A highly selective turn-on fluorescence probe with large Stokes shift for detection of palladium and its applications in environment water and living cells

Dual channel chemosensor for successive detection of environmentally toxic Pd2+ and CN- ions and its application to cancer cell imaging

BACKGROUND

Detecting and neutralizing Pd2+ ions are a significant challenge due to their cytotoxicity, even at low concentrations. To address this issue, various chemosensors have been designed for advanced detection systems, offering simplicity and the potential to differentiate signals from different analytes. Nonetheless, these chemosensors often suffer from limited emission response and complex synthesis procedures. As a result, the tracking and quantification of residual palladium in biological systems and environments remain challenging tasks, with only a few chemosensing probes available for commercial use.

RESULTS

In this paper, a straightforward approach for the selective detection of Pd2+ ions is proposed, which involves the design, synthesis, and utilization of a propargylated naphthalene-derived probe (E)-N'-((2-(prop-2-yn-1-yloxy)naphthalen-1-yl)methylene)benzohydrazide (NHP). The NHP probe exhibits sensitive dual-channel colorimetry and fluorescence Pd2+ detection over other tested metal ions. The detection process is performed through a catalytic depropargylation reaction, followed by an excited state intramolecular proton transfer (ESIPT) process, the detection limit is as low as 11.58 × 10-7 M under mild conditions. Interestingly, the resultant chemodosimeter adduct (E)-N'-((2-hydroxynaphthalen-1-yl)methylene)benzohydrazide (NHH) was employed for the consecutive detection of CN- ions, exhibiting an impressive detection limit of 31.79 × 10-8 M. Validation of both detection processes was achieved through 1H nuclear magnetic resonance and density functional theory calculations. For real-time applications of the NHP and NHH probes, smartphone-assisted detection, and intracellular detection of Pd2+ and CN- ions within HeLa cells were studied.

SIGNIFICANCE

This research presents a novel naphthalene derivative for visually detecting environmentally toxic Pd2+ and CN- ions. The synthesized probe selectively binds to Pd2+, forming a chemodosimeter. It successfully detects CN- ions through colorimetry and fluorimetry, offering a low detection limit and quick response. Notably, it's the first naphthalene-based small molecule to serve as a dual probe for toxic analytes - palladium and cyanide. Moreover, it effectively detects Pd2+ and CN- intracellularly in cancer cells.

A novel AIE material for sensing of Erythromycin in pure water by hydrogen bond in portable test strips and cellular imaging applications

Erythromycin could be used to treat various bacterial infection, but it was harmful to the colonic microflora. Therefore, it is highly desirable to develop a fluorescence probe that could selectively and sensitively detect Erythromycin in pure water. In this work, a fluorescent probe named EHMC, which exhibited aggregation-induced emission (AIE) characteristic in solid state and water/EtOH binary solvent was developed for "turn on" sensing Erythromycin in pure water with high selectivity and sensitivity (detection limit: 1.78 × 10-8 M). Also, there are fewer interference from other antibiotics in the detection process of probe EHMC for Erythromycin. Moreover, probe EHMC could as a portable test strips for highly selective detection of Erythromycin and identification of different concentrations of Erythromycin. In addition, living cells imaging experiments displayed that probe EHMC could detect Erythromycin in A549 cells and BEAS-2B cells successfully. Combined with the theoretical calculation results The sensing mechanisms that the CO in Erythromycin and OH in EHMC formed intermolecular hydrogen bond and further formed new aggregates were confirmed by job' plot, 1H NMR, FT-IR, ESI-MS, DLS and TEM and DFT calculation.

Dabcyl as a Naked Eye Colorimetric Chemosensor for Palladium Detection in Aqueous Medium

Industrial activity has raised significant concerns regarding the widespread pollution caused by metal ions, contaminating ecosystems and causing adverse effects on human health. Therefore, the development of sensors for selective and sensitive detection of these analytes is extremely important. In this regard, an azo dye, Dabcyl 2, was synthesised and investigated for sensing metal ions with environmental and industrial relevance. The cation binding character of 2 was evaluated by colour changes as seen by the naked eye, UV-Vis and 1H NMR titrations in aqueous mixtures of SDS (0.02 M, pH 6) solution with acetonitrile (99:1, v/v). Out of the several cations tested, chemosensor 2 had a selective response for Pd2+, Sn2+ and Fe3+, showing a remarkable colour change visible to the naked eye and large bathochromic shifts in the UV-Vis spectrum of 2. This compound was very sensitive for Pd2+, Sn2+ and Fe3+, with a detection limit as low as 5.4 × 10-8 M, 1.3 × 10-7 M and 5.2 × 10-8 M, respectively. Moreover, comparative studies revealed that chemosensor 2 had high selectivity towards Pd2+ even in the presence of other metal ions in SDS aqueous mixtures.

A novel fluorescent molecule based on 1,2,3-triazole for determination of palladium (II) and hydrazine hydrate in aqueous system

In recent years, hydrazine hydrate has been widely used in various fields as fuel and chemical raw materials, etc. However, hydrazine hydrate is also a potential threat to living body and natural environment. The effective method is urgently needed to detect hydrazine hydrate in our living environment. Secondly, as a precious metal, palladium has attracted more and more attention because of its excellent properties in industrial manufacturing and chemical catalysis. However, its potential danger is also slowly approaching, so it is necessary to find an excellent way to detect palladium, too. Herein, a fluorescent molecule, 4,4',4'',4'''-(1,4-phenylenebis(2H-1,2,3-triazole-2,4,5-triyl)) tetrabenzoic acid (NAT), was synthesized. Firstly, NAT has very high selectivity and sensitivity for determination of Pd²⁺, because Pd²⁺ can coordinate well with carboxyl oxygen of NAT. The detection performance of Pd²⁺ is that the linear range is from 0.06 to 4.50 μM and the detection limit is 16.4 nM. Furthermore, the chelate (NAT-Pd²⁺) can continue to be used for quantitative determination of hydrazine hydrate with a linear range of 0.05-6.00 μM and the detection limit is 19.1 nM. The interaction time of NAT-Pd²⁺ and hydrazine hydrate is about 10 min. Of course, it also has good selectivity and strong anti-interference ability for many common metal ions, anions and amine like compounds. At last, the ability of NAT to quantitatively detect Pd²⁺ and hydrazine hydrate in actual samples has also been verified and the results are very satisfactory.

Lighting up trace carbon monoxide and residual palladium species by a low cytotoxic mitochondria targetable red fluorescent probe: Its large scaled applications

High levels of residual palladium can lead to serious negative health effects. Carbon monoxide (CO) is a significant gasotransmitter in transporting intermolecular and intramolecular signals to balance several physiological processes. Therefore, there is a need for rapid detection of CO and palladium residue. To address these issues, we have designed a novel light-up fluorescent probe for the detection of Pd and CO. It can not only detect Pd and CO selectively with a remarkable chromogenic and red fluorescent response over other metal ions allowing detection with naked eyes but also discriminate Pd⁰ and Pd²⁺/Pd⁴⁺ species. The detection reaction is confirmed by HPLC analysis. The probe demonstrates biocompatibility and mitochondrial target ability for potential biological applications. The practical applications based on drug residue and soil analysis, and smartphone have been successfully performed. Bioimaging of the concentration change of Pd and CO in HeLa cells using the probe is successfully applied. Therefore, the present approach can provide early diagnosis of Pd and CO with low detection limit, low cytotoxicity, high selectivity, and sensitivity.

Tm3+ Ion Blue Emission Quenching by Pd2+ Ions in Barium Phosphate Glasses: Fundamental Analysis toward Sensing Applications

The quenching effect of Pd²⁺ ions on the blue emission from Tm³⁺ was investigated for the first time using barium phosphate glass as model matrix. Glasses containing fixed Tm₂O₃ at 0.5 mol % and PdO up to 0.3 mol % (added relative to P₂O₅) were prepared by melting and first characterized for basic structural properties by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. Thermal properties were then evaluated by differential scanning calorimetry (DSC). The focus was thereafter on evaluating the optical properties by absorption and photoluminescence (PL) spectroscopy with decay kinetics assessment. XRD confirmed the amorphous nature of the glasses synthesized. The vibrational spectroscopy assessment consistently exhibited the IR- and Raman-active bands characteristic of phosphate glasses, showing no significant variation with PdO codoping. The DSC analysis revealed all glasses possessed high thermal stability assessed by the differences (ΔT = T_g - T_x ≥ 154 °C) between glass transition temperatures (T_g) and onset of crystallization (T_x). A tendency of the T_g values to increase with PdO contents was however exhibited. In addition, specific enthalpies of crystallization showed magnitudes decreasing with increasing PdO concentration, thus suggesting crystallization suppression by Pd²⁺. Concerning the optical properties, it was observed that codoping the glasses with PdO (0.1-0.3 mol %) led to the development of the visible Pd²⁺ d-d absorption band (peak ≈415-410 nm). In addition, drastic PL quenching of the Tm³⁺ blue emission around 452 nm (¹D₂ → ³F₄ transition) was induced by Pd²⁺. Analyzing PL decay curves obtained by exciting Tm³⁺ ions at 359 nm while monitoring 452 nm emission revealed decreased ¹D₂ state lifetimes. Thus, a potential of Tm³⁺ for analytical sensing of Pd²⁺ in various matrices was suggested. Ultimately determining quenching constants from the PL data and based on the comparison of results from emission intensity and decay rates, likely Tm³⁺ → Pd²⁺ energy transfer processes underlying the PL quenching were proposed.