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The sensor platform of zinpyr 4 (ZP4) through pyrrole-for-pyridyl substitution is modified and the effects of this variation on both photophysical and metal-binding properties are evaluated. The utility of aniline-based ZP probes for select biological imaging applications are investigated.

The preparation of QZ1, 2-[2-chloro-6-hydroxy-3-oxo-5-(quinolin-8-ylaminomethyl)-3H-xanthen-9-yl]benzoic acid, and QZ2, 2-[6-hydroxy-3-oxo-4,5-bis-(quinolin-8-ylaminomethyl)-3H-xanthen-9-yl]benzoic acid, two fluorescein-based dyes derivatized with 8-aminoquinoline are prepared and their photophysical, thermodynamic, and zinc-building kinetic properties are presented. Due to their low background fluorescence and highly emissive Zn(II) complexes, QZ1 and QZ2 have a large dynamic range fold fluorescence enhancements upon Zn(II) coordination.

Adult neurogenesis (i.e., proliferation and differentiation of neuronal precursors in the adult brain) is responsible for adding new neurons in the dentate gyrus of the hippocampus and in the olfactory bulb. We describe herein that adult mice mutated in the cell cycle regulatory gene Ccnd2, encoding cyclin D2, lack newly born neurons in both of these brain structures. In contrast, genetic ablation of cyclin D1 does not affect adult neurogenesis. Furthermore, we show that cyclin D2 is the only D-type cyclin (out of D1, D2, and D3) expressed in dividing cells derived from neuronal precursors present in the adult hippocampus. In contrast, all three cyclin D mRNAs are present in the cultures derived from 5-day-old hippocampi, when developmental neurogenesis in the dentate gyrus takes place. Thus, our results reveal the existence of molecular mechanisms discriminating adult versus developmental neurogeneses.

The synthesis of a difluorofluorescein monocarboxaldehyde platform and its use for preparing ZP8, a new member of the Zinpyr family of neuronal Zn(super 2+) sensors, are described. It was found that by combining an aniline photoinduced electron transfer (PET) switch and an electron-withdrawing fluorescein scaffold, ZP8 displays reduced background fluorescence and improved dynamic range compared to previous ZP probes.

Zinc is an essential metal ion for human growth and development, the disruption of cellular Z[n.sup.2+] homeostasis being implicated in several major disorders including Alzheimer's disease, diabetes, and cancer. The molecular mechanisms of Z[n.sup.2+] physiology and pathology are insufficiently understood, however, owing in part to the lack of tools for measuring changes in intracellular Z[n.sup.2+] concentrations with high spatial and temporal fidelity. To address this critical need, we have synthesized, characterized, and applied an intracellular fluorescent probe for the ratiometric imaging of Z[n.sup.2+] based on a tautomeric seminaphthofluorescein platform. Zin-naphthopyr 1 (ZNP1) affords single-excitation, dual-emission ratiometric detection of intracellular Z[n.sup.2+] through Z[n.sup.2+]-controlled switching between fluorescein and naphthofluorescein tautomeric forms. The probe features visible excitation and emission profiles, excellent selectivity responses for Z[n.sup.2+] over competing C[a.sup.2+] and M[g.sup.2+] ions at intracellular concentrations, a dissociation constant ([K.sub.d]) for Z[n.sup.2+] of

Gold and magnetite composite nanoparticles have been prepared by a unique laser process. Both source colloid solutions of gold and magnetite were mixed and irradiated by an Nd:YAG laser (532 nm). The composite formation by a 'nanosoldering' effect was confirmed by microscope observations. Index Terms--Composite, gold, laser, magnetite, nanoparticle.

The alkylguanine transferase (AGT) labeling method is evaluated for the immobilization of a fluorescent zinc sensor of the Zinpyr family onto targeted organelles. This method has also provided a way to visualize a turn-on emission response to addition of zinc.

Thiophene moieties are incorporated into previously described Zinspy(ZS) fluorescent Zn(II) sensor motifs to provide enhanced fluorescence properties, low-micromolar dissociation constants for Zn(II) and improved Zn(II) selectivity. Halogenation of the xanthenone and benzoate moieties of the fluorescein platform systematically modulates the excitation and emission profiles, pH-dependent fluorescence, Zn(II) affinity, and Zn(II) complexation rates, offering a general approach for tuning multiple properties of xanthenone-based metal ion sensors.

The synthesis and characterization of a fluorescent nickel-nitrilotriacetic acid (NTA)-fluorescein probe and its ability to mark extracellular proteins containing genetically programmable polyhistidine sequences are described. The results show that the highly luminous property allows NTA-DCF (DCF = 2',7'-dichlorofluorescein) to serve as a small yet highly fluorescent label for polyhistidine sequences.