A novel and simple fluorescence probe for detecting main group magnesium ion in HeLa cells and Arabidopsis

Use of curcumin-modified diamond nanoparticles in cellular imaging and the distinct ratiometric detection of Mg2+/Mn2+ ions

An intrinsically luminescent curcumin-modified nanodiamond derivative (ND-Cur) has been synthesized as an effective probe for cell imaging and sensory applications. DLS data allowed the particle size of ND-Cur to be estimated (170.6 ± 46.8 nm) and the zeta potential to be determined. The photoluminescence signal of ND-Cur was observed at 536 nm, with diverse intensities at excitation wavelengths of 350 to 450 nm, producing yellow emission with a quantum yield (Φ) of 0.06. Notably, the results of the MTT assay and cell imaging experiments showed the low toxicity and biocompatibility of ND-Cur. Subsequently, investigations of the selectivity towards Mg²⁺ and Mn²⁺ ions were performed by measuring intense fluorescence peak shifts and "Turn-off" responses, respectively. In the presence of Mg²⁺, the fluorescence peak (536 nm) was shifted and then displayed two diverse peaks at 498 and 476 nm. On the other hand, for Mn²⁺ ions, ND-Cur revealed a fluorescence-quenching response at 536 nm. Fluorescence studies indicated that the nanomolar level detection limits (LODs) of Mg²⁺ and Mn²⁺ ions were approximately 423 and 367 nM, respectively. The sensing mechanism, ratiometric changes and binding site were established through PL, FTIR, Raman, SEM, TEM, DLS and zeta potential analyses. Furthermore, the effective determination of Mg²⁺ and Mn²⁺ ions by ND-Cur has been validated through cell imaging experiments.

Systematic approach of chromone skeleton for detecting Mg2+, ion: Applications for sustainable cytotoxicity and cell imaging possibilities

The systematic studies of chromone appended novel chemosensors, favored to Mg²⁺ ion detection, these were analyzed and characterized by different spectroscopic techniques such as NMR, mass spectroscopy, FTIR and optical techniques. The binding demeanor of the ligands was executed with the library of metal ions and shown the good coordination with Mg²⁺ ion to the ligand's cavity. Both ligands demonstrated good binding behavior with Mg²⁺ ion. The ligands represented 1: 1 stoichiometry with Mg²⁺ ions through Job's plot. The low limit of detection of Mg²⁺ ion was determined as 2.56 × 10^-6 and 1.28 × 10^-6 for L_a and L_b respectively. No interference was occurred in Inference study by foreign metal ions that supported the specific detection of Mg²⁺ ion among the other metal ions. Further, the cytotoxicity assay test of these chromone appended ligands revealed that both ligands and their respective compound with Mg²⁺ ion shown negligible toxicity with HeLa cancer cell line. Further, due to the fluorescence properties of the ligands, with or without Mg²⁺ ion was successfully tested in bioimaging experiment of HeLa cancer cell lines and found that ligands with Mg²⁺ ions represented good imaging with HeLa cancer cell.

A near-infrared ratiometric fluorescent probe based on the CN double bond for monitoring SO2 and its application in biological imaging

A near-infrared ratiometric fluorescent probe based on CN double bond was developed for monitoring SO₂ and its application in biological imaging.

One-pot synthesis of a recyclable ratiometric fluorescent probe based on MOFs for turn-on sensing of Mg2+ ions and bioimaging in live cells

This work illustrates the design and construction of a fascinating recyclable ratiometric fluorescent probe based on MOFs (Fe₃O₄/RhB@Al-MOFs) via a simple one-step approach.

Exploration research on synthesis and application of a new dye containing di-2-picolyamine

A newly designed fluorescence dye L based on di-2-picolyamine (DPA) moiety as a chelator was obtained under the protection of N₂ at 120°C, and KI as catalyst with relatively better yield. More interestingly, L not only could selectively and sensitively detect Cu²⁺ ions in aqueous medium but also examine the Cu²⁺ ions of the actual water samples. Nevertheless, L could be visual in Hela cells with excellent cell permeability, viz, monitoring exogenous Cu²⁺ ions as well as realizing an "on-off-on" process.

Fluorescent probes for the detection of magnesium ions (Mg2+): from design to application

Magnesium ions (Mg²⁺) play essential roles in various physiological and pathological processes, its abnormal homeostasis in cells is related to many diseases, such as diabetes, neuromuscular disorders, hypertension and other cardiovascular disorders. Investigation on the regulation of magnesium in cellular processes has attracted considerable interest in the past several decades. Among those reported strategies, fluorescent imaging technology has become a powerful and cost-effective tool for the real-time monitoring of magnesium distribution, uptake and trafficking, due to its superior features of high sensitivity and non-invasiveness, as well as excellent spatial and temporal fidelity. Herein, we critically summarize the progresses in the intracellular magnesium detection with fluorescent imaging probes. Our discussion focuses on the recent contributions concerning fluorescent imaging probes for mapping magnesium in biological processes. All the candidates are organized according to their acceptor structures. The sensing mechanisms of fluorescent probes are also highly taken into account. Challenges, trends and prospects of fluorescent imaging technology in magnesium detection are also set forth.

Herein, progress in intracellular magnesium detection with fluorescent probes is critically summarized in this work.

Systematic approach in Mg2+ ions analysis with a combination of tailored fluorophore design

A systematic study of a series of diaza-18-crown-6 8-hydroxyquinoline (DCHQ) chemosensors, devoted to Mg(II) ion detection, was performed. Functionalization of DCHQ by peripheral substituents allowed the development of novel all-solid-state optodes via inclusion inside PVC-based polymeric films. The influence on the DCHQ-based optode response of the lipophilic sites functionalization and of the nature of the plasticizer, was investigated. Fluorimetric studies on optodes sensitivity towards a number of different metal cations (Ca²⁺, Na⁺, K⁺, Li⁺, Co²⁺, Cd²⁺, Pb²⁺, Cu²⁺, Hg²⁺, Zn²⁺) and NH₄⁺ were carried out. The results demonstrated the suitability of the DCHQ optodes to perform fast monitoring (<10s) of magnesium (II) ions. Emission light signal was sufficiently brilliant to be captured by a low-cost computer webcam. The phenyl-substituted DCHQ-Ph derivative showed the best performance with a wide range for Mg(II) ion determination between 2.7 × 10^-7 and 2.2 × 10^-2 mol/L. It was possible, therefore, to determine the concentrations of Mg(II) in commercial fertilizer samples by DCHQ-Ph-based optodes with acceptable results: recoveries of 96.2-104.9% and relative standard deviation (RSD, n = 6) less than 5%. Moreover, in comparison to single sensors, the use of an array composed of five optodes (the ones showing the best performances in the preliminary tests) has allowed to reduce the RSD of magnesium determination in real samples (down to 3.7% with respect to 5.5% for single optodes) and to achieve a detection limit (estimated by s/n = 3 method) as low as 4.6 × 10^-7 mol/L.

Chiral-aminoquinoline-based fluorescent pH probe with large stokes shift for bioimaging

The aminoquinoline derivatives, (R)- and (S)-2-phenyl-2-(quinolin-6-ylamino)ethan-1-ol (R-PEO and S-PEO), were synthesized by a tandem one-pot three-step CN coupling method where Smiles rearrangement was the key procedure. The selected compound R-PEO showed a significant fluorescence enhancement with a turn-on ratio over 98-fold and enabled the real time determination of proton concentration in acidic solution. The fluorescence intensity of R-PEO exhibited strong pH-dependent performance with a large Stokes shift (115nm) and responded linearly to minor pH change within the range of 3.8-6.0. With the help of ¹H NMR spectrum, we also confirmed the protonation of the quinoline unit should be the proposed reaction. Compared with the conjugated acid of N-hexylquinolin-6-amine (NQA), the conjugated acid of R-PEO shows significant planar intramolecular charge transfer (PICT) character. Furthermore, biological imaging proved that R-PEO probe can be used to monitor the pH change of S. cerevisiae in vivo.

An optical material for the detection of trace S2O32- in milk based on a copper complex

A novel S₂O₃^2- luminescent sensor (Cu²⁺-p-CPIP) was developed and the presence of S₂O₃^2- caused an obvious fluorescence enhancement at 420 nm upon excitation at 330 nm, which could be distinguished with the naked eye under a UV lamp. Remarkably, the compound exhibited excellent selective and sensitive response to S₂O₃^2- over other common anions with a micromolar limit of detection (0.442 μM) in DMSO/H₂O (v/v, 1:1) buffer. The absorbance intensity and the color of Cu²⁺-p -CPIP solution changed gradually with the increase of S₂O₃^2- concentration. The proposed method was applied to the determination of S₂O₃^2- in milk samples and the recoveries were 97.5-105%. The preparation of Cu²⁺-p -CPIP exhibited the quick, simple and facile advantages. The results showed that Cu²⁺-p -CPIP can be a good candidate for simple, rapid and sensitive colorimetric detection of S₂O₃^2- in aqueous solution.