Always positive covalent organic nanosheet enabling pH-independent adsorption and removal of Cr(â ¥).

Rapid and highly effective removal of hexavalent chromium (Cr(Ⅵ)) is extremely vital to water resources restoration and environmental protection. To overcome the pH limitation faced by most ionic absorbents, an always positive covalent organic nanosheet (CON) material was prepared and its Cr(VI) adsorption and removal capability was investigated in detail. As-prepared EB-TFB CON (TFB = 1,3,5-benzaldehyde, EB = ethidium bromide) shows strong electropositivity in the tested pH range of 1 ∼ 10, display a pH-independent Cr(VI) removal ability, and work well for Cr(VI) pollution treatment with good anti-interference capability and reusability in a wide pH range covering almost all Cr(VI)-contaminated real water samples, thus eliminating the requirement for pH adjustment. Moreover, the nanosheet structure, which is obtained by a facile ultrasonic-assisted self-exfoliation, endows EB-TFB CON with fully exposed active sites and shortened mass transfer channels, and the Cr(VI) adsorption equilibrium can be reached within 15 min with a high adsorption capacity of 280.57 mg·g-1. The proposed Cr(VI) removal mechanism, which is attributed to the synergetic contributions of electrostatic adsorption, ion exchange and chemical reduction, is demonstrated by experiments and theoretical calculations. This work not only provides a general Cr(VI) absorbent without pH limitation, but also presents a paradigm to prepare ionic CONs with relatively constant surface charges.

DNA-Functionalized Porphyrinic Metal-Organic Framework-Based Drug Delivery System for Targeted Bimodal Cancer Therapy.

A DNA-functionalized porphyrinic MOF (porMOF) drug delivery system was successfully constructed. porMOF as a photosensitizer and drug delivery carrier can integrate photodynamic therapy (PDT) and chemotherapy. Via the strong coordination interaction between the zirconium cluster of porMOF and the terminal phosphate group of DNA, the stable modification of the DNA layer on the porMOF surface is achieved. Meanwhile, the introduction of C/G-rich base pairs into the DNA double-stranded structure provides more binding sites of chemotherapeutic drug doxorubicin (DOX). AS1411, an aptamer of nucleolin proteins that are overexpressed by cancer cells, is introduced in the double-stranded terminal, which can endow the nanosystem with the ability to selectively recognize cancer cells. C-rich sequences in DNA double strands form an i-motif structure under acidic conditions to promote the highly efficient release of DOX in cancer cells. In vitro and in vivo experiments demonstrate that the synergistic PDT/chemotherapy modality achieves highly efficient cancer cell killing and tumor ablation without undesirable side effects.

Telomerase-activated Au@DNA nanomachine for targeted chemo-photodynamic synergistic therapy.

We successfully designed a smart activatable nanomachine for cancer synergistic therapy. Photodynamic therapy (PDT) and chemotherapy can be activated by intracellular telomerase while anti-cancer drugs can be effectively transported into tumour cells. An Sgc8 aptamer was designed, which can specifically distinguish tumour cells from normal cells and perform targeted therapy. The nanomachine entered the tumour cells by recognising PTK7, which is overexpressed on the surface of cancer cells. Then, the "switch" of the system was opened by TP sequence extension under telomerase stimulus. So, the chemotherapeutic drug DOX was released to achieve the chemotherapy, and the Ce6 labelled Sgc8-apt was released to activate the PDT. It was found that if no telomerase existed, the Ce6 would always be in an "off" state and could not activate the PDT. Telomerase is the key to controlling the activation of the PDT, which effectively reduces the damage photosensitisers cause to normal cells. Using in vitro and in vivo experiments, the nanomachine shows an excellent performance in targeted synergistic therapy, which is expected to be utilised in the future.

Efficient food safety analysis for vegetables by a heteropore covalent organic framework derived silicone tube with flow-through purification.

A heteropore covalent organic framework incorporated silicone tube (S-tube@PDA@COF) was used as adsorbent to purify the matrices in vegetable extracts. The S-tube@PDA@COF was fabricated by a facile in-situ growth method and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and N2 adsorption-desorption. The as-prepared composite exhibited high removal efficiency of phytochromes and recovery (81.13-116.62%) of 15 chemical hazards from 5 representative vegetable samples. This study opens a promising avenue toward the facile synthesis of covalent organic frameworks (COFs)-derived silicone tubes for streamline operation in food sample pretreatment.