Showing papers by "Bianhua Liu published in 2016"

Real-Time Discrimination and Versatile Profiling of Spontaneous Reactive Oxygen Species in Living Organisms with a Single Fluorescent Probe

Abstract: Fluorescent probes are powerful tools for the investigations of reactive oxygen species (ROS) in living organisms by visualization and imaging. However, the multiparallel assays of several ROS with multiple probes are often limited by the available number of spectrally nonoverlapping chromophores together with large invasive effects and discrepant biological locations. Meanwhile, the spontaneous ROS profilings in various living organs/tissues are also limited by the penetration capability of probes across different biological barriers and the stability in reactive in vivo environments. Here, we report a single fluorescent probe to achieve the effective discrimination and profiling of hydroxyl radicals (•OH) and hypochlorous acid (HClO) in living organisms. The probe is constructed by chemically grafting an additional five-membered heterocyclic ring and a lateral triethylene glycol chain to a fluorescein mother, which does not only turn off the fluorescence of fluorescein, but also create the dual reactive...

Color-Multiplexing-Based Fluorescent Test Paper: Dosage-Sensitive Visualization of Arsenic(III) with Discernable Scale as Low as 5 ppb

Abstract: Fluorescent colorimetry test papers are promising for the assays of environments, medicines, and foods by the observation of the naked eye on the variations of fluorescence brightness and color. Unlike dye-absorption-based pH test paper, however, the fluorescent test papers with wide color-emissive variations with target dosages for accurate quantification remain unsuccessful even if the multicolorful fluorescent probes are used. Here, we report the dosage-sensitive fluorescent colorimetry test paper with a very wide/consecutive “from red to cyan” response to the presence and amount of arsenic ions, As(III). Red quantum dots (QDs) were modified with glutathione and dithiothreitol to obtain the supersensitivity to As(III) by the quenching of red fluorescence through the formation of dispersive QDs aggregates. A small amount of cyan carbon dots (CDs) with spectral blue-green components as the photostable internal standard were mixed into the QDs solution to produce a composited red fluorescence. Upon the ad...

Atomic Oxygen Tailored Graphene Oxide Nanosheets Emissions for Multicolor Cellular Imaging.

Abstract: Graphene oxide (GO) has been widely used as a fluorescence quencher, but its luminescent properties, especially tailor-made controlling emission colors, have been seldom reported due to its heterogeneous structures. Herein, we demonstrated a novel chemical oxidative strategy to tune GO emissions from brown to cyan without changing excitation wavelength. The precise tuning is simply achieved by varying reaction times of GO nanosheets in piranha solution, but there is no need for complex chromatography separation procedures. With increasing reaction times, oxygen content on the lattice of GO nanosheets increased, accompanied by the diminution of their sizes and sp2 conjugation system, resulting in an increase of emissive carbon cluster-like states. Thereby, the luminescent colors of GO were tuned from brown to yellow, green, and cyan, and its fluorescent quantum yields were enhanced. The obtained multicolored fluorescent GO nanosheets would open plenty of novel applications in cellular imaging and multiplex...

Fluorescent paper sensor fabricated by carbazole-based probes for dual visual detection of Cu2+ and gaseous H2S

Abstract: We report a fluorescent carbazole-based probe to achieve visual detection of Cu2+ and gaseous H2S with paper sensors in a fluorescent “on–off–on” mode. A common carbazole mother molecule is reconstructed by dual substitute and hydrazine reactions to obtain triple dentates to a single Cu2+ ion, and thus the fluorescence of the carbazole ring is strongly quenched by the captured Cu2+. Subsequently, the coordinative Cu2+ can be snatched by S2− via the formation of CuS, leading to the recovery of carbazole fluorescence. The above reactions provide the sensitive and prompt detection of Cu2+ and S2− with the limits of 65 nM and 0.29 μM, respectively. The reusability of the “on–off–on” fluorescent switch is well demonstrated by a recycling experiment with alternate additions of Cu2+ and S2−. Moreover, paper sensors are fabricated and used for the visual detection of Cu2+ and gaseous H2S with the limits of 10−6 M and 15 ppm.

Visualization of exhaled hydrogen sulphide on test paper with an ultrasensitive and time-gated luminescent probe.

Abstract: Luminescent chemosensors for hydrogen sulphide (H2S) are of great interest because of the close association of H2S with our health. However, current probes for H2S detection have problems such as low sensitivity/selectivity, poor aqueous-solubility or interference from background fluorescence. This study reports an ultrasensitive and time-gated “switch on” probe for detection of H2S, and its application in test paper for visualization of exhaled H2S. The complex probe is synthesized with a luminescent Tb3+ centre and three ligands of azido (–N3) substituted pyridine-2,6-dicarboxylic acid, giving the probe high hydrophilicity and relatively fast reaction dynamics with H2S because there are three –N3 groups in each molecule. The introduced –N3 group as a strong electron-withdrawing moiety effectively changes the energy level of ligand via intramolecular charge transfer (ICT), and thus breaks the energy transferring from ligand to lanthanide ion, resulting in quenching of Tb3+ luminescence. On addition of H2S, the –N3 group can be reduced to an amine group to break the process of ICT, and the luminescence of Tb3+ is recovered at a nanomolar sensitivity level. With a long lifetime of luminescence of Tb3+ centre (1.9 ms), use of a time-gated technique effectively eliminates the background fluorescence by delaying fluorescence collection for 0.1 ms. The test paper imprinted by the complex probe ink can visualize clearly the trace H2S gas exhaled by mice.