682results about How to "Improve detection limit" patented technology

The invention provides compositions and methods for the detection and/or quantification of biological targets (e.g., nucleic acids and proteins) by the nucleic acid-templated creation of one or more reaction products, for example, epitopes, enzyme substrates, enzyme activators, and ligands. The reaction products can be detected and/or quantitated after signal amplification using an amplification system.

Disclosed herein are diagnostic assays using surface enhanced Raman spectroscopy (SERS)-active particles, including liquid-based assays; magnetic capture assays; microparticle-nanoparticle satellite structures for signal amplification in an assay; composite SERS-active particles useful for enhanced detection of targets; and sample tubes and processes for using the same.

An instrument for fluorometric assays in liquid samples is disclosed. The instrument may include multiple optical channels for monitoring a first fluorophore associated with a target analyte and a second fluorophore associated with a control. The disclosed instrument finds utility in any number of applications, including microfluidic molecular biological assays based on PCR amplification of target nucleic acids and fluorometric assays in general.

The invention relates to a multifunctional double-layer core-shell structure magnetic nano particle. In the invention, a magnetic nano particle with a particle size of 1-300 nm is used as a core and coated with a double-layer shell consisting of a SiO2 layer with a thickness of 1-200 nm and a hydrolyzed silane coupling agent layer is 1-100 nm thick and comprises one or more multifunctional groups; the particle size and the shell layer thickness can be controlled through regulating the volumes, the weight ratios and the reaction time of the magnetic core, a silicon dioxide precursor, a silane coupling agent and a catalyst in a preparation process; the total particle size of the nano particle can be as small as 5-50 nm and as large as 700-800 nm; the nano particle can have superparamagnetism, paramagnetism and ferromagnetism according to the change of the magnetic core particle size; and one or more bioactive molecules can be connected into the shell layer of the magnetic nano particle or to the surface of the shell layer through a chemical method or a physical method. The invention also provides a preparation method of the multifunctional double-layer core-shell structure magnetic nano particle and application thereof. The particle preparation method has the advantages of simplicity, moderate condition, low cost and easy realization of industrial production. The nano particle can obtain different functions through connecting different bioactive molecules and can be applied to the fields of protein enrichment, biological detection, separation and purification, targeted drug carriers, cell imaging and medical imaging.

Apparatus including an ion trap, a controller connected to the ion trap, wherein the controller includes a memory containing computer readable instructions which, when executed, cause the controller to send control signals to the ion trap so that the ion trap produce and maintain a trapping field in the ion trap, a waveform generator to change the trapping field so that ions of a predetermined mass in the trapping chamber are selectively moved; a secondary waveform generator to change the orbits of the ions; an energy source to excite ions to emit photons, an optical detector to detect the emitted photons, and a processor which can apply fast-Fourier transform analysis of the time-domain signal of the detected emitted photons to generate a frequency or mass spectrum related to mass-to-charge ratio of the ions.

From a plurality of pictures 1-1 through 1-3 captured at successive time intervals, pictures 2-1 through 2-3 of regions determined in accordance with the movement of the celestial object are cut out. By deriving median values in regard to the same pixels in each of the cut-out pictures 2-1 through 2-3, a median value picture 3-1 is created. By deriving median values, the influence of large numbers of fixed starts that hinder the detection of the moving celestial object that moves in the cut-out pictures is eliminated, and only the moving celestial object is permitted to remain. When deriving median value, pixel values indicating singular values are eliminated in advance, so that the effects of the images of large bright light sources and the lost pixels that output no pixel values are effectively reduced. Further, when an average value picture is created using a plurality of median value pictures previously obtained, the detection limit increases and a dark moving celestial object that cannot be detected using a single observation picture can be extracted.

A distance of flight (DOF) approach to mass spectroscopy in which the resolution among the various ion masses is accomplished in space rather than time. A separate detector is associated with each ion mass resolution element. The DOF mass spectrometer can serve as one element in a tandem arrangement which has the capability to produce a full two-dimensional precursor/product spectrum for each bunch of ions extracted from the source. A “distance-of-flight” (DOF) mass analyzer is used in combination with time-of-flight (TOF) mass analysis for precursor and product dispersion. All the precursor ions can undergo a mass changing reaction simultaneously, while still retaining the essential information about the particular precursor m/z value from which each product ion m/z value emanated. Through the use of a two-dimensional detector, all the products ions from all the precursors can be detected for each batch of ions analyzed.

Methods of screening for enzyme stereoselectivity that include detecting isotopically labeled products by mass spectrometry are provided. The methods are particularly suitable for screening enzyme libraries for stereoselectivity.

The invention relates to inspection and quarantine systems for biomedicine, agriculture, food hygiene and the like and particularly relates to an absolute quantification type digital nucleic acid analytic system based on an efficient liquid drop microreactor. The absolute quantification type digital nucleic acid analytic system is mainly used for detecting the molecular structure of nucleic acid so as to analyze attributes of organisms and belongs to the fields of biological and medical detection. The absolute quantification type digital nucleic acid analytic system comprises a confocal fluorescence image collecting system, a micro-fluidic chip, a temperature circulating heating system, an electric loading platform, an automatic sample feeding device, a controller and a computer. The formation and PCR amplification of micro-droplets are finished by virtue of the same micro-fluidic chip, namely the micro-fluidic chip has a droplet formation function and a PCR amplification (microreactor) function. According to the absolute quantification type digital nucleic acid analytic system, the complexity of the absolute quantification type nucleic acid analysis process is reduced, the nucleic acid analysis process is finished in a one-button manner, and culture and bacteria-proliferating processes are omitted, so that the rapid detection is realized, the sensitivity of the absolute quantification type nucleic acid detection is greatly improved, meanwhile, the sample consumption of the absolute quantification type nucleic acid analysis is substantially reduced, and the high throughput detection is realized.

A plasma source mass spectrometer (20) having an ion beam extraction electrode (45) associated with a skimmer cone (40) to restrict the pumping of gas from a region (60) immediately behind the skimmer cone orifice (42) to provide a higher pressure (e.g. 1-10⁻² Torr) in the region (60) compared to the pressure downstream of the electrode (45) (e.g. 10⁻³-10^{31 4} Torr). This provides a collisional gas volume (60) for plasma (28) for attenuating polyatomic and multicharged interfering ions prior to extraction of an ion beam (49). In one embodiment a substance (e.g. hydrogen) can be supplied into the region (60) to assist attenuation of polyatomic and multicharged interfering ions by reactive or collisional interactions.

The invention discloses a preparation method of a ratiometric fluorescent probe for bivalent copper ions. The preparation method comprises the following steps: 1) synthetizing cadmium telluride quantum dots: controlling the molar ratio of Cd2<+>:TGA:Te2<-> in a reaction product to be 1:2.5:0.5; 2) synthetizing amino-modified carbon quantum dots; 3) synthetizing blue-fluorescence carbon quantum dots doped with SiO2 nanoparticles: during synthesis, the volume ratio of the amino-modified carbon quantum dots obtained in the step 2), a chitosan solution of which the W/V is 0.5 percent, cyclohexane, Triton X-100, hexyl alcohol, ammonia water, TEOS and APTES is 5:1:750:177:180:5:6:3; 4) dispersing the cadmium telluride quantum dots obtained in the step 1) and the blue-fluorescence carbon quantum dots obtained in the step 3) in an MES buffer solution, adding a mixed solution of EDC and NHS, carrying out stirring, centrifugation and cleaning to obtain the probe. The probe prepared according to the method comprises nano particles containing the cadmium telluride quantum dots and the amino-modified carbon quantum dots, and has nucleus-satellite hybrid spherical structures. The invention further discloses application of the ratiometric fluorescent probe to detection of Cu2<+>. The ratiometric fluorescent probe has the advantages that the detection limit is very excellent, namely only 1.0*10<7>M; the preparation is simple; no expensive equipment is required.

The invention discloses a trace gas measurement device and method with adoption of photo-acoustic spectroscopy. A photo-acoustic cell with a double-resonant-cavity structure is used for measurement, two resonant cavities have different lengths and radiuses but have the same resonance frequency, and the same to-be-measured gas enters the two resonant cavities from buffer gas chambers in two ends of the photo-acoustic cell and flows out from a buffer gas chamber between the two resonant cavities. The concentration of the gas is measured indirectly through differential resonance photo-acoustic signals of the two resonant cavities, the influence of related noise caused by a photo-acoustic effect in solids can be reduced obviously, the detecting signal to noise ratio of the photo-acoustic signals is increased, and the detection limit of the trace gas can be further improved.

In one embodiment, a method and system is provided for detecting target materials using a combination of stroboscopic signal amplification and Raman spectroscopy techniques.

The invention discloses a method for preparing a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite modified electrode. The method comprises the following steps of: uniformly mixing PEDOT:PSS aqueous dispersion liquid and Nafion, which are taken as raw materials, and then directly dispensing a mixture on the surface of a composite modified electrode; and in the conventional three-electrode system, performing secondary electrochemical doping by using hydrophobic ionic liquid, and thus obtaining the PEDOT:PSS composite modified electrode which is high in water resistance and high in conductivity. The PEDOT:PSS composite modified electrode which is prepared by the method fully combines the film-forming property of the PEDOT:PSS aqueous dispersion liquid, the adhesion characteristic, biological compatibility and anti-interference characteristic of the Nafion, high conductivity and hydrophobicity of the ionic liquid and the electrochemical catalysis characteristic of a nanometer material, can be applied to electrochemical biosensors or electrochemical sensors, is directly applicable to electrochemical detection of auxin, roxithromycin, vitamin C, benzenediol isomer, organophosphorus, glucose, hydrogen peroxide and the like, and has the characteristics of good detection effect, short response time, high water resistance, wide linear range, high sensitivity, high anti-interference, high stability and the like.

The invention discloses a high sensitive biochemical sensor based on a resonance oscillation type micro cantilever beam structure. The biochemical sensor comprises a resonance oscillation chamber, a cantilever beam and a Whist bridge type detection circuit, wherein a micro column structure (3), a liquid storage tank (4) and a liquid leakage hole (5) through which biochemical solution flows are etched at the free end of the cantilever beam; the support end of the cantilever beam is connected with the Whist bridge type detection circuit; the Whist bridge type detection circuit is composed four U-shaped piezoresistance bars (1), three input electrodes (8, 9, 10) and two output electrodes (7, 11); and the four piezoresistance bars (1) are connected with the input electrodes (8, 9, 10) and the output electrodes (7, 11) through a signal transmission line (2). With the adoption of the biochemical sensor, micro biochemical molecules can be sensed with a high sensitivity by detecting the frequency change after an object to be tested is absorbed; biochemical molecules with micromass can be detected; and the biochemical sensor can be widely used in engineering fields such as medicine and chemistry.