Thermally Induced Persistent Covalent-Organic Frameworks Radicals.

Persistent covalent-organic framework (COF) radicals hold important applications in magnetics and spintronics; however, their facile synthesis remains a daunting challenge. Here, three p-phenylenediacetonitrile-based COFs (named CityU-4, CityU-5, and CityU-6) were synthesized. Upon heat treatment (250 °C for CityU-4 and CityU-5 or 220 °C for CityU-6), these frameworks were brought into their persistent radical forms (no obvious changes after at least one year), together with several observable factors, including color changes, red-shifted absorption, the appearance of electron spin resonance (ESR) signals, and detectable magnetic susceptibility. The theoretical simulation suggests that after heat treatment, lower total energy and nonzero spin density are two main factors to guarantee persistent COFs radicals and polarized spin distributions. This work provides an efficient method for the preparation of persistent COF radicals with promising potentials.

An ultrasound-activatable platinum prodrug for sono-sensitized chemotherapy.

Despite the great success achieved by photoactivated chemotherapy, eradicating deep tumors using external sources with high tissue penetration depth remains a challenge. Here, we present cyaninplatin, a paradigm of Pt(IV) anticancer prodrug that can be activated by ultrasound in a precise and spatiotemporally controllable manner. Upon sono-activation, mitochondria-accumulated cyaninplatin exhibits strengthened mitochondrial DNA damage and cell killing efficiency, and the prodrug overcomes drug resistance as a consequence of combined effects from released Pt(II) chemotherapeutics, the depletion of intracellular reductants, and the burst of reactive oxygen species, which gives rise to a therapeutic approach, namely sono-sensitized chemotherapy (SSCT). Guided by high-resolution ultrasound, optical, and photoacoustic imaging modalities, cyaninplatin realizes the overall theranostics of tumors in vivo with superior efficacy and biosafety. This work highlights the practical utility of ultrasound to precisely activate Pt(IV) anticancer prodrugs for the eradication of deep tumor lesions and broadens the biomedical uses of Pt coordination complexes.

Single-layer HNb3O8 with strong and nearby Lewis and Brønsted acid sites boosts amide bond hydrolysis for urease mimicking.

Urea pollution is a growing environmental concern, and its removal via catalytic hydrolysis is challenging due to the resonance-stabilized amide bonds. In nature, this reaction is catalyzed by ureases in many soil bacteria. However, the remedy of this problem with natural enzymes is not feasible as they are easily denatured and require high costs for both preparation and storage. Given this, the development of nanomaterials bearing enzyme-like activity (nanozymes) with advantages such as low production cost, simple storage, and pH/thermal stability has attracted much attention over the past decade. As inspired by the mechanism of urease-catalyzed urea hydrolysis, the co-presence of Lewis acid (LA) and Brønsted acid (BA) sites is imperative to proceed with this reaction. Herein, layered HNb3O8 samples with intrinsic BA sites were adopted for investigation. The layer reduction of this material to few-/single layers can expose Nb sites with various LA strengths depending on the degree of NbO6 distortion. Among the catalysts examined, single-layer HNb3O8 bearing strong LA and BA sites displays the best hydrolytic activity towards acetamide and urea. This sample with high thermal stability was found to outperform urease at temperatures higher than 50 °C. The acidity-activity correlation established in this study is believed to guide the future design of industrial catalysts to remediate urea pollution.

A nanocomposite consisting of ionic liquid-functionalized layered Mg(II)/Al(III) double hydroxides for simultaneous electrochemical determination of cadmium(II), copper(II), mercury(II) and lead(II).

An electrochemical sensor is described for the simultaneous determination of Cd2+, Cu2+, Hg2+ and Pb2+ using square wave anodic stripping voltammetry. A glassy carbon electrode (GCE) was modified with N,N-dimethyl-N-2-propenyl-2-propen-1-aminium chloride homopolymer ionic liquid doped into magnesium(II)-aluminium(III) layered double hydroxides. The morphology investigations suggest that the material possesses typical interconnected laminated micropores and a mesoporous architecture dispersed on the surface of the GCE. This accelerates mass diffusion and facilitates the deposition-stripping process of metal ions. Key operational parameters including pH, deposition potential, deposition time and the quantity of nanomaterial on the GCE were optimized. The following figures of merit for the ions Cd2+, Cu2+, Hg2+ and Pb2+ are obtained under optimum conditions: (a) detection limits of 250, 25, 250 and 16 ng L-1; (b) linear ranges from 0.5 to 20, 0.05 to 20, 0.5 to 20 and 0.05 to 20 µg L-1, and (c) peak potentials of -768, +42, +302 and - 541 mV (vs. Ag/AgCl). The modified GCE was successfully applied to the determination of these ions in spiked black tea extract and in dried tangerine peel. Graphical abstractSchematic representation of novel electrochemical sensor based on a glassy carbon electrode modified with IL-Mg/Al-LDHs composites for the simultaneous detection of Pb2+, Cd2+, Cu2+ and Hg2+.