Responsive Fluorophore Aggregation Provides Spectral Contrast for Fluorescence Lifetime Imaging

Schleyer, Kelton A.; Datko, Benjamin D.; Burnside, Brandon; Cui, Chao; Ma, Xiaowei; Grey, John K.; Cui, Lina

doi:10.1002/cbic.202000056

Cited by 6 publications

(3 citation statements)

References 58 publications

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“…31−34 Although a high reactivity between CBT and Cys could contribute to the successful application of probes in living systems, the intermolecular condensation reaction largely depends on the local probe concentration, which is compromised by the highly dynamic in vivo environments. Moreover, owing to the presence of a high concentration of endogenous free Cys (20−200 μM), 35 it might also react with the CBT groups to outcompete the condensation between CBT and linked Cys group. Generally, the chemical concentration of the probes, especially PET tracers, is very low at target tissues.…”

Section: ■ Introductionmentioning

confidence: 99%

Stimuli-Responsive Macrocyclization Scaffold Allows In Situ Self-Assembly of Radioactive Tracers for Positron Emission Tomography Imaging of Enzyme Activity

et al. 2022

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Target-enabled bioorthogonal reaction and self-assembly of a small-molecule probe into supramolecules have shown promise for molecular imaging. In this paper, we report a new stimuli-responsive bioorthogonal reaction scaffold (SF) for controlling in situ self-assembly by engineering the condensation reaction between 2-cyanobenzothiazole and cysteine. For probes with the SF scaffold, intramolecular cyclization took place soon after activation, which could efficiently outcompete free cysteine even at a low concentration and result in efficient aggregation in the target. Through integration with different enzyme-responsive substrates and an ammoniomethyl-trifluoroborate moiety (AmBF3), two radioactive positron emission tomography (PET) tracers, [18F]SF-DEVD and [18F]SF-Glu, were designed, which showed high stability under physiological conditions and could produce clear PET signal in tumors to detect enzyme activity (e.g., caspase-3, γ-glutamyltranspeptidase) timely and accurately. Our results demonstrated that the scaffold SF could serve as a general molecular scaffold in the development of smart PET tracers for noninvasive imaging of enzyme activity, which could contribute to tumor detection and treatment efficacy evaluation.

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Section: ■ Introductionmentioning

confidence: 99%

Stimuli-Responsive Macrocyclization Scaffold Allows In Situ Self-Assembly of Radioactive Tracers for Positron Emission Tomography Imaging of Enzyme Activity

et al. 2022

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“…In fact, regulation of disassembly has already attracted considerable research attention in the field of controlled drug release. , Moreover, coupling ENS and disassembly would be an effective approach to mimic the cellular signal transduction cascades with feedback loops . In addition, it would be fruitful to introduce other local changes (e.g., ligand–receptor interactions, , coordination, , pH response, ionic interaction, redox reactions, ,− bioorthogonal reactions, ,,, and dynamic covalent bonds − ) into the substrates of ENS for designing sophisticated molecular systems that can control emergent properties of molecular assemblies and modulate cellular functions.…”

Section: Discussionmentioning

confidence: 99%

Enzymatic Noncovalent Synthesis

et al. 2020

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Enzymatic reactions and noncovalent (i.e., supramolecular) interactions are two fundamental nongenetic attributes of life. Enzymatic noncovalent synthesis (ENS) refers to a process where enzymatic reactions control intermolecular noncovalent interactions for spatial organization of higher-order molecular assemblies that exhibit emergent properties and functions. Like enzymatic covalent synthesis (ECS), in which an enzyme catalyzes the formation of covalent bonds to generate individual molecules, ENS is a unifying theme for understanding the functions, morphologies, and locations of molecular ensembles in cellular environments. This review intends to provide a summary of the works of ENS within the last decade and emphasize ENS for functions. After comparing ECS and ENS, we describe a few representative examples where nature uses ENS, as a rule of life, to create the ensembles of biomacromolecules for emergent properties/functions in a myriad of cellular processes. Then, we focus on ENS of man-made (synthetic) molecules in cell-free conditions, classified by the types of enzymes. After that, we introduce the exploration of ENS of man-made molecules in the context of cells by discussing intercellular, peri/intracellular, and subcellular ENS for cell morphogenesis, molecular imaging, cancer therapy, and other applications. Finally, we provide a perspective on the promises of ENS for developing molecular assemblies/processes for functions. This review aims to be an updated introduction for researchers who are interested in exploring noncovalent synthesis for developing molecular science and technologies to address societal needs.

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“…[6][7][8] For example, small molecule probes can be activated by the target enzyme, and due to the change in hydrophobicity before and after enzyme activation, they can self-assembly into nanometersized particles or aggregates and retain at site of activation. [9][10][11][12][13][14][15][16] Another strategy is to form a covalent bond between the reporter moiety and intracellular proteins via the reaction between a labile electrophilic moiety on the imaging probe and nucleophiles such as thiols or amines on proteins. 6,[17][18][19][20] Quinone methide (QM) chemistry has been explored to form covalent bonds between the fluorescent probe and surrounding proteins.…”

Section: Introductionmentioning

confidence: 99%

A Versatile Linker for Probes Targeting Hydrolases via In Situ labeling

Liu

Chen

et al. 2021

Preprint

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Hydrolases are important molecules that are involved in a wide range of biological functions and their activities are tightly regulated in healthy or diseased states. Detecting or imaging the activities of hydrolases, therefore, can reveal underlying molecular mechanisms in the context of cells to organisms, and their correlation with different physiological conditions can therefore be used in diagnosis. Due to the nature of hydrolases, substrate-based probes can be activated in their catalytic cycles, and cleavage of covalent bonds frees reporter moieties. For test-tube type bulk detection, spatial resolution is not a measure of importance, but for cell- or organism-based detection or imaging, spatial resolution is a key factor for probe sensitivity that influences signal-to-background ratio. One strategy to improve spatial resolution of the probes is to form a covalent linkage between the reporter moiety and intracellular proteins upon probe activation by the enzyme. In this work, we developed a generalizable linker chemistry that would allow in situ labeling of various imaging moieties via quinone methide species. To do so, we synthesized probes containing a monofluoromethyl or a difluoromethyl groups for β-galactosidase activation, while using fluorescein as a fluorescent reporter. The labeling efficacy of these two probes was evaluated in vitro. The probe bearing a monofluormethyl group exhibited superior labeling efficiency in imaging β-galactosidase activity in living cells. This study provides a versatile linker for applying quinone methide chemistry in the development of hydrolase-targeting probes involving in situ labeling.

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Responsive Fluorophore Aggregation Provides Spectral Contrast for Fluorescence Lifetime Imaging

Cited by 6 publications

References 58 publications

Stimuli-Responsive Macrocyclization Scaffold Allows In Situ Self-Assembly of Radioactive Tracers for Positron Emission Tomography Imaging of Enzyme Activity

Stimuli-Responsive Macrocyclization Scaffold Allows In Situ Self-Assembly of Radioactive Tracers for Positron Emission Tomography Imaging of Enzyme Activity

Enzymatic Noncovalent Synthesis

A Versatile Linker for Probes Targeting Hydrolases via In Situ labeling

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