Rational construction of probes rendering ratiometric response to the cancer-specific enzyme NQO1

Abstract Pursuit of fluorescent probes for identification of cancer biomarkers benefits reliable predictions of early cancer detection. Here, a strategy employing polymeric micelle assembly for encapsulation of a new enzyme (NQO1)-responsive small molecule was established for facile access to nanoprobes with favorable features in bioimaging, such as good aqueous solubility, enhanced photo-stability and biocompatibility. In the presence of the enzyme NQO1, these nanoprobes underwent ratiometric fluorescence changes from yellow-green fluorescence signals to red fluorescence signals. By exploiting this favorable ratiometric response to NQO1, we explored these nanoprobes for evaluation of enzyme activity in living cells, which showed distinct differentiation between NQO1-positive cancer cells and NQO1-negative cells.