Xiaoqun Cao

A ratiometric fluorescent probe for sensing sulfite based on a pyrido[1,2-a]benzimidazole fluorophore

A new fluorophore pyrido[1,2-a]benzimidazole was synthesized and used as a ratiometric fluorescent probe based on an intramolecular charge transfer (ICT) mechanism for sensing sulfite. The probe showed high selectivity and sensitivity toward SO32− with a fast response time (10 s) and a detection limit of 10.6 nM. Furthermore, the probe showed great potential for the detection of SO32− in real samples (dry white wine).

An indolizine–rhodamine based FRET fluorescence sensor for highly sensitive and selective detection of Hg2+ in living cells

An indolizine–rhodamine-based ratiometric fluorescent probe was designed and successfully synthesized. The probe shows a large Stokes shift (204 nm), high sensitivity and high selectivity. The detection limit was calculated to be as low as 8.76 nM. The probe could quickly (5 min) detect Hg2+ over a wide pH range from 5 to 10. Furthermore, it could be used for imaging Hg2+ in living cells.

A mitochondria-targeting ratiometric fluorescent probe for the detection of hypochlorite based on the FRET strategy

In this study, a ratiometric fluorescent probe (IRP) for −OCl was designed based on the fluorescence resonance energy transfer (FRET) platform. The probe was fabricated by integrating an imidazo[1,5-a]pyridine moiety (donor) with a rhodamine moiety (acceptor). We evaluated its properties for recognizing −OCl and the results implied that IRP possessed high selectivity, a real-time detection possibility and brilliant photostability. The fluorescence intensity ratios (I575/I467) of IRP displayed desirable −OCl-dependent performance and responded linearly to −OCl in the concentration range of 0.5–3.5 μM. Also, IRP was applied to image endogenous −OCl with a mitochondria-targeting ability, due to the introduction of the quaternized pyridine moiety. Therefore, IRP may be used for further mitochondrial −OCl-related studies.

A simple but effective fluorescent probe for the detection of bisulfite

A new fluorescence probe (PML) for sensing HSO3− was developed based on a Michael addition reaction mechanism. The probe was composed of carbazole and 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene)malononitrile moieties and can be easily synthesized. The carbazole-based probe can selectively detect HSO3− and shows good sensitivity with the limit of detection of 2.08 × 10−6 M in a PBS : DMF = 1 : 1 buffer solution. Upon addition of HSO3−, the intense fluorescence of the probe was quenched, and the color markedly changed from red to colorless. In addition, the probe can be used to detect HSO3− in dry white wine.

A fluorescent probe for the detection of HOCl in lysosomes

In this study, a new fluorescent probe (LR1) for lysosomal HOCl was developed by integrating a morpholine moiety, a lysosome-targeting group, into the rhodamine framework. LR1 exhibited remarkable fluorescence intensity enhancement at 582 nm upon HOCl titration with a low detection limit (2.6 nM), which indicated that the probe may be capable of monitoring HOCl fluctuations at trace levels. Moreover, the probe was applied in cellular fluorescence imaging, and the results demonstrated that it could sense endogenous HOCl with low cytotoxicity in RAW264.7 cells. In addition, LR1 was found to be capable of monitoring HOCl changes in lysosomes owing to the introduction of morpholine, which served as a lysosome-targeting group. We expect that the probe has great potential as a practical molecular tool for exploring HOCl-related biology in lysosomes.

A rhodamine B-based probe for the detection of HOCl in lysosomes

A rhodamine B-based derivative (RL1) was developed as a specific fluorescent probe for HOCl. Meanwhile, morpholine moiety was introduced into the probe. It was found that the probe could display highly selective, sensitive and naked-eye detection upon the addition of HOCl. And the detection limit (LOD) was calculated to be as low as 2.8 nM. Furthermore, cellular confocal microscopic studies revealed that the introduction of morpholine moiety realized the lysosome-targeting capability. Moreover, RL1 was successfully applied for the imaging of endogenous HOCl with low cytotoxicity. Therefore, all the desirable features made probe RL1 particularly suitable for HOCl detection in aqueous buffer solution samples as well as the bio-imaging applications.