Aug 2026· Chemistry - An Asian Journal· Vol 21 16, pp.
e70954
· 0 citations· 40 references
Medicine
Abstract
Formaldehyde (FA), a toxic and carcinogenic compound used extensively in industrial and preservation processes, requires reliable and selective detection methods, particularly in environmental, food, and biomedical samples. Herein, we report the development of a water-soluble, naphthalimide-based fluorescent polymeric probe, DCP-1, for the selective and rapid sensing of FA in aqueous solutions at physiological pH. The polymer has aromatic amine functional groups in its side chains, which specifically react with FA to form a stable imine. This transformation inhibits the native photoinduced electron transfer (PET), resulting in a distinct "turn-on" fluorescence response in an aqueous medium. The generation of the imine adduct was confirmed by mass spectrometry (MS) and 1H NMR spectroscopy for the representative reaction between a small molecule analogue and FA. DCP-1 exhibits excellent sensitivity, detecting FA at concentrations as low as 1.28 nM and displaying a strong fluorescence response within minutes at 100 nM FA. The probe exhibited reversible behavior upon bisulfite addition, demonstrating its ability to be reused efficiently for multiple FA detection cycles with consistent performance. Density functional theory (DFT) calculations further validated the proposed PET-based sensing mechanism.
Fluorogenic probes are highly useful tools for the detection of target molecules in chemical biology and (bio)material science, as they can often be applied in situ and do not depend on purification. Over the past years, a variety of alkyne-based fluorogenic probes have been proposed to detect azides, paving the way for live cell imaging and biomaterial analysis. Unfortunately, undesirable photophysical properties and poor solubility in aqueous solutions hamper the widespread use of these fluorogenic compounds. This work describes a water-soluble azide probe with high fluorescence enhancement (130-fold increase in intensity) upon reaction. We find accurate determination of azide densities on a polymer scaffold at low micromolar concentrations in PBS buffer. Additionally, by functionalizing the probe with biomolecules, we built a single-step (bio)molecule labeling and analysis vehicle. As proof of principle, a peptide was conjugated to polymer scaffolds and conversions could be accurately followed in situ. Altogether, our probe is a promising new chemical biology tool for analysis in physiological conditions.
Lotte Gerrits, Lisa Verdellen, M. Peeters et al.· Biomacromolecules· 0 citations
A series of iminophosphorane-functionalized naphthalimide derivatives (4a-4e) were synthesized and evaluated as fluorescent sensors. Among them, the trimethylammonium-functionalized derivative 4e exhibited pronounced solvent-dependent fluorescence, characteristic of an intramolecular charge transfer (ICT) process. In acetonitrile, 4e showed excellent selectivity toward Sn(II) ions, accompanied by significant fluorescence quenching and a spectral shift resulting from preferential coordination of Sn(II) to the iminophosphorane nitrogen atom. Fluorescence titration experiments revealed sensitive detection of Sn(II) with a limit of detection of 86.3 nM and a 1:1 binding stoichiometry. These findings were supported by Job's plot analysis and Stern-Volmer studies, which indicated a static quenching mechanism. In addition, probe 4e displayed marked fluorescence enhancement over the acidic pH range of 3.0-6.0, which was attributed to protonation-regulated photoinduced electron transfer (PET). Complementary DFT and TD-DFT calculations provided molecular-level insight into the sensing mechanisms by elucidating the Sn(II)-induced ICT inhibition and protonation-regulated PET modulation. The probe also exhibited good stability, high pH selectivity, and low cytotoxicity toward RAW264.7 macrophage cells. Fluorescence imaging studies further demonstrated its ability to monitor intracellular pH variations, with fluorescence being suppressed in lipopolysaccharide-stimulated macrophages as a result of increased intracellular acidification. These results highlight the potential of 4e as a multifunctional fluorescent probe for environmental sensing and biological imaging.
Quynh Nguyen Nhu Pham, Thitiporn Pattarakankul, T. Palaga et al.· Bioorganic chemistry (Print)· 0 citations
Sulfites are widely used as preservatives and antioxidants in food, but excessive intake poses health risks. Therefore, rapid, sensitive, and on‑site detection of sulfites is essential for food safety. In this work, a cationic small‑molecule fluorescent probe was synthesized via the condensation of
N
‑ethylcarbazole (electron donor) and a benzoindolium ion (electron acceptor). It exhibits a D–π–A architecture with an intramolecular charge transfer (ICT) effect, showing red fluorescence at 617 nm. Upon reaction with HSO
3
−
through Michael addition at the conjugated C═C bond, the ICT pathway is blocked, leading to fluorescence quenching. The probe displays excellent selectivity for HSO
3
−
(limit of detection = 0.1 µM). Significantly, it can be simply deposited onto filter paper to fabricate easy‐to‐use test strips. Under a 365 nm UV lamp, the test strips exhibit a visible color change from red to blue with increasing HSO
3
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concentration, allowing naked‑eye detection. Coupled with a smartphone color‑reading application, a linear relationship between the blue‐to‐red intensity ratio (B/R) and HSO
3
−
concentration enables rapid on‑site quantitative analysis. The test strips were successfully applied to detect residual HSO
3
−
in various dried fruit samples. This work provides a simple, low‑cost, and practical method for detecting sulfite levels in food and environmental samples.
Kanli Wang, Chenle Liao, Qian Cao et al.· ChemistrySelect· 0 citations
Experimental data indicate that probe CDP can effectively detect N2H4 across a broad pH range (5-12) and demonstrates significant potential for imaging N2H4 in living cells and mice models.
Zhuoran Song, Haoqi Zhang, Xiaoqing Yang et al.· Ecotoxicology and Environmen...· 0 citations
Reactive aldehydes—formaldehyde (FA), malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), and acrolein—occupy a central role in epigenetic regulation, lipid peroxidation, ferroptosis, and cardiovascular disease, yet their transient nature and low intracellular concentrations have long made them difficult to quantify in living systems. Over the past decade, reaction-based small-molecule fluorescent probes have emerged as the principal tool for addressing this challenge, and this review provides a systematic account of that progress. We compare the six main conjugation chemistries that underlie current probe design—2-aza-Cope/Mannich cascade, hydrazone/oxime formation, Michael addition, Schiff base condensation, and 2-aminothiophenol cyclization—alongside the three photophysical strategies used to convert these reactions into quantitative signals: intensity turn-on, ratiometric dual-emission, and fluorescence lifetime imaging (FLIM). Attention is given to advances reported between 2020 and 2025, including organelle-targeted ratiometric formaldehyde sensors (MitoRFAP-2, NucRFAP-2), the first ratiometric acrolein probe for visualizing ferroptosis, lysosome-targeted malondialdehyde reporters for atherosclerosis staging, and near-infrared-compatible platforms validated in three-dimensional organoids and in vivo models. This review also critically examines the limitations that continue to constrain the field, including insufficient selectivity testing under physiologically relevant conditions, the pH-dependence of hydrazone equilibria, the frequently overlooked distinction between probes that report free aldehyde concentration and those that report ALDH enzyme activity, and the continued absence of reversible, real-time sensors. Closing these gaps will determine whether aldehyde imaging grows from a set of smart probes into a quantitative, widely trusted platform for studying redox and carbonyl biology in living systems. Reaching that point will depend on three criteria: better NIR fluorophores, effective bioconjugation chemistry, and machine-learning tools that guide probe design.
Eva-Maria Bryan, Ozlem Dilek· Italian National Conference...· 0 citations
A novel near-infrared ratiometric fluorescent probe designed and synthesized by rationally linking dicyanoisophorone with 2-(2-hydroxyphenyl)benzothiazole provides a reliable and versatile tool for the visual monitoring of fluoride ions in both environmental and biological contexts.
Qi Zhou, Wen-Hao Hu, Ke Xiao et al.· Analytical Methods· 0 citations
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