Design and synthesis of NQO1 responsive fluorescence probe and its application in bio-imaging for cancer diagnosis.

As an over-expressed flavoprotein in several kinds of tumor cells, NAD(P)H: quinone oxidoreductase-1 (NQO1) is considered as a potent biomarker in early-stage cancer diagnosis. Developing a fast, selective and sensitive method of monitoring NQO1 on cellular level will greatly promote cancer diagnosis in clinical practice. In this paper, a fast NQO1 responsive fluorescence probe SYZ-30 containing quinone acid and 7-nitro-2,1,3-benzoxadiazole (NBD) fluorophore is constructed. The probe could selectively respond to NQO1 and rapidly emit strong fluorescence in vitro within only 5 min. Notably, the peak fluorescent intensities at 550 nm showed a linear relationship with NQO1 concentrations in the range of 3-30 ng/ml and limit of detection (LOD) was 0.0667 ng/ml. Furthermore, it was validated that the probe has good biocompatibility and could be applied for bio-imaging in NQO1 over-expressed cancer cells, together with its mitochondria targeting ability. Importantly, confocal fluorescence imaging confirmed the NQO1 detection ability on cellular level, which can be used for real-time detection of several cancer subtypes like adenocarcinoma. To conclude, the probe is rapidly responsive, highly sensitive and selective which will potentially become a practical tool for early cancer detection and diagnosis.