colorimetric detection method comprises the following steps of: (1) mixing specific DNA which can be specifically combined with the target molecules with a solution to be detected for reaction; (2) mixing the reaction solution which is obtained in the step (1) with a nanometer-gold solution of which the number of moles is 0.01 to 1 time that of the specific DNA for reaction; and (3) adding a high-salt solution with the reaction concentration between 10 and 600 mM, and observing color change of the solution. In the operation process of the invention, DNA is not needed to be marked, expensive equipment is not needed need, and the existence of the target molecules can be determined only by observing the color change of the nanometer-gold solution. Therefore, the invention is simple, convenient and fast, has low cost, high specificity and high sensitive detection of any target molecules, is especially suitable for open-air analysis and high-throughput screening, and has wide application range.

The invention discloses a mercuric ion or cysteine detecting electrochemical DNA biosensor and a manufacturing method and application thereof.The electrochemical DNA biosensor comprises a glassy carbon electrode serving as a working electrode of a three-electrode system; the surface of a reactive end of the glassy carbon electrode is modified by composite membrane composed of auto-doped polyaniline nanofiber, ordered mesoporous carbon and nano-scale gold particles; a DNA capture probe, with the nucleotide sequence SEQ ID NO.1 is assembled on the surface of the composite membrane.The manufacturing method includes steps of modifying auto-doped polyaniline nanofiber and ordered mesoporous carbon, electrodepositing nano-scale gold particles, assembling the DNA capture probe and the like.The mercuric ion or cysteine detecting electrochemical DNA biosensor capable of detecting two different target substances has the advantages of high stability, long service life, high interference resistance capacity, wide detection scope and low limit in detection and is applied to detection of mercuric ion or cysteine.

The invention relates to a preparation method and application of a pancreatic cancer immunosensor based on gold electrodeposition and Au@Ag / CuO-GS as markers, and particularly relates to preparation of a sandwich-type electrochemical immunosensor for detecting pancreatic cancer tumor markers by adopting Au@Ag / CuO-GS as a detection antibody marker. By using excellent biocompatibility and high catalytic performance of the Au@Ag / CuO-GS, the prepared sensor has relatively high sensitivity and relatively wide detection range; and the detection limit can reach 1.5fg / mL.

The invention relates to a preparation method and an application of a gynecological tumor marker immune sensor constructed with ordered mesoporous carbon. The invention belongs to the technical field of novel nano-grade functional material and biosensor. The preparation method is characterized by: (1) the preparation of an ordered mesoporous carbon nano-grade material; (2) the preparation of an ordered mesoporous carbon-toluidin blue composite material; and (3) the preparation of the gynecological tumor marker immune sensor. The gynecological tumor marker immune sensor provided by the invention has the advantages of fast identification, high sensitivity, low detection limit, low cost, and convenient operation. With the gynecological tumor marker immune sensor, high-sensitivity, specific, rapid, and accurate detections of various gynecological tumor markers can be realized. Sample determination can be finished in 3min, such that batched sample determination can be realized within a short period of time.

The invention discloses a preparing method and application of a sandwich type electrochemical luminescence immunosensor for detecting a tumor marker. The method comprises the steps of synthesizing magnetic oxidized graphene, wherein a coupling reagent and a tumor marker primary antibody are immobilized onto the surface of magnetic graphite oxide in sequence to obtain the functional oxidized graphene; preparing functional carbon nitride, wherein gold nanoparticles and a tumor marker secondary antibody are immobilized onto the surface of a carbon nitride film in sequence to obtain the functional carbon nitride; finally adsorbing the functional oxidized graphene, the tumor marker to be detected and the functional carbon nitride onto the surface of a magnetic glassy carbon electrode in sequence. The obtained sandwich type electrochemical luminescence immunosensor serves as a working electrode, a platinum electrode is taken as a counter electrode and an Ag / AgCl electrode or saturated calomel electrode is taken as a reference electrode to calculate the accurate concentration of the tumor marker in a sample solution to be detected. Detection speed is high, the sensitivity and accuracy of detection results are high, and specificity is high.

The invention discloses a photoelectrochemical adaptor sensor as well as a preparation method and application thereof. The photoelectrochemical adaptor sensor comprises a conductive glass electrode, wherein the reacting end surface of the conductive glass electrode is modified with a composite membrane consisting of phosphorus hybridization graphite phase carbon nitride nanosheets loading gold nanoparticles; and a specific adaptor probe is self-assembled on the surface of the membrane. The preparation method of the photoelectrochemical adaptor sensor comprises the following step: modifying thephosphorus hybridization graphite phase carbon nitride nanosheets loading the gold nanoparticles and the specific adaptor probe on the reacting end surface of the conductive glass electrode. The sensor disclosed by the invention has the advantages of high stability, long service life, high anti-jamming capability, wide detection range, low detection limit and the like. The preparation method of the photoelectrochemical adaptor sensor has the advantages of simple technology, convenient operation, safety, low cost, no pollution, high production efficiency and the like. The sensor disclosed by the invention can be widely applied to detecting pollutants (such as antibiotics) in mediums such as a water body and a living body and has the advantages of high utilization rate, wide application range, high application value and the like.

The invention discloses a water channel urine protein optical label-free specific detection device and method. The device includes optical fiber engraved with tilted fiber grating, a sulfhydryl compound and an AQP2 antibody; the side and the end face of the optical fiber are respectively plated with a layer of metal film with different thicknesses to form an optical fiber sensing probe; the sulfhydryl compound self-assembles into a monomolecular film on the metal film of the optical fiber side, and the AQP2 antibody is fixed on the monomolecular film surface through a catalyst; after fixation of the AQP2 antibody, the optical fiber sensing probe is immersed into a urine stock solution containing AQP2 antigen, and polarized light is input into optical fiber, the characteristic that the metal film surface plasma resonance wave of the optical fiber side is sensitive to the external environment change is utilized to detect the specific binding of AQP2 antigen and AQP2 antibody. The device and the method provided by the invention can realize specific detection of water channel urine protein, replace wavelength demodulation technique with amplitude modulation technique, the detection process is free of label to a detection sample, and also has the advantages of simplicity and speediness, etc.

The invention discloses a construction method for a double-component light-induced electrochemical immunosensor based on a dendritic titanium dioxide nano-rod-strontium titanate (B-TiO2 NRs-SrTiO3) hetero-junction, and through the method, detecting alpha-fetoprotein and carbohydrate antigen 153 simultaneously an be achieved. The B-TiO2 NRs-SrTiO3 hetero-junction is synthesized by utilizing a hydrothermal method, so that carrier separation and hole transportation are promoted, and the photocurrent density produced by the B-TiO2 NRs-SrTiO3 is remarkably increased by compared with that produced by B-TiO2 NRs. On the basis of the B-TiO2 NRs-SrTiO3 hetero-junction, beta-galactosidase and acetylcholin esterase are taken as a signal marker for specifically catalyzing hydrolysis of p-aminobenzypylgalactoside and acetylcholine to produce p-aminophenol and choline in situ to serve as sacrificial electron donors respectively for distinguishing photocurrent signals. Because of proper signal difference, the sensor can realize high-sensitivity detection of the alpha-fetoprotein and the carbohydrate antigen 153.

The invention belongs to the technical field of sensors, and relates to a preparation method and application of a ratio type fluorescent probe. The preparation method comprises the following steps: dissolving fluorescein, zinc acetate and terephthalic acid in DMF (Dimethyl Formamide), carrying out ultrasonic treatment and heating, and after a reactant is cooled, conducting washing and drying to obtain an FSS-coated MOF-5 fluorescent material; and dissolving the FSS-coated MOF-5 fluorescent material in water, adding guanosine monophosphate and europium nitrate under a stirring condition, and conducting washing, centrifuging and drying to obtain the FSS-coated MOF-5-coated GMP / Eu fluorescent probe. The ratio type fluorescent probe prepared by the invention can realize specific detection of tetracycline antibiotics, does not need specific biological materials such as antigens, antibodies or aptamers and the like, and can reduce the time and cost for preparing a specific fluorescent sensor; meanwhile, various color changes can be generated under an ultraviolet lamp, so that semi-quantitative visual detection of tetracycline is realized; and the detection is rapid and accurate, the operation is simple, the probe is not easily influenced by the environment, and the quality and safety of food are guaranteed.

The invention discloses a method and a special kit for detecting a bean pod mottle virus. The kit comprises colloidal gold chromatography test paper, a colloidal gold-marking antibody and a specific primer for amplifying a substance to be tested. In the invention, the high sensitivity of nucleic acid amplification and the advantages of the rapidness, the simplicity and the convenience and the visibility of the colloidal gold chromatography method are combined, the PCR (polymerase chain reaction) specific primer is modified, and then the antibody of a specific modifier is marked by colloidal gold to finally realize the specificity detection of an amplified target nucleic acid fragment. The method has wide practicability. Proved by an experimental result, the method has accurate and reliable detection result. The method saves time and labor and has simple operation.

The invention belongs to the technical field of preparation of detection materials, and relates to a preparation method of a magnetic ferroferric oxide nanosphere-based novel pH-responsive imprinted material. The preparation method comprises the following steps: firstly preparing ferroferric oxide nanoparticles and synthesizing mesoporous silicon dioxide coated ferroferric oxide nanospheres, and then performing chemical double bond modification on the mesoporous silicon dioxide coated ferroferric oxide nanospheres; finally, preparing the magnetic nanosphere-based pH-responsive imprinted material. The pH-responsive imprinted material prepared according to the preparation method provided by the invention can solve the problem that the surface of a base material is difficult to be directly coated with a molecularly imprinted polymer layer; the imprinted material adopts a significant core-shell structure consistent with the purpose of the invention; in addition, through combination of theperformance of the molecularly imprinted material and a pH-responsive intelligent material, the pH-responsive imprinted material is successfully applied to efficient detection of sulfamethoxazole.

The invention discloses a sandwich type electrochemistry immunosensor which is prepared based on a sodamide group smectite and a nanometer multi-hole gold membrane, and belongs to the technical field of function materials and biological sense. The sandwich type electrochemistry immunosensor provided by the invention can carry out amido functionalization on the sodium group smectite, an antibody and enzyme are conveniently fixed, and meanwhile, the favorable biological activities of the antibody and the enzyme are kept; a favorable three-dimensional serial perforated structure and biocompatibility of the nanometer multi-hole gold membrane are utilized, and the favorable catalytical property of the antibody is directly fixed, and the sensitivity of the sensor is notably improved; and the sodium group smectite which is cheap and is easily available is utilized, and the cost of the sensor is greatly reduced. The sandwich type electrochemistry immunosensor provided by the invention can realize high sensitiveness and specificity and rapid exact detection of multiple tumor markers.

The invention discloses a nano electrochemical enzyme sensor for detecting trichloroacetic acid (TCA) or sodium nitrite (NaNO2) as well as a preparation method and application of the nano electrochemical enzyme sensor. A base electrode selected by the nano electrochemical enzyme sensor is a carbon ionic liquid electrode (CILE), a composite film composed of a magnesium metal-organic frameworks nanometer material (Mg-MOFs-74), gold nanoparticles (AuNPs) and muscle hemoglobin (Mb) is modified on the surface of the CILE, and a Nafion film is assembled on the surface of the composite film. The preparation method comprises the following steps: modifying the Mg-MOFs-74, performing electro-deposition on the AuNPs, assembling the Mb and Nafion film and the like. The nano electrochemical enzyme sensor capable of being used for detecting the TCA or NaNO2 is constructed in the invention, is capable of respectively detecting two target substances, is wide in detection range and low in detection limit, and can be used for determining samples containing the TCA or NaNO2.

The invention relates to an LAMP primer for detecting Brucella and a kit containing the same. The LAMP primer comprises inner primers, namely FIP and BIP, outer primers, namely F3 and B3, and two pairs of ring primers, namely LF1 and LB1 or LF2 and LB2; the kit comprises the LAMP primer, Bst DNA polymerase, and a reaction buffer solution containing dNTPs. The kit utilizes loop-mediated isothermal amplification reactions (LAMP), carries out a specific amplification on target gene BCSP31 by using Bst polymerase and the LAMP primer, and is capable of rapidly, accurately, and conveniently detecting the Brucella in a human blood sample or milk. The detection method has a high sensitivity, the lower limit of detection can reach 35 fg, the reaction time is short, expensive instruments are not needed, the operability is strong, moreover, the product detection is convenient, the product can be detected by naked eyes or through a dyeing method, so the kit has a very high practical value.

The invention belongs to the field of immunity detection of an anti-zika virus (ZIKV) antibody, and particularly relates to a ZIKV E antigen and application thereof in detecting the anti-ZIKV antibody. After a ZIKV gene group and the expression protein thereof are analyzed, the E antigen for specifically detecting the anti-ZIKV antibody is found, the anti-ZIKV antibody in human blood is specifically detected by the founded E antigen, and a kit for detecting the anti-ZIKV antibody is prepared. The method for detecting the anti-ZIKV antibody has the advantages that the use of ZIKV with strong infection ability is effectively avoided in the detection process, so that the risk of a whole experiment is decreased; by adopting the technical scheme, the operation is simple and easy, the repeatability is good, and the like; the method can be easily popularized and applied.

The invention discloses a photoelectrochemical aptamer sensor and a preparation method and application thereof. The photoelectrochemical aptamer sensor comprises a conductive glass electrode, the surface of the reaction end of the conductive glass electrode is modified with a composite nano material, and an aptamer probe is self-assembled on the surface of the composite nano material; and the composite nano material is a gold nanoparticle modified sulfur hybrid hexagonal boron nitride nanosheet loaded with graphite phase carbon nitride. The preparation method comprises the step of sequentiallyloading the gold nanoparticle-modified graphite-phase carbon nitride-loaded sulfur hybrid hexagonal boron nitride nanosheet and the aptamer probe on the surface of the reaction end of the conductiveglass electrode. The sensor has the advantages of high stability, long service life, strong anti-interference capability, wide detection range, low detection limit and the like, the preparation methodis simple in process, safe, pollution-free and low in cost, and the sensor can be widely used for detecting pollutants in media such as water bodies and organisms, and has the advantages of high utilization rate, wide application range, high application value and the like.

The invention belongs to the technical field of a biosensor and discloses a preparation method of the electrochemiluminescence biosensor for detecting mercury ions. Carbon nitride quantum dots are taken as a new-type co-reacant, so an electrochemiluminescence signal of a luminophor [Ru(dcbpy)<3><2+>] can be enhanced. In order to realize specific detection for the mercury ions, DNA1 and DNA2 rich in T bases are imported, and the DNA1 and the DNA2 are connected with the luminophor and the co-reacant. Pairing bonding can be carried out on the DNA1 and the DNA2 through utilization of the mercury ions. Distance between the luminophor and the co-reacant is closer, so the electrochemiluminescence signal is further enhanced. According to the constructed electrochemiluminescence biosensor, a detection limit for the mercury ions is 3.3x10 <-15>mol.L<-1>. The electrochemiluminescence biosensor provided by the invention is low in cost, high in sensitivity and good in selectivity and is applicableto practical application detection of mercury ion content in surface water.

The invention discloses a method for detecting a target DNA or protein based on a double-amplification method, wherein the method comprises the following steps: (1) incubating a sample to be tested with a probe, wherein the incubation condition comprises the temperature of 20-40 DEG C and the time of 0.5-1 h; (2) adding endonuclease, wherein the incubation condition comprises the temperature of 20-40 DEG C and the time of 1-3 h; and during incubation, cutting the probe by the endonuclease and releasing a DNA fragment containing 3'OH; (3) adding terminal transferase (TdT) and dNTP, and generating a long-chain DNA of G-quadruplex at a gap end of DNA; (4) adding the solution after reaction in the step (3) to an MES buffer and hemin, and incubating for 15-60 min; and then adding ABTS and H2O2,and carrying out UV detection. The target DNA or protein is detected according to the strength of absorption light signals. The method is a new simple method for signal amplification and sensitive detection of biomolecules.

The invention discloses an electrochemical sensor for detecting lead ions and / or cadmium ions, and a preparation method and an application thereof. The electrochemical sensor includes a glassy carbonelectrode, of which the surface of a reaction terminal is modified by ordered mesoporous carbon supporting hollow spherical bismuth oxide, which is formed with the ordered mesoporous carbon as a carrier, of which the surface supports the hollow spherical bismuth oxide. The preparation method includes a step of modifying the ordered mesoporous carbon supporting hollow spherical bismuth oxide onto the surface of the reaction terminal of the glassy carbon electrode. The electrochemical sensor has advantages of good stability, long service life, wide detection range, low detection limit, good selectivity and strong anti-interference capability. The preparation method has simple processes, low cost and convenient operations, is pollution-free and has extensive application range. The electrochemical sensor is used for detecting lead ions and / or cadmium ions, has simple operation, low cost, short responsive time and high sensitivity, and has great application prospect.

The present invention provides a ribonuclease detection method, which comprises the following steps that: 1) a body fluid sample is acquired from an individual subject; 2) the body fluid sample contacts double-stranded nucleic acid, such that the double-stranded nucleic acid can be cut by ribonuclease possibly existing in the body fluid sample; and 3) products after contacting in the step 2) are detected so as to detect content of the ribonuclease in the body fluid sample. The present invention further provides applications of the detection method and a tumor detection kit. With the ribonuclease detection substrate and the detection method, activities and contents of ribonucleases in sera derived from different tumor patients can be sensitively and accurately detected, such that operation is convenient, and detection cost is substantially reduced. In addition, high application values are provided for early detection, efficacy evaluation, population mass screening and other large-scale applications of a plurality of diseases.

The invention discloses a photoelectrochemical aptamer sensor and a preparation method and application thereof. The sensor comprises a working electrode, the reaction end face of which is modified with a composite film, wherein the composite film is composed of a graphite phase carbon nitride nanosheet composite material jointly modified by gold nanoparticles / cerium dioxide quantum dots; and a specific aptamer probe is self-assembled on the surface of the composite film. The preparation method comprises the following steps: modification of CeO2QDs / Au / g-C3N4 and fixation of the specific aptamer probe. The photoelectrochemical aptamer sensor disclosed by the invention has the advantages of high stability, long service life, strong anti-interference capability, wide detection range, low detection limit and the like, can realize specific detection of target objects in media such as water bodies and organisms, and is high in utilization rate, high in use value and good in application prospect. The preparation method of the sensor has the advantages of simple process, convenience in operation, safety, low cost, no pollution, high manufacturing efficiency and the like, is suitable for large-scale preparation and is beneficial to industrial application.