Heavy metal ions are highly toxic and widely spread as environmental pollutants. New strategies are being developed to simultaneously detect and remove these toxic ions. Herein, we take the intrinsic advantage of covalent organic frameworks (COFs) and develop fluorescent COFs for sensing applications. As a proof-of-concept, a thioether-functionalized COF material, COF-LZU8, was "bottom-up" integrated with multifunctionality for the selective detection and facile removal of mercury(II): the π-conjugated framework as the signal transducer, the evenly and densely distributed thioether groups as the Hg(2+) receptor, the regular pores facilitating the real-time detection and mass transfer, together with the robust COF structure for recycle use. The excellent sensing performance of COF-LZU8 was achieved in terms of high sensitivity, excellent selectivity, easy visibility, and real-time response. Meanwhile, the efficient removal of Hg(2+) from water and the recycling of COF-LZU8 offers the possibility for practical applications. In addition, X-ray photoelectron spectroscopy and solid-state NMR investigations verified the strong and selective interaction between Hg(2+) and the thioether groups of COF-LZU8. This research not only demonstrates the utilization of fluorescent COFs for both sensing and removal of metal ions but also highlights the facile construction of functionalized COFs for environmental applications.

The structural uniqueness of covalent organic frameworks (COFs) has brought these new materials great potential for advanced applications. One of the key aspects yet to be developed is how to improve the robustness of covalently linked reticular frameworks. In order to make the best use of π-conjugated structures, we develop herein a "killing two birds with one stone" strategy and construct a series of ultrastable benzoxazole-based COFs (denoted as LZU-190, LZU-191, and LZU-192) as metal-free photocatalysts. Benefiting from the formation of benzoxazole rings through reversible/irreversible cascade reactions, the synthesized COFs exhibit permanent stability in the presence of strong acid (9 M HCl), strong base (9 M NaOH), and sunlight. Meanwhile, reticulation of the benzoxazole moiety into the π-conjugated COF frameworks decreases the optical band gap and therefore increases the capability for visible-light absorption. As a result, the excellent photoactivity and unprecedented recyclability of LZU-190 (for at least 20 catalytic runs, each with a product yield of 99%) have been illustrated in the visible-light-driven oxidative hydroxylation of arylboronic acids to phenols. This contribution represents the first report on the photocatalytic application of benzoxazole-based structures, which not only sheds new light on the exploration of robust organophotocatalysts from small molecules to extended frameworks but also offers in-depth understanding of the structure-activity relationship toward practical applications of COF materials.

In recent years, food safety issues have drawn growing concerns from society. In order to efficiently detect and prevent food safety problems and trace the accountability, building a reliable traceability system is indispensable. It is especially essential to accurately record, share, and trace the specific data within the whole food supply chain, including the process of production, processing, warehousing, transportation, and retail. The traditional traceability systems have issues, such as data invisibility, tampering, and sensitive information disclosure. The blockchain is a promising technology for the food safety traceability system because of the characteristics, such as the irreversible time vector, smart contract, and consensus algorithm. This paper proposes a food safety traceability system based on the blockchain and the EPC Information Services and develops a prototype system. The management architecture of on-chain & off-chain data is proposed as well, through which the traceability system can alleviate the data explosion issue of the blockchain for the Internet of Things. Furthermore, the enterprise-level smart contract is designed to prevent data tampering and sensitive information disclosure during information interaction among participants. The prototype system was implemented based on the Ethereum. According to the test results, the average time of information query response is around 2 ms, while the amount of on-chain data and query counts are 1 GB and 1000 times/s, respectively. INDEX TERMS Food safety, traceability, blockchain, EPCIS, on-chain & off-chain, smart contract.

The development of oral insulin using the eligen technology represents a significant advance in insulin administration which is expected to improve the quality of life of diabetic patients. As clinical studies progress, a great deal of interest has focused on the process by which this technology enables insulin absorption from the intestinal lumen into the bloodstream. The eligen technology employs low molecular weight compounds (termed drug delivery agents or carriers) which interact weakly and non-covalently with insulin, increasing its lipophilicity and thereby its ability to cross the gastrointestinal epithelium. In this study we investigated the mechanism of insulin absorption across caco-2 cell monolayers with one of these drug delivery agents, N-[8-(2-hydroxybenzoyl)amino] caprylate (SNAC). Our results show that SNAC increases insulin permeability approximately ten fold across cell monolayers and does so without affecting mannitol permeability or disrupting cell membranes. Confocal microscopy and immunocytochemistry revealed that insulin is transported transcellularly without detectable alteration of the tight junctions between adjacent cells. SNAC also appears to play some role in protecting insulin from proteolytic degradation, potentially allowing for more intact insulin to be available at the site of absorption.

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