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An Aggregation-Induced Fluorescence Probe for Detection Hsub.2S and Its Application in Cell Imaging
Monitoring hydrogen sulfide (H[sub.2]S) in living organisms is very important because H[sub.2]S acts as a regulator in many physiological and pathological processes. Upregulation of endogenous H[sub.2]S concentration has been shown to be closely related to the occurrence and development of tumors, atherosclerosis, neurodegenerative diseases and diabetes. Herin, a novel fluorescent probe HND with aggregation-induced emission was designed. Impressively, HND exhibited a high selectivity, fast response (1 min) and low detection limit (0.61 μM) for H[sub.2]S in PBS buffer (10 mM, pH = 7.42). Moreover, the reaction mechanism between HND and H[sub.2]S was conducted by Job’s plot, HR-MS, and DFT. In particular, HND was successfully employed to detect H[sub.2]S in HeLa cells.
Journal Article
The Day-Glo brothers : the true story of Bob and Joe Switzer's bright ideas and brand-new colors
The story of Bob and Joe Switzer, the brothers who invented Day-Glo colors.
Book
Determination of Fumonisin Bsub.1 by Aptamer-Based Fluorescence Resonance Energy Transfer
Fumonisin FB is produced by Fusarium moniliforme Sheld, of which FB[sub.1] is the most common and the most toxic. The establishment of a rapid detection method is an important means to prevent and control FB[sub.1] pollution. A highly sensitive fluorescent sensor based on an aptamer for the rapid detection of fumonisin B[sub.1] (FB[sub.1]) in corn was established. In this study, 5-carboxyfluorescein (FAM) was labeled on the aptamer of FB[sub.1] (F10). F10 was adsorbed on the surface of graphene oxide (GO) by π-π stacking. The FAM fluorescence signal could be quenched by fluorescence resonance energy transfer between fluorescent molecules and graphene oxide (GO). In the presence of FB[sub.1], the binding efficiency of the aptamer to GO was reduced. Therefore, the content of FB[sub.1] in corn samples was determined by fluorescence measurements of mixed FAM-labeled F10, GO and corn samples. This method had a good linear relationship in an FB[sub.1] concentration range of 0–3000 ng/mL. The equation was y = 0.2576x + 10.98, R[sup.2] = 0.9936. The limit of detection was 14.42 ng/mL, and the limit of quantification was 43.70 ng/mL. The recovery of a spiked standard in the corn sample was 89.13–102.08%, and the time of detection was 30 min.
Journal Article
Praseodymium selective fluorescence recognition based on GdPO.sub.4: Tb.sup.3+ probe via energy transfer from Tb.sup.3+ to Pr.sup.3+ ions
A novel strategy is proposed based on the efficient energy transfer from Tb.sup.3+ to Pr.sup.3+ for the sensitive and selective discrimination of praseodymium ions due to the matched energy levels of .sup.5D.sub.4 (Tb.sup.3+) and .sup.3P.sub.0 (Pr.sup.3+). The electron of Tb.sup.3+ transfers from the ground state to the excited state under the excitation of ultraviolet light and relaxes to the .sup.5D.sub.4 level. In the presence of Pr.sup.3+ the electron has no time to return to the ground state, thus it transfers to the .sup.3P.sub.0 level of Pr.sup.3+ resulting in the quenching of Tb.sup.3+ luminescence. In the case of GdPO.sub.4: Tb.sup.3+ nanowire, its fluorescence intensity at 545 nm linearly decreased when Pr.sup.3+ concentration ranged from 1 x 10.sup.-7 to 1 x 10.sup.-5 M, and the detection limit was 75 nM. To further investigate the sensing mechanism, CePO.sub.4: Tb.sup.3+, YPO.sub.4: Tb.sup.3+, and YBO.sub.3: Tb.sup.3+ nanoparticles were also synthesized for Pr.sup.3+ ion detection. For all materials, similar fluorescence quenching by Pr.sup.3+ ions occurred, which confirmed the efficient energy transfer from Tb.sup.3+ to Pr.sup.3+ ions. Graphical abstract
Journal Article
Facile microwave-assisted synthesis of Ti.sub.3C.sub.2 MXene quantum dots for ratiometric fluorescence detection of hypochlorite
A dual-channel \"naked-eye\" colorimetric and ratio fluorescent probe has been developed based on titanium carbide quantum dots for the detection of curcumin and hypochlorite (ClO.sup.-). The fluorescence emission of Ti.sub.3C.sub.2 MXene quantum dots (Ti.sub.3C.sub.2 MQDs) is in the range 350-600 nm, and the maximum emission peak is at 430 nm that overlaps with the UV absorption of curcumin at 430 nm to a large extent. This facilitates the fluorescence resonance energy transfer (FRET) between Ti.sub.3C.sub.2 MQDs and curcumin. When ClO.sup.- is added, the phenolic and methoxy groups of curcumin are oxidized to quinones, resulting in the restoration of the fluorescence of Ti.sub.3C.sub.2 MQD. In addition, the probe designed makes it easier to distinguish colors with the naked eye to detect curcumin and ClO.sup.-. The linear detection range of curcumin was 0.05-10 [mu]M, and the detection limit was 20 nM. The linear detection ranges of ClO.sup.- are 25-150 [mu]M and 150-275 [mu]M, and the detection limit is 5 [mu]M. This study is the first report on the determination of curcumin and ClO.sup.- based on Ti.sub.3C.sub.2 MQDs by dual-channel \"naked-eye\" colorimetric and ratio fluorescence method.
Journal Article
The 5IP/Isub.3/2→6IP/Isub.J Electric Dipole Forbidden Transitions in Rubidium
This paper presents a general review of the results of the experimental and theoretical work carried out by our research group to study the 5P[sub.3/2]→6P[sub.J] electric quadrupole transition in atomic rubidium. The experiments were carried out with room-temperature atoms in an absorption cell. A steady-state population of atoms in the 5P[sub.3/2] excited state is produced by a a narrow-bandwidth preparation laser locked to the D2 transition. A second CW laser is used to produce the forbidden transition with resolution of the 6P[sub.J] hyperfine states of both rubidium isotopes. The process is detected by recording the 420(422) nm fluorescence that occurs when the atoms in the 6P[sub.J] state decay directly into the 5S ground state. The fluorescence spectra show a strong dependence on the relative polarization directions of the preparation laser and the beam producing the forbidden transition. This dependence is directly related to a strong anisotropy in the populations of the 5P[sub.3/2] intermediate magnetic substates, and also to the electric quadrupole selection rules over magnetic quantum numbers. A calculation based on the rate equations that includes velocity and detuning dependent transition rates is adequate to reproduce these results. The forbidden transition is also shown to be an ideal probe to measure the Autler–Townes splitting generated in the preparation of the 5P[sub.3/2] state. Examples of spectra obtained with cold atoms in a magneto-optical trap (MOT) are also presented. These spectra show the expected Autler–Townes doublet structure with asymmetric line profiles that result as a consequence of the red-detuning of the trapping laser in the MOT.
Journal Article
Study of the Optical Features of Tbsup.3+:CaYAlOsub.4 and Tbsup.3+/Prsup.3+:CaYAlOsub.4 Crystals for Visible Laser Applications
Single crystals of Tb[sup.3+] single-doped and Tb[sup.3+]/Pr[sup.3+] co-doped CaYAlO[sub.4] were produced by the Czochralski method. The room-temperature polarized absorption spectra, emission spectra, and decay curves were recorded and analyzed in detail. The absorption cross-section around 487 nm was found to be 1.53 × 10[sup.−22] cm[sup.2] for the π polarization in the Tb[sup.3+]:CaYAlO[sub.4] crystal and increased to 5.23 × 10[sup.−22] cm[sup.2] in the Tb[sup.3+]/Pr[sup.3+]:CaYAlO[sub.4] crystal. The spectroscopic parameters were calculated through the Judd–Ofelt theory. For the Tb[sup.3+]:CaYAlO[sub.4] crystal, the emission bands of green light at 546 nm and yellow light at 587 nm had fluorescence branching ratios of 64.7% and 6.65% with cross-sections of 8.82 × 10[sup.−22] cm[sup.2] (σ-polarization) and 0.44 × 10[sup.−22] cm[sup.2] (π-polarization), respectively. The decay lifetimes of [sup.5]D[sub.4] multiplets were measured to be 1.41 ms and 1.1 ms for Tb[sup.3+]:CaYAlO[sub.4] and Tb[sup.3+]/Pr[sup.3+]:CaYAlO[sub.4] crystals, respectively. The energy transfer mechanisms of Tb[sup.3+] and Pr[sup.3+] and their emission spectral intensities at different temperatures were analyzed. As the temperature increased, the luminescence intensity of the Tb[sup.3+]:CaYAlO[sub.4] and Tb[sup.3+]/Pr[sup.3+]:CaYAlO[sub.4] crystals decreased almost linearly with the CIE coordinate variation, from (0.370, 0.621) to (0.343, 0.636) and from (0.345, 0.638) to (0.246, 0.698), respectively. The results indicate the potential of Tb[sup.3+]:CaYAlO[sub.4] and Tb[sup.3+]/Pr[sup.3+]:CaYAlO[sub.4] crystals as visible laser materials with a wide temperature range.
Journal Article
Fluorescent Labeling of Peroxisome and Nuclear in IColletotrichum aenigma/I
Anthracnose is one of the most widespread and destructive diseases in grapes. Grape anthracnose can be caused by various Colletotrichum species, such as Colletotrichum gloeosporioides and Colletotrichum cuspidosporium. In recent years, Colletotrichum aenigma was reported as a causal agent of Grape anthracnose in China and South Korea. Peroxisome is an important organelle in eukaryotes, which plays a very important role in the growth, development, and pathogenicity of several plant-pathogenic fungal species i, but it has not been reported in C. aenigma. In this work, the peroxisome of C. aenigma was labeled with a fluorescent protein, using green fluorescent protein (GFP) and red fluorescent protein (DsRED and mCherry) as reporter genes. Via Agrobacterium tumefaciens-mediated transformation (AtMT), two fluorescent fusion vectors to mark the peroxisomes, with GFP and DsRED, respectively, were introduced into a wild-type strain of C. aenigma. In the transformants, bright dots of green or red fluorescence in hyphae and spores could be seen in the strains labeled peroxisome. The nuclei labeled by the same method showed bright round fluorescent spots. In addition, we also combined fluorescent protein labeling with chemical staining to show the localization more clearly. The ideal peroxisome and nuclear fluorescence-labeled C. aenigma strain was obtained, which provided a reference for the study of its growth, development, and pathogenicity.
Journal Article