A multi-functional fluorescent probe for visualization of H2S and viscosity/polarity and its application in cancer imaging.

As an important endogenous gasotransmitter, hydrogen sulfide (H2S) plays a critical role in various physiological functions and has been regarded as a biomarker of cancer due to its overexpression in cancer cells. In addition, the early stages of cancer are often accompanied by abnormalities in the intracellular microenvironments, and distinguishing between cancer cell/tissues and normal cell/tissues is of great significance to the accuracy of cancer diagnosis. However, deep insights into the simultaneous detection of H2S and viscosity/polarity variations in cancer cells/tissues are rarely reported. In this work, we designed and synthesized a mitochondria-targeting fluorescent probe PDQHS, which exhibits high selectivity for H2S with an emission peak around 632 nm and excellent response (17-fold) to viscosity/polarity beyond 706 nm. Meanwhile, PDQHS shows good biocompatibility and can specifically accumulate into mitochondria. Using PDQHS, the visual distinguishing of cancer cells from normal cells was achieved via dual-channel detection of H2S and viscosity/polarity. More importantly, PDQHS has been successfully applied to visualize endogenous and exogenous H2S in living cells and tumor tissue. Obviously, compared to the detection of a single biomarker, monitoring multiple biomarkers simultaneously through dual-channel response is conducive to amplifying the detection signal, providing a more sensitive and reliable imaging tool in the tumor region, which is beneficial for cancer prediction.

A water-soluble 1,8-naphthalimide-based fluorescent pH probe for distinguishing tumorous tissues and inflammation in mice.

A water-soluble fluorescent probe BPN, by introducing a piperazine as the pH-sensitive fluorescence signaling motif to the hydrophilic propionic acid-substituted 1,8-naphthalimide fluorophore, is highly sensitive to pH changes within cytoplasm matrix in living cells, as well as pH-related diseases models. Owing to the protonation-induced inhibition of the photoinduced electron transfer (PET) from piperazine to naphthalimide fluorophore, BPN displayed a significant fluorescence enhancement (more than 131-fold) upon the pH decreasing from 11.0 to 3.0. The linear range was between pH 6.4 to 8.0 with a pKa value of 6.69 near the physiological pH, which was suitable for cytosolic pH research. Furthermore, BPN exhibited a large Stokes shift (142 nm), good water solubility, excellent photostability, high selectivity and low cytotoxicity. All these advantages were particularly beneficial for intracellular pH imaging. Using BPN, we demonstrated the real-time monitoring of cytosolic pH changes in living cells. Most importantly, BPN has not only been successfully applied for distinguishing inflammation in mice, but also the surgical specimens of cancer tissue, making it of great potential application in cancer diagnosis.

Activated recovery of PVC from contaminated waste extension cord-cable using a weak acid.

Waste electronic and electrical equipment are complex mixtures of valuable and/or toxic materials, which pose serious challenges in their recycling or disposal, for example, electrical transmission wires insulated in polyvinyl chloride materials. These materials are frequently found contaminated with toxic chemical elements, such as Pb, Hg, Cr, or Cd, and are discarded without decontamination. To resolve this problem, we developed a microwave-assisted extraction process to remove toxic metals from plastic e-waste. We processed diluted (30 wt%) citric acid at 210 °C for 1 h inside a pressurized vessel heated by microwave, and found it was suitable not only for the extraction of the toxic metals (∼100%) but also for a significant plastic recovery (>50 wt%). To predict an optimized process window, the support vector regression machine learning algorithm was applied, which reduced the amount of experimentation required while still giving accurate results. Conditions optimized for the reference sample also led to maximum extraction of toxic metals from real-life extension cord waste. We also report that the recovered plastic's properties remained intact after the extraction.

Rational Design of an Iridium-Tungsten Composite with an Iridium-Rich Surface for Acidic Water Oxidation.

Developing highly active and stable water oxidation catalysts with reduced cost in acidic media plays a critical role in clean energy technologies such as fuel cells and electrolyzers. Precious iridium-based oxides are still the only oxygen evolution reaction (OER) catalysts with reasonable activity and stability in acid. Herein, we design iridium-tungsten composites with a metallic tungsten-rich core and an iridium-rich surface by the sol-gel method followed by hydrogen reduction. The thus obtained iridium-tungsten catalyst shows much higher intrinsic water oxidation activity (100 mA/mgIr at an overpotential of 290 mV) and stability (100 h at 10 mA/cm2geom) together with reduced iridium content (33 wt % only) as compared with pure iridium oxide. An operando method using H2O2 as a probe molecule is developed to determine the relative adsorption strength of the reaction intermediates (*OH and *OOH) in the OER process. Detailed characterization shows that the tungsten-incorporated surface not only modulates the adsorption energy of oxygen intermediates on iridium but also enhances the stability of iridium species in acid, while the metallic tungsten core exhibits high electrical conductivity, all of which collectively give rise to the much enhanced catalytic performance of iridium-tungsten composite in acidic water oxidation. A single-membrane electrode assembly is further prepared to demonstrate the advantages and potential application of iridium-tungsten composite in practical proton exchange membrane electrolyzers.

Breaking Long-Range Order in Iridium Oxide by Alkali Ion for Efficient Water Oxidation.

Oxygen electrochemistry plays a critical role in clean energy technologies such as fuel cells and electrolyzers, but the oxygen evolution reaction (OER) severely restricts the efficiency of these devices due to its slow kinetics. Here, we show that via incorporation of lithium ion into iridium oxide, the thus obtained amorphous iridium oxide (Li-IrO x) demonstrates outstanding water oxidation activity with an OER current density of 10 mA/cm2 at 270 mV overpotential for 10 h of continuous operation in acidic electrolyte. DFT calculations show that lithium incorporation into iridium oxide is able to lower the activation barrier for OER. X-ray absorption characterizations indicate that both amorphous Li-IrO x and rutile IrO2 own similar [IrO6] octahedron units but have different [IrO6] octahedron connection modes. Oxidation of iridium to higher oxidation states along with shrinkage in the Ir-O bond was observed by in situ X-ray absorption spectroscopy on amorphous Li-IrO x, but not on rutile IrO2 under OER operando conditions. The much more "flexible" disordered [IrO6] octahedrons with higher oxidation states in amorphous Li-IrO x as compared to the periodically interconnected "rigid" [IrO6] octahedrons in crystalline IrO2 are able to act as more electrophilic centers and thus effectively promote the fast turnover of water oxidation.