Novel Pyrazine-Bridged D-A-D Type Charge Neutral Probe for Membrane Permeable Long-Term Live Cell Imaging.

Pei Liu,Wenxuan Zhao,Suna Chen,Qiutang Wang,Dan Bai,Shuqi Wu,Liang Xu

doi:10.3389/fchem.2021.782827

Abstract

A novel donor–acceptor–donor (D-A-D) type compound containing pyrazine as the acceptor and triphenylamine as the donor has been designed and synthesized. The photophysical properties and biocompatibility of this probe, namely (OMeTPA)2-Pyr for live cell imaging were systematically investigated, with observed large Stokes shifts, high photostability, and low cytotoxicity. Furthermore, we demonstrated that (OMeTPA)2-Pyr could permeate live cell membranes for labeling. The proposed mechanism of this probe was the binding and shafting through membrane integral transport proteins by electrostatic and hydrophobic interactions. These salient and novel findings can facilitate the strategic design of new pyrazine-fused charge-neutral molecular platforms as fluorescent probes, for long-term in situ dynamic monitoring in live cells.

Highlights

Using fluorescent probes for long-term monitoring of live cells is the key to understanding and modulating molecular events happening within organelles, unraveling the physiological dynamics
Pyrazine was chosen as the core acceptor moiety, which reacted with 4-methoxytriphenylamine as the donor group
As the LUMOs are relatively concentrated on the pyrazine core, the intramolecular charge transfer (ICT) effect would be promoted upon excitation during the imaging process to ensure the photostability (Yang et al, 2020; Liu et al, 2021)

Summary

INTRODUCTION

Using fluorescent probes for long-term monitoring of live cells is the key to understanding and modulating molecular events happening within organelles, unraveling the physiological dynamics. Lou et al reported a D-A-D type curcuminoid-based fluorophore with a high signal to noise ratio (SNR) for biothiol recognition in living cells (Yang et al, 2020). Zhang et al and Wang et al reported fluorescent imaging via triphenylamine (TPA)-based probes (AS2CP-TPA, TTVP) with hydrophilic pyridinium salt moiety (Liu et al, 2020a), demonstrated a fast staining protocol. These probes were limited to stain the cell plasma membrane, required additives such as lipid vesicle reagents (Morris et al, 2009; Suzuki et al, 2016; Han et al, 2017). There is still an unmet demand for rational design and synthesis of novel probes with synthetic simplicity, tunable photophysical properties, greater stability, and biocompatibility (Liu et al, 2020b; Wang et al, 2020)

RESULTS AND DISCUSSION

CONCLUSION

METHODS

DATA AVAILABILITY STATEMENT