36results about How to "Achieve high specificity detection" patented technology

The invention discloses an electrochemical sensor for detecting isocarbophos and acetamiprid at same time and a method system of the electrochemical sensor; the electrochemical sensor comprises an electrode, a beacon probe layer, a 6-mercaptohexan-1-ol (MCH) closure layer, and a homogenous reaction product layer sequentially from inside to outside; the beacon probe layer is modified with methylene blue and ferrocene having electrochemical signals not mutually affected; a preparation method comprises: polishing the electrode, treating with H2SO4 and H2O2, and modifying the surface of the electrode with a beacon probe. The electrochemical sensor according to the invention is simple to prepare and has good performance stability, the electrode is highly repeatable, and the electrochemical sensor is applicable to the detection of isocarbophos and acetamiprid in terms of food safety and the actual application of biosensor industrialization; the electrochemical sensor can provide quick online detection for isocarbophos and acetamiprid in food, and isocarbophos and acetamiprid detection limits are 0.12 ppb and 0.37 ppb respectively.

The invention relates to the technical field of a biosensor, and particularly relates to a fluorescence biosensor for detecting UDG (Uracil-DNA Glycosylase) on the basis of a polymerase-assisted feedback rolling circle amplification and endonuclease amplification fluorescence method. The invention aims to solve problems of both low specificity and low sensitivity of a method for detecting UDG in the prior art. The biosensor for detecting the UDG on the basis of a feedback rolling circle amplification technology achieves a rolling circle amplification effect on matching of phi29 polymerase andendonuclease IV, implements fluorescence resonance energy transfer of a fluorophore and a Quenching group and performs a homogeneous reaction on mixed liquid. A preparation method comprises: constructing a circular template and a composite probe; feeding back a rolling circle amplification signal and carrying out fluorescence detection. Specific hydrolysis of the UDG on a basic group U is utilized, and by utilizing such specific reaction, the UDG can be accurately measured and meanwhile, interference can also be avoided; by utilizing endonuclease IV circle amplification, a signal amplificationeffect is achieved.

The invention relates to an aptamer based salmonella typhimurium detection biosensor and a preparation method thereof. Signal amplification is realized by continuous generation and cyclic utilization of Primer, and consequently high-sensitivity detection of salmonella typhimurium is realized, and lower detection limit can be acquired. The aptamer based salmonella typhimurium detection biosensor is high in specificity and sensitivity, low in cost and quick in detection. By the detection method, a salmonella typhimurium detection limit is 5-15cfu/mL, and a detection range is 1*10-1*107cfu/mL.

The invention relates to the technical field of biosensors, and particularly relates to a fluorescent biosensor for detecting ochratoxin A based on a rolling ring amplification mediated catalytic hairpin self-assembly and incision enzyme feedback amplification method. According to the fluorescent biosensor, as for a detection mode, a fluorescence method is adopted for detection, and a luminoscopeis utilized; before detection, a padlock probe and a connecting probe form an annular template probe; then a target object is added to a homogeneous solution of a complex probe I, a complex probe II,HP 2 and HP 3, incubating is carried out for 120 minutes at 37 DEG C, and the target object and an aptamer sequence are bound; the multiple feedback amplification process is completed under the actionof a phi29 DNA polymerase and an endonuclease IV, so that signal amplification is realized; and then, the luminoscope is used for setting the excitation wavelength to be 399 nm, the fluorescence intensity at 610 nm is detected, and the detection range is 560-640 nm. Meanwhile, the invention further provides a preparation method for the biosensor. The preparation method has the advantages of beingmild in reaction condition and easy to operate.

The invention relates to the electrochemical sensor technology field and especially relates to an electrochemical sensor for detecting a lead ion. A CP2 layer, a HP1-HP2-HP3-CP1-AuNP layer, and a [Ru(NH3)6]<3+> layer are sequentially modified on an electrode. The manufacturing method comprises the following steps of preprocessing the electrode; modifying the CP2 layer to an electrode surface; modifying the HP1-HP2-HP3-CP1-AuNP layer to the electrode surface; and modifying the [Ru(NH3)6]<3+> layer to the electrode surface. The specific identification of a DNA enzyme is used to realize the highspecificity detection of target object lead ions. The cutting effect of the DNA enzyme of lead ion specific identification and a CHA reaction are used to realize the increase of a signal through two-step cycle and one-step amplification modes so as to realize the high-sensitivity detection of lead ions and obtain a lower detection limit. Through the connection performance of nanogold, an effect that the signal is continuously enhanced is achieved.

The invention provides a method for detecting miRNA-155 based on an aptamer. The biological detection method is established based on specific recognition of the aptamer and a target object by means of the chain extension effect of phi29 DNA polymerase in rolling circle amplification, the cutting action of endonuclease on a nucleic acid chain at a specific site, and the fluorescence signal generating characteristic of a fluorophore of a molecular beacon. The detection method has the advantages that the detection speed is high, the detection limit is low, and specificity is high. Defects of existing miRNA-155 detection methods can be overcome, and quick and accurate quantitative detection of miRNA-155 can be achieved.

The invention relates to the technical field of biosensors, in particular to an electrochemical biosensor for detecting Salmonella typhimurium and provides a preparation method of the electrochemical biosensor. The electrochemical biosensor is prepared by modifying an electrode with a HAP2 layer, and homogeneously reacting a mixed liquid. An aptamer of Salmonella typhimurium is used as a recognizing matter to highly specifically detect Salmonella typhimurium in a target by making use of specific recognizing property of the aptamer; the target is recycled through the use of nucleic instrumental enzymes, and signal amplification is achieved.

The invention discloses a high-specificity loop-mediated isothermal amplification (LAMP) method. The method comprises the following steps of: 1, designing an amplification primer; 2, designing sgRNA;3, carrying out amplification; and 4, carrying out specific detection of an amplification product. According to the amplification method provided by the invention, femtogram-level pollution removal can be implemented; the false positive rate of detection of the conventional LAMP method is effectively reduced; and the detection accuracy is improved. Meanwhile, the invention further discloses application of the high-specificity LAMP method to gene detection.

The invention discloses a DNA detection method based on a solid-phase rolling circle amplification-nanogold-terahertz technology. According to the invention, gold magnetic nanoparticles are used as acarrier, and a solid-phase rolling circle amplification technology is utilized to realize first signal amplification of DNA detection; a local surface plasma resonance signal is enhanced by using a THz metamaterial to realize a second amplification effect on the DNA detection signal; a DNA amplification sample is modified by utilizing nanogold with high refractive index, and a third amplificationeffect of a detection signal is realized, so that high-sensitivity detection of DNA is realized on the basis of a triple signal amplification effect of target DNA detection. In addition, on one hand,a solid-phase roll-back amplification method is used for carrying out specific amplification on the target DNA; on the other hand, the gold magnetic nanoparticles are used for separating DNA amplification products to avoid signal interference of non-target molecules, so that high-specificity detection of DNA is realized on the basis of the two technologies.

The invention provides a biosensor for detecting salmonella typhimurium, which comprises a gold electrode, and a capture probe layer and a RCA product layer, which successively modify the gold electrode externally. The preparation method is carried out through specificity recognition of an aptamer. The produced electrode is high in sensitivity and specificity and can be used for quickly detecting the salmonella typhimurium.

The invention discloses construction and application of a terminal transferase activity analysis method based on an alternating-current impedance technology, which comprises the following steps of: introducing cytidine triphosphate (dCTP) into the surface of a gold electrode modified by 5 '-sulfydryl DNA by using TdT to form a C-rich DNA long chain; the DNA long chain is kept in an irregular single-chain state under the condition that the pH value is 7.0; a relatively large electrochemical impedance value is obtained; on the contrary, under the condition that the pH value is 5.8, due to the fact that C is partially protonated, a stable i-motif structure can be formed; a small electrochemical impedance value (semi-protonated C-rich DNA in i-motif is beneficial to electron conduction) is obtained, a very meaningful electrochemical impedance switch is formed, the electrochemical impedance value depends on the activity of TdT, and based on this, dynamic analysis of the activity of TdT in different microenvironments and screening of small-molecule inhibitors of TdT are realized.