Belovari, Mateja; Pašalić, Lea; Pem, Barbara; Jurković, Marta; Topolovčan, Nikola; Gredičak, Matija; Piantanida, Ivo; Bakarić, Danijela (2025) Search for the smallest switch-on, water soluble and a phase-sensitive fluorimetric probe for lipid membranes: N-aryl isoindolin-1-one core. Microchemical Journal, 208 . ISSN 0026-265X
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Abstract
Studies of lipidous membranes are of utmost interest in biomedical applications, whereby fluorescent stains of membranes often play an essential role. Only a few stains are of small molecular weight, which could allow easier incorporation in lipid membranes. Here we present the discovery of a new structural entity applicable for membrane staining, 3-hydroxy-3-methyl-2-phenylisoindolin-1-one, whereby a study of a series of analogues (all Mw < 350) revealed their emission is strongly solvatochromic. Detailed studies revealed that fine-tuning of substituents strongly controls lipophilicity and emissive response, the optimum performance showing analogues with substituents on N-aryl moiety, particularly pronounced for p-hydroxy (5), o, p-dimethoxy (6) and p-methyl (7) derivatives, latter showing the highest logP. Chosen p-methyl (7) is characterised by the unique switch-on fluorescence in visible range upon membrane binding, based on very strong bathochromic shift (Δλ = +80–100 nm) between water (λ = 375 nm) and membrane (λ = 460 nm), in comparison to referent stain Laurdan® under the same conditions (Δλ = +20 nm). The novel neutral probe 7 prefers incorporation into the non-polar part of the lipid bilayers, not disturbing their properties. Future perspectives aim for the development of a structurally new group of low molecular weight lipid membrane stains, which eventually could be in situ tethered by “click” chemistry to the free propargyl bond of referent building block with a variety of additional functions.
| Item Type: | Article | ||||||||||||||||
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| Uncontrolled Keywords: | switch-on fluorescent probes ; phosphatidylcholine (PC) and sphingomyelin (SM) lipids, lipid phase-dependent fluorescent response ; UV-Vis and FTIR spectroscopy ; MD simulations | ||||||||||||||||
| Subjects: | NATURAL SCIENCES NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Chemistry > Physical Chemistry NATURAL SCIENCES > Chemistry > Analytic Chemistry NATURAL SCIENCES > Chemistry > Organic Chemistry |
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| Divisions: | Division of Organic Chemistry and Biochemistry | ||||||||||||||||
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| Depositing User: | Danijela Bakarić | ||||||||||||||||
| Date Deposited: | 15 Jan 2026 11:51 | ||||||||||||||||
| URI: | http://fulir.irb.hr/id/eprint/10804 | ||||||||||||||||
| DOI: | 10.1016/j.microc.2024.112335 |
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