Recent Advances in Dual-target-activated Fluorescent Probes for Biosensing and Bioimaging.

Fluorescent probes have been powerful tools for visualizing and quantifying multiple dynamic processes in living cells. However, the currently developed probes are often constructed by conjugation a fluorophore with a recognition moiety and given signal-output after triggering with one singly target interest. Compared with the single-target-activated fluorescent probes mentioned above, the dual-target-activated ones, triggering with one target under stimulus (such as photoirradiation, microenvironment) or another targets, have the advantages of advoiding nonspecific activation and "false positive" results in complicated environments.

Efficient fluorescence resonance energy transfer-based ratiometric fluorescent cellular imaging probe for Zn(2+) using a rhodamine spirolactam as a trigger.

This letter described the design and synthesis of a novel fluorescein-appended rhodamine spirolactam derivative and its preliminary application as a ratiometric fluorescent cellular imaging probe for Zn(2+). The ratiometric fluorescent signal change of the probe is based on an intramolecular fluorescence resonance energy transfer (FRET) mechanism modulated by a specific metal ion induced ring-opening process of the rhodamine spirolactam (acting as a trigger). In the new developed sensing system, the emission peaks of the two fluorophores are well-resolved, which can avoid the emission spectra overlap problem generally met by spectra-shift type probes and benefits for observation of fluorescence signal change at two different emission wavelengths with high resolution.

Highly sensitive and selective colorimetric and off-on fluorescent chemosensor for Cu2+ in aqueous solution and living cells.

The design and synthesis of a novel rhodamine spirolactam derivative and its application in fluorescent detections of Cu(2+) in aqueous solution and living cells are reported. The signal change of the chemosensor is based on a specific metal ion induced reversible ring-opening mechanism of the rhodamine spirolactam. It exhibits a highly sensitive "turn-on" fluorescent response toward Cu(2+) in aqueous solution with an 80-fold fluorescence intensity enhancement under 10 equiv of Cu(2+) added.

A ratiometric chemosensor for fluorescent determination of Hg(2+) based on a new porphyrin-quinoline dyad.

Quinolin-8-ol p-[10',15',20'-triphenyl-5'-porphyrinyl]benzoate (1) was synthesized for the first time and developed as a ratiometric fluorescent chemosensor for recognition of Hg(2+) ions in aqueous ethanol with high selectivity. The 1-Hg(2+) complexation quenches the fluorescence of porphyrin at 646nm and induces a new fluorescent enhancement at 603nm. The fluorescent response of 1 towards Hg(2+) seems to be caused by the binding of Hg(2+) ion with the quinoline moiety, which was confirmed by the absorption spectra and (1)H NMR spectrum.

A fluorescent chemical sensor for Hg(II) based on a corrole derivative in a PVC matrix.

A fluorescent chemical sensor for Hg(II) using 5,10,15-tris(pentafluorophenyl)corrole (H(3)(tpfc)) as fluorophore is described in this paper. The response of the sensor is based on the fluorescence quenching of H(3)(tpfc) by coordination with Hg(II). H(3)(tpfc) based sensor shows a linear response towards Hg(II) in the concentration range from 1.

A fluorescent probe for zinc ions based on N-methyltetraphenylporphine with high selectivity.

N-methyl-alpha,beta,gamma,delta-tetraphenylporphine (NMTPPH) has been used to detect trace amount of zinc ions in ethanol-water solution by fluorescence spectroscopy. The fluorescent probe undergoes a fluorescent emission intensity enhancement upon binding to zinc ions in EtOH/H(2)O (1:1, v/v) solution. The fluorescence enhancement of NMTPPH is attributed to the 1:1 complex formation between NMTPPH and Zn(II) which has been utilized as the basis for the selective detection of Zn(II).

A porphyrin derivative containing 2-(oxymethyl)pyridine units showing unexpected ratiometric fluorescent recognition of Zn2+ with high selectivity.

A porphyrin derivative (1), containing two 2-(oxymethyl)pyridine units has been designed and synthesized as chemosensor for recognition of metal ions. Unlike many common porphyrin derivatives that show response to different heavy metal ions, compound 1 exhibits unexpected ratiometric fluorescence response to Zn(2+) with high selectivity. The response of the novel chemosensor to zinc was based on the porphyrin metallation with cooperating effect of 2-(oxymethyl)pyridine units.

A highly selective potentiometric sensor of molybdate based on a mu-oxo-bridged manganeseporphyrin dimer.

A novel high-selective potentiometric sensor for molybdate was prepared with a PVC membrane combining mu-oxo-bis[5,10,15,20-tetra(p-methylphenyl)porphinatomanganese(III)] [[Mn(p-Me)TPP](2)O] as an electroactive material and 2-nitrophenyl octyl ether (o-NPOE) as a plasticizer in the percentage ratio of 3:65:32, [Mn(p-Me)TPP](2)O:o-NPOE:PVC (w:w). The sensor exhibited a linear response with a Nernstian slope of 30.5 mV per decade within a concentration range of 2.

A wide pH range optical sensing system based on a sol-gel encapsulated amino-functionalized corrole.

The synthesis of a new compound, 10-(4-aminophenyl)-5,15-dimesitylcorrole, and its application for the preparation of optical chemical pH sensors is described. The dye materials were immobilized in a sol-gel glass matrix and characterised upon exposure to aqueous buffer solutions. The response of the sensor is based on the fluorescence intensity changing of corrole owing to multiple steps of protonation and deprotonation.