24 results about "Fluorescence biosensor" patented technology

The invention discloses an aptamer-mediated EXPARs-molecular beacon fluorescent biosensor as well as a preparation method and application of the aptamer-mediated EXPARs-molecular beacon fluorescent biosensor. The construction and detection process of the sensor comprises three key steps: protein binding aptamer, exponential isothermal amplification (EXPAR) and molecular beacon fluorescence resonance energy transfer (FRET). Through the ingenious design of the EXPAR system, the system realizes triple signal amplification, the detection sensitivity is remarkably improved, and Abeta42 and Abeta40 amyloid proteins as low as 100fM level can be detected. Besides, based on the sequence specificity of the aptamer and the highly specific design of each nucleic acid sequence involved in the detection system, the method can be used for simultaneously detecting the Abeta42 amyloid protein and the Abeta40 amyloid protein or other substances in the same system (such as a plasma sample), so that the detection efficiency is improved.

The invention belongs to the technical field of biosensors, and provides a rolling circle amplification-based DNA / AgNCs detection ATP fluorescent biosensor, which comprises: a PL chain complementarily combined with AgNCs-L1 and L2 chains; the PL chain is a product obtained by rolling circle amplification of an annular template with a nucleotide sequence as shown in SEQ ID NO: 1 and a P chain with a nucleotide sequence as shown in SEQ ID NO: 2 as a primer; the nucleotide sequence of the L2 chain is shown as SEQ ID NO.4, and the 5'end of the L2 chain is modified with BHQ1. The sensor has the advantages of being high in detection speed, easy to operate, low in price, low in detection limit, high in specificity and the like, the defects of an existing ATP detection method can be overcome, and rapid and accurate quantitative detection of ATP is achieved.

The invention relates to the technical field of photochemical biosensing detection, and discloses a fluorescent biosensor, system and method for detecting tumor markers, commercialized filter paper is used as a substrate, a silica-based sensitive layer is constructed on the surface of the substrate by a sol-gel method to obtain a nanopore membrane, and specific capture of target molecules is realized by introducing click chemistry. The stability and the tolerance of a sensing system are improved. The method is simple and convenient to operate, high in result visualization degree, capable of greatly shortening the detection time, high in specificity, high in sensitivity, high in precision, good in reproducibility and low in cost, and can be widely applied to tumor marker detection.

The invention belongs to the technical field of biosensors, and provides a vibrio parahaemolyticus fluorescent biosensor based on a DNA (deoxyribonucleic acid) reticular nanostructure, which comprises DNF (at) AuNCs, DNA-H, Apt-T, H6 and Mg < 2 + >. The sensor disclosed by the invention has the advantages of high detection speed, simplicity in operation, low price, low detection limit, high specificity and the like, can make up the defects and deficiencies of the existing detection method of the vibrio parahaemolyticus, and realizes rapid and accurate quantitative detection of the vibrio parahaemolyticus.

The invention relates to the technical field of biosensors, in particular to a transgenic corn CP4-EPSPS protein aptamer molecular beacon fluorescent biosensor. According to the invention, a systematic aptamer rational cutting and conformation adaptation strategy is constructed, the strategy obtains an initial aptamer through magnetic bead-SELEX screening, and the CP4-EPSPS protein aptamer is precisely cut and optimized by adopting the steps of loop region active core positioning, stem region structure optimization and base binding domain identification, so that the binding performance and the structural stability are remarkably improved. Subsequently, on the basis of stable conformational characteristics, a complementary chain competition sensing mechanism is designed, and a transgenic corn CP4-EPSPS protein aptamer molecular beacon fluorescent biosensor is successfully constructed, so that amplification-free high-sensitivity rapid detection of CP4-EPSPS protein is realized, and a solution is provided for supervision of transgenic crops.

The invention discloses a hybridization chain reaction fluorescent biosensor and a preparation method and application thereof, red cell membrane coated gold nanoparticles are used as a reaction substrate, the surface of the gold nanoparticles is covalently connected with a sulfydryl modification initiation probe aiming at target miRNA through an Au-S bond, and the red cell membrane coated gold nanoparticles are treated by Fe < 3 + >. According to the method, the red cell membrane completely coats the gold nanoparticles, so that common false positive signals in a complex body fluid environment are remarkably reduced; the hybridization chain reaction is limited on the surface of the cell membrane, so that the local concentration of the hairpin probe is improved, the chain amplification process is accelerated, and the detection time is shortened; sufficient sites are provided for probe fixation and HCR polymerization by utilizing the large specific surface area of the gold nanoparticles, and the signal amplification factor is further enhanced; fe < 3 + > is introduced to perform surface modification on the red cell membrane coated gold nanoparticles, so that non-specific binding is effectively inhibited, blank background fluorescence is remarkably reduced, and the signal-to-noise ratio is increased.

The application relates to the field of biotechnology, in particular to a fluorescent biosensor, a preparation method thereof, an miRNA21 detection kit and application. The fluorescent biosensor comprises a Cas12a protein, a crRNA sequence of the Cas12a, a blocking chain, an activating chain and an ssDNA report probe modified with a fluorescent report group and a fluorescent quenching group, and the nucleotide sequence of the crRNA sequence is shown in SEQ ID NO. 1. The application combines cascade chain displacement isothermal amplification and Cas nucleases, and realizes one-step rapid detection of miRNA21 through fluorescent signal output; the application only needs DNA and RNA sequence design and Cas12a protein, and the cutting of the Cas protein is used to release the fluorescent signal, so that miRNA21 can be quickly, efficiently and accurately detected, the detection difficulty and cost are greatly reduced, and the application is suitable for resource-limited environments and on-site rapid detection.

The invention discloses a CRISPR-Cas14a1 and ERA fluorescent biosensor for rapidly detecting ichthyophthirius multifilis and application of the CRISPR-Cas14a1 and ERA fluorescent biosensor, and particularly relates to the field of molecular biological detection technologies and biosensing. Wherein the nucleotide sequence of the specific sgRNA is as shown in SEQ ID NO. 3. The biosensing system comprises an ERA amplification module which comprises at least one pair of primers capable of specifically amplifying 18S rRNA gene segments of ichthyophthirius multifilis; the CRISPR-Cas14a1 detection module comprises the CRISPR-Cas14a1 specific sgRNA (small guide ribonucleic acid) according to the claim 1 and a Cas14a1 protein of the CRISPR-Cas14a1 specific sgRNA according to the claim 1; and the signal reading module comprises a reporter molecule which can be subjected to trans-cleavage by the Cas14a1 protein and can generate a detectable signal. The biosensor has the advantages of high specificity, quick response and no complex amplification.

The invention belongs to the technical field of detection, and particularly relates to a fluorescent biosensor for lead ion detection and a preparation method and application thereof. The preparation method comprises the following steps: carrying out sulfydryl activation treatment on sulfo-GR-5S and sulfo-Poly-T by using TCEP, then taking sulfo-GR-5S and sulfo-Poly-T and gold nanoparticles as reactants, and constructing a primary gold-labeled probe through a halide ion auxiliary modification strategy; taking the primary gold-labeled probe and biotin-labeled GR-5E as reactants, and performing hybridization annealing treatment to obtain a bifunctional gold-labeled probe; and by taking the bifunctional gold-labeled probe and streptavidin magnetic beads as reactants, carrying out biotin-streptavidin binding reaction, so as to obtain the AuNP-coated MB probe. The probe is used for lead ion detection, the linear detection range is 1-500 nM, the detection limit is 0.34 nM, the probe shows excellent performance in actual sample analysis, and the recovery rate reaches 91.6-117%.

The invention provides a self-assembled antibody-gold nanocluster, a fluorescent biosensor, a preparation method and application, and belongs to the technical field of fluorescent biosensors. The invention provides a self-assembled antibody-gold nanocluster. The self-assembled antibody-gold nanocluster is prepared from the following raw materials: an antibody, chloroauric acid and a reducing agent, the molar ratio of the antibody to the chloroauric acid is (1: 60)-(1: 80); the antibody is combined with the gold nanoparticles in the gold nanocluster through surface sulfydryl. In the invention, under the action of a reducing agent, chloroauric acid is reduced into gold nanoparticles, and an antibody can be combined with the gold nanoparticles through surface sulfydryl to generate self-assembly, so that the self-assembled antibody-gold nanocluster is obtained. The self-assembled antibody-gold nanocluster disclosed by the invention can be synthesized by a one-step method, and a signal nanocluster (gold nanocluster) is generated in situ in a single antibody protein molecule template, so that the inherent defects that the chemical coupling efficiency is low, the biological activity is easy to damage and the like are overcome.

The application belongs to the field of biosensors and detection technologies, and relates to a preparation method of an RCA-GO aptamer fluorescent biosensor, which comprises the following steps: first, preparing a quantum dot coupled fluorescent probe; then, preparing a circular DNA template CDT; and finally, preparing a rolling circle amplification product RCAP, which is hybridized with the quantum dot coupled fluorescent probe at a volume ratio of 1:1, and GO solution is added to prepare the RCA-GO aptamer fluorescent biosensor after incubation at 37 DEG C. The prepared RCA-GO aptamer fluorescent biosensor is applied to fluorescent detection of aflatoxin B1 (AFB1) and ochratoxin A (OTA). The quantum dots have low preparation cost, high coupling activity, and a mature and stable preparation method. The aptamer that is not combined with the target substance is combined with Padlock to form CDT, and a rolling circle amplification reaction is performed, so that the fluorescent signal is greatly enhanced, the detection of AFB1 and OTA is realized, the theoretical basis is mature, and the reliability is good. The fluorescent probe coupled with the quantum dots has stable signal and high sensitivity, and the double-stranded structure (RCAP / QDs-cDNA) formed has good stability and is not prone to false positive signals.

The invention discloses a multivalent aptamer fluorescent biosensor for detecting pseudomonas aeruginosa and a preparation method of the multivalent aptamer fluorescent biosensor, sequence template design is carried out based on an aptamer (F23), a long multivalent ligand with repeated aptamer units is synthesized through RCA rolling circle amplification, and through the synergistic effect between the aptamer units and a formed'capture net ', the fluorescent biosensor is used for detecting the pseudomonas aeruginosa. The binding efficiency with the target pseudomonas aeruginosa is remarkably improved, and the sensitivity of a detection system is enhanced.

The invention provides a chlorogenic acid nucleic acid aptamer sequence and a fluorescent biosensor and in-vitro anti-oxidation application thereof. A specific nucleic acid aptamer with high affinity to chlorogenic acid is screened and obtained through an SELEX (systematic evolution of ligands by exponential enrichment) technology, and a signal closing type fluorescent biosensor is constructed based on the specific nucleic acid aptamer. According to the sensor, target chlorogenic acid is used for inducing an aptamer hairpin structure to be closed, an FRET effect is triggered to cause end-labeled Cy5 fluorescence signals to be quenched, so that ultra-sensitive detection of chlorogenic acid is realized, the detection limit is as low as 1.85 nM, and the sensor has the advantages of high specificity and simplicity and convenience in operation. In addition, it is found for the first time that a compound formed by combining the aptamer and chlorogenic acid can significantly enhance the in-vitro antioxidant activity of the aptamer, and a new direction is provided for application of the aptamer in the fields of functional food and drug synergy.

This invention discloses a method for detecting organophosphorus pesticides using a self-cascaded Pt@Fe-CDs nanozyme, belonging to the field of chemical analysis and detection technology. This method synthesizes Pt@Fe-CDs nanozymes using iron-doped carbon dots (Fe-CDs) as a reducing agent and template. Pt@Fe-CDs simultaneously possess ascorbic acid oxidase-like and peroxidase-like activities. Under the catalysis of alkaline phosphatase, they hydrolyze L-ascorbic acid-2-phosphate trisodium salt to AA. Based on the fact that organophosphorus pesticides can inhibit ALP activity and hinder AA2P dephosphorylation, leading to a reduction in AA and thus causing changes in fluorescence and colorimetric signals, a simple and sensitive dual-signal fluorescence / colorimetric sensing platform for organophosphorus pesticides is constructed, with a detection limit of 0.28-0.53 ng / mL. The colorimetric and fluorescence biosensors established in this invention exhibit excellent performance in terms of sensitivity, specificity, and accuracy in actual samples.

The invention discloses a method for detecting uranyl ions in a biological sample based on DNAzyme, and relates to the technical field of biosensing. The invention provides a detection method and application. The fluorescent biosensor is constructed by taking DNAzym for specifically recognizing uranyl ions as a molecular recognition element and modifying a fluorophore and a quenching group at two ends of the molecular recognition element respectively. When the DNAzyme is combined with the uranyl ions, a specific cleavage reaction is carried out, a fluorescence signal is generated, and quantitative detection of the uranyl ions is realized. In particular, for a biological sample with complex components, the pretreatment process is optimized, including digestion, drying, resuspension, pH adjustment and reducing agent addition, and impurity interference is effectively removed. The method has the characteristics of simplicity and convenience in detection operation, rapidness in detection, high specificity and the like, can be used for detecting uranyl ions with lower concentration, is suitable for uranium exposure personnel monitoring and environmental pollution evaluation, and provides an efficient detection means for nuclear safety and medical diagnosis.

This invention proposes a capsaicin nucleic acid aptamer and its ratiometric fluorescent biosensor application. A capsaicin-specific nucleic acid aptamer with nanomolar affinity for capsaicin was obtained using the RNase-SELEX screening strategy. Furthermore, a ratiometric fluorescent biosensor was constructed using the pruned aptamer. A dual-signal response is achieved through competitive binding / conformational regulation of the aptamer by capsaicin and the nucleic acid dye SYBR Green II. Quantitative detection of capsaicin is achieved through a linear relationship between the fluorescence ratio and capsaicin concentration, exhibiting advantages such as high sensitivity and strong anti-interference capability.

The application belongs to the technical field of nucleic acid detection, and specifically discloses a lanthanide metal organic framework DNA sensor as well as a preparation method and application thereof. The lanthanide metal organic framework (LaMOF) surface is not fully coordinated with metal sites, and the chemical coordination reaction activity of the oligonucleotide phosphate group is utilized. A capture DNA strand complementary to a target DNA is coupled to the LaMOF surface to construct a fluorescence biosensor based on the LaMOF. The synthesis steps are simple, complex synthesis reactions are avoided, the solvent is non-toxic and environmentally friendly, the operation is simple, and the time cost and reagent cost are low. Then, the luminescent metal organic framework and the in-situ fluorescence quenching reaction are combined to detect nucleic acids, the amount of the target DNA is specifically converted into a fluorescence signal, and quantitative analysis of free nucleic acid cfDNA is realized. The method has a good linear correlation in a concentration range of 25-250 nM, is high in precision, and is good in reproducibility.

The invention relates to a method for detecting an SNV (Single Nucleotide Virus) of an HLA-B * 15: 02TA (Human Leukocyte Antigen-B * 15: 02TA gene. According to the method, rapid and accurate detection is realized on the basis of an RPA-CRISPR-Cas12a double-recognition SNV strategy; according to the method, RPA is combined with a CRISPR-Cas system, a new strategy for double recognition of SNV is adopted, and the fluorescent biosensor is constructed according to the new strategy: (1) a mismatched basic group is introduced into the first six spacer sequences of crRNA away from a target gene PAM sequence, so that the specific differentiation of a mutant gene (MT) and a wild gene (WT) is improved, which is the first recognition of SNV; and (2) rapidly enriching MT by using the retardation type RPA, namely identifying the SNV for the second time. Preferably, according to the method disclosed by the invention, the combination of the retarding type RPA and the inhibiting CRISPR-Cas12a is further carried out in a one-tube method, so that the rapid and accurate dual recognition of the SNV is realized. The rapid, accurate, simple and convenient detection of the HLA-B * 15: 02TA rash gene is realized, and the kit has a wide clinical application prospect.

The invention discloses a fluorescence sensor for nuclear receptor ligand activity evaluation. According to the sensor, non-covalent adsorption and fluorescence quenching characteristics of graphene oxide (GO) are utilized, an activated state nuclear receptor is taken as an effect marker, and fluorescence-labeled co-regulation polypeptide molecules and a GO combined nuclear hormone reaction element (HRE) are taken as recognition elements, so that the dual-recognition fluorescent biosensor is constructed; the activation effect of the compound is evaluated by detecting the signal change of the fluorescent marker. In the construction of the biosensor, HRE is non-covalently bound to GO. When the ligand activates the nuclear receptor, the nuclear receptor in an activated state can recruit HRE and dissociate the co-inhibiting factor, and the co-activating factor is recruited. The co-regulatory factor polypeptide is labeled with fluorophore, and the nuclear receptor ligand activity is evaluated by detecting the change of fluorescence intensity by using the non-covalent HRE adsorption and fluorescence quenching characteristics of GO. The fluorescence sensor disclosed by the invention can effectively evaluate the activity of the compound nuclear receptor ligand, is suitable for multiple fields of environmental pollutant screening, food safety detection and the like, and has an important application value in the aspect of evaluating the human health risk of the compound.

The invention discloses an AuNPs-DNA three-dimensional nano device, a preparation method thereof and application of the AuNPs-DNA three-dimensional nano device in FEN1 enzyme detection.The SR DNA with the 3'end modified with FAM and the 5 'end modified with-SH serves as a signal output molecule, meanwhile, long-chain DNA walker is modified on the surfaces of gold nanoparticles to serve as a walking foot of the DNA nano device, SR can be hybridized with the DNA walker, and a lambda exonuclease (lambda-EXO) cleavage site is generated; in the presence of a DNA protection fragment (P), P and DW are hybridized to form double strands, hybridization of DW and SR is prevented, and because an enzyme recognition site of SR is protected, no fluorescence signal is emitted. According to the constructed three-dimensional DNA nano device, in the presence of FEN1, due to the fact that FEN1 cuts 5 'Flap, lambda-EXO cutting sites are generated, DW is hybridized with SR after being released, more lambda-EXO cutting sites are generated, fluorescence signals are released, and sensitive, simple and convenient detection of FEN1 can be achieved through the fluorescence signals through a fluorescence biosensor.

The invention discloses a DNA fluorescent biosensor with double signal amplification, and belongs to the field of molecular biology, the DNA fluorescent biosensor comprises a B-H composite probe, a fuel chain F, an R1 reporter probe, an R2 reporter probe and a cutting incision enzyme, the B-H composite probe is composed of a hairpin chain H and a DNA chain B, the R1 reporter probe and the R2 reporter probe are DNA chains simultaneously modified with a fluorescence reporter group and a fluorescence quenching group; the fluorescent group and the quenching group are modified on the same DNA chain by optimizing the probe, and a dual signal amplification mechanism is adopted, so that the detection sensitivity is remarkably improved, and the detection limit can reach 3pM.

The invention provides a magnetic control ratio fluorescent biosensor based on RPA-CRISPR / Cas12a as well as a preparation method and application of the magnetic control ratio fluorescent biosensor, and belongs to the technical field of fluorescent biosensors and pathogenic bacterium detection. The magnetic control ratio fluorescence biosensor comprises a fluorescence reference signal element, a fluorescence response signal element and a specific recognition element, according to the magnetic control ratio fluorescent biosensor, high-sensitivity and specific detection of staphylococcus aureus and salmonella is realized through the magnetic and fluorescent characteristics of the fluorescent reference signal element, the fluorescent characteristic of the fluorescent response signal element and the nucleic acid cleavage activity of Cas12a; the magnetic control ratio fluorescent biosensor has a built-in calibration function, can reduce interference brought by the environment and instruments, has good selectivity to staphylococcus aureus and salmonella, has good anti-interference performance to other bacteria, and can be used for rapid detection in the field of food safety.

Disclosed are leave-one-out GFP (LOO_GFP) biosensors immobilized in Ubx (Drosphila protein Ultrabithorax) that form immobilized and stabilized fluorescent protein biosensor systems (LOO_GFP-Ubx systems). These LOO_GFP-Ubx systems have an enhanced fluorescent signaling to noise ratio. Also disclosed are methods of making LOO_GFP-Ubx systems and methods of using such systems to detect analyte. In preferred embodiments, the LOO_GFP-Ubx system has the eighth β strand or eleventh f strand of OPT GFP left out.