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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.

Fluorimetric and colorimetric analysis strategies have been developed for simultaneously probing Fe3+ and Fe2+ ions in blood or tap water using nitrogen-doped carbon dots (N-Cdots). Herein, the N-Cdots were prepared using melamine by a neutralization heat reaction one-step synthesis route showing high aqueous solubility and environmental stability. Importantly, unlike common carbon dots (Cdots) that generally display one emission of blue fluorescence, they can display excitation-dependent tunable emissions. Moreover, the bright blue-green fluorescence of N-Cdots could be specifically quenched by Fe3+ or Fe2+ ions simultaneously, showing a color change. Herein, the fluorescent quenching of N-Cdots is thought to result from the aggregation of N-Cdots triggered by the unique coordination interactions between Fe3+ or Fe2+ ions and amine and amide groups of N-Cdots. The developed analysis strategies were employed for the evaluation of the total iron levels in blood or tap water, with a detection limit down to about 5.0 nM, exemplified for Fe3+ ions. These strategies could be promising for use in practical applications for the clinical diagnosis of iron-relative diseases (i.e., anemia and cancers) and environmental monitoring of iron pollution. In addition, this one-step neutralization heat reaction route as a facile green synthesis candidate may be tailored for the fabrication of a variety of Cdots, especially those with doped heteroatoms (i.e., nitrogen) for extensive applications in biomedical and environmental fields. [ABSTRACT FROM AUTHOR]

Rapid detection and accurate analysis of trace samples is an important prerequisite for precision medicine. Here we integrated capillary with ultrasound to induce biomarkers enrichment in nanoliter samples, and developed a nanoliter sample enrichment analysis method for ultra-trace miRNA biosensing. The interaction between ultrasonic field and capillary provides a gradient ultrasound field, which is essential for the aggregation of functionalized microspheres along with the enrichment of specific biomarkers. The results indicated that the enrichment of the biomarkers effectively enhanced the fluorescence intensity, and the limit of detection reaches 7.8✕10−12 M in 100 nL. Such integrated device can realize ultrasonic enrichment and visual analysis of target samples, and provides a new idea for rapid and highly sensitive detection of ultra-trace biomarkers in clinical diagnosis. • A nanoliter sample enrichment detection method for ultra-trace miRNA biosensing. • Integrated capillary with ultrasound enables capture and enrichment of specific trace biomarkers. • Such integrated device provides a new idea for rapid and highly sensitive detection in clinical diagnosis. [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]

The bifunctional probe NBOS showed absorbance-ratiometic sensing for Ag+ over a pH range from 6 to 7.5 and fluorescence "turn on" signal response towards Zn2+ in the pH range of 6–10 in EtOH/H 2 O (9/1, V/V, pH = 7.4) mixture. • The probe NBOS characterized by X-ray Crystallography showed sensing for Ag+ and Zn2+ through two different optical modes. • The sensing mechanism of NBOS with Ag+ and Zn2+ were investigated by FT-IR, HNMR, job'plot, ESI-MS. • The coordination mode of NBOS /Zn2+ was further confirmed by DFT calculation. • Probe NBOS could be used to detect Zn2+ in walnut and living cells. • NBOS was designed to construct an NOT and OR logic gate controlled by Ag+ and Zn2+. In this work, naphthalene with good biocompatibility was selected, and the probe NBOS was synthesized with 2-Amino-phenol and 2-Amino-benzenethiol. The structure of probe NBOS was confirmed by X-ray Crystallography. Furthermore, the probe showed absorbance-ratiometic sensing for Ag+ over a pH range from 6 to 7.5 and fluorescence "turn on" signal response towards Zn2+ in the pH range of 6–10 in EtOH/H 2 O (9/1, V/V, pH = 7.4) mixture. The detection limit was obtained to be 4.24 μM for Ag+ and 3.17 nM for Zn2+. Moreover, it could be efficiently recycled by treating Na 2 EDTA. The sensing mechanism of probe NBOS toward Ag+ and Zn2+ was investigated by FT-IR, HNMR, job'plot and ESI-MS. Typically, the coordination mode of NBOS with Zn2+ was confirmed by DFT calculation. Moreover, probe NBOS was successfully applied in the detection Ag+ and Zn2+ in real water samples. Importantly, probe NBOS could be used to detect Zn2+ in walnut and living cells. Based on the high throughput analysis strategy, absorbance and fluorescence signals of NBOS could be designed as a NOT and OR logic gate controlled by Ag+ (Input 1) and Zn2+ (Input 2). [ABSTRACT FROM AUTHOR]