Fluorescence umpolung enables light-up sensing of N-acetyltransferases and nerve agents

Abstract

Intramolecular charge transfer (ICT) is a fundamental mechanism that enables the development of numerous fluorophores and probes for bioimaging and sensing. However, the electron-withdrawing targets (EWTs)-induced fluorescence quenching is a long-standing and unsolved issue in ICT fluorophores, and significantly limits the widespread applicability. Here we report a simple and generalizable structural-modification for completely overturning the intramolecular rotation driving energy, and thus fully reversing the ICT fluorophores’ quenching mode into light-up mode. Specifically, the insertion of an indazole unit into ICT scaffold can fully amplify the intramolecular rotation in donor-indazole-π-acceptor fluorophores (fluorescence OFF), whereas efficiently suppressing the rotation in their EWT-substituted system (fluorescence ON). This molecular strategy is generalizable, yielding a palette of chromophores with fluorescence umpolung that spans visible and near-infrared range. This strategy expands the bio-analytical toolboxes and allows exploiting ICT fluorophores for light-up sensing of EWTs including N-acetyltransferases and nerve agents.

Ratiometric imaging of butyrylcholinesterase activity in mice with nonalcoholic fatty liver using an AIE-based fluorescent probe

“…3, TB-BChE and TCFIS exhibited fluorescence enhancement in a high viscosity environment, which contributed to the restricted intramolecular motion (RIM). [49][50][51] The fluorescence images of TCFIS and TB-BChE were further investigated in the solid state (Fig. S15, ESI †), and the fluorescence quantum yields of TCFIS and TB-BChE in the solid state were measured to be 0.50% and 0.01%, respectively.…”

Sequence-Activated Fluorescent Nanotheranostics for Real-Time Profiling Pancreatic Cancer

“…(ii) TCM-U11 was also released and formed small AIE nanoparticles. 68 , 69 Consequently, the donor–acceptor distance was beyond the operating range of FRET, resulting in the enhancement of TCM-U11 at 650 nm. All of these results strongly supported the fact that the proposed sequence-activated nanotheranostic TCM-U11&Cy@P had the desired capacity for real-time tracking of the programmed acidic pH-triggered and subsequent size transformation process via dual-channel fluorescence.…”

Regulation of Fluorescence Solvatochromism To Resolve Cellular Polarity upon Protein Aggregation

“…Common solvatochromic fluorophores usually harbor an electron-donating moiety (donor) and an electron-withdrawing moiety (acceptor) connected by an aromatic bridge (D-π-A type). ,,− Such a structural feature results in a polar excited state upon photoinduced intramolecular charge transfer (ICT), rendering the molecule solvatochromic (Figures c and a). Structural modulation of both donor and acceptor has been widely demonstrated to regulate the resulting solvatochromic properties, such as changes in emission wavelength, quantum yield, Stokes shift, etc. ,,,,, …”