A General Strategy for the Semisynthesis of Ratiometric Fluorescent Sensor Proteins with Increased Dynamic Range

We demonstrate how a combination of self-labeling protein tags and unnatural amino acid technology permits the semisynthesis of ratiometric fluorescent sensor proteins with unprecedented dynamic range <i>in vitro</i> and on live cells. To generate such a sensor, a binding protein is labeled with a fluorescent competitor of the analyte using SNAP-tag in conjugation with a second fluorophore that is positioned in vicinity of the binding site of the binding protein using unnatural amino acid technology. Binding of the analyte by the sensor displaces the tethered fluorescent competitor from the binding protein and disrupts fluorescence resonance energy transfer between the two fluorophores. Using this design principle, we generate a ratiometric fluorescent sensor protein for methotrexate that exhibits large dynamic ranges both <i>in vitro</i> (ratio changes up to 32) and on cell surfaces (ratio change of 13). The performance of these semisynthetic sensor proteins makes them attractive for applications in basic research and diagnostics

Quinoline-Based Fluorescent Probe for Ratiometric Detection of Lysosomal pH

A new pH-responsive fluorescent probe has been reported based on protonation-activable resonance charge transfer. In aqueous solution, probe PQ-Lyso exhibits ratiometric detection of pH changes with a large hypsochromic shift of 76 nm and remarkable changes in the fluorescence intensity ratio (<i>R</i> = <i>F</i>_494 nm/<i>F</i>_570 nm, <i>R</i>/<i>R</i>₀ = 105). Furthermore, PQ-Lyso, which is localized to lysosomes in living cells, can calibrate lysosomal pH using fluorescence ratiometry

Rapid Detection of Hydrogen Peroxide Based on Aggregation Induced Ratiometric Fluorescence Change

In surfactant solution, probe D-BBO can detect H₂O₂ with an enhanced reaction rate (<i>k</i>_obs = 1.83 × 10^–2 s^–1) and a large bathochromic shift of 105 nm. Furthermore, D-BBO displays a highly selective response to H₂O₂ over other reactive oxygen species under identical conditions

Synthesis and Self-Assembly of Perylenetetracarboxylic Diimide Derivatives with Helical Oligo(l‑lactic acid)_<i>n</i> Segments

Three perylenetetracarboxylic diimide (PDI) derivatives consisting of a short oligo­(l-lactic acid)_<i>n</i> (O-LLA) segment at one imide nitrogen were synthesized. The polymers were characterized by ¹H NMR and gel permeation chromatography (GPC). Their properties were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) experiments, scanning electron microscopy (SEM), electronic absorption, and circular dichroism (CD) spectroscopy. The self-assembly behavior of these PDIs in molten state as well as in solvent was examined. It was found that the structure and the morphology of the self-assembly of these polymers depend on the relative length of the O-LLA segment. The PDIs with longer O-LLA chains present liquid crystal properties with an obvious phase transition from disordered phase to an ordered (α) phase, which cannot be found for the PDIs with short O-LLA segments. The long O-LLA segments also caused a left-handed helicity for the aggregates of the PDIs from solution. This research demonstrated that one can control the order, aggregation mode, and morphology of the molecular aggregates by changing the length of the O-LLA chains. This information can be useful in the design of new organic materials that exhibit molecular aggregation

Rational Design of a Ratiometric and Targetable Fluorescent Probe for Imaging Lysosomal Zinc Ions

Fluorescent detecting and tracking of zinc ions in living cells has become more and more important because the physiological and pathological functions of zinc are highly associated with the timing and discrete distribution of subcellular zinc ion. For the detection of subcellular zinc concentrations with high spatial and temporal reliability, we report the design, synthesis, properties, and bioimaging evaluation of a fluorescent probe, <b>DQZn4</b>, composed of a quinoline scaffold as the ratiometric signaling unit for Zn²⁺ and a dimethylethylamino group as the targeting anchor for lysosomes. In acidic aqueous solution (pH = 5.2), <b>DQZn4</b> features fluorescence emission maximum at 542 nm due to the resonance charge transfer in 4-alkoxy substituted quinoline. Upon binding Zn²⁺, the probe displays significant fluorescent turn-on and ratiometric detection of Zn²⁺ with blue shift of 47 nm and remarkable fluorescence ratio changes (<i>R</i> = <i>F</i>₄₉₅/<i>F</i>_542 nm, <i>R</i>/<i>R</i>₀ = 5.1). Confocal imaging experiments establish that <b>DQZn4</b> is able to localize to lysosomes and respond to lysosomal zinc changes in living cells by using fluorescence ratiometry

Facile Fabrication of a Silver Dendrite-Integrated Chip for Surface-Enhanced Raman Scattering

A facile approach to fabricating a surface-enhanced Raman scattering (SERS)-active chip by integrating silver dendrites with copper substrate through a one-step process was explored. The structures of dendrites were synthesized and controlled by an AgNO₃/PVP aqueous system, and the fabrication parameters amount of AgNO₃/PVP and reaction time were systematically investigated. The optimized silver dendrites, closely aggregated on the surface of the copper chip, exhibited high SERS activity for detecting rhodamine 6G at a concentration as low as 3.2 × 10^–11 M. Meanwhile, the prepared SERS-active chip displayed a high thermal stability and good reproducibility. Moreover, the potential application for analysis of polycyclic aromatic hydrocarbons was demonstrated by detection of fluoranthene at a low concentration of 4.5 × 10^–10 M. This SERS-active chip prepared by the convenient and high-yield method would be a promising means for rapid detection under field conditions

Additional file 1 of Hsa-microRNA-27b-3p inhibits hepatocellular carcinoma progression by inactivating transforming growth factor-activated kinase-binding protein 3/nuclear factor kappa B signalling

Additional file 1. Additional Figures S1–S4 and Tables S1–S5

Plot of the first two PCoA axes using the 2811 SNPs.

<p>The red squares correspond to waxy maize germplasms; the blue rhombuses correspond to common maize germplasms.</p

Candidate loci under positive selection detected in this study.

<p>Candidate loci under positive selection detected in this study.</p

Frequency distribution of genetic diversity of gene diversity and PIC within the waxy maize, common maize and the entire datasets.

<p>Frequency distribution of genetic diversity of gene diversity and PIC within the waxy maize, common maize and the entire datasets.</p