A sensitive colorimetric and ratiometric fluorescent probe for mercury species in aqueous solution and living cells

A highly sensitive and selective fluorescent probe for inorganic and organic mercury species displays colorimetric and ratiometric response in a buffer solution via mercury promoted cleavage reaction. The probe is demonstrated to detect CH(3)HgCl in living cells.     

A ratiometric fluorescent probe for imaging hydroxyl radicals in living cells

A novel fluorescent probe, the detection mechanism of which is based on the 'on-off' switching of a FRET triggered by the *OH-induced cleavage of a DNA strand, has been developed for the ratiometric imaging of *OH.     

A mitochondria-targeted fluorescent probe for ratiometric detection of hypochlorite in living cells

A new fl uorescent probe 1 was designed for mitochondrial localization and ratiometric detection of hypochlorite in living cells. It is noteworthy that a high Pearson’s co-localization coeffi cient (Rr) we have obtained was calculated to be 0.97.     

An effective colorimetric and ratiometric fluorescent probe for bisulfite in aqueous solution

We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO₃⁻) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO₃⁻ based on the Michael addition reaction with a limit of detection 5.3 × 10⁻⁸ M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application.     

A ratiometric merocyanine-based fluorescent probe for detecting hydrazine in living cells and zebra fish

We developed a merocyanine-based fluorescent probe,NEPB,for tracing hydrazine(N_2 H_4) in a ratiometric manner with large Stokes shifts and long emission wavelength.The fluorescence color of probe NEPB changed from green to yellow upon addition of hydrazine.Probe NEPB displayed high selectivity and sensitivity to hydrazine in solution,and could ratiometrically monitor N_2 H_4 in living cells and zebrafish with low cytotoxicity.     

A 4-hydroxynaphthalimide-derived ratiometric fluorescent chemodosimeter for imaging palladium in living cells

A highly selective ratiometric fluorescent chemodosimeter derived from 4-hydroxynaphthalimide was designed and synthesized to image palladium species in living cells by virtue of a palladium-catalyzed depropargylation reaction, and it could monitor three typical palladium species (0, + 2 and + 4) without additional reagents.     

A ratiometric fluorescent chemosensor for Al in aqueous solution based on aggregation-induced emission and its application in live-cell imaging

A ratiometric fluorescent chemosensor 1 was developed for the detection of Al³⁺ in aqueous solution based on aggregation-induced emmision (AIE). The chemosensor showed the fluorescence of its aggregated state and Al³⁺-chelated soluble state in the absence and in the presence of Al³⁺, respectively, and resulted in a fluorescence ratio (I₄₆₁/I₅₃₇) response to Al³⁺ in neutral aqueous solution at a detection limit as low as 0.29 μmol L⁻¹. The method was also highly selective to Al³⁺ over other physiological relevant metal ions investigated in this study. Taking advantage of its AIE characteristics, the chemosensor was successfully applied on test papers for simple and rapid detection of Al³⁺. Moreover, the application of 1 for the imaging of Al³⁺ in living cells by ratiometric fluorescence changes was also achieved.     

A ratiometric fluorescent probe for cyanide based on FRET

On the basis of FRET from 4-(N,N-dimethylamino)benzamide to fluorescein, a new ratiometric fluorescence probe bearing a hydrazone binding unit was developed for highly selective and sensitive detection of CN(-) in aqueous solution.     

Development of an ICT-based ratiometric fluorescent hypochlorite probe suitable for living cell imaging

We have judiciously constructed a novel ICT-based ratiometric OCl(-) probe capable of ratiometric imaging in the live cells based on the new OCl(-)-promoted de-diaminomaleonitrile reaction.     

A new turn-on fluorescence probe for Zn in aqueous solution and imaging application in living cells

We designed and synthesized a new pyrazoline-based turn-on fluorescence probe for Zn²⁺ by the reaction of chalcone and thiosemicarbazide. The structure of the probe was characterized by IR, NMR and HRMS spectroscopy. The probe (L) exhibits high selectivity and sensitivity for detecting Zn²⁺ in buffered EtOH/HEPES solution (EtOH/HEPES = 1/1, pH 7.2) with 80-fold fluorescence enhancement, which is superior to previous reports. Job’s plot analysis revealed 1:1 stoichiometry between probe L and Zn²⁺ ions. The association constant estimated by the Benesi–Hildebrand method and the detection limit were 3.92 × 10³ M⁻¹ and 5.2 × 10⁻⁷ M, respectively. A proposed binding mode was confirmed by ¹H NMR titration experiments and density functional theory (DFT) calculations. The probe is cell-permeable and stable at the physiological pH range in biological systems. Because of its fast response to Zn²⁺, the probe can monitor Zn²⁺ in living cells. Moreover, the selective binding of L and Zn²⁺ was reversible with the addition of EDTA in buffered EtOH/HEPES solution and Zn²⁺ could be imaged in SH-SY5Y neuron cells.     

A selective fluorescent probe for carbon monoxide imaging in living cells

A genetically encoded fluorescent probe is capable of selectively detecting carbon monoxide inside living cell. The probe, named COSer (CO sensor), consists of a circularly permuted yellow fluorescent protein (cpYFP) inserted into the regulatory domain of the bacterial CO-sensing protein, CooA, which gives the probe its selective CO-binding property.     

A near-infrared fluorescent probe for monitoring ozone and imaging in living cells

A near-infrared fluorescent probe (Trp-Cy) for endogenous ozone is presented, which exhibited a large stokes shift about 140 nm and a rapid fluorescence response to ozone with high selectivity and sensitivity.     

Developing a novel ratiometric fluorescent probe based on ESIPT for the detection of pH changes in living cells

As an important parameter of intracellular metabolism, pH plays important roles in maintaining normal physiological processes. The abnormal pH could cause disorder of cell function which may cause neurological diseases. Herein, we present two novel ratiometric fluorescent probes to detect pH changes. The probes employed 2-(2′-hydroxyphenyl)benzothiazole as fluorescent platform, and displayed desirable fluorescence response to pH on the basis of excited state intramolecular proton transfer (ESIPT) process. The probe BtyC-1 showed green fluorescence at 546 nm under acidic conditions, while it displayed strong blue fluorescence at 473 nm and weak green fluorescence at 546 nm under alkaline conditions. Biological experiments demonstrated that the probe BtyC-1 could be successfully applied for the ratiometric imaging of cellular pH and the NH₄Cl-induced pH changes in living cells.     

A highly selective colorimetric and ratiometric fluorescent chemodosimeter for imaging fluoride ions in living cells

A simple but highly selective colorimetric and ratiometric fluorescent chemodosimeter was designed and synthesized to detect fluoride ions (F(-)) in aqueous solution and living cells by virtue of the strong affinity of F(-) toward silicon.     

A unique two-photon fluorescent probe based on ICT mechanism for imaging palladium in living cells and mice

Palladium(0) as one of the vital transition metals, is employed in numerous industries, such as drug synthesis, aerospace high-tech field and automobile industry. When the Pd(0) enter into the body, it will bind with thiol-containing amino acids, DNA, RNA, and other biomolecules damaging to human health. Thus, developing a novel tool for monitoring and imaging of Pd(0) in vivo is very urgent. In the work, based on a intramolecular charge transfer (ICT) mechanism a two-photon fluorescent probe NIPd had been designed and synthesized for the recognition Pd(0). In vitro experiments data displayed that probe NIPd exhibited a 13-fold fluorescent increase for Pd(0) in 30 min in the aqueous solution with a detection limit of 16 nmol/L. It also showed the outstanding selectivity and antijamming performance. More importantly, NIPd could be served as a two-photon fluorescent probe for real-time monitoring Pd(0) in living cells and mice.     

A unique two-photon fluorescent probe based on ICT mechanism for imaging palladium in living cells and mice

Palladium(0) as one of the vital transition metals, is employed in numerous industries, such as drug synthesis, aerospace high-tech field and automobile industry. When the Pd(0) enter into the body, it will bind with thiol-containing amino acids, DNA, RNA, and other biomolecules damaging to human health. Thus, developing a novel tool for monitoring and imaging of Pd(0) in vivo is very urgent. In the work, based on a intramolecular charge transfer (ICT) mechanism a two-photon fluorescent probe NIPd had been designed and synthesized for the recognition Pd(0). In vitro experiments data displayed that probe NIPd exhibited a 13-fold fluorescent increase for Pd(0) in 30 min in the aqueous solution with a detection limit of 16 nmol/L. It also showed the outstanding selectivity and antijamming performance. More importantly, NIPd could be served as a two-photon fluorescent probe for real-time monitoring Pd(0) in living cells and mice.     

A chloroacetate based ratiometric fluorescent probe for cysteine detection in biosystems

The specific detection of cysteine (Cys) over homocysteine (Hcy), glutathione (GSH) and other amino acids is of great significance for studying its biological functions as well as for the diagnosis of related diseases. Chloroacetyl group was often used as a reaction site for cysteine fluorescent probes for its sensitivity and selectivity. However, high background fluorescence and low stability are common problems encountered by such probes. Here, four chloroacetyl group based fluorescent probes (C1, C2, C3, and H4) was synthesized for a comparative study. We found that the inefficient quenching ability of chloroacetyl group turned into an advantage when connected with a ratiometric fluorophore. With the modification of chloroacetyl group, probe H4 displayed excellent ratiometric property and great selectivity for Cys, the stability was also improved. Additionally, the probe was successfully applied for quantitative detection of Cys in fetal bovine serum and real-time imaging in living HeLa cells with low toxicity.     

A colorimetric and ratiometric fluorescent probe for palladium

A colorimetric and ratiometric fluorescent probe for the palladium species has been developed based on the Pd(0)-catalyzed cleavage of an allyoxycarbonyl group of amines under mild conditions. The probe displays a highly sensitive and selective response with significant changes in both color (from colorless to jade-green) and fluorescence (from blue to green), through the ICT process.