97 results about "Ratiometric fluorescence" patented technology

The invention discloses a method for distinguishing similar antibiotics by using a fluorescent sensing array based on YOLOv5 target recognition. The method comprises the following steps: S1, preparing GMP-Tb solid powder; s2, mixing the GMP-Tb solid powder with a rhodamine B solution in proportion to obtain a multi-proportion fluorescent probe; s3, mixing antibiotics with different concentrations with the multi-proportion fluorescent probe to obtain a fluorescent sensing array; s4, collecting color images in the fluorescent sensing array and dividing the color images into a training set and a test set; s5, constructing an OLOv5 optic nerve model, inputting the acquired color image into a YOLOv5 optic nerve model, and outputting a feature value of the acquired color image; s6, inputting the characteristic value of the color image into a classifier model for prediction classification to obtain a distinguishing result; and S7, inputting a color image formed by mixing the to-be-detected antibiotic and the multi-proportion fluorescent probe into the YOLOv5 optic nerve model to obtain a characteristic value of the color image, and then outputting a distinguishing result through the classifier model.

The invention discloses a preparation method and application of a granzyme B response near-infrared two-region ratiometric fluorescent probe (DCGA). The DCGA combines the NIR-II dual-emission fluorescence characteristic of rare earth ions with a ratio-type signal response mode, the sensitivity and signal stability of in-vivo fluorescence imaging are greatly improved, ultralow or enhanced F1060nm fluorescence signals are respectively shown before and after interaction with granzyme B (GzmB), F1525nm fluorescence signals are almost kept unchanged, and the DCGA can be used for detecting the in-vivo fluorescence imaging of the granzyme B (GzmB). Therefore, the self-calibration ratio fluorescence imaging GzmB activity change is realized. The DCGA is applied to tumor treatment of immunotherapy drugs, and responders and non-responders of immunotherapy can be distinguished in a non-invasive early stage through ratio fluorescence signals of the DCGA. Therefore, the fluorescent probe can be used as an effective GzmB active NIR-II ratio fluorescence imaging tool, and is expected to provide powerful support for immunotherapy research, precision medicine and personalized diagnosis and treatment.

The invention discloses a dual-emission molecular imprinting ratiometric fluorescence sensor, a preparation method thereof and application of the dual-emission molecular imprinting ratiometric fluorescence sensor in aureomycin detection, and belongs to the technical field of chemical sensors. The preparation method of the sensor comprises the following steps: preparing silicon dioxide-quantum dot composite nanoparticles, and preparing a molecularly imprinted polymer by taking salicylamide as a template molecule; and mixing the molecularly imprinted polymer and the silicon dioxide-quantum dot composite nanoparticles in an HEPES buffer solution by adopting a post-mixing strategy to construct the dual-emission molecularly imprinted ratiometric fluorescence sensor. The double-emission molecular imprinting ratiometric fluorescence sensor has the beneficial effects that the double-emission molecular imprinting ratiometric fluorescence sensor provided by the invention is rich in fluorescence color change, rapid, high-sensitivity and visual detection of aureomycin can be realized, the whole detection process is simple, convenient and rapid, and the double-emission molecular imprinting ratiometric fluorescence sensor is suitable for being widely popularized in practical application.

The invention provides a ratio fluorescent probe for detecting aureomycin in meat food and a detection method. After an aureomycin solution is added into the prepared Au NCs ratiometric fluorescent probe solution, a fluorescence emission band of a reaction system at 620 nm is almost unchanged, and a fluorescence emission band at 425 nm is remarkably enhanced. Meanwhile, the color of a reaction system under an ultraviolet lamp is gradually changed from red to purple along with the increase of the concentration of the aureomycin, and quantitative detection of the aureomycin can be realized by utilizing the characteristics. The detection method disclosed by the invention comprises two detection methods, one is a ratio fluorescent probe detection method, and quantitative detection is realized by utilizing linear correlation between the F425 / F620 fluorescence intensity ratio and the chlortetracycline concentration. The other method is a visual quantitative detection method, a fluorescent paper chip image is collected by using a smart phone and converted into a corresponding RGB value, and quantitative detection is realized by using a linear relationship between an R / B value and the chlortetracycline concentration. The detection method disclosed by the invention has the advantages of high selectivity, high sensitivity, simplicity in operation, obvious phenomenon and good stability and repeatability.

The invention provides a ratiometric fluorescence sensing system and a preparation method and application thereof, and the preparation method comprises the following steps: respectively preparing a silicon oxide-based aggregation-induced emission material and a copper-doped carbon dot material, and mixing the silicon oxide-based aggregation-induced emission material and the copper-doped carbon dot material with an ascorbic acid-2-phosphoric acid material to construct the ratiometric fluorescence sensing system. The fluorescent probe is applied to ferric ion detection, in-vitro detection of biomarkers or fluorescence imaging. The technical scheme provided by the invention has good stability, accuracy and practical application potential.

The invention belongs to the technical field of fluorescent probes, and provides a design strategy of a molecularly imprinted polymer ratiometric fluorescent probe based on two-color carbon dots in order to solve the problems that a current molecularly imprinted polymer fluorescent probe based on a single emission carbon dot is poor in detection result precision and is easily influenced by external environment interference and operation errors and the like. The fluorescent probe can be used for detecting catechol. The blue light-emitting carbon dots and the yellow light-emitting carbon dots are synthesized through traditional hydro-thermal synthesis; on the basis of blue luminous carbon dots, a molecularly imprinted polymer based on the blue luminous carbon dots is synthesized through a sol-gel method, and the molecularly imprinted polymer is combined with yellow luminous carbon dots through physical action. The ratiometric fluorescence strategy has the advantages of rapidness, effectiveness, stable performance, strong anti-interference capability, no need of expensive instruments and equipment, simplicity and convenience in operation, low detection cost and the like, solves the problem of low selectivity of single-fluorescence carbon dot detection, increases signal sources of imprinted polymer detection, and more importantly, reduces background interference due to colorimetric imprinting, so that the detection efficiency is improved. And the detection accuracy is improved.

The invention discloses application of a ratiometric fluorescence sensor based on a fluorescein isothiocyanate labeled metal organic framework in escherichia coli detection. The method comprises the following steps: synthesizing ZTMs by taking TPPS as a ligand, and then fully incubating with FITC to prepare ZTMs (at) FITC; according to the present invention, Escherichia coli is used to reduce Cu < 2 + > to Cu < + >, such that the fluorescence intensity of ZTMs (at) FITC is changed, the fluorescence intensity of the emission peak at the 515 nm position is reduced, the fluorescence intensity of the emission peak at the 683 nm position is increased, and the color of the solution is observed to gradually change from yellow to orange and finally to red under the 365 nm ultraviolet light; and rapid and sensitive detection of the escherichia coli is realized through the ratio of the fluorescence intensities of the two emission peaks. According to the detection method, the accuracy of a detection result is improved, errors caused by environment, instruments and manual operation can be avoided, professional operators are not needed, the method has the advantages of being rapid, simple and independent of expensive instruments and equipment, and the detection cost is reduced.

The invention discloses a ratiometric fluorescent probe for detecting enrofloxacin. The ratiometric fluorescent probe is obtained by packaging gold nanoclusters (AuNCs) in an MOFs (Metal-Organic Frameworks) material based on a metal organic framework, the gold nanocluster AuNCs takes glutathione as a precursor and is prepared from gold chloride trihydrate; the MOFs material is formed by assembling a metal ion Zn < 2 + > and an organic ligand 2-methylimidazole. The obtained ratiometric fluorescence probe is suitable for ratiometric fluorescence detection of an enrofloxacin-containing sample, especially an animal-derived food sample, the detection method is convenient and rapid, the detection result is accurate and stable, and qualitative and quantitative analysis is facilitated. An enrofloxacin ratiometric fluorescence detection analysis method constructed by using the ratiometric fluorescence probe is short in detection time, low in detection cost and beneficial to practical application and popularization.

The application discloses an aggregation-induced emission compound with double fluorescence emission characteristics and a preparation method and application thereof, and the proportional fluorescence probe has a structure of general formula I. The probe molecule has a polar response group tetraphenyl ethylene as a fluorescence report unit, introduces a hydrophilic oxygen atom, connects an alpha carbon of an acetamide, and connects a polar detection sensitization group Tag chain on an amino group of the acetamide. The probe molecule improves the conjugation degree of oxygen atom lone pair electrons and a tetraphenyl ethylene pi electron system, so that the probe molecule simultaneously produces n→pi* and pi→pi* molecular transitions, and a proportional fluorescence probe which can sensitively respond to polarity change is constructed. The fluorescence probe designed in the application has the advantages that the fluorescence probe is not easily interfered by probe concentration, a detection environment and light bleaching, and experiments prove that the proportional fluorescence intensity of the fluorescence probe can sensitively respond to polarity, and the proportional fluorescence intensity and water content are linearly fitted, so that the purposes of detecting water content in an organic reagent and alcohol content in wine are achieved.

The invention discloses a preparation method of a portable paper-based ratiometric fluorescence sensor APBA-CsPbBr3 at-UiO-66 / Ru, which comprises the following steps: 1, adding lead bromide and cesium bromide into N, N-dimethylformamide, then adding 5-bromovaleric acid and an oleylamine ligand, and stirring; 2, perfluorooctyltriethoxysilane is added, and a precursor solution is obtained; 3, adding zirconium chloride and terephthalic acid into N, N-dimethylformamide to obtain a homogeneous solution; 4, after heating, UiO-66 is obtained; 5, stirring the precursor solution, APBA, UiO-66 and tris (2, 2-dipyridyl) ruthenium chloride hexahydrate to obtain a composite material; and 6, dropwise adding the composite material solution into the filter paper. The APBA modified material is adopted as a recognition unit, the APBA modified material and the paper base construct a fluorescence sensing platform, visual quantitative analysis of oxytetracycline in water is achieved, and the device is convenient to carry, low in detection limit, high in anti-interference performance, easy and convenient to operate and suitable for on-site rapid detection of oxytetracycline.

This invention discloses a dual-emission molecularly imprinted ratiometric fluorescence sensor, its preparation method, and its application in the detection of chlortetracycline, belonging to the field of chemical sensor technology. The preparation method of this sensor includes the following steps: preparing silica-quantum dot composite nanoparticles; preparing a molecularly imprinted polymer using salicylamide as a template molecule; and using a post-mixing strategy to mix the molecularly imprinted polymer and silica-quantum dot composite nanoparticles in HEPES buffer to construct the dual-emission molecularly imprinted ratiometric fluorescence sensor. The advantages of this invention are: the dual-emission molecularly imprinted ratiometric fluorescence sensor provided by this invention exhibits rich fluorescence color changes, enabling rapid, highly sensitive, and visual detection of chlortetracycline; and the entire detection process is simple, convenient, and fast, making it suitable for widespread application in practical applications.

The present invention discloses a method for detecting clioquinol by ratio fluorescence based on AuNCs / CDs@SiO2. In the present invention, gold nanoclusters and carbon dots coated with silica are compounded to prepare AuNCs / CDs@SiO2. A CuCl2 solution, clioquinol solutions with different concentrations, and H2O are added to a centrifuge tube for reaction; AuNCs / CDs@SiO2 is added to the reaction mixture for reaction; after the reaction, a fluorescence photometer is used to measure the fluorescence emission spectrum of the resulting mixed solution, excited under an Xe lamp, and the fluorescence intensities at wavelengths of 420 nm and 595 nm are recorded; and a standard working curve is plotted with the CQ concentration as the abscissa and the fluorescence intensity ratio at 420 nm and 595 nm as the ordinate; the above steps are repeated for the clioquinol sample to be tested, and the fluorescence intensity ratio after the reaction of the sample to be tested with the system is measured respectively by a fluorescence photometer, and the concentration of clioquinol CQ to be tested is obtained through calculation. Using the method of the present invention to detect clioquinol, both the sensitivity and the accuracy are relatively high.

The present invention discloses a lipid droplet-targeted bifunctional ratiometric fluorescent probe and its application in the preparation of a •OH detection reagent, wherein the structure of the bifunctional ratiometric fluorescent probe is as follows: #imgabs0#. The bifunctional ratiometric fluorescent probe of the present invention can respond to different concentrations of •OH with ratiometric fluorescence, with a detection limit as low as 1.18nM and a difference between the two emission peaks as high as 140 nm, enabling dual-channel detection without crosstalk. Cytotoxicity tests have shown that the probe has good biocompatibility, and confocal fluorescence microscopy experiments have shown that the probe has good photostability for HepG2 cells, has the ability to monitor changes in endogenous and exogenous •OH concentrations in cells through dual channels, and has the ability to image lipid droplets (R 2 =0.85), which is suitable for confocal fluorescence imaging of intracellular lipid droplet tracking.

The invention belongs to the field of antibiotic detection, and relates to detection of norfloxacin (NOR). The invention provides a Luminol-Eu-NCDs ratiometric fluorescent probe as well as a preparation method and application of the Luminol-Eu-NCDs ratiometric fluorescent probe. According to the application, a novel ratiometric fluorescence sensor is constructed through covalent linkage of Luminol-Eu self-assembled and synthesized by AIE and NCDs derived from Listeria monocytogenes. The Luminol-Eu NPs with the AIE effect overcomes the fluorescence quenching characteristic of a traditional fluorophore in a high concentration or aggregation state, so that the reference fluorescence brightness of fluorescence analysis is greatly improved. In addition, due to the introduction of the Luminol-Eu NPs, the sensitivity and the accuracy of NOR detection can also be improved. On the basis, a simple ratio fluorescence sensor with high selectivity is developed, and the ratio fluorescence sensor is used for detecting NOR residues in a milk sample.

The invention discloses a label-free proportional type luminous aptamer biosensor for staphylococcus aureus enterotoxin A (SEA). The label-free proportional type luminous aptamer biosensor comprises the following steps: (1) advanced evolution screening of a complex matrix high-adaptability aptamer; (2) rationally cutting the aptamer assisted by computer simulation; (3) a construction strategy of the label-free proportional biosensor; (4) a label-free proportional SEA bifunctional biosensor sequence; (5) optimizing conditions of the label-free proportional SEA biosensor; and (6) SEA detection. The design principle is that fluorescence of SEA and ThT is excited to different degrees on the basis of a competitive binding effect between an SEA target and a small molecule nucleic acid dye thioflavin T (ThT) as well as a luminous nucleic acid aptamer, so that the ratio of fluorescence signals of the SEA and the ThT is in a linear relationship with the target concentration, and finally, rapid, label-free and low-cost proportional fluorescence detection of the SEA is realized.

This invention discloses a GSH-functionalized carbon dots / rhodamine B ratiometric fluorescence system, its construction method, and its application in nitrite detection. GSH-CDs are synthesized via a one-step hydrothermal method by mixing citric acid, o-phenylenediamine, glutathione, and hydrochloric acid in water. Unreacted precursors and small molecules are removed by purification, and the GSH-CDs are obtained by freeze-drying. The ratiometric fluorescence system is constructed by mixing rhodamine B, GSH-CDs, and an acidic buffer solution. The fluorescence intensity ratio F of GSH-CDs to rhodamine B is established. 460 / F 590 With nitrite (NO2) ‑ A calibration curve between concentrations was obtained, and the NO2 in the actual sample was experimentally detected using the spiked recovery method. ‑ Content. Under acidic conditions, with NO2... ‑ With increasing concentration, the GSH-CDs / RhB fluorescence intensity ratio (I 460 / I 590 Significant changes occurred, with the fluorescence intensity ratio compared to NO2. ‑ There is a good linear relationship between concentrations. Compared with the detection platform based on GSH-CDs, the ratio fluorescence system provided by this invention has a lower detection limit and significantly higher sensitivity.

The invention belongs to the technical field of fluorescent probes, and particularly relates to a fluorescent probe for detecting pyrophosphoric acid or pyrophosphate based on ratiometric fluorescence, a preparation method and application. According to the fluorescent probe, cyclotriphosphazene is taken as a core platform, a naphthalimide-triphenylamine luminophore and a terpyridine recognition unit are introduced, a multi-arm fluorescent probe is integrally formed, coordination terpyridine interacts with metal ions Zn < 2 + >, fluorescence signals are induced to change, and therefore sensitive detection on PPi is achieved. The fluorescent probe has the advantages of quick response, high selectivity, interference resistance and low cost, and has important application value in the fields of environmental science, biological science and the like.

The present invention provides a novel metal nanomaterial, specifically a silver cluster metal nanomaterial, a preparation method, and its application. Over a wide temperature range, there is a one-to-one correspondence between the emission intensity at 545 nm and the emission intensity at 505 nm. This property demonstrates the material's superior ratiometric fluorescence thermometry performance. The silver cluster metal nanomaterial can be used as a nanofluorescence thermometer and has great application potential in high-tech fields such as biomedicine (such as cell metabolism, pathology, medical imaging, and drug delivery) and electronic component manufacturing.

This invention belongs to the field of food and agricultural product safety testing technology, specifically relating to a rapid detection method for parathion and its application. Based on the parathion-induced blue shift in fluorescence of silicon nanoparticles, ascorbic acid is reacted with 3-aminopropyltriethoxysilane to generate green fluorescent silicon nanoparticles. During the formation of silicon nanoparticles, parathion can embed itself into the porous structure of the silicon nanoparticles through host-guest interactions, causing a change in the excited state of the silicon nanoparticles. This affects the fluorescence emission of the silicon nanoparticles, resulting in a blue shift in the fluorescence emission peak, changing from green fluorescence to blue fluorescence, specifically manifested as an increase in fluorescence intensity at 422 nm and a decrease in fluorescence intensity at 520 nm. By establishing the relationship between ratiometric fluorescence signal or fluorescence color change and parathion concentration, specific detection of parathion is achieved. This invention requires no enzymes or antibodies for parathion detection, is inexpensive, fast, easy to operate, highly sensitive, and has good specificity.

This invention provides a method for constructing a donor-acceptor type perylene diimide-based porous conjugated polymer probe and detecting methamphetamine and amphetamine solutions. The method synthesizes donor-acceptor type perylene diimide-based porous conjugated polymer probes with different topologies by combining an electron acceptor perylene diimide derivative and an electron donor aggregation-induced emission fluorophore via a succinate coupling reaction. When used for the detection of methamphetamine and amphetamine, this system exhibits a clear ratiometric fluorescence response, with the fluorescence color gradually changing from yellow-green to orange and orange-red, demonstrating a significant ratiometric fluorescence response. It features fast response speed, high detection sensitivity, good selectivity, and no interference from other common structurally and property-similar substances, enabling the differentiation and identification of methamphetamine and amphetamine.

The invention belongs to the technical field of food detection, and particularly relates to a molecular imprinting ratiometric fluorescence sensor as well as a preparation method and application thereof. The preparation method comprises the following steps: firstly, preparing SiO2 microspheres by adopting an improved Stober method, then respectively preparing a bCDs (at) SiO2 composite material and rCDs by adopting a one-step hydrothermal method, and finally, preparing the molecular imprinting ratio fluorescence sensor bCDs (at) SiO2amp by taking the bCDs (at) SiO2 composite material and the rCDs as fluorescence sources and adopting a sol-gel method. The sensor can be used for high-selectivity and high-sensitivity detection of the ethyl carbamate.

The invention belongs to the technical field of detection of organophosphorus pesticide residues in agricultural products, and particularly relates to a dual-mode detection method of isocarbophos, which comprises the following steps: mixing Fe3O4 (at) Cu-BTC / Apt, CS / S and N-CDs, adding an STE buffer solution, incubating to form a hybrid compound Fe3O4 (at) Cu-BTC / Apt-CS / S and N-CDs, and removing unreacted CS / S and N-CDs through magnetic separation; washing the compound, and resuspending the compound in a PBS buffer solution; adding an ICP (inductively coupled plasma) solution into the buffer solution, incubating, and removing supernate through magnetic separation to obtain a precipitate; and adding a HAc-NaAc buffer solution, an OPD solution and an H2O2 solution into the precipitate, fully reacting, measuring the absorbance value of the reaction system at 450 nm, and measuring the fluorescence intensities at 465 nm and 575 nm under the excitation wavelength of 390 nm. Two independent detection results of colorimetric and ratiometric fluorescence can be mutually verified, so that the results are more accurate, and false positive and false negative results are avoided; a colorimetric mode provides a result which can be observed by naked eyes, and a ratio fluorescence mode ensures high sensitivity of a detection result; finally, the dual-mode detection method has the advantages of simplicity, convenience, high accuracy, high sensitivity and the like.

One embodiment of the present invention provides a peptide-based real-time proportional fluorescence sensor with excellent selectivity for methylmercury ions and mercury ions, and a method for detecting methylmercury and mercury ions using the same. According to one embodiment of the present invention, the peptide-based real-time proportional fluorescence sensor with excellent selectivity for methylmercury ions and mercury ions dissolves well in a pure aqueous solution (1% DMSO), is excited by visible light, and can recognize Hg(II) and methylmercury with high sensitivity through proportional fluorescence behavior. In particular, it exhibits a fast detection speed for methylmercury and has high water solubility, but this fluorescence sensor penetrates well into cells and can sensitize Hg(II) and methylmercury inside the cell through a change in the ratio of red and green fluorescence.

The present invention provides a fluorescent probe and its preparation method and application. The structural formula of the fluorescent probe is as follows: The preparation method is: 7-N,N-diethylamino-2H-chromene-3-aldehyde, 4-methyl-N-(4'-boronic acid pinacol benzyl) pyridine bromide, a catalyst and a solvent are stirred, mixed and heated under reflux for reaction, and then filtered and recrystallized to obtain a fluorescent probe product. The probe has good water solubility, biocompatibility and is positively charged. The solution color is purple-red, the absorption peak is at 540nm, and the fluorescence peak is at 720nm (near-infrared region), which can be used for near-infrared biological fluorescence imaging. The probe has the property of realizing ratiometric colorimetry and ratiometric fluorescence response to peroxynitrite. After reacting with peroxynitrite in a CH3CN-pbs (v / v=1:1, v / v, pH=7.4) solution, the color of the probe solution changes from purple-red to slightly yellow, A 410nm / A 540nm The probe has a linear relationship with the concentration of peroxynitrite in the range of 0 to 10 μM, with a detection limit of 95 nM. The red fluorescence of the probe gradually weakens at 720 nm and the bright yellow fluorescence gradually increases at 568 nm. 568nm / I 720nm The probe has a linear relationship with peroxynitrite concentration in the range of 0 to 16 μM, with a detection limit of 10 nM. The probe has the advantages of high sensitivity, low detection limit, and low background fluorescence interference.

This invention discloses the construction and application of a multifunctional ratiometric fluorescence sensing platform based on aggregation-induced emission nanozymes, belonging to the field of nanocomposite materials technology. This invention involves the stepwise synthesis of a zirconium-based aggregation-induced emission metal-organic framework (Zr-TCPE) and cadmium telluride quantum dots (CdTe QDs), followed by the preparation of a Zr-TCPE / CdTe ratiometric fluorescent nanozyme using an electrostatic self-assembly method. In this composite material, Zr-TCPE exhibits organophosphorus hydrolase-like activity, specifically catalyzing the hydrolysis of para-oxygen and phosphorus, resulting in specific quenching of its fluorescence at 475 nm. Meanwhile, the fluorescence of CdTe QDs remains stable at 585 nm, enabling self-calibrated detection through the ratio of the two fluorescence signals. This invention features mild synthesis conditions and simple operation. The constructed sensing platform has a detection range spanning four orders of magnitude, a low detection limit, strong anti-interference ability, and excellent long-term stability over 24 days. It can be effectively used for rapid and highly sensitive detection of para-oxygen and phosphorus in complex samples of organophosphorus pesticides.

The invention belongs to the field of food safety detection, and particularly relates to a norfloxacin visual ratio fluorescence detection method based on an integrated detection device and application of the norfloxacin visual ratio fluorescence detection method. The integrated detection device provided by the invention comprises a filtering module and a detection module, the filtering module comprises a first container as well as modified sodium alginate hydrogel and glass wool which are filled in the first container; the modified sodium alginate hydrogel comprises a sodium alginate matrix and polyvinyl alcohol doped in the sodium alginate matrix; the detection module comprises a second container and a sodium alginate hydrogel bead which is filled in the second container and comprises a probe; the probe comprises a copper nano-cluster which is coordinated with terbium ions and modified by dithioerythrine. The integrated detection device provided by the invention is simple to operate and reliable in result, realizes rapid detection and visual response of norfloxacin, and has very high practicability and wide applicability.

The present invention discloses a method based on Ce 3+ / Ce 4+ A fluorescence and colorimetric dual-mode detection method for the simultaneous determination of hydrogen peroxide and organophosphorus using a cascade simulated enzyme reaction belongs to the field of fluorescence sensing detection technology. The present invention combines a smartphone color recognition application with a ratiometric fluorescence sensor to achieve real-time visual detection of H2O2 and OPs. The materials used in the present invention are not only low-cost and easy to obtain, but also do not require material synthesis, simplifying the detection process. In addition, the sensor is combined with a smartphone color recognition application to further simplify the detection workflow and achieve real-time data analysis and result feedback. This method provides a simple, efficient and economical solution for monitoring organophosphorus pesticides in agricultural products.

The present invention discloses a ratiometric fluorescence sensor, a preparation method thereof and an application, belonging to the technical field of chemical detection. The ratiometric fluorescence sensor of the present invention is prepared by the following method: adding a g-C3N4 nanosheet solution, an Eu(NO3)3·6H2O solution and a sodium citrate solution into a Tris-HCl buffer solution in sequence, mixing evenly, and incubating; after the incubation is completed, freeze-drying the incubation solution to obtain a g-C3N4 / CitNa / Eu nanoprobe, that is, the ratiometric fluorescence sensor. The ratiometric fluorescence sensor of the present invention can realize the rapid, intuitive and quantitative determination of tetracycline antibiotics remaining in a sample, has high sensitivity, good visualization effect, and can be used in combination with a smart phone for portable detection.

The present invention provides a detection method and application of a ratio-type fluorescence sensor for detecting OTA based on CHA. A ratio-type fluorescence sensor is constructed by using CDs and FAM as dual-emission fluorescence probes in combination with the CHA signal amplification technology. Finally, the ratio F FAM / F CDs is used to achieve the quantitative detection of ochratoxin A, with a linear range of 5.0 pg / mL - 3.0 ng / mL and a detection limit of 1.5 pg / mL. The ratio-type fluorescence sensor for detecting ochratoxin A in the present invention not only has a self-calibration function, can eliminate the interference of various variable or difficult-to-quantify factors such as probe concentration, polarity, temperature, and excitation intensity, broaden the response range, and effectively improve the accuracy and reliability of the detection results, but also does not involve enzymes such as proteases in the whole operation process, is less affected by the external environment, has high sensitivity, low requirements for operating conditions and operating costs, can achieve the accurate detection of ultra-trace OTA, and has the value of industrial application and popularization.

This invention proposes a ratiometric fluorescent probe molecule for detecting peroxynitrite, its preparation method, and its application, aiming to solve a problem in the technical field of fluorescent sensing materials. The ratiometric fluorescent probe molecules of this invention are HPIP-T-BnB and HPIP-K-BnB. The structural formulas of HPIP-T-BnB and HPIP-K-BnB are: [Insert structural formula here], and the structural formulas of HPIP-K-BnB are: [Insert structural formula here]. The preparation method includes the following steps: 4'-(diphenylamino)-4-(imidazo[1,2-a]pyridin-2-yl)-[1,1'-biphenyl]-3-ol or 4'-(9H-carbazole-9-yl)-4-(imidazo[1,2-a]pyridin-2-yl)-[1,1'-biphenyl]-3-ol undergoes a nucleophilic substitution reaction with 2-(4-(bromomethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxoborhecyclopentane to obtain HPIP-T-BnB and HPIP-K-BnB. The probes prepared in this invention can detect ONOO⁻ with high selectivity, high sensitivity, and quantification, and have been successfully applied to ratiometric fluorescence imaging of exogenous and endogenous ONOO⁻ in live cells. This provides a reliable and crucial tool for mechanism research and drug development in related diseases.