Stimuli-responsive colorimetric and NIR fluorescence combination probe for selective reporting of cellular hydrogen peroxide.

Hydrogen peroxide (H(2)O(2)) is a key reactive oxygen species and a messenger in cellular signal transduction apart from playing a vital role in many biological processes in living organisms. In this article, we present phenyl boronic acid-functionalized quinone-cyanine (QCy-BA) in combination with AT-rich DNA (exogenous or endogenous cellular DNA), i.e., QCy-BA⊂DNA as a stimuli-responsive NIR fluorescence probe for measuring in vitro levels of H(2)O(2). In response to cellular H(2)O(2) stimulus, QCy-BA converts into QCy-DT, a one-donor-two-acceptor (D2A) system that exhibits switch-on NIR fluorescence upon binding to the DNA minor groove. Fluorescence studies on the combination probe QCy-BA⊂DNA showed strong NIR fluorescence selectively in the presence of H(2)O(2). Furthermore, glucose oxidase (GOx) assay confirmed the high efficiency of the combination probe QCy-BA⊂DNA for probing H(2)O(2) generated in situ through GOx-mediated glucose oxidation. Quantitative analysis through fluorescence plate reader, flow cytometry and live imaging approaches showed that QCy-BA is a promising probe to detect the normal as well as elevated levels of H(2)O(2) produced by EGF/Nox pathways and post-genotoxic stress in both primary and senescent cells. Overall, QCy-BA, in combination with exogenous or cellular DNA, is a versatile probe to quantify and image H(2)O(2) in normal and disease-associated cells.