Ultrabright and Fluorogenic Probes for Multicolor Imaging and Tracking of Lipid Droplets in Cells and Tissues

Planarizable push-pull probes have been introduced to demonstrate physical forces in biology.However,the donors and acceptors needed to polarizem echanically planarized probes are incompatible with their twisted resting state.T he objective of this study was to overcome this "flipper dilemma" with chalcogen-bonding cascade switches that turn on donors and acceptors only in response to mechanical planarization of the probe.T his concept is explored by molecular dynamics simulations as well as chemical double-mutant cycle analysis. Cascade switched flipper probes turn out to excel with chemical stability,red shifts adding up to high significance,and focused mechanosensitivity.M ost important, however,i st he introduction of an ew,g eneral and fundamental concept that operates with non-trivial supramolecular chemistry,solves an important practical problem and opens aw ide chemical space.Planarizable push-pull (PP) chromophores have been introduced [1] as mechanosensitive [2] fluorescent membrane probes [1][2][3] to image membrane tension [4] in living cells. [5,6] The current best is constructed around twisted dithienothiophene (DTT) dithienothiophene S,S-dioxide (DTTO2) conjugates ( Figure 1a,D ' = S, A' = SO 2 ). [7] Thet wo "flippers" [7] are twisted out of coplanarity by repulsion between the methyls (light blue circles) and the s holes (dark blue ovals) [8][9][10][11] on the sulfurs next to the connecting bond ( Figure 1b,l eft, 1). The PP system is prepared first with "sulfide" donors and "sulfone" acceptors in the DTT and the DTTO2b ridges, respectively (Figure 1b, 8,9). Conjugation of DTT and DTTO2u pon mechanical co-planarization then turns on this intrinsic PP system and shifts the excitation maximum to the red (Figure 1b,r ight). Thee mission maximum is nearly mechanoinsensitive because the probes emit only from the planar form. [12] To achieve significant red shifts upon planarization in the ground state,a dditional PP donors Da nd acceptors Aa re required (Figure 1a). These exocyclics ubstituents represent atrue dilemma because in the twisted resting state,the DTT donors and DTTO2 acceptors,a tl east partially decoupled from each other and equipped with extra Da nd A, could become too rich and too poor in electron density,respectively, and decompose easily (Figure 1a). Because both DTTs and DTTO2are comparably electron-rich, [13] this problem is more pronounced on the DTT side.T herefore,Dand As hould ideally turn on only in response to flipper planarization. Sulfides,p reviously introduced as covalent PP turn-on donors, [12] failed to afford operational probes. [14] Non-covalent 1,4-chalcogen bonds (1,4-CBs) [8][9][10][11] as in 1 were more successful, also because spontaneous degradation into reactive Figure 1. a) Flipper dilemma and b) CB cascade switch:a)Inplanarizable PP probes, exocyclic donors D D and acceptors A A are needed in planar but incompatiblew ith twisted form. b) Twisting of the central bond (1)turns off PP D D (2,r ed circle), and A A (3,b lue circle) because Lewis base Y( 5)hardly...

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confidence: 99%

A Chalcogen‐Bonding Cascade Switch for Planarizable Push–Pull Probes

et al. 2019

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“…Cascade switched flipper probes turn out to excel with chemical stability,red shifts adding up to high significance,and focused mechanosensitivity.M ost important, however,i st he introduction of an ew,g eneral and fundamental concept that operates with non-trivial supramolecular chemistry,solves an important practical problem and opens aw ide chemical space.Planarizable push-pull (PP) chromophores have been introduced [1] as mechanosensitive [2] fluorescent membrane probes [1][2][3] to image membrane tension [4] in living cells. Cascade switched flipper probes turn out to excel with chemical stability,red shifts adding up to high significance,and focused mechanosensitivity.M ost important, however,i st he introduction of an ew,g eneral and fundamental concept that operates with non-trivial supramolecular chemistry,solves an important practical problem and opens aw ide chemical space.…”

mentioning

confidence: 99%

“…Planarizable push-pull (PP) chromophores have been introduced [1] as mechanosensitive [2] fluorescent membrane probes [1][2][3] to image membrane tension [4] in living cells. [5,6] The current best is constructed around twisted dithienothiophene (DTT) dithienothiophene S,S-dioxide (DTTO2) conjugates ( Figure 1a,D ' = S, A' = SO 2 ).…”

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confidence: 99%

A Chalcogen‐Bonding Cascade Switch for Planarizable Push–Pull Probes

et al. 2019

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Planarizable push-pull probes have been introduced to demonstrate physical forces in biology.However,the donors and acceptors needed to polarizem echanically planarized probes are incompatible with their twisted resting state.T he objective of this study was to overcome this "flipper dilemma" with chalcogen-bonding cascade switches that turn on donors and acceptors only in response to mechanical planarization of the probe.T his concept is explored by molecular dynamics simulations as well as chemical double-mutant cycle analysis. Cascade switched flipper probes turn out to excel with chemical stability,red shifts adding up to high significance,and focused mechanosensitivity.M ost important, however,i st he introduction of an ew,g eneral and fundamental concept that operates with non-trivial supramolecular chemistry,solves an important practical problem and opens aw ide chemical space.Planarizable push-pull (PP) chromophores have been introduced [1] as mechanosensitive [2] fluorescent membrane probes [1][2][3] to image membrane tension [4] in living cells. [5,6] The current best is constructed around twisted dithienothiophene (DTT) dithienothiophene S,S-dioxide (DTTO2) conjugates ( Figure 1a,D ' = S, A' = SO 2 ). [7] Thet wo "flippers" [7] are twisted out of coplanarity by repulsion between the methyls (light blue circles) and the s holes (dark blue ovals) [8][9][10][11] on the sulfurs next to the connecting bond (Figure 1b,l eft, 1). The PP system is prepared first with "sulfide" donors and "sulfone" acceptors in the DTT and the DTTO2b ridges, respectively (Figure 1b, 8,9). Conjugation of DTT and DTTO2u pon mechanical co-planarization then turns on this intrinsic PP system and shifts the excitation maximum to the red (Figure 1b,r ight). Thee mission maximum is nearly mechanoinsensitive because the probes emit only from the planar form. [12] To achieve significant red shifts upon planarization in the ground state,a dditional PP donors Da nd acceptors Aa re required (Figure 1a). These exocyclics ubstituents represent atrue dilemma because in the twisted resting state,the DTT donors and DTTO2 acceptors,a tl east partially decoupled from each other and equipped with extra Da nd A, could become too rich and too poor in electron density,respectively, and decompose easily (Figure 1a). Because both DTTs and DTTO2are comparably electron-rich, [13] this problem is more pronounced on the DTT side.T herefore,Dand As hould ideally turn on only in response to flipper planarization. Sulfides,p reviously introduced as covalent PP turn-on donors, [12] failed to afford operational probes. [14] Non-covalent 1,4-chalcogen bonds (1,4-CBs) [8][9][10][11] as in 1 were more successful, also because spontaneous degradation into reactive Figure 1. a) Flipper dilemma and b) CB cascade switch:a)Inplanarizable PP probes, exocyclic donors D D and acceptors A A are needed in planar but incompatiblew ith twisted form. b) Twisting of the central bond (1)turns off PP D D (2,r ed circle), and A A (3,b lue circle) because Lewis base Y( 5)hardly ...

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“…To overcome such drawbacks and enhance the staining stability and selectivity for lipid droplets, the quest for new fluorogenic probes with superior photophysics and different operation modes was undertaken. [16] Prospective advances in molecular platforms for LDs staining have been recently published, exploiting numerous hydrophobic fluorogenic probes including AIEgens (aggregation induced emission luminogens), [17][18][19][20][21][22] solvatochromic StatoMerocyanine dyes, [23] and solvatofluorochromic fluorophores displaying emission from intramolecular charge transfer excited states. [24][25][26][27] In our laboratory, we have recently developed a new set of environment responsive D-π-A fluorophores and demonstrated their high biocompatibility, fine-tuned spectroscopic properties, and their smooth chemical transformation into molecular probes for biological applications.…”

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confidence: 99%

Visualization of intracellular lipid droplets using lipophilic benzothiazole-based push-pull fluorophores at ultralow concentration

et al. 2019

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In this study we describe the development of new lipophilic and biocompatible benzothiazole-based push-pull fluorophores as potent fluorogenic probes for the specific staining of intracellular lipid droplets (LDs) at ultralow concentration (≤ 100 nM). These new fluorophores, harboring a D-π-A framework featuring an extended π-conjugated spacer, a lipophilic tertiary amine (D) and hydrophobic aryl groups (A), were prepared by an efficient and practical synthetic route. The photophysical studies of these compounds underlined their high polarity sensitivity, characterized by a strong solvatochromic effect and the large Stokes shifts values (λ em 465-630 nm, Δλ up to 6751 cm -1 ). Finally, the in cellulo investigations of D1 revealed its ability to selectivity accumulate in LDs and to allow their remarkable visualization using confocal fluorescence microscopy.

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Ultrabright and Fluorogenic Probes for Multicolor Imaging and Tracking of Lipid Droplets in Cells and Tissues

Cited by 310 publications

References 73 publications

A Chalcogen‐Bonding Cascade Switch for Planarizable Push–Pull Probes

A Chalcogen‐Bonding Cascade Switch for Planarizable Push–Pull Probes

A Chalcogen‐Bonding Cascade Switch for Planarizable Push–Pull Probes

Visualization of intracellular lipid droplets using lipophilic benzothiazole-based push-pull fluorophores at ultralow concentration

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