The Novel Poly(azomethine-urethane): Synthesis, Morphological Properties and Application as a Fluorescent Probe for Detection of Zn2+ Ions

Salicylaldehyde built fluorescent probe for dual sensing of Al3+, Zn2+ ions: Applications in latent fingerprint, bio-imaging & real sample analysis

This Schiff base chemosensor (SNN) detected dual ions, Al3+ and Zn2+ ions selectively. Fluorescence spectrum investigations showed that Al3+ ions increased fluorescence intensity, notably at 493 nm. Introducing Zn2+ ions caused a significant blue shift of roughly ∼65 nm at a wavelength of 434 nm, resulting in a notable change in fluorescence intensity. When binding Al3+/Zn2+ ions, the SNN receptor uses three methods. Inhibition of photoinduced electron transfer (PET), excited state intramolecular proton transfer (ESIPT), and restriction of CN isomerization. The jobs plot method found that SNN + Al3+ and SNN + Zn2+ complexations had a 1:1 stoichiometry. DFT, LC-HRMS, and 1H NMR titration confirm this conclusion. The probe SNN's limit of detection (LOD) for Al3+/Zn2+ ions was 3.99 nM and 1.33 nM. Latent fingerprint (LFP), food samples, pharmaceutical products, and E. coli pathogen bio-imaging have all used the SNN probe to identify Al3+ and Zn2+ ions.

Smart sensory polymer for straightforward Zn(II) detection in pet food samples

We report on an innovative method to measure the Zn(II) concentration in commercial pet food samples, both wet and dry food. It is based on a colorimetric sensory polymer prepared from commercial monomers and 0.5 % of a synthetic monomer having a quinoline sensory core (N-(8-(2-azidoacetamido)quinolin-5-yl)methacrylamide). We obtained the sensory polymer as crosslinked films by thermally initiated bulk radical polymerization of the monomers of 100 μm thickness, which we punched into Ø6 mm sensory discs. The immersion of the discs in water solutions containing Zn(II) turned the fluorescence on, allowing for the titration of this cation using the G parameter of a digital picture taken to the discs. The limits of detection and quantification were 29 and 87 µg/L, respectively. Furthermore, we measured the concentration of Zn(II) even in the presence of other cations, detecting no significant interferences. Thus, in a further step, we obtained the concentration of Zn(II) from 15 commercial pet food samples, ranging from 19 to 198 mg/kg, following a simple extraction procedure and contacting the extractant with our sensory discs. These results were contrasted with that obtained by ICP-MS as a reference method.

Synthesis, physico-chemical characterization, and environmental applications of meso porous crosslinked poly (azomethine-sulfone)s

To develop innovative mesoporous crosslinked poly(azomethine- sulfone)s with environmental applications, a simple Schiff base condensation technique based on barbituric acid BA or condensed terephthaldehyde barbituric acid TBA in their structures as monomeric units are applied. Different analysis methodologies and viscosity measurements identify them as having stronger heat stability and an amorphous structure. The photophysical features of the multi stimuli response MSR phenomenon are observable, with white light emission at higher concentrations and blue light emission at lower concentrations. Their emission characteristics make them an excellent metal ions sensor through diverse charge transfer methods. They can have a better inhibition efficiency and be employed as both mixed-type and active corrosion inhibitors according to their fluorescence emission with metals, demonstrating their capacity to bind with diverse metals. The adsorption of two distinct dye molecules, Methylene blue MB cationic and sunset yellow SY anionic, on the mesoporous structures of the polymers is investigated, revealing their selectivity for MB dye adsorption. Quantum studies support these amazing discoveries, demonstrating a crab-like monomeric unit structure for the one that is heavily crosslinked.

Highly selective and sensitive detection of glutathione over cysteine and homocysteine with a turn-on fluorescent biosensor based on cysteamine-stabilized CdTe quantum dots

In this work, cysteamine (CA) stabilized CdTe quantum dots (QDs) (CA-CdTe QDs) and sodium citrate stabilized gold nanoparticles (AuNPs) were prepared. Because of the strong electrostatic interaction and spectral overlap of emission spectrum of CA-CdTe QDs and absorption spectrum of AuNPs, a highly effective fluorescence resonance energy transfer (FRET) system was formed and the fluorescence of CA-CdTe QDs was strongly quenched. The synthesized CA-CdTe and AuNPs were self-assembled to large clusters due to the electrostatic attraction and the fluorescence of CA-CdTe was sharply quenched as a result of FRET. Under the optimum pH of 5.5, the positive GSH could assemble with negative AuNPs through electrostatic interaction and destroy the FRET system of CA-CdTe and AuNPs, due to the red shift of absorption wavelength of AuNPs caused by aggregation. The fluorescence of CA-CdTe recovered, and the recovered fluorescence efficiency shows a linear function against the GSH concentrations from 6.7 nM to 0.40 μM, with a detecting limit of 3.3 nM. The quenched emission of CA-CdTe could be recovered attributed to the aggregation of AuNPs by GSH. Under optimal conditions, the sensing system was successfully applied in the detection of GSH in real human blood plasma samples with a recovery of 99.5-102.3%, showing a promising future for the highly sensitive and selective GSH detection in the human blood plasma samples.

Novel multi-stimuli-responsive supramolecular gel based on quinoline for the fluorescence ultrasensitive detection of Fe3+and Cu2

A novel gelator molecular based on quinolone (MN) has been successfully designed and synthesized. The gelator MN could self-assemble to form a supramolecular gel (OMN), which showed obvious aggregation-induced emission (AIE) in iso-Propyl alcohol (i-PrOH). Furthermore, the supramolecular organogel OMN realized ultrasensitive detection of Fe³⁺ and Cu²⁺ in aqueous medium and fluorescent quenching at 427 nm. The sensing mechanism between supramolecular gel and metal ions was fully investigated via FE-SEM, FT-IR, XRD and XPS. Meanwhile, a thin film based on responsive supramolecular gel OMN was prepared, which could be used as multi-stimuli-responsive fluorescent display materials for the detection of Fe³⁺ and Cu²⁺.

A dual responsive colorimetric sensor based on polyazomethine and ascorbic acid for the detection of Al (III) and Fe (II) ions

In the present paper, a novel double cation target colorimetric sensor was developed for the detection of Al (III), and Fe (II) ions. It was composed of ascorbic acid in a polyazomethine matrix, and polyazomethine was used to form a homogenous matrix for mixing ascorbic acid. The photophysical properties of the colorimetric sensor were clarified by using UV-Vis and fluorescence spectrophotometers. It was found that the developed sensor was exhibited good naked eye selectivity, and sensitivity toward Al (III), and Fe (II) ions with excellent photostability. Furthermore, the detection limit of the sensor was calculated as 0.398 µM (0.096 ppm) and 0.185 µM (0.051 ppm) for Al (III), and Fe (II), respectively. The applicability of the colorimetric sensor in environmental (tap and sea waters) and biological (Bovine serum albumin) solutions was also studied, and the results exhibited that the developed sensor could be successfully applied to monitoring environmental and biological samples.