60results about How to "Enables fluorescence imaging" patented technology

The invention provides a composite nano-grade novel material based on cancer early-stage integrated detection, diagnoses, and treatment, and a preparation method thereof. According to the invention, gold nano-cage (gold nano-box) and nano-grade iron oxide are assembled, such that gold nano-cage (box) / nano-grade iron oxide composite particles are synthesized. With an assembling method from the inside to the outside, the gold nano-cage (box) is first prepared; iron oxide is nucleated and grown in the gold nano-cage (box); with a surfactant (such as glucan or the like), mono-dispersed iron oxide is obtained; the iron oxide is packaged by using biological molecules, such that the gold nano-cage (box) / nano-grade iron oxide composite particles are obtained; surface modification is carried out by using biological targeting molecules (antibodies or DNA molecules). The material is used in tumor magnetic resonance imaging, fluorescence imaging, dark field imaging, specific targeting multifunctional diagnosis, and photothermal therapy. The material can also be used as a targeting medicine carrier.

The invention relates to a nano probe for copper ion fluorescence imaging in cells and a preparation method for the nano probe. The preparation method comprises the following steps: firstly, synthesizing up-conversion nana particles with core-shell structures, CS-UCNPs for short; then, by taking a CTAB (cetyltrimethyl ammonium bromide) as a template agent and a surfactant, coating a layer of mesoporous SiO2 on the surfaces of the CS-UCNPs to obtain mesoporous coated nano particles CS-UCNPs@mSiO2 with compounding functions; finally, performing covalent bond assembly on functional modified rhodamine organic dye RHB precursors capable of identifying metal copper ions in a singular manner and the CS-UCNPs@mSiO2 to construct an organic-inorganic hybrid nano probe CS-UCNPs@mSiO2-RBH, thereby realizing fluorescence detecting and living cell fluorescence imaging of copper ions in an aqueous solution. The preparation method disclosed by the invention has the advantages of being simple in process, convenient to operate and easy to control structure. The prepared nano fluorescence probe has the characteristics of a uniform dimension, a stable structure, low toxicity and good biocompatibility, and a potential application value in the fields of up-conversion fluorescence labeling, fluorescence detecting and the like of cells or tissues.

The invention provides a washing-free long-time cell membrane fluorescence imaging reagent. The side chain of the reagent is an ethylene glycol chitosan macromolecule containing a hydrophobic unit and a low-efficiency fluorescence unit. Based on multi-site anchoring, the reagent has the advantages of good biocompatibility, simple synthesis, low cost and convenience in staining, does not need washing, cannot be easily endocytosed by cells, and can be used as a long-time cell membrane specificity tracing labelling probe.

The invention discloses a quaternary ammonium salinization fluorescence silicon dot which comprises a silicon-containing nanoparticle and alkyl betaine subjected to covalent grafting on the surface of the nanoparticle. The invention also discloses a preparation method of the quaternary ammonium salinization fluorescence silicon dot and application thereof in aspects such as bacteria resistance and bacteria imaging. Compared with the prior art, the invention has the advantages that a silicon dot of which the surface is provided with amino is subjected to quaternary ammonium salinization through a one-step reaction by utilizing the alkyl betaine, high water solubility of the silicon dot is maintained, and the silicon dot is endowed with excellent selective bacteria resistance and bacteria imaging effects. Moreover, the quaternary ammonium salinization silicon dot has the advantages of high purity degree, high stability, low preparation cost and the like, and a fluorescent marker does not need to be added.

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 fluorescence probe and a simple and convenient method for preparing the same. Molecules are designed, and the fluorescence probe with up-conversion properties and capability of testing the viscosity by the aid of two-photon fluorescence imaging can be synthesized. The simple and convenient method includes carrying out reaction on cyclopentanone and 4-dimethylamino allylbenzene aldehyde in organic solvents in the presence of alkali to obtain a precipitate which is the fluorescence probe. The cyclopentanone and the 4-dimethylamino allylbenzene aldehyde are used as raw materials. The fluorescence probe and the simple and convenient method have the advantages that the fluorescence probe can be applied to carrying out sensor detection on the viscosity of solution and cells, and the sensor detection includes fluorescence detection and cell imaging detection; the cell viscosity fluorescence probe is a simple, speedy and sensitive cell viscosity detection reagent, not only can be used for single-photon fluorescence measurement, but also is applicable to two-photon fluorescence measurement, and accordingly the fluorescence probe and the method have broad application prospects in the field of biological molecular detection.

The invention relates to a carbon dot used as an antitumor drug and a preparing method and application of the carbon dot. With arginine being a carbon source, arginine is completely dissolved with water, and an appropriate amount of thylenediamine is added and subjected to ultrasonic dissolving and microwave heating to obtain the target product carbon dot. Since cancer cells themselves in an organism contain hydrogen peroxide, the carbon dot can be used for treating cancer. The carbon dot can not only conduct fluorescence imaging, but also has the advantages of being high in biocompatibility,large in NO releasing amount, long in acting circular time, high in drug stability, cheap, easy to obtain and the like.

The invention discloses a nano reagent based on melittin and a preparation method and an application thereof. The nano reagent is prepared by melittin, an organic dye, and hyaluronic acid. The preparation of the nano reagent is simple, hemolytic activity of melittin is greatly reduced, and the nano reagent can realize in-vivo tumour fluorescence imaging and obvious antineoplastic curative effect.The nano reagent can be effectively enriched at a tumour area after being subjected to intravenous injection in body, and can track the distribution condition of the nano reagent in the body through afluorescence signal, besides the chemotherapeutic anticancer activity of melittin, the organic dye components in the nano reagent can generate response on laser irradiation and increases the anticancer effect, so that the chemotherapy and phototherapy-combined for anticancer can be realized. In addition, the bio-security of the agent is good, the nano reagent can be widely used for preparing in-vivo cancer diagnosis and treatment-integrated medicines, and in-vivo treatment for melittin is realized.

The invention relates to a phosphorus-doped fluorescent carbon point with a high fluorescent quantum yield as well as a preparation method and application thereof. According to the technical scheme, purified carbon point solid powder is obtained by taking tannic acid and polyethylenimine (PEI), adding de-ionized water and phosphoric acid, then transferring the mixture into a hydrothermal reaction kettle, keeping the heat and reacting for 2h to 6h in a temperature range of 140 DEG C to 240 DEG C, naturally cooling at a room temprature to obtain a light brown nano carbon point crude product solution, and centrifuging, dialyzing, refining, freezing and drying. The carbon point provided by the invention can be used for cell imaging and a photodegradation treatment process of contained organic dyestuffs. The fluorescent quantum yield of the prepared fluorescent carbon point can reach 25.4 percent. After being stored in a dark place for 6 months, the carbon point still can emit bright blue fluorescent light under the illumination of a 365nm ultraviolet lamp and the carbon point has good stability at a room temperature.

The invention discloses a virus-like hollow oxide loaded near-infrared two-b region excited rare earth nanocrystal and a preparation method and application thereof. According to the nanocrystal and the preparation method, an Er and Ho doped NaErF4:2%Ho@NaYF4 rare earth nanomaterial is synthesized through a hydrothermal method, then the nanomaterial is modified on a surface of a virus-like hollow manganese oxide poured into IR1064 through an amidation reaction, and a fluorescent composite probe which is good in biocompatibility and responds to a tumor microenvironment is obtained. According to the fluorescent composite probe, after the manganese oxide is degraded at a tumor, manganese ions are used for chemodynamic therapy and nuclear magnetic resonance imaging contrast agents of metastasis, released rare earth nanocrystals have excitation of 1530 nm and emitted lights of 650 nm and 1180 nm, the light of 1180 nm can be used for tumor imaging navigation surgical resection with no background interference and high resolution and tissue penetrating power in a near-infrared second region, and the light of 650 nm can used for near-infrared first region fluorescence imaging.

The invention discloses a micromolecular fluorescent probe for detecting hypochlorous acid, and a preparation method and application thereof, and relates to the technical field of biological detection. The preparation method of the fluorescent probe comprises the following steps: reacting 8-hydroxy-nonalonidin-9-formaldehyde represented by formula (II) with ethyl acetate and piperidine in an alcohol to obtain a coumarin derivative represented by formula (III); and reacting the coumarin derivative of the formula (III) with methanesulfonic acid and 2-mercaptoethanol in an organic solution in aninert atmosphere to obtain a compound represented by formula (I), namely the fluorescent probe disclosed by the invention. The fluorescent probe provided by the invention has very high selectivity andsensitivity, and can be used for detecting the exogenous hypochlorous acid of living cells and fluorescence imaging of HOCl dynamic change in inflammatory cells as the micromolecular fluorescent probe for detecting the hypochlorous acid.

The invention discloses a preparation method of a poly(N-isopropyl acrylamide) sphere modified fluorescent silicon dot, the prepared fluorescent silicon dot and application. The preparation method comprises the following steps: reacting sodium citrate and 3-aminopropyl triethoxysilane in glycerol to prepare a silicon nanocrystalline quantum dot; reacting silicon nanocrystalline quantum dots, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and folic acid in pure water to obtain folic acid modified silicon nanocrystalline quantum dots; and reacting N-isopropylacrylamide, N,N'-methylene diacrylamide, the folic acid modified silicon nanocrystalline quantum dots and potassium persulfate in pure water to obtain the fluorescent silicon dots modified by the polyisoacrylamide spheres. The polyisoacrylamide sphere modified fluorescent silicon dot prepared by the method is low in cytotoxicity, has a function of responding to temperature change, can be used for cancer cell in-situ imaging and temperature detection, and is simple and feasible in preparation process and easy for large-scale production.

The invention relates to a near-infrared fluorescent probe for hydrogen polysulfides, and a preparation method and application of the near-infrared fluorescent probe, and belongs to the field of chemistry and analysis detection. The near-infrared fluorescent probe NIR-CPS for detecting hydrogen polysulfides has relatively large stokes shift (100nm), and has the advantages of good selectivity, highsensitivity, low limit of detection (18nM) and good biocompatibility. In a phosphate buffer saline (PBS), fluorescence intensity shows a good linear relation with the concentration of hydrogen polysulfides, so that the probe is suitable for quantitatively detecting hydrogen polysulfides. The probe NIR-CPS also realizes fluorescence imaging of hydrogen polysulfides in MCF-7 cells. More importantly, the probe NIR-CPS also realizes sensitive detection of endogenous hydrogen polysulfides generated by induction of lipopolysaccharide at a living body level, and is relatively high in response and relatively stable in fluorescence intensity.

The invention discloses a near-infrared molecular probe based on malonaldehyde response, a preparation method and application of the near-infrared molecular probe based on malonaldehyde response, and the near-infrared molecular probe based on malonaldehyde response takes xanthene-derived organic dye as a parent structure and contains an electron withdrawing group nitryl and a malonaldehyde reaction site benzoyl hydrazine group. The molecular conjugation degree is changed through the nucleophilic reaction of the hydrazine group of the o-nitrobenzoyl hydrazine and the MDA, so that the change of absorbance is caused, and the MDA detection is realized. The invention provides application of the molecular probe, a nano-probe NPs for MDA detection and imaging is prepared, the nano-probe takes near-infrared absorption CS-R and amphiphilic polymer DSPE-PEG2000 as main bodies, and a conjugated system of the CS-R in the nano-probe is changed through an addition reaction of MDA, so that fluorescence imaging is realized, detection and imaging with high sensitivity and good specificity on MDA are realized, and the problems of short wavelength and poor penetration depth of a conventional malondialdehyde probe are greatly improved.

The invention discloses a long-time cell membrane imaging agent, which is characterized by comprising a component A and a component B. The component A is a glycol chitosan polymer with the side chain containing biotin and a hydrophobic unit; and the component B is an avidin molecule grafted with fluorescein isothiocyanate FITC. The cell membrane imaging reagent provided by the invention has good biological compatibility and good imaging effect, and can stay on the cell membrane for a long time without being swallowed, and can be used as a novel cell membrane imaging agent.

The invention provides a PDT compound and a preparation method and application thereof. A stable complex is formed by an axial ligand, an ion ligand and a structure-adjusted porphyrin compound, so that red shift of an absorption spectrum of the compound is realized, the PDT compound with strong phototoxicity, large tissue penetration depth and good biocompatibility is obtained, and the PDT compound also has photothermal effect and fluorescence property, the treatment effect can be improved, and the damage of photodynamic therapy to an organism can be reduced.

The invention discloses a three-dimensional blood flow velocity imaging method and device based on lamellar light. The three-dimensional blood flow velocity imaging method comprises the following steps of performing layered irradiation on a sample through the lamellar light; collecting each layer of signals scattered when the layered light irradiates the sample, and for each layer, collecting a frame of image at a time interval of 1 / f to obtain m frames of original blood flow images until the images at all the layers are collected; constructing the m frames of original blood flow images to obtain dynamic blood flow images at the th layer until dynamic blood flow images of all layers are obtained; performing three-dimensional reconstruction on the dynamic blood flow images of all layers toobtain three-dimensional blood vessel distribution; and calculating the three-dimensional blood vessel speed according to the three-dimensional blood vessel distribution. The device comprises a lamellar light irradiation system, a collecting system and a processing system. Compared with the prior art, the three-dimensional blood vessel speed can be well obtained. The method and device are mainly applied to the technical field of image processing.

The invention belongs to the technical field of fluorescence labeling, and particularly relates to an amino-substituted chromene quinoline type fluorescence marker as well as preparation and application thereof. According to the invention, amino groups of aromatic amine compounds and two ortho-chlorine-containing aldehyde coumarins are subjected to a one-step cyclization reaction to obtain a series of novel nitrogen-containing heterocyclic compounds. The compound has excellent fluorescence emission performance and also has good light stability in different organic solvents. According to the invention, the problem of poor light stability of cyanine dyes is effectively solved, and different organelles can be marked at the cellular level. The nitrogen heterocyclic ring is introduced, so that the biocompatibility of the compound is improved, and a good foundation is laid for biological application. Besides, the raw materials of the reaction are cheap and easy to obtain, the steps for synthesizing the marker are simple and easy to operate, the production cost can be effectively reduced while the performance of the marker is not reduced, and certain commercial value is achieved.

The invention discloses a method for detecting trace Fe<3+>, Hg<2+> and Cu<2+> in living cells through double-channel fluorescence imaging. A triamine-ethylamine derivative called as a probe for shortserves as a fluorescence imaging probe for detection of trace Fe<3+>, Hg<2+> and Cu<2+> in living cells through double-channel fluorescence imaging, and the trace Fe<3+>, Hg<2+> and Cu<2+> in livingcells are detected through double-channel fluorescence imaging. By means of the method, detection of multiple target ions can be realized. The probe and Fe<3+>, Hg<2+> and Cu<2+> form a probe-Fe<3+> complex, a probe-Hg<2+> complex and a probe-Cu<2+> complex respectively, strong fluorescence with different wavelengths is emitted, and the method facilitates detection, is good in visibility, high insensitivity and good in selectivity and can realize real-time online detection of Fe<3+>, Hg<2+> and Cu<2+> ions in the cells.

The invention discloses a nano diagnosis and treatment agent, a preparation method and application thereof, wherein the nano diagnosis and treatment agent comprises nano particles, and the nano particles comprise an inner core of a small molecular prodrug responsive to active oxygen, and a shell formed by coating the surface of the inner core with an amphiphilic polymer. The nano diagnosis and treatment agent is formed by depositing a small molecular prodrug and an amphiphilic polymer in water, and nano particles are simple in component and good in stability, have tumor response imaging and treatment effects and have good application prospects in the field of tumor diagnosis and treatment.

The invention relates to a fusarium moniliforme SiC quantum dot fluorescence labeling method and particularly relates to a fluorescence labeling method for fusarium moniliforme SiC in different growth stages by cytotoxicity-free aqueous phase silicon carbide quantum dots, and a long-time-period fluorescence imaging technology for living cells. The method comprises the following steps of preparing a mixed solution of slant strain fusarium moniliforme and a PD culture medium; preparing a mixed culture medium of a mycete liquid-SiC quantum dot aqueous phase solution from the mixed solution and an SiC quantum dot aqueous phase solution at a volume ratio of 3:1; performing constant-temperature shaking culture on the mixed culture medium at a temperature of 28 DEG C and a speed of 200r / min for 3-10 days, thereby obtaining a fusarium moniliforme SiC quantum dot fluorescent mark; applying the mark to seedling root dip dyeing, thereby realizing dynamic monitoring, tracing and fluorescence imaging of a process that the fusarium moniliforme infects plant roots. The method is simple and effective, is low in cost and is capable of realizing fluorescence labeling of the fusarium moniliforme in different periods.

The invention relates to the technical field of chemical synthesis, in particular to a compound, a preparation method thereof, a fluorescent probe and an antitumor drug. The invention discloses a compound as shown in a formula (I) which is described in the specification. The compound is accurately targeted and recognized through a hyaluronic acid ligand-receptor mediation effect; the overexpressedesterase in tumor cells releases TP-PPh3 by destroying an ester bond between the TP-PPh3 and hyaluronic acid, and fluorescence quenched by aggregation of the TP-PPh3 can be recovered. At mitochondrial respiration period, the proton pump in the membrane transports protons to the space in the mitochondrial membrane to form a mitochondrial transmembrane potential with high negativity, so that triphenylphosphine cations have the mitochondrial targeting capability, a mitochondrial region of a tumor can emit red fluorescence under the irradiation of near-infrared light, and fluorescence imaging ofthe tumor part is realized. When a laser of 650-980nm is used for irradiating tumor tissues, the TP-PPh3 can convert absorbed light energy into heat energy, so that tumors are ablated, and photothermal therapy is realized.

The invention discloses an NIR-II fluorescence enhancement liposome and a preparation method and application thereof. The liposome film of the NIR-II fluorescence enhancement liposome contains an NIR-II fluorescent probe IR1061, and indocyanine green is wrapped in liposome watercore. The preparation method comprises the steps of enabling components of the liposome film to disperse in an organic solvent, performing rotary evaporation and film formation, removing remaining organic solvents, adding the indocyanine green solution, and performing hydration. The NIR-II fluorescence enhancement liposome is free from inorganic nanometer materials, through co-carrying of ICG and IR1061, the fluorescence enhancement liposome which is notably higher than single components is obtained, and is higher than the IR1061 liposome (about 4 times), and a liposome emission peak causes red shift; and the fluorescence intensity of the NIR-II fluorescence enhancement liposome is greatly improved, so that required fluorescent imaging can be realized within low-dose low-power conventional exposure time.

The invention discloses a preparation method and application of electropositive polymer fluorescent carbon quantum dots with a gene vector function, and relates to the preparation method and application of the fluorescent carbon quantum dots. The invention aims at solving the problems of heavy metal ions, low yield of quanta and unstable fluorescent property in the existing semiconductor fluorescent nano particles. The preparation method comprises the following steps: 1, adding organic acid and a cationic high molecular polymer, performing ultrasonic dissolution at room temperature to form a mixed solution; 2, charging the mixed solution into a reaction kettle, and heating for reaction until the color of the mixed solution turns into black brown; 3, adding water with the volume being 2 times of that of the black brown solution into the black brown solution, removing solid by centrifuging, and reserving the solution; and 4, adding deionized water to the solution, uniformly mixing and then recentrifuging the solution, removing solid, and then performing dialyses treatment to obtain the water solution of polymer carbon quantum dots. The polymer fluorescent carbon quantum dots synthesized by the method have superior fluorescent stability and high yield of quanta which is over 60%. The preparation method is used for preparing the polymer fluorescent carbon quantum dots.

The invention discloses a turn-back continuous multi-mode hyperspectral imaging system, which comprises a fixed support part, a transmission control module, a light source module, a spectral imaging module and a control and data processing center module. By the multi-mode hyperspectral imaging system, point scattering, reflection, transmission and interaction imaging modes can be achieved, so that a plurality of quality and safety indicators of a to-be-tested sample can be simultaneously achieved; and a relatively accurate decision is provided for experimental study and industrial production. Furthermore, a fluorescent hyperspectral imaging technology can be achieved by exchanging a light source; and the turn-back continuous multi-mode hyperspectral imaging system can also be achieved by combining a microscopic imaging technology. A multispectral chip is etched by a stroboscopic light source or a semiconductor on the basis of the turn-back continuous multi-mode hyperspectral imaging system, so that a corresponding multispectral imaging system can be built; and the industrial high-flux detection requirements are met.

The invention discloses a near-infrared selenocysteine fluorescent probe as well as a preparation method and application thereof. The structure of the near-infrared fluorescent probe for detecting selenocysteine is shown as (I), and the near-infrared fluorescent probe has the advantages of high reaction speed, good selectivity, high sensitivity and low detection limit. Under the physiological pH value, after the fluorescent probe reacts with selenocysteine with different concentrations, the fluorescence intensity and concentration show a good linear relationship, and the fluorescent probe is suitable for quantitative detection of selenocysteine, is used for fluorescence imaging of selenocysteine in human lung cancer cells A549, and can quantitatively detect selenocysteine in cells.

The present invention relates to a polyhydrogen sulfide fluorescent probe and its preparation method and application, its fluorescent probe AIE-PS2 has a larger Stokes shift (254nm), good selectivity, high sensitivity, low detection limit (9nM ), high fluorescence response times (75 times) and good biocompatibility. In PBS buffer, the fluorescence intensity and Na 2 S 4 (0‑20μM) concentration has a good linear relationship, indicating that the probe is suitable for the quantitative detection of polyhydrogen sulfide in vivo; the probe AIE‑PS2 can detect endogenous and exogenous polyhydrogen sulfide at the cellular level Imaging, and further applied AIE‑PS2 to realize the fluorescence imaging of polyhydrogen sulfide in MCF‑7 cells, which is an effective tool for visual and quantitative detection of polyhydrogen sulfide. The structural formula of the fluorescent probe AIE‑PS2 is as follows.

The invention discloses a method for detecting trace amounts of Ca<2+>, Sr<2+> and Ba<2+> in active cancer cells through single-channel fluorescence imaging. By using classic calixarene [4] derivativeas a probe, and the trace amounts of Ca<2+>, Sr<2+> and Ba<2+> in the active cancer cells are respectively detected through the single-channel fluorescence imaging. According to the method disclosedby the invention, detection on multi-target ions can be realized; a coordination compound of a probe-Ca<2+>, a probe-Sr<2+> and a probe-Ba<2+> can be respectively formed by the probe disclosed by theinvention and Ca<2+>, Sr<2+> and Ba<2+> in the cells, and intense fluorescence with different wavelengths can be emitted, so that detection is conveniently carried out, the visibility is good, the sensitivity is good, the selectivity is good, and real-time on-line detection of the Ca<2+>, Sr<2+> and Ba<2+> in the cells can be realized.

The invention relates to a ratio-type fluorescent molecular probe for detecting hypochlorite ions and its preparation method and application, belonging to the technical field of chemical fluorescent materials; the invention uses compound 6-bromo-2-(2-morpholinoethyl) ‑1H‑benzo[iso]quinoline‑1,3(2H)‑diketone and coumarin aldehyde are used as raw materials to obtain the probe described in the present invention; the present invention is based on coumarin and naphthalimide A fluorophore constructed a novel lysosome-localized fluorescent probe, and used it for the ratiometric detection of ClO‑, realizing the detection of endogenous or exogenous ClO ‑ fluorescence imaging.

The invention discloses a method for assaying trace Al3+ in living cells by double-channel fluorescence imaging, which assays trace Al3+ in living cells by double-channel fluorescence imaging with a probe with the chemical name of tri[di(naphthylthioureido)-rhodamine formamido]ethylamine fluorescence imaging probe for assaying trace Al3+ in the living cells by double-channel fluorescence imaging. In the method disclosed by the invention, the probe and Al3+ are formed into a complex in the cells, strong fluorescence is emitted, consequently, assay is convenient, visuality is good, sensitivity is high, selectivity is good, and the Al3+ ions in the cells can be assayed on line in real time.