Turn-off fluorescent nanoprobe based on carbon dots synthesised by UV/HO advanced oxidation for the detection of bisphenol A in canned foods.

A novel assay was developed based on a turn-off fluorescent probe using the in situ generation of carbon dots (CDs) by means of UV/HO advanced oxidation of carbohydrates for the detection of bisphenol A (BPA) in food. Different parameters involved in the synthesis of CDs for the direct recognition of BPA have been optimised and a sensing mechanism is outlined. The presence of HO during CD synthesis causes a fluorescence enhancement due to the action of highly oxidant HO radicals formed throughout the photochemical reaction.

Droplet-based luminescent sensor supported onto hydrophobic cellulose substrate for assessing fish freshness following smartphone readout.

In this work, two sensitive droplet-based luminescent assays with smartphone readout for the determination of trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) are reported. Both assays exploit the luminescence quenching of copper nanoclusters (CuNCs) produced when exposed to volatile nitrogen bases. In addition, hydrophobic-based cellulose substrates demonstrated their suitability as holders for both in-drop volatile enrichment and subsequent smartphone-based digitization of the enriched colloidal solution of CuNCs.

Detection of gases and organic vapors by cellulose-based sensors.

The growing interest in the development of cost-effective, straightforward, and rapid analytical systems has found cellulose-based materials, including cellulose derivatives, cellulose-based gels, nanocellulosic materials, and the corresponding (nano)cellulose-based composites, to be valuable platforms for sensor development. The present work presents recent advances in the development of cellulose-based sensors for the determination of volatile analytes and derivatives of analytical relevance. In particular, strategies described in the literature for the fabrication and modification of cellulose-based substrates with responsive materials are summarized.

Kinetic spectrophotometric assay for the determination of vitamin C in cosmetics following ultrasound-assisted emulsification.

In this work, a new analytical approach based on ultrasound-assisted emulsification followed by a photoreaction with methylene blue (MB) and kinetic analysis by UV-vis spectrophotometry has been developed for the determination of L-ascorbic acid (AA) in cosmetic samples. The emulsification of cosmetic samples results in a transparent solution that allows an easy and rapid quantitation by UV-vis spectrophotometry. The emulsified sample is mixed with a MB aqueous solution and this mixture is subjected to irradiation with a tungsten lamp for 5 min (fixed-time kinetic assay).

Fluorescent paper-based sensor integrated with headspace thin-film microextraction for the detection of acyclic N-nitrosamines following in situ photocatalytic decomposition.

Background: In this work, a novel analytical approach based on the photocatalytic decomposition of N-nitrosamines combined with headspace thin-film microextraction of the generated nitrogen oxides such as NO has been developed for the determination of the acyclic N-nitrosamine fraction in drinking water samples. A hydrophilic cellulose substrate modified with fluorescent silver nanoclusters (Ag NCs) was used both as extractant and sensing platform. A quenching effect of Ag NCs fluorescence occurs as the concentration of N-nitrosamines increases.