Enlarging the Stokes Shift by Weakening the π‐Conjugation of Cyanines for High Signal‐to‐Noise Ratiometric Imaging

Abstract

The signal‐to‐noise ratio (SNR) is one of the key features of a fluorescent probe and one that often defines its potential utility for in vivo labeling and analyte detection applications. Here, it is reported that introducing a pyridine group into traditional cyanine‐7 dyes in an asymmetric manner provides a series of tunable NIR fluorescent dyes (Cy‐Mu‐7) characterized by enhanced Stokes shifts (≈230 nm) compared to the parent cyanine 7 dye (<25 nm). The observed Stokes shift increase is ascribed to symmetry breaking of the Cy‐Mu‐7 core and a reduction in the extent of conjugation. The fluorescence signals of the Cy‐Mu‐7 dyes are enhanced upon confinement within the hydrophobic cavity of albumin or via spontaneous encapsulation within micelles in aqueous media. Utilizing the Cy‐Mu‐7, ultra‐fast in vivo kidney labeling in mice is realized, and it is found that the liver injury will aggravate the burden of kidney by monitoring the fluorescence intensity ratio of kidney to liver. In addition, Cy‐Mu‐7 could be used as efficient chemiluminescence resonance energy transfer acceptor for the reaction between H 2 O 2 and bisoxalate. The potential utility of Cy‐Mu‐7 is illustrated via direct monitoring fluctuations in endogenous H 2 O 2 levels in a mouse model to mimic emergency room trauma.

Development of Human Serum Albumin Fluorescent Probes in Detection, Imaging, and Disease Therapy

“…Recently, our research group prepared another NIR probe 99 by introducing the pyridine group into conventional cyanine dyes in an asymmetric manner (Figure 30), 163 which exhibited a Stokes shift of 230 nm. The fluorescence signal was enhanced when probe 99 was confined within the hydrophobic cavity of albumin or micelles, realizing ultrafast, high-contrast kidney fluorescence labeling and fluorescence detection of acute kidney injury in mice.…”

“…Structure of probe 99 and its application schematic diagram. Adapted with permission from ref . Copyright 2022 The Authors.…”

A Rationally Designed Prodrug for the Fluorogenic Labeling of Albumin and Theranostic Effects on Drug-Induced Liver Injury

“…9,20−24 It has been suggested that covalent binding exhibits better selectivity and stability to resist interference from small biomolecules and drugs. 9,20,23,25 Ajayaghosh et al developed self-assembling dyes that form nonfluorescent nanoparticles, and HSA can selectively disassemble and covalently bind to generate a fluorescent response. 26 He et al orthogonally functionalized HSA using covalent and supramolecular approaches to modular peptides, achieving specific optical visualization and photodynamic ablation of malignant liver tumors of human origin.…”

Colorimetric detection of ozone in aqueous solution and imaging in living cells using a novel hemicyanine dye

“…They have attracted more and more attention from researchers in recent years as fluorescent probes. 23–25…”