A novel fluorescence sensor for uranyl ion detection based on a dansyl-modified peptide

A conjugated oligoelectrolyte for the recognition of uranyl ion in aqueous and soil samples via RGB method

The development of selective and practically applicable sensors for monitoring trace uranyl ions (UO22+) in an aqueous medium is the biggest challenge. This study presents the development of a conjugated oligoelectrolyte-based probe (COE) for the selective detection of UO22+ ions in water bodies. The COE is a water-soluble probe having an organic backbone with two ionic pendants at the terminal points. It changes its color to a dark yellow selectively in the presence of UO22+ ions. This visible change was integrated with a smartphone RGB color quantification method. The COE displayed an RGB chemo-dosimeter to selectively monitor UO22+ ions without interference from other metal ions. In the parallel experiment, COE displays a spectrofluorimetric emission signal at λems. = 525 nm (with λexc. = 420 nm), which exhibits quenching of signal when interacted with UO22+ ions. The limit of detection (LOD) is found to be 3.07 × 10-2 µM and 4.50 µM by spectrofluorimetric and RGB color value methods, respectively. 1H NMR and XPS analysis investigated the mode of interaction, and it suggested that the quenching of the emission signal was due to the interaction between the electron-rich azomethine site of COE and UO22+ ion. The smartphone-based RGB color analysis makes COE a potential probe with reduced operation time and offers a fresh approach for the immediate, real-time detection of UO22+ ions in aqueous and soil samples.

Engineering an upconversion fluorescence sensing platform with "off-on" pattern through specific DNAzyme-mediated signal amplification for supersensitive detection of uranyl ion

An upconversion fluorescence sensing platform was developed with upconversion nanoparticles (UCNPs) as energy donors and gold nanoparticles (AuNPs) as energy acceptors, based on the FRET principle. They were used for quantitative detection of uranyl ions (UO22+) by amplifying the signal of the hybrid chain reaction (HCR). When UO22+ are introduced, the FRET between AuNPs and UCNPs can be modulated through a HCR in the presence of high concentrations of sodium chloride. This platform provides exceptional sensitivity, with a detection limit as low as 68 pM for UO22+ recognition. We have successfully validated the reliability of this method by analyzing authentic water samples, achieving satisfactory recoveries (89.00%-112.50%) that are comparable to those of ICP-MS. These results indicate that the developed sensing platform has the capability to identify trace UO22+ in complex environmental samples.

An amphiphilic dansyl based multianalyte sensor for the detection of Hg2+, PPi, and TNP: A three-in-one chemical sensor

A fluorescent dansyl-based amphiphilic probe, 5-(dimethylamino)-N-hexadecylnaphthalene-1-sulfonamide (DLC), was synthesized and characterized to detect multiple analytes at different sensing environments. In acetonitrile, DLC detects nitro explosives such as trinitrophenol (TNP) and 2,4-dinitrophenol (2,4-DNP) by an emission "on-off" response method, and the detection limits (LOD) were estimated to be as low as 4.3 µM and 17.4 µM, respectively. Amphiphilic long chains of the probe were embedded into lipid bilayers to form nanoscale vesicles DLC.Ves. Nanovesicular probe DLC.Ves was found to be highly selective for Hg2+ among other metal ions and for pyrophosphate (PPi) ions among various anions. DLC.Ves could detect Hg2+ with a turn "on-off" emission and PPi with ratiometric change in emission at 525 nm. It is proposed that DLC.Ves could detect Hg2+ via the Hg2+-induced aggregation quenching mechanism and PPi through the Hydrogen bonding. The LODs are estimated as 6.41 µM and 70.9 µM for Hg2+ and PPi, respectively. 1H NMR, SEM, and fluorescence lifetime measurements confirmed the binding mechanism. Thus, it is believed that the simple fluorescent probe DLC could be a prominent sensor to detect multiple analytes depending on the sensing medium.