Solid polymer substrates and coated fibers containing 2,4,6-trinitrobenzene motifs as smart labels for the visual detection of biogenic amine vapors.

Attempts to polymerize trinitrobenzene derivatives (TNB) have been fruitless so far. Accordingly, polymers containing TNB have not been exploited in spite of their envisaged potential applications. Here, we describe two ways for preparing polymers with TNB moieties thus overcoming the previously reported polymerization impairments. We also report on the exploitation of the materials, both obtained as tractable transparent films and coated fibers, as smart labels for the visual detection of amine vapors. More precisely, amines in the atmosphere surrounding the sensory materials diffuse into them reacting with the TNB motifs forming highly colored Meisenheimer complexes, giving rise to development of color and to the naked eye sensing phenomenon. This is the case of highly volatile amines, such as trimethylamine, produced in food spoilage, specifically in the deterioration of fish or meat, for which the color development of the smart labels can be used as a visual test for food freshness.

An organic/inorganic hybrid membrane as a solid "turn-on" fluorescent chemosensor for coenzyme A (CoA), cysteine (Cys), and glutathione (GSH) in aqueous media.

The preparation of a fluorogenic sensory material for the detection of biomolecules is described. Strategic functionalisation and copolymerisation of a water insoluble organic sensory molecule with hydrophilic comonomers yielded a crosslinked, water-swellable, easy-to-manipulate solid system for water "dip-in" fluorogenic coenzyme A, cysteine, and glutathione detection by means of host-guest interactions. The sensory material was a membrane with gel-like behaviour, which exhibits a change in fluorescence behaviour upon swelling with a water solution of the target molecules. The membrane follows a "turn-on" pattern, which permits the titration of the abovementioned biomolecules. In this way, the water insoluble sensing motif can be exploited in aqueous media. The sensory motif within the membrane is a chemically anchored piperazinedione-derivative with a weakly bound Hg(II). The response is caused by the displacement of the cation from the membrane due to a stronger complexation with the biomolecules, thus releasing the fluorescent sensory moieties within the membrane.

Forced solid-state interactions for the selective "turn-on" fluorescence sensing of aluminum ions in water using a sensory polymer substrate.

Selective and sensitive solid sensory substrates for detecting Al(III) in pure water are reported. The material is a flexible polymer film that can be handled and exhibits gel behavior and membrane performance. The film features a chemically anchored salicylaldehyde benzoylhydrazone derivative as an aluminum ion fluorescence sensor. A novel procedure for measuring Al(III) at the ppb level using a single solution drop in 20 min was developed. In this procedure, a drop was allowed to enter the hydrophilic material for 15 min before a 5 min drying period. The process forced the Al(III) to interact with the sensory motifs within the membrane before measuring the fluorescence of the system. The limit of detection of Al(III) was 22 ppm. Furthermore, a water-soluble sensory polymer containing the same sensory motifs was developed with a limit of detection of Al(III) of 1.5 ppb, which was significantly lower than the Environmental Protection Agency recommendations for drinking water.

Selective and sensitive detection of aluminium ions in water via fluorescence "turn-on" with both solid and water soluble sensory polymer substrates.

A solid substrate comprised of a cross-linked polymer network is shaped as a film with gel-like behaviour and is used to detect aluminium ions in water; concurrently, a water soluble sensory polymer synthesised towards the same purpose is also discussed. The detection in both systems was achieved via fluorescence "turn-on". The limits of detection for Al(III) were 1.6 and 25ppb for the former and latter materials, respectively; these levels are significantly lower than the EPA recommendations for drinking water.

Methacrylate copolymers with pendant piperazinedione-sensing motifs as fluorescent chemosensory materials for the detection of Cr(VI) in aqueous media.

A fluorogenic sensory film, or dense membrane, capable of detecting Cr(VI), Fe(III), and Hg(II) in water was prepared. The film was prepared by a bulk radical polymerization of different comonomers, one of which contained a piperazinedione motif as sensory fluorophore. The film exhibited gel-like behavior and was highly tractable, even after being swollen in water. The sensing conditions were chosen to overcome interference from iron and mercury cations, giving rise to a material with a detection limit of 1 ppb for Cr(VI).