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Alcohol solvents especially isopropanol were demonstrated for the first time to endow silver nanoclusters (AgNCs) in water with dramatically enhanced red fluorescence. More importantly, the specific iodide recognition capability of the AgNCs could thus be obtained towards a highly selective fluorimetric assay for detecting iodide ions in urine.

Histidine can trigger bimetallic gold/copper nanoclusters to turn on strong red fluoresence, which is capable of sensing nanomolar levels of histidine selectively. [ABSTRACT FROM AUTHOR]

Abstract Metal-free fluorescent covalent organic frameworks (COFs) were synthesized initially with Q-Graphene (QG) scaffolds by the one-step covalent reactions of melamine-aldehyde and phenol-aldehyde poly-condensations using paraformaldehyde. It was discovered that onion-like hollow QG, which consists of multi-layer graphene and different carbon allotropes having a high proportion of folded edges and surface defects, could endow the scaffolded COFs with enhanced green fluorescence and environmental stability. Unexpectedly, they could exhibit the powerful absorption for Cu2+ ions resulting in the specific quenching of fluorescence. A fluorimetric strategy with QG-scaffolded COFs was thereby developed to probe Cu2+ ions separately in blood and wastewater with the linear concentration ranges of 0.0010–10.0 μM (limit of detection of 0.50 nM) and 0.0032–32.0 μM (limit of detection of 2.4 nM), respectively, promising the potential applications for the field-applicable monitoring of Cu2+ ions in the clinical and environmental analysis fields. In addition, the prepared COFs sorbents were employed to absorb Cu2+ ions in wastewater showing high removal efficiency. More importantly, such an one-pot fabrication route with hollow QG scaffolds may be tailorable extensively for the preparation of a variety of metal-free multifunctional COFs with enhanced fluorescence, water solubility, environmental stability, and metal removal capability. Graphical abstract Image 1 Highlights • Metal-free COFs were polymerized onto the scaffolds of hollow Q-Graphene (QG). • QG-scaffolded COFs could present enhanced fluorescence, high aqueous stability, and photostability. • The fluorescence of QG-scaffolded COFs could be quenched by Cu2+ ions towards the ultrasensitive copper analysis. • The QG-scaffolded COF could serve as powerful sorbents for the removal of Cu2+ ions in wastewater with high efficiency. [ABSTRACT FROM AUTHOR]

Supramolecular self-assemblies enabled to obtain architectures with amusing properties for various applications including optical device, biosensing and bioimaging. Herein, bimetallic copper-cerium nanoclusters (Cu/Ce NCs) spheres dispersed in isopropanol (IPA)/phosphate buffer (PB, 10 mM, pH7.0) mixed solution can be aggregated to form non-fluorescent nanowire network through self-assembly. Interestingly, the non-fluorescent Cu/Ce NCs nanowire network can be further aggregated blocky structure in the presence of cysteine (Cys), with a strong red fluorescence turn-on. Moreover, the Cys-induced turn-on efficiency of Cu/Ce NCs dispersed in 60% (v/v) IPA/PB mixed solution is 2.7-times that value in PB solution. The Cys-triggered red fluorescence turn-on of Cu/Ce NCs presumably due to the solvent-caused aggregation-induced emission, given rise to by the strong coordination interaction of Ce with carboxyl groups of Cys, and Cu with Cys via the thiol group to link with Cu/Ce NCs by Cu S bonding. Additionally, it was found that the Cu/Ce NCs dispersed in 60% IPA/PB mixed solution exhibited good storage stability and repeatability. Then, based on Cys-triggered red fluorescence turning on, fluorimetric sensing Cys was developed with a wide linear range of 10–32,000 nM and detection limit of 3 nM (S/N = 3). The other common species didn't affect Cys detection. Furthermore, the as-proposed assay can be applied to measure Cys in actual samples accurately and reproducibly. Thereafter, featured by the solvent-induced self-assembly of metal NCs, which is envisioned to cast broad potential applications in designing luminescent materials, biosensing, clinical diagnosis and optoelectronic device. [Display omitted] • Bimetallic Cu/Ce NCs in IPA/water mixed solution aggregated to form nanowire network through self-assembly. • The Cu/Ce NCs nanowire network further triggered by Cys to form blocky structure with a strong red fluorescence turn-on. • The Cys-triggered red fluorescence turn-on of Cu/Ce NCs presumably caused by the strong coordination interaction. • Sensitive and selective fluorimetric biosensor capable of detecting Cys at nM level. [ABSTRACT FROM AUTHOR]

Highly selective and sensitive monitoring of peroxynitrite (ONOO-) in living systems is of significance since it is closely related with the occurrence of multiple diseases. Herein, we successfully constructed ultrathin NAP@Cd-3,5-PDC (NAP@Cd-3,5-PDC-NS, NAP: 2-(6-(4-methylpiperazin-1-yl)− 1,3-dioxo-1 H-benzo[de]isoquinolin-2(3 H)-yl) acetic acid, 3,5-PDC = 3,5-pyridine dicarboxylic acid) fluorescent nanosheets through a simple solution route and subsequent ultrasonication at room temperature. Experiments revealed that the presence of Cd-3,5-PDC-NS significantly enhanced the fluorescence emission of NAP. Under excitation of 398 nm light, the as-obtained NAP@Cd-3,5-PDC-NS could emit about 7-fold stronger photoluminescence than NAP with an equivalent concentration. Also, the as-obtained composite nanosheets could be stably dispersed in phosphate buffer solution (PBS) for 42 days without obvious structure and fluorescence changes. Intriguingly, the strong fluorescence of NAP@Cd-3,5-PDC-NS could be severely quenched by ONOO- without interferences from some other active species, anions/cations, and amino acids. The detection limit of NAP@Cd-3,5-PDC-NS for ONOO- was as low as 61.5 nM, which was 15 times lower than that of the NAP probe alone. Moreover, the as-obtained fluorescent probe could be applied to HepG2 cell imaging, showing its potential application in disease diagnosis. • Ultrathin NAP@Cd-3,5-PDC NS is prepared by a simple solution route and subsequent ultrasonication. • As-obtained NAP@Cd-3,5-PDC NS can form stable sol in PBS and emit strong fluorescence. • Strong fluorescence of NAP@Cd-3,5-PDC NS is sensitively and selectively quenched by ONOO-. • NAP@Cd-3,5-PDC NS sensor bears a far lower detection limit down to 61.5 nM for ONOO-. • NAP@Cd-3,5-PDC NS can be applied for imaging of HepG2 cell. [ABSTRACT FROM AUTHOR]