谷胱甘肽稳定的CdTe量子点荧光猝灭法测定痕量过氧化氢

以谷胱甘肽稳定的CdTe量子点作为荧光探针,基于荧光猝灭法对过氧化氢进行了定量检测,考察了缓冲溶液体系、量子点浓度、反应时间等多种因素的影响。实验结果表明,在pH=7.2的Na2HPO4-NaH2PO4缓冲液中,反应时间为15min,过氧化氢浓度为1.0×10-6～3.0×10-5 mol/L范围时,其线性回归方程为△F=9.78+7.56c(10-6 mol/L),线性相关系数和检测限分别为0.9992和1.27×10-8 mol/L。谷胱甘肽稳定的CdTe量子点荧光猝灭法已用于水样的测定,回收率在96%～103%之间,相对标准偏差RSD不大于3.3%,结果令人满意。     

A targetable fluorescent probe for imaging hydrogen peroxide in the mitochondria of living cells

We present the design, synthesis, and biological applications of mitochondria peroxy yellow 1 (MitoPY1), a new type of bifunctional fluorescent probe for imaging hydrogen peroxide levels within the mitochondria of living cells. MitoPY1 combines a chemoselective boronate-based switch and a mitochondrial-targeting phosphonium moiety for detection of hydrogen peroxide localized to cellular mitochondria. Confocal microscopy and flow cytometry experiments in a variety of mammalian cell types show that MitoPY1 can visualize localized changes in mitochondrial hydrogen peroxide concentrations generated by situations of oxidative stress.     

Design of a novel mitochondria targetable turn-on fluorescence probe for hydrogen peroxide and its two-photon bioimaging applications

Considering that hydrogen peroxide (H₂O₂) plays significant roles in oxidative stress, the cellular signal transduction and essential biological process regulation, the detection and imaging of H₂O₂ in living systems undertakes critical responsibility. Herein, we have developed a novel two-photon fluorescence turn on probe, named as Pyp-B for mitochondria H₂O₂ detection in living systems. Selectivity studies show that probe Pyp-B exhibit highly sensitive response toward H₂O₂ than other reactive oxygen species (ROS) and reactive nitrogen species (RNS) as well as biologically relevant species. The fluorescence colocalization studies demonstrate that the probe can localize in the mitochondria solely. Furthermore, as a bio-compatibility molecule, the highly selective and sensitive of fluorescence probe Pyp-B have been confirmed by its cell imaging application of H₂O₂ in living A549 cells and zebrafishes under the physiological conditions.     

Development of a highly sensitive fluorescence probe for hydrogen peroxide

Hydrogen peroxide is believed to play a role in cellular signal transduction by reversible oxidation of proteins. Here, we report the design and synthesis of a novel fluorescence probe for hydrogen peroxide, utilizing a photoinduced electron transfer strategy based on benzil chemistry to control the fluorescence. The practical value of this highly sensitive and selective fluorescence probe, NBzF, was confirmed by its application to imaging of hydrogen peroxide generation in live RAW 264.7 macrophages. NBzF was also employed for live cell imaging of hydrogen peroxide generated as a signaling molecule in A431 human epidermoid carcinoma cells.     

A FRET-based approach to ratiometric fluorescence detection of hydrogen peroxide

We report the synthesis, properties, and biological applications of Ratio-Peroxyfluor-1 (RPF1), a new ratiometric fluorescent reporter for hydrogen peroxide. RPF1 is comprised of a two-fluorophore cassette, where the spectral overlap between coumarin donor and fluoran/fluorescein acceptor partners can be controlled by the chemoselective peroxide-mediated deprotection of boronic ester pendants on the acceptor dye. RPF1 features good selectivity for hydrogen peroxide over a variety of reactive oxygen species, including superoxide and nitric oxide, a ca. 8-fold increase in fluorescence intensity ratio (lambda517/lambda464) upon H2O2 reaction, and excitation and emission profiles in the visible region. Experiments with viable yeast mitochondria show that RPF1 can monitor and quantify endogenous production of H2O2, establishing the potential utility of this approach for probing peroxide biology in living systems.     

Design of a novel mitochondria targetable turn-on fluorescence probe for hydrogen peroxide and its two-photon bioimaging applications

Considering that hydrogen peroxide (H₂O₂) plays significant roles in oxidative stress, the cellular signal transduction and essential biological process regulation, the detection and imaging of H₂O₂ in living systems undertakes critical responsibility. Herein, we have developed a novel two-photon fluorescence turn on probe, named as Pyp-B for mitochondria H₂O₂ detection in living systems. Selectivity studies show that probe Pyp-B exhibit highly sensitive response toward H₂O₂ than other reactive oxygen species (ROS) and reactive nitrogen species (RNS) as well as biologically relevant species. The fluorescence colocalization studies demonstrate that the probe can localize in the mitochondria solely. Furthermore, as a bio-compatibility molecule, the highly selective and sensitive of fluorescence probe Pyp-B have been confirmed by its cell imaging application of H₂O₂ in living A549 cells and zebrafishes under the physiological conditions.     

A selective, cell-permeable optical probe for hydrogen peroxide in living cells

We present the synthesis, properties, and biological applications of Peroxyfluor-1 (PF1), a new type of optical probe for intracellular imaging of hydrogen peroxide in living biological samples. PF1 utilizes a boronate deprotection mechanism to provide unprecedented selectivity and optical dynamic range for detecting H2O2 in aqueous solution over similar reactive oxygen species including superoxide, nitric oxide, tert-butyl hydroperoxide, and hydroxyl radical. We further demonstrate the value of this reagent for biological applications by imaging changes in [H2O2] in living mammalian cells.     

Gas-sensing internal enzyme fiber optic biosensor for hydrogen peroxide

Feasibility is demonstrated for a novel gas-sensing, internal enzyme biosensing scheme for the selective measurement of hydrogen peroxide. Two horseradish peroxidase catalysed reactions are evaluated for the detection of hydrogen peroxide as it crosses a microporous Teflon membrane at 37 degrees C. The rate at which hydrogen peroxide crosses the membrane is determined by either a fluorescence or chemiluminescence measurement and this rate is related to the concentration of hydrogen peroxide in the sample solution. Detection limits of 0.7 mM and 10 muM are estimated for the fluorescence and chemiluminescence methods, respectively. Selectivity is demonstrated for hydrogen peroxide over ascorbic acid, uric acid and tyrosine.     

硼酸及硼酸酯类过氧化氢荧光探针的最新研究进展

生物新陈代谢过程中产生的过氧化氢（H2O2）是生命活动所必需的,但是过量过氧化氢的存在可以引发多种疾病,因此对体内过氧化氢的检测具有重要意义.采用荧光探针法,借助激光共聚焦成像技术能够实现对活细胞和组织内的过氧化氢＂实时、可见、定量＂的检测,为深入阐明过氧化氢在生理和病理过程中所起的作用提供了一个重要手段.本文按荧光探针的结构分类,对近几年来以硼酸及硼酸酯基团作为荧光开关的具有高选择性和灵敏度的过氧化氢荧光探针进行了综述,主要探讨其设计思想、作用机制及应用,为过氧化氢探针的设计提供了新思路.     

A new route to self-assembled tin dioxide nanospheres: fabrication and characterization

Nearly monodispersed self-assembled tin dioxide (SnO2) nanospheres with intense photoluminescence (PL) were synthesized using a new wet chemistry technique. Instead of coprecipitating stannous salts, bulk tin (Sn) metal was oxidized at room temperature in a solution of hydrogen peroxide and deionized water containing polyvinylpyrrolidone (PVP) and ethylenediamine (EDA). SnO2 nanocrystals were produced with diameters of approximately 3.8 nm that spontaneously self-assembled into uniform SnO2 nanospheres with diameters of approximately 30 nm. Analysis was performed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV-vis absorption spectroscopy, PL spectroscopy, and fluorescence lifetime measurements. The SnO2 nanospheres displayed room-temperature purple luminescence with an intense band at 394 nm (approximately 3.15 eV) and a high quantum yield of approximately 15%, likely as a result of emission from the surface states of SnO2/PVP complexes. The present study could open a new avenue to large-scale synthesis of self-assembled functional oxide nanostructures with technological applications as purple emitters, biological labels, gas sensors, lithium batteries, and dye-sensitized solar cells.     

A Novel Fluorescent Probe for Hydrogen Peroxide and Its Application in Bio-Imaging

Hydrogen peroxide (H₂O₂) plays an important role in the human body and monitoring its level is meaningful due to the relationship between its level and diseases. A fluorescent sensor (CMB) based on coumarin was designed and its ability for detecting hydrogen peroxide by fluorescence signals was also studied. The CMB showed an approximate 25-fold fluorescence enhancement after adding H₂O₂ due to the interaction between the CMB and H₂O₂ and had the potential for detecting physiological H₂O₂. It also showed good biocompatibility and permeability, allowing it to penetrate cell membranes and zebrafish tissues, thus it can perform fluorescence imaging of H₂O₂ in living cells and zebrafish. This probe is a promising tool for monitoring the level of H₂O₂ in related physiological and pathological research.     

Boronate-based fluorescent probes for imaging cellular hydrogen peroxide

The syntheses, properties, and biological applications of the Peroxysensor family, a new class of fluorescent probes for hydrogen peroxide, are presented. These reagents utilize a boronate deprotection mechanism to provide high selectivity and optical dynamic range for detecting H2O2 in aqueous solution over similar reactive oxygen species (ROS) including superoxide, nitric oxide, tert-butyl hydroperoxide, hypochlorite, singlet oxygen, ozone, and hydroxyl radical. Peroxyresorufin-1 (PR1), Peroxyfluor-1 (PF1), and Peroxyxanthone-1 (PX1) are first-generation probes that respond to H2O2 by an increase in red, green, and blue fluorescence, respectively. The boronate dyes are cell-permeable and can detect micromolar changes in H2O2 concentrations in living cells, including hippocampal neurons, using confocal microscopy and two-photon microscopy. The unique combination of ROS selectivity, membrane permeability, and a range of available excitation/emission colors establishes the potential value of PR1, PF1, PX1, and related probes for interrogating the physiology and pathology of cellular H2O2.     

设计p-n同质结构实现碳氮光催化剂的全解水性能

非金属氮化碳(CN)因其独特的光催化性能而备受关注.本文利用水热处理、高温烧结、高能球磨和烧结的方法成功制得一种具有混合结构的CN光催化剂.先以三聚氰胺为原料进行水热处理(180℃,24 h),过滤干燥后,转移到高纯氩气保护下的管式炉中,于550℃处理1 h得到CN材料.然后将CN用三聚氰胺和氟化铵水热180℃处理24 h,过滤、干燥、煅烧(550℃,1 h)得到第二种材料.最后将其与CN材料按等比例混合,经高能球磨研磨,再于管式炉中在气氛保护下淬火,得到最终催化剂样品.由于这种结构的界面作用,使CN光催化剂显示出了高的光催化活性.它的产氢效果可以高达17028.82μmol h^–1g^–1,在420 nm光照下,其光量子效率也达到11.2%.随后,采用纳秒级别的时间分辨萤光(PL)光谱测得其荧光寿命为9.9 ns.有助于电子与空穴参与反应更有趣的是,在不加牺牲剂时,该光催化剂具有高效的全解水效果,其产氢效率为270.95μmol h^–1g^–1,产氧效率为115.21μmol h^–1g^–1,有望实际用于全解水反应中.另外,通过紫外可见漫反射光谱,PL光谱和材料的比表面等测试来考察该CN光催化剂效果好的原因.发现该材料具有更高比表面积有更多活性点参与反应.同时,通过电化学测试获得了肖特基曲线和电流-电压曲线,发现该光催化剂里含有少量的pn结构,这种结构使材料在弱光下也会产生光生载流子,实际上它是起到光生载流子的激发作用,即在相同光照下,就会产生更多的光生载流子数量,从而进一步提高了其催化效果.因此,本工作对优化碳氮光催化剂的催化效果有很好的指导意义.     

Fibre optic fluorometric enzyme sensors for hydrogen peroxide and lactate,based on horseradish peroxidase and lactate oxidase

An optical biosensor for the determination of hydrogen peroxide based on immobilized horseradish peroxidase is described. The fluorescence of the dimeric product of the enzyme catalysed oxidation of homovanillic acid is utilized to determine the concentration of H₂O₂. The membrane-bound enzyme is attached to a bifurcated fibre bundle permitting excitation and detection of the fluorescence by a fluorometer. The response of the sensor is linear from 1 to 130 M hydrogen peroxide; the coefficient of variation is 3%. The sensor is stable for more than 10 weeks. The operating pH for maximal sensor response is 8.15. This allows the sensor to be used in combination with oxidase reactions producing hydrogen peroxide, as is demonstrated with a co-immobilized lactate oxidase-horseradish peroxidase optode for the determination of L-lactate. The fluorescence intensity of this sensor depends linearly on the concentration of lactate between 3 and 200 M and a throughput of 10 samples per hour is possible. The precision is in the same range as that of the monoenzyme optode. The lifetime of the bienzyme sensor for lactate is considerably shorter than that of the peroxidase sensor; it is limited by the stability of the immobilized lactate oxidase enzyme. The sensor has been applied to the determination of lactate in control serum.     

A highly selective fluorescence turn-on detection of hydrogen peroxide and d-glucose based on the aggregation/deaggregation of a modified tetraphenylethylene

A new selective fluorescence turn-on detection of hydrogen peroxide was established by taking advantage of the aggregation induced-emission (AIE) behavior of tetraphenylethylene unit and the reaction of hydrogen peroxide toward the arylboronic ester group in compound 1. Moreover, compound 1 was successfully utilized for the selective detection of d-glucose in aqueous solution.     

Application of crude extract of kohlrabi (Brassica oleracea gongylodes) as a rich source of peroxidase in the spectrofluorometric determination of hydrogen peroxide in honey samples.

Crude extract of kohlrabi (Brassica oleracea gongylodes) was prepared by a simple procedure and its enzymatic activity and total protein concentration were determined. It was found that this crude extract is a rich source of peroxidase (POx) and has high specific activity. Cross-linked polyvinylpyrrolidone was used as a stabilizer in the preparation of the crude extract. The POx activity of kohlrabi crude extract did not vary for at least 2 months when deoxygenated and stored at 4 degrees C. This extract was applied for the spectrofluorometric determination of hydrogen peroxide using homovanillic acid as a fluorogenic substrate. POx catalyzes the hydrogen peroxide oxidation of homovanillic acid to produce a dimer which shows strong fluorescence at 420 nm with excitation at 312 nm. In the optimum conditions, the calibration graph for hydrogen peroxide was linear up to 190 ng mL(-1), with a detection limit of 4.4 ng mL(-1). The relative standard deviation (RSD) was 1.48% for 50 ng mL(-1) hydrogen peroxide. The proposed method was successfully applied to the determination of hydrogen peroxide in honey. The concentration-time profile of H2O2 produced upon dilution of honey was studied and H2O2 contents of some different honeys from various areas of Iran were determined.     

Reactive Oxygen Species (ROS) Activated Liposomal Cell Delivery using a Boronate-Caged Guanidine Lipid

We report boronate-caged guanidine-lipid 1 that activates liposomes for cellular delivery only upon uncaging of this compound by reactive oxygen species (ROS) to produce cationic lipid products. These liposomes are designed to mimic the exceptional cell delivery properties of cell-penetrating peptides (CPPs), while the inclusion of the boronate cage is designed to enhance selectivity such that cell entry will only be activated in the presence of ROS. Boronate uncaging by hydrogen peroxide was verified by mass spectrometry and zeta potential (ZP) measurements. A microplate-based fluorescence assay was developed to study the ROS-mediated vesicle interactions between 1 -liposomes and anionic membranes, which were further elucidated via dynamic light scattering (DLS) analysis. Cellular delivery studies utilizing fluorescence microscopy demonstrated significant enhancements in cellular delivery only when 1 -liposomes were incubated with hydrogen peroxide. Our results showcase that lipid 1 exhibits strong potential as an ROS-responsive liposomal platform for targeted drug delivery applications.     

Fluorometric determination of hydrogen peroxide using resorufin and peroxidase

A fluorometric method for the determination of hydrogen peroxide using resorufin as a substrate for peroxidase is described. Two procedures were developed for the determination of hydrogen peroxide. One involves the addition of hydrogen peroxide sample to a solution of peroxidase and resorufin in phosphate buffer, pH 6.4. Fluorescence measurements are performed before and after hydrogen peroxide addition. The within-run CVs for final concentrations of hydrogen peroxide of 200 and 40 nmol/liter were 1.7 and 7.6%, respectively, and the limit of quantitation was 9 nmol/liter. The second procedure, in which the initial reaction of hydrogen peroxide with resorufin is performed in citrate buffer at pH 4.5, and then the fluorescence is measured after the pH is adjusted to 9.2 with borate buffer, has a limit of quantitation of 4.4 nmol/liter with a within-run CV of 6.5% for a final hydrogen peroxide concentration of 20 nmol/liter. The method is linear at least up to 1 μmol/liter.     

Colour-responsive fluorescent oxy radical sensors

A series of fluorene-fused benzoquinones (Q1-Q5) were prepared by thermolysis of 4-fluorenyl-4-hydroxycyclobutenones. Red fluorescence observed for Q2 is switched by reduction to blue fluorescence by formation of the hydroquinone. Reaction with hydrogen peroxide restores the original fluorescence colour. The potential use of compound Q2 as a reactive oxygen species detector is discussed.     

Flow-injection determination of hydrogen peroxide based on fluorescence quenching of chromotropic acid catalyzed with Fe(II)

Flow-injection analysis system (FIA system), which was based on Fe(II)-catalyzed oxidation of chromotropic acid with hydrogen peroxide, was developed for the determination of hydrogen peroxide. The chromotropic acid has a fluorescence measured at λ_em = 440 nm (emission wavelength) with λ_ex = 235 nm (excitation wavelength), and the fluorescence intensity at λ_em = 440 nm quietly decreased in the presence of hydrogen peroxide and Fe(II), which was caused by Fe(II)-catalyzed oxidation of chromotropic acid with hydrogen peroxide. By measuring the difference of fluorescence intensity, hydrogen peroxide (1.0 × 10⁻⁸-1.0 × 10⁻³ mol L⁻¹) could be determined by the proposed FIA system, whose analytical throughput was 40 samples h⁻¹. The relative standard deviation (RSD) was 1.03% (n = 10) for 4.0 × 10⁻⁸ mol L⁻¹ hydrogen peroxide. The proposed FIA technique could be applied to the determination of hydrogen peroxide in rain water samples.