Rational Development of Near‐Infrared Fluorophores with Large Stokes Shifts, Bright One‐Photon, and Two‐Photon Emissions for Bioimaging and Biosensing Applications

Abstract

Fluorophores with near-infrared emissions play a crucial role in numerous bioimaging and biosensing applications, owing to their deep penetration depths, low auto-fluorescence, and minimal tissue damages. Herein, the rational development of a new class of near-infrared fluorophores with bright one-photon and two-photon emissions at ≈740 nm, large Stokes shifts (≈80 nm), significant two-photon action absorption cross-section (≈185 GM at 820 nm), excellent water solubility, outstanding photostability, and low toxicity is reported. Their biological applications in mitochondrial labelling, deep tissue imaging, and H S detection in live cells and mice are also demonstrated. In addition, a rational design strategy for enlarging the Stokes shifts and enhancing two-photon emissions of these fluorophores is presented. These fluorophores will serve as a useful platform for developing novel imaging and sensing agents, and the design methodologies will inspire the molecular engineering of abundant high-performance near-infrared fluorophores.

Hybrid Rhodamine Fluorophores in the Visible/NIR Region for Biological Imaging

“…[12] Another limitation of classic rhodamine dyes is their Stokes shift of less than 35 nm, which can result in self-quenching and fluorescence detection errors owing to excitation backscattering effects.N arrowing the HOMO-LUMO gap can increase emission wavelength, leading to al arger Stokes shift. [13] Nitrogen insertion at the mesoposition of pyronine, [14] incorporation of ar otary substituent to 6-(diethylamino)-1,2,3,4-tetrahydroxanthylium, [15] and pseudo-Stokes shift through donor-acceptor energy transfer [16] can also enlarge Stokes shift. [13,17] These deficiencies of rhodamine dyes have been the driving force for their continued development over the last decades.I na ddition, ideas for creating ratiometric NIR rhodamine dyes with large Stokes shifts have recently been proposed.…”

Simultaneous Monitoring of Temperature and Ca2+ Concentration Variation by Fluorescent Polymer during Intracellular Heat Production

“…Curcumin and its derivatives have been applied as near-infrared (NIR) probes for detection of amyloid-β deposits due to their high-affinity binding and high quantum yield properties. − However, the poor water solubility of curcumin restricts its application in intracellular temperature sensing. Meanwhile, FAM usually needs dimethyl sulfoxide (DMSO) or surfactant F127 to aid dissolution in aqueous media as auxiliaries when it is applied for Ca 2+ sensing, which results in side effects on living cells.…”

The Role of Photochemical Reactions in the Development of Advanced Soft Materials for Biomedical Applications

“…A solution to these issues seems to be only dependent upon the advances in light technology. However, photoresponsive molecules can be optimized, since the absorption of several photons is dependent on its symmetry and polarity . Hence, reaction times and yields can be improved affecting positively the process performance.…”