Azulene-Derived Fluorescent Probe for Bioimaging: Detection of Reactive Oxygen and Nitrogen Species by Two-Photon Microscopy

Abstract

Two-photon fluorescence microscopy has become an indispensable technique for cellular imaging. Whereas most two-photon fluorescent probes rely on well-known fluorophores, here we report a new fluorophore for bioimaging, namely azulene. A chemodosimeter, comprising a boronate ester receptor motif conjugated to an appropriately substituted azulene, is shown to be an effective two-photon fluorescent probe for reactive oxygen species, showing good cell penetration, high selectivity for peroxynitrite, no cytotoxicity, and excellent photostability.

Boronate-Based Probes for Biological Oxidants: A Novel Class of Molecular Tools for Redox Biology

“…•− and • NO (Zielonka et al, 2012b), numerous boronate redox probes were developed and reported for the detection of cellular ONOO − (Yu et al, 2012;Rios et al, 2016;Sedgwick et al, 2017;Murfin et al, 2019;Weber et al, 2020). CBA was also used in combination with the immuno-spin trapping technique to demonstrate ONOO − -mediated protein radical formation in microglial cells exposed to lipopolysaccharide (Kumar et al, 2014).…”

“…The CBA probe was used to demonstrate the formation of ONOO − as the product of the reaction of and • NO, when used at different ratios (Zielonka et al, 2010 ) and as a product of the reaction of HNO with O 2 (Smulik et al, 2014 ). Following the CBA- and FlAmBE ( 22 )-based detection of ONOO − in RAW 264.7 macrophages stimulated to coproduce and • NO (Zielonka et al, 2012b ), numerous boronate redox probes were developed and reported for the detection of cellular ONOO − (Yu et al, 2012 ; Kim J. et al, 2014 ; Rios et al, 2016 ; Sedgwick et al, 2017 ; Murfin et al, 2019 ; Weber et al, 2020 ). CBA was also used in combination with the immuno-spin trapping technique to demonstrate ONOO − -mediated protein radical formation in microglial cells exposed to lipopolysaccharide (Kumar et al, 2014 ).…”

A Colorimetric Chemosensor Based on a Nozoe Azulene That Detects Fluoride in Aqueous/Alcoholic Media

“…This fact has been exploited for its use in a range of colorimetric sensors. Examples include sensors for silver (Wakabayashi et al, 2013), nitrite (Murfin et al, 2020), mercury (Wakabayashi et al, 2007(Wakabayashi et al, , 2008(Wakabayashi et al, , 2012Razus et al, 2011;Birzan et al, 2017;Buica et al, 2018Buica et al, , 2019, phosphate (Lichosyt et al, 2016(Lichosyt et al, , 2018, and reactive oxygen species (Murfin et al, 2019).…”

Development of Heterocycle-Substituted and Fused Azulenes in the Last Decade (2010–2020)

“…Murafuji et al demonstrated the synthesis of azulene-substituted cyclic boronic acid esters 156a – 156e by the reaction of 2-azulenylboronic acid 155 with several diols ( Scheme 52 ) [ 73 ]. The reaction of 2-azulenyl lithium 154 with trimethyl borate yields a boronic acid ester, which is then hydrolyzed by acid to give 2-azulenylboronic acid 155 .…”