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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.

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.

In this study, we developed a coumarin–rhodamine based fluorescence resonance energy transfer (FRET) system RC1 as a ratiometric pH probe. The probe with a pKa of 4.98 was constructed by integrating a coumarin moiety as an FRET donor with a rhodamine moiety as an FRET accepter. Upon addition of H+, the coumarin emission at 477 nm decreased and the rhodamine emission at 582 nm increased simultaneously. The fluorescence intensity ratio (I477/I582) displayed excellent pH-dependent performance and responded linearly to minor pH changes in the range of 4.20–6.00. The probe exhibited brilliant selectivity among different amino acids, metal cations and the ATP. Moreover, it has been successfully applied in fluorescence imaging in HeLa cells and the results indicated that the probe could selectively stain lysosomes with low cytotoxicity and excellent photostability. We also applied RC1 to monitor intracellular pH variations induced by dexamethasone. Therefore, RC1 could act as a practical tool for the detection of pH in weakly acidic conditions and provide essential information in medicinal analysis and real biological systems.

A new simple-structure fluorescent probe RL based on the special affinity of Pd2+ to double bond ligands has been designed and synthesized. RL shows high selectivity and sensitivity for Pd2+ with a detection limit of 21.3 nM (2.3 ppb) in the presence of other competing metal ions in aqueous media. Furthermore, RL has potential applications in Pd2+ analysis in natural water and in a reactor involving a Pd2+catalytic reaction.

A novel compound, 2-(1,5-diphenyl-4,5-dihydro-1H-pyrazol-3-yl)phenyl acrylate (probe L), was designed and synthesized as a highly sensitive and selective fluorescent probe for recognizing and detecting glutathione among cysteine, homocysteine and other amino acids. The structures of related compounds were characterized using IR, NMR and HRMS spectroscopy analysis. The probe is a non-fluorescent compound. On being mixed with glutathione in buffered EtOH:PBS=3:7 solution at pH 7.4, the probe exhibited the blue emission of the pyrazoline at 474 nm and a 83-fold enhancement in fluorescence intensity. This probe is very sensitive and displayed a linear fluorescence off-on response to glutathione with fluorometric detection limit of 8.2 × 10(-8)M. The emission of the probe is pH independent in the physiological pH range. Live-cell imaging of HeLa cells confirmed the cell permeability of the probe and its ability to selectively discriminate GSH from Cys and Hcy in cells. The toxicity of the probe was low in cultured HeLa cells.

Novel Fe 3 O 4 magnetic nanoparticles (MNPs) modified with low toxic 3-glycidoxypropyltrimethoxysilane (GPTMS) and lysine (Lys) were synthesized. The MNPs were characterized by transmission electron microscopy, X-ray diffraction, infra-red spectra and thermogravimetric analysis. The MNPs were used to remove anionic dyes and cationic dyes, including methyl blue (MB), orange I (OR), acid red 18 (AR) and methylene blue (MEB), azure I (AZ), from aqueous solution. We investigated organic dye uptake capacity of Fe 3 O 4 @GPTMS@Lys as a function of contact time, dye concentration, and different pH. Furthermore, adsorption isotherms and kinetics were studied to understand the mechanism by which the MNPs adsorb dyes. To our delight, the improved adsorbent can not only enhance the maximum adsorption capacity for anionic dyes but also efficiently remove cationic dyes (AZ and MEB) from aqueous solution.

We developed a rhodamine–rhodanine-based pH probe with pKa = 4.85 in buffer solution. The fluorescence intensity exhibited strong pH-dependent performance and responded linearly to minor pH fluctuations within the range of 4.2–5.2. In addition, the fluorescence microscopic images suggested this probe had excellent cell membrane permeability and could image weak acid pH changes of lysosomes in live cells without auto-fluorescence and interference from the complex intracellular environment. The results demonstrated that the probe had great potential in monitoring H+ in vitro and in living cells.

This present work describes the preparation and adsorption behavior of Fe3O4 magnetic nanoparticles (MNPs) modified with 3-glycidoxypropyltrimethoxysilane (GPTMS) and glycine (Gly). The magnetic nanoparticles which can excellently remove both anionic and cationic dyes in severe environment (highly acidic or strong alkaline) were synthesized by a simple method. The MNPs were characterized by transmission electron microscopy (TEM), X-ray diffraction, infra-red (IR) spectra, and thermogravimetric analysis (TGA). We investigated organic dye uptake capacity of Fe3O4@GPTMS@Gly as a function of contact time, dye concentration and pH. Furthermore, adsorption isotherms and kinetics were studied to understand the adsorption mechanism of the MNPs. In addition, desorption of the MNPs was carried out by adjusting pH with HCl or NaOH solution. The adsorbent can effectively remove both anionic and cationic dyes from aqueous solution and shows reusability and high separation efficiency.

A series of novel oxazolo[3,2-a]pyrazolo[1,5-d]pyrazin-5-ones were synthesized by the reaction of ethyl 3-aryl-1-(2-oxo-2-arylethyl)-1H-pyrazole-5-carboxylate derivatives and aminoethanol under microwave-assisted one-step and solvent-free conditions.