The Missing Chalcogen Bonding Donor: Strongly Polarized Oxygen of Water.

A biscyclen molecular cabin, synthesized by connecting two cyclen macrocycles with four linkages, entraps a Li+···H2O···Li+ trimer with a water molecule clamped by two Li+ ions. This configuration results in strongly polarized water, characterized by a water proton resonance shift of up to 10.00 ppm. The arrangement facilitates unprecedented O-centered chalcogen bonds between the lone pairs of pyridinyl nitrogen atoms and polarized water oxygen, as confirmed by X-ray crystallography, NMR spectroscopy, and theoretical calculations. Further observation of O-centered chalcogen bonding in a H2O·(LiCl)2 cluster suggests its widespread presence in hydrated salt systems.

A triphenylamine-based fluorescent probe with phenylboronic acid for highly selective detection of Hg2+ and CH3Hg+ in groundwater.

Mercury is a highly toxic heavy metal and it poses a serious threat to the natural environment and human health. Thus, selective detection of trace mercury (e.g. inorganic mercury and methylmercury) in the environment is critical yet challenging. Herein, we describe the rational design and facile synthesis of a new triphenylamine-based phenylboronic acid fluorescent probe (TPA-PBA) for selective detection of Hg2+ and CH3Hg+. Due to the inherent specificity of the displacement reaction between phenylboronic acid and mercury, this probe exhibits exceptionally high selectivity towards Hg2+/CH3Hg+ against other tested ions with ppb-level sensitivity. More importantly, the probe TPA-PBA is effective and selective in detecting Hg2+/CH3Hg+ in tap water and real-world groundwater, indicating its potential practical applications in in situ and online mercury detection in real-world scenarios. With TPA-PBA based test strips Hg2+ can be distinguished from CH3Hg+ by the naked eye. This study could accelerate the development of low-cost, highly efficient and selective fluorescent probes for rapid trace mercury detection.

Super metal hydrogels constructed from a simple tripodal gelator and rare earth metal ions and its application in highly selective and ultrasensitive detection of histidine.

A series of stable super metal hydrogels (TP-Ms, M = Tb3+, Eu3+, La3+ and Ce3+) with a low critical gelation concentration (2.28 × 10-3 M, 0.1%) was successfully constructed by forming hierarchical assemblies of a tripodal gelator (TP) with rare earth metal ions (Tb3+, Eu3+, La3+ and Ce3+). Interestingly, the super metal hydrogels TP-Eu and TP-La show a specific and ultrasensitive response to histidine (His). The addition of a series of amino acids into the metal hydrogels TP-Eu and TP-La showed that only His could induce distinct fluorescent enhancement for TP-Eu and TP-La, while other amino acids did not significantly interfere with the His sensing process. The LODs of super metal-hydrogel TP-Eu and TP-La for His are (1.83-1.94) × 10-9 and (1.83-1.85) × 10-9 M, respectively. In addition, constructing super supramolecular metal hydrogels by hierarchical assemblies of an easily synthesized tripodal gelator and rare earth metal ions is a novel and efficient approach to the design and development of multi-functional super supramolecular metal hydrogel-based materials.

A novel supramolecular AIE π-gel for fluorescence detection and separation of metal ions from aqueous solution.

A novel supramolecular aggregation induced emission (AIE) π-gel (ONT) was constructed by using a functionalized trimesic amide (TCP) molecule assembled with a bis-pyridine functionalized naphthalene diimide (ND) molecule using a non-covalent interaction. The ONT showed strong AIE at 468 nm. Furthermore, the ONT could detect and adsorb ferric (Fe3+) or cupric (Cu2+) ions from water. Meanwhile, a thin film based on supramolecular AIE π-gel ONT was prepared, which could be used as a fluorescent security display material for detecting Fe3+ or Cu2+. Thus, the AIE π-gel ONT shows potential for practical applications in efficient multi-analyte detection and separation and as a fluorescent display material.

A novel AIE-based supramolecular polymer gel serves as an ultrasensitive detection and efficient separation material for multiple heavy metal ions.

Recently, ultrasensitive stimuli-responsive materials have received extensive attention due to their high sensitivity and wide applications. Herein, we report a novel approach to design ultrasensitive responsive materials by rationally introducing the aggregation-induced emission (AIE) effect into supramolecular polymer gels. According to this approach, by rationally introducing self-assembly moieties and a fluorophore, the obtained gelator DNS can act as an AIEgen; it showed strong AIE after aggregating into the supramolecular polymer gel GDNS. More interestingly, because the aggregation of DNS led to amplification of the detective signal, the AIE-based supramolecular polymer gel GDNS could ultrasensitively detect the heavy metal ions Hg2+, Cu2+, and Fe3+ by a signal amplification mechanism; the lowest detection limits reached 10-11 M. In addition, the xerogel of GDNS could adsorb and separate Hg2+, Cu2+, and Fe3+ from aqueous solution with favourable adsorption properties, and the adsorption rates ranged from 94.70% to 99.37%. Furthermore, the gel GDNS could act as a convenient test kit for Hg2+, Cu2+, and Fe3+ as well as a smart fluorescent display material.

A novel bis-component AIE smart gel with high selectivity and sensitivity to detect CN-, Fe3+ and H2PO4.

A novel bis-component AIE-gel TG was facilely constructed from two "easy-to-synthesize" tripodal gelators by a simple host-guest self-assembly process. Interestingly, the TG shows strong aggregation-induced emission (AIE) and could be used for highly efficient and sensitive detection and separation of ions (CN-, Fe3+ and H2PO4-). The LODs (limits of lowest detection) of TG for CN-, Fe3+ and H2PO4- are in the range of 4.93 × 10-9-7.80 × 10-8 M. Meanwhile, the xerogel of TG could adsorb and separate Fe3+ from aqueous solutions, and the adsorption rate is 96%. In addition, a thin film based on the TG could act as a convenient test kit for the detection of CN- and Fe3+. What is more, the TG-Fe film could not only be used as an erasable secure fluorescent display material, but also as a convenient reversible H2PO4- test kit.

Renal clearable magnetic nanoparticles for magnetic resonance imaging and guided therapy.

Magnetic resonance imaging (MRI) is a non-invasive, radiation-free imaging technique widely used for disease detection and therapeutic evaluation due to its infinite penetration depth. Magnetic nanoparticles (MNPs) have unique magnetic and physicochemical properties, making them ideal as contrast agents for MRI. However, the in vivo toxicity of MNPs, resulting from metal ion leakage and long-term accumulation in the reticuloendothelial system (RES), limits their clinical application. To overcome these challenges, there is considerable interest in the development of renal-clearable MNPs that can be completely cleared through the kidney, reducing retention time and potential toxic risks. In this review, we provide an overview of recent advancements in the development of renal-clearable MNPs for disease imaging and treatment. We discuss the factors influencing renal clearance, summarize the types of renal-clearable MNPs, their synthesis methods, and biomedical applications. This review aims to offer comprehensive information for the design and clinical translation of renal-clearable MNPs. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing.

Photo-controllable binding and release of HP2O73- using an azobenzene based smart macrocycle.

Herein, we describe the design and synthesis of an unusual azobenzene-bearing macrocycle 1, whose trans isomer was found able to 100% transform into its cis configuration under photoirradiation, for selectively recognizing HP2O73- with reversibly photo-controllable binding and release properties.