Iodide plays a vital role in many biological processes, including neurological activity and thyroid function. Due to its physiological relevance, a method for the rapid, sensitive, and selective detection of iodide in food, pharmaceutical products, and biological samples such as urine is of great importance. Herein, we demonstrate a novel and facile strategy for constructing a fluorescence turn-on sensor for iodide based on a T-Hg(II)-T complex (T=thymine). A fluorescent anthracene-thymine dyad (An-T) was synthesized, the binding of which to a mercury(II) ion lead to the formation of a An-T-Hg(II)-T-An complex, thereby quenching the fluorescent emission of this dyad. In this respect, the dyad An-T constituted a fluorescence turn-off sensor for mercury(II) ions in aqueous media. More importantly, it was found that upon addition of iodide, the mercury(II) ion was extracted from the complex due to the even stronger binding between mercury(II) ions and iodide, leading to the release of the free dyad and restoration of the fluorescence. By virtue of this fluorescence quenching and recovery process, the An-T-Hg(II)-T-An complex constitutes a fluorescence turn-on sensor for iodide with a detection limit of 126 nM. Moreover, this sensor is highly selective for iodide over other common anions, and can be used in the determination of iodide in drinking water and biological samples such as urine. This strategy may provide a new approach for sensing some other anions.

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A facile strategy was employed to create a fluorescence resonance energy transfer (FRET) based ratiometric sensing system for ferric ions in all-aqueous media by using nanosized poly(ethylene oxide)-b-polystyrene micelles as the scaffold. A hydrophobic fluorescent dye nitrobenzoxadiazolyl derivative (NBD), which served as the energy transfer donor, was incorporated into the micelle core during the micelle formation; a spirolactam rhodamine derivative (SRhB-OH) was chosen as a sensitive and selective sensor for Fe(III) ions and was then 'adsorbed' into the micelle core/corona interface. A highly efficient ring-opening reaction of SRhB-OH induced by Fe(III) generates the long-wavelength rhodamine B fluorophore which can act as the energy acceptor; thus, the micelle nanoparticles can serve as a FRET-based ratiometric detection system for ferric ions. The effects of PS block length on the ion sensing performance of the micelles were investigated, and it has been found that the micelles formed by the copolymer with moderate block length (PEO(113)-b-PS(115)) were preferable as the scaffold for the FRET system and exhibited a sensitive and selective sensing capacity for Fe(III) with a detection limit of 1 microM. This nanoparticle-based sensing strategy may be utilized to construct other ratiometric chemosensors by replacing the current dyes with other suitable ones.

Various aryl seleno/thiocyanates have been synthesized via the electrochemical deborylative seleno/thiocyanation of arylboronic acids under ambient conditions.

Due to the dangerous nature of anthrax, the development of a cost-effective, sensitive and field-portable sensor for the anthrax biomarker--calcium dipicolinate (CaDPA)--is of exceptional significance for both military and civilian use. Herein, a flexible polymer-film-based ratiometric sensor for detecting CaDPA was demonstrated. A reference dye and a probe ligand were covalently immobilized onto the film surface through a highly selective and efficient "click chemistry" reaction. The reference dye, whose fluorescence intensity does not change with varying amounts of CaDPA, offers a non-interfering internal calibration. The ethylenediaminetetraacetic acid (EDTA)-based ligand binds with Eu(III) and serves as the probe. In the absence of CaDPA, the film sensor exhibited almost no red fluorescence because the Eu(III) ions themselves give no emission without sensitization by CaDPA owing to the small molar absorption coefficients of Eu(III) ions. The presence of CaDPA induces a significantly enhanced emission intensity of the sensor, and thereby enables the film as a ratiometric sensor for CaDPA. This sensor can selectively detect CaDPA in water with a detection limit of 100 nM. Moreover, this sensor exhibited strong anti-interfering capability, it can not only be used in milieus that contain various amino acids and some biologically-abundant cations, but can also be usable in some biological fluids such as urine and serum. This test-paper-like film sensor is suitable for portable field analysis and needs no extra protective measures during transport due to its flexibility, and it can easily be separated from the analyte solution after the detection.