Wen-Jing Wang,Jun-Mei Xia,Xin Hai,Ming-Li Chen,Jian-Hua Wang
The nucleophilic substitution reaction between 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) and –NH2 groups on amino-functionalized carbon dots (CDs) produces a novel carbon dot-based hybrid, CDs@NBD for short. In addition to the characteristic fluorescence emission of carbon dots at λex/λem = 360/443 nm, the CDs@NBD hybrid gives rise to new photoluminescence at λex/λem = 460/544 nm, which is significantly quenched by p-phenylenediamine (PPD) via static quenching. This provides a novel sensing approach for fluorometric detection of PPD with CDs@NBD as a probe. A linear calibration graph is obtained within two concentration ranges of 0.1–1.0 μmol L−1 and 1.0–10.0 μmol L−1, along with a detection limit of 56 nmol L−1 and a RSD of <3% (at 1.0 μmol L−1). The common coexisting species in environmental and biological sample matrices cause no obvious interferences on the detection of PPD. The colour change of the CDs@NBD hybrid solution with the variation in PPD concentration also facilitates visual detection of PPD, which further demonstrates promising applications in environmental and biological sample analysis.
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.
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