ESIPT-Based Photoactivatable Fluorescent Probe for Ratiometric Spatiotemporal Bioimaging

Abstract

Photoactivatable fluorophores have become an important technique for the high spatiotemporal resolution of biological imaging. Here, we developed a novel photoactivatable probe (PHBT), which is based on 2-(2-hydroxyphenyl)benzothiazole (HBT), a small organic fluorophore known for its classic luminescence mechanism through excited-state intramolecular proton transfer (ESIPT) with the keto form and the enol form. After photocleavage, PHBT released a ratiometric fluorophore HBT, which showed dual emission bands with more than 73-fold fluorescence enhancement at 512 nm in buffer and more than 69-fold enhancement at 452 nm in bovine serum. The probe displayed a high ratiometric imaging resolution and is believed to have a wide application in biological imaging.

Excited State Dynamics of Thermally Activated Delayed Fluorescence from an Excited State Intramolecular Proton Transfer System

“…Small ESIPT molecules demonstrating TADF have been reported as attractive materials for OLED emitters, sparking new interest in this molecular design. The spectral sensitivity of ESIPT materials to changes in the surrounding medium also allows them to also be used in imaging and as fluorescent probes. ,,− In contrast to D–A­(−D) materials, while rISC and TADF have been reported in several ESIPT materials no definitive experimental evidence for the underlying mechanism has been forthcoming. − Additionally, the utilization of ESIPT emitters in OLEDs remains a challenge due to their limitations of low photoluminescence quantum yield and concentration quenching of the excited keto state. Understanding the rISC mechanism and factors impacting emission efficiency is crucial to enable rational design of future ESIPT emitters.…”

A brand-new type of excited-state proton transfer (ESIPT) molecule based on sulfoxide/sulfenic acid tautomerism

“…The luminescent material exhibiting the ESIPT phenomenon can emit dual fluorescence simultaneously, rendering it exceptionally suitable for fabricating white organic OLEDs. 1,[11][12][13] Moreover, the principle of ESIPT can find application in the design of fluorescent probes, [14][15][16] bioimaging techniques, [17][18][19][20] sunscreen formulations, [21][22][23] and optical materials. 4,24,25 In the conventional ESIPT process, the compound in its ground state undergoes excitation to the excited state.…”

Interaction Study between ESIPT Fluorescent Lipophile-Based Benzazoles and BSA

“…10000 cm −1 ) [14,15]. These photophysical features allow these compounds to be applied as pH sensors [16][17][18][19], WOLEDs [20][21][22][23][24][25], optical sensors [26][27][28], bioimaging [29][30][31][32][33][34][35], and lipid probes [36][37][38][39][40].…”