Aggregation-Induced Emission Photosensitizer with Ag(I)-π Interaction-Enhanced Reactive Oxygen Species for Eliminating Multidrug Resistant Bacteria.

Multidrug-resistant (MDR) bacteria pose serious threats to public health due to the lack of effective and biocompatible drugs to kill MDR bacteria. Photodynamic antibacterial therapy has been widely studied due to its low induction of resistance. However, photosensitizers that can efficiently generate reactive oxygen species (ROS) through both type I and type II mechanisms and that have the capability of multiple modes of action are rarely reported. Addressing this issue, we developed a near-infrared-emitting triphenylamine indole iodoethane (TTII) and its silver(I) self-assembled (TTIIS) aggregation-induced emission (AIE) photosensitizer for multimode bacterial infection therapy. TTII can efficiently produce both Type I ROS •OH and Type II ROS 1O2. Interestingly, the Ag(I)-π interaction contributed in TTIIS efficiency promotion of the generation of 1O2. Moreover, by releasing Ag+, TTIIS enabled photodynamic-Ag(I) dual-mode sterilization. As a result, TTIIS achieved an effective enhancement of antibacterial activity, with a 1-2-fold boost against multidrug-resistant Escherichia coli (MDR E. coli). Both TTII and TTIIS at a concentration as low as 0.55 µg mL-1 can kill more than 98% of methicillin resistant Staphylococcus aureus (MRSA) on MRSA-infected full-thickness defect wounds of a mouse, and both TTII and TTIIS were effective in eliminating the bacteria and promoting wound healing.

A Coumarin-Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide.

In this study, we synthesized a coumarin-hemicyanine-based deep red fluorescent dye that exhibits an intramolecular charge transfer (ICT). The probe had a large Stokes shift of 287 nm and a large molar absorption coefficient (ε = 7.5 × 105 L·mol-1·cm-1) and is best described as a deep red luminescent fluorescent probe with λem = 667 nm. The color of probe W changed significantly when it encountered cyanide ions (CN-). The absorption peak (585 nm) decreased gradually, and the absorption peak (428 nm) increased gradually, so that cyanide (CN-) could be identified by the naked eye. Moreover, an obvious fluorescence change was evident before and after the reaction under irradiation using 365 nm UV light. The maximum emission peak (667 nm) decreased gradually, whilst the emission peak (495 nm) increased gradually, which allowed for the proportional fluorescence detection of cyanide (CN-). Using fluorescence spectrometry, the fluorescent probe W could linearly detect CN- over the concentration range of 1-9 µM (R2 = 9913, RSD = 0.534) with a detection limit of 0.24 µM. Using UV-Vis spectrophotometry, the linear detection range for CN- was found to be 1-27 µM (R2 = 0.99583, RSD = 0.675) with a detection limit of 0.13 µM. The sensing mechanism was confirmed by 1H NMR spectroscopic titrations, 13C NMR spectroscopy, X-ray crystallographic analysis and HRMS. The recognition and detection of CN- by probe W was characterized by a rapid response, high selectivity, and high sensitivity. Therefore, this probe provides a convenient, effective and economical method for synthesizing and detecting cyanide efficiently and sensitively.

Pyrene-Based Cationic Fluorophores with High Affinity for BF4-, PF6-, and ClO4- Anions: Detection and Removal.

Anions play an indispensable role in the balance and regulation of the ecological environment and human health; however, excess anions can cause serious ecological and environment problems. Therefore, the detection and removal of excess anions in aqueous solution is not only a technological problem but also crucial for environmental protection. Herein, a set of water-soluble pyrene-based cationic fluorophores were synthesized, which exhibit high sensitivity for the detection of the anions BF4-, PF6-, and ClO4- via electrostatic interactions. Such fluorescent probes exhibit "turn-on" emission characteristics even at low concentrations of anions due to anion-π+ interactions. Moreover, these fluorescence probes act as efficient precipitating agents for the removal of the BF4-, PF6-, and ClO4- anions from an aqueous environment. This work opens up new avenues for future research on pyrene-based fluorophores as turn-on fluorescence probes for anion detection and as excellent precipitating agents in environmental settings.

A Turn-On Fluorescent Chemosensor for Cyanide Ion Detection in Real Water Samples.

We have designed and synthesized a novel simple colorimetric fluorescent probe with aggregation-induced emission (AIE) properties. Probe 5-(4-(diphenylamine)phenyl) thiophen-2-formaldehyde W exhibited a turn-on fluorescent response to cyanide ion (CN-), which induces distinct visual color changes. Probe W exhibited a highly selective and sensitive ratiometric fluorescence response for the detection of CN- over a wide pH range (4-11) and in the presence of common interferents. The linear detection of CN- over the concentration range of 4.00-38.00 µM (R 2 = 0.9916, RSD = 0.02) was monitored by UV-Vis absorption spectrometry (UV-Vis) with the limit of detection determined to be 0.48 µM. The linear detection of CN- over the concentration range of 8.00-38.00 µM was examined by fluorescence spectrophotometry (R 2 = 0.99086, RSD = 0.031), and the detection limit was found to be 68.00 nM. The sensing mechanisms were confirmed by 1H NMR spectroscopic titrations, X-ray crystallographic analysis, and HRMS. Importantly, probe W was found to show rapid response, high selectivity, and sensitivity for cyanide anions in real water samples, over the range of 100.17∼100.86% in artificial lake water and 100.54∼101.64% in running water by UV-Vis absorption spectrometry, and over the range of 99.42∼100.71% in artificial lake water and 100.59∼101.17% in running water by fluorescence spectrophotometry. Importantly, this work provides a simple and effective approach which uses an economically cheap and uncomplicated synthetic route for the selective, sensitive, and quantitative detection of CN- ions in systems relevant to the environment and health.

Synthesis, Crystal Structure and Bioactivity of Phenazine-1-carboxylic Acylhydrazone Derivatives.

A phenazine-1-carboxylic acid intermediate was synthesized from the reaction of aniline and 2-bromo-3-nitro-benzoic acid. It was then esterified and reacted with hydrazine hydrate to afford phenazine-1-carboxylic hydrazine. Finally, 10 new hydrazone compounds 3a-3j were obtained by the condensation reaction of phenazine-1-carboxylic acid hydrazide and the respective aldehyde-containing compound. The structures were characterized by 1H and 13C NMR spectroscopy, MS and single crystal X-ray diffraction. The antitumor activity of the target compounds in vitro (HeLa and A549) was determined by thiazolyl blue tetrazolium bromide. The results showed that compound (E)-N'-(2-hydroxy-4-(2-(piperidine-1-yl) ethoxy) benzyl) phenazine-1-carbonyl hydrazide 3d exhibited good cytotoxic activity.

A Highly Selective Turn-On Fluorescent Probe for the Detection of Zinc.

A novel turn-on fluorescence probe L has been designed that exhibits high selectivity and sensitivity with a detection limit of 9.53 × 10-8 mol/L for the quantification of Zn2+. 1H-NMR spectroscopy and single crystal X-ray diffraction analysis revealed the unsymmetrical nature of the structure of the Schiff base probe L. An emission titration experiment in the presence of different molar fractions of Zn2+ was used to perform a Job's plot analysis. The results showed that the stoichiometric ratio of the complex formed by L and Zn2+ was 1:1. Moreover, the molecular structure of the mononuclear Cu complex reveals one ligand L coordinates with one Cu atom in the asymmetric unit. On adding CuCl2 to the ZnCl2/L system, a Cu-Zn complex was formed and a strong quenching behavior was observed, which inferred that the Cu2+ displaced Zn2+ to coordinate with the imine nitrogen atoms and hydroxyl oxygen atoms of probe L.

A 1-Hydroxy-2,4-Diformylnaphthalene-Based Fluorescent Probe and Its Detection of Sulfites/Bisulfite.

A novel 1-hydroxy-2,4-diformylnaphthalene-based fluorescent probe L was synthesized by a Knoevenagel reaction and exhibited excellent sensitivity and selectivity towards sulfite ions (SO32-) and bisulfite ions (HSO3-). The detection limits of the probe L were 0.24 µM using UV-Vis spectroscopy and 9.93 nM using fluorescence spectroscopy, respectively. Furthermore, the fluorescent probe L could be utilized for detection in real water samples with satisfactory recoveries in the range 99.20%~104.30% in lake water and 100.00%~104.80% in tap water by UV-Vis absorption spectrometry, and in the range 100.50%~108.60% in lake water and 102.70%~103.80% in tap water by fluorescence spectrophotometry.

Dynamic Coordination between a Triphenylamine-Functionalized Salicylaldehyde Schiff Base and a Copper(II) Ion.

The coordination between a ligand and a metal is a spontaneous and uncontrollable process. In this Article, we successfully observe the formation of metal coordination in a triphenylamine-functionalized salicylaldehyde Schiff base with a copper(II) ion. The ligand TPA-Py first reacts with Cu2+ in a stepwise process to afford the dynamic complex TPA-Py@Cu2+ ([ligand]:[Cu2+] = 1:1), which further reacts with an extra copper(II) ion to afford 2TPA-Py@4Cu2+ with the following stepwise (or cumulative) stability constants: K1 = 4.0694 × 103 and K2 = 1.0761 × 106, respectively. The entire metal coordination process can be visualized, and the coordination mode of the probe toward copper was further evaluated by ultraviolet-visible/fluorescence spectra, single-crystal X-ray diffraction, density functional theory calculations, high-resolution mass spectra, and nuclear magnetic resonance spectroscopic titrations. Compound TPA-Py exhibited excellent sensitivity and specificity toward copper(II) ions in THF/water media with a low limit of detection of 2.687 × 10-7 mol L-1. In addition, TPI-An-Py can be applied to the detection of Cu2+ in real samples with satisfactory recoveries in the range of 100-112% in lake water and 98-101% in tap water. This Article not only reports an excellent fluorescence probe for copper(II) ion detection but also presents an instance for more fully understanding the metal coordination process.

A Simple Turn-off Schiff Base Fluorescent Sensor for Copper (II) Ion and Its Application in Water Analysis.

An aniline-functionalized naphthalene dialdehyde Schiff base fluorescent probe L with aggregation-induced enhanced emission (AIEE) characteristics was synthesized via a simple one-step condensation reaction and exhibited excellent sensitivity and selectivity towards copper(II) ions in aqueous media with a fluorescence " turn-off " phenomenon. The detection limit of the probe is 1.64 × 10-8 mol·L-1. Furthermore, according to the results of the UV-vis/fluorescence titrations, Job's plot method and 1H-NMR titrations, a 1:2 stoichiometry was identified. The binding constant between L and Cu2+ was calculated to be Ka = 1.222 × 103. In addition, the AIEE fluorescent probe L could be applied to detection in real water samples with satisfactory recoveries in the range 99.10-102.90% in lake water and 98.49-102.37% in tap water.

The Composition-Dependent Photoluminescence Properties of Non-Stoichiometric ZnxAgyInS1.5+x+0.5y Nanocrystals.

A facile hot injection approach to synthesize high-quality non-stoichiometric ZnxAgyInS1.5+x+0.5y nanocrystals (NCs) in the size range of 2.8-3.1 nm was presented. The fluorescence spectra had single band gap features, and indicated the formation of alloy states rather than simple composite structures. The chemical compositions, photoluminescence (PL) emission wavelengths, and quantum yields of ZnxAgyInS1.5+x+0.5y nanocrystals were significantly influenced by the concentration of an organic capping agent. The appropriate proportion of 1-dodecanthiol in the precursor prevented the precipitation, increased the fluorescence quantum yield, and improved their optical properties. The proper ratio of capping agent allowed Zn, Ag, and In to form a better crystallinity and compositional homogeneity of ZnxAgyInS1.5+x+0.5y nanocrystals. The photoluminescence was tunable from blue to red in the range of 450-700 nm as the Ag content changed independently. The PL and absorption spectra of ZnxAgyInS1.5+x+0.5y nanocrystals showed a significant blue shift with the decrease of Ag content in the precursor. As there were no obvious differences on the average particle sizes of ZnxAgyInS1.5+x+0.5y samples, these results fully revealed the composition-dependent photoluminescence properties of ZnxAgyInS1.5+x+0.5y nanocrystals. The relative quantum yield reached 35%. The fluorescence lifetimes (τ1=115-148 ns and τ2=455-483 ns) were analogous to those of AgInS2 and (AgIn)xZn2(1-x)S2.

Salinomycin attenuates liver cancer stem cell motility by enhancing cell stiffness and increasing F-actin formation via the FAK-ERK1/2 signalling pathway.

Salinomycin has recently been identified as an antitumour drug for several types of cancer stem cell (CSC) treatments. However, the effects of salinomycin on the migratory and invasive properties of liver cancer stem cells (LCSCs) are unclear. In present study, we investigated the effect of salinomycin on the migration and invasion of LCSCs, and examined the molecular mechanisms underlying the anticancer effects of salinomycin. Here we showed that the migration and invasion of LCSCs were significantly suppressed in a salinomycin dose-dependent manner. Moreover, western blot analysis showed that salinomycin repressed the phosphorylation of focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK1/2). Taken together, these findings provide new evidence that salinomycin suppresses the migration and invasion of LCSCs by inhibiting the expression of the FAK-ERK1/2 signalling pathway. In addition, the analysis of the mechanical properties showed that salinomycin increased cell stiffness in LCSCs via the FAK, and ERK1/2 pathways, suggesting that the inhibition of LCSC migration might partially contribute to the increase in cell stiffness stimulated by salinomycin. To further examine the role of salinomycin on cell motility and stiffness, the actin cytoskeleton of LCSCs was detected. The increased F-actin filaments in LCSCs induced by salinomycin reflected the increase in cell stiffness and the decrease in cell migration. Overall, these results showed that salinomycin inhibits the migration and invasion of LCSCs through the dephosphorylated FAK and ERK1/2 pathways, reflecting the changes in cell stiffness resulting from the increased actin cytoskeleton.

[Effect of Conditioned Medium from Endothelial Cells on Cancer Stem Cell Phenotype of Hepatoma Cells].

In this study, we aimed to investigate the influences of conditioned medium from human umbilical vein endothelial cells (HUVEC) on cancer stem cell phenotype of human hepatoma cells. HUVEC and human hepatoma cells (MHCC97H) were cultured, respectively, and then the MHCC97H cells were co-cultured with conditioned medium from HUVEC (EC-CM) with Transwell system. Anti-cancer drug sensitivity, colony-formation, migration/invasion ability, expression of cancer stem cell marker and sphere formation were performed to determine the cancer stem cell phenotype in MHCC97H cells. We found that MHCC97H cells co-cultured with EC-CM exhibited significantly higher colony-formation ability and lower sensitivity of anti-cancer drugs 5-FU and Cis. Transwell assay showed that treatment with EC-CM obviously increased migration and invasion of MHCC97H cells. Moreover, increased sphere forming capability and expression of CD133 in MHCC97H cells were observed after co-cultured with EC-CM. These results suggested that EC-CM could promote cancer stem cell phenotype of hepatoma cells.