Cellular copper import by nanocarrier systems, intracellular availability, and effects on amyloid beta peptide secretion.

Studies in animals have reported that normalized or elevated Cu levels can inhibit or even remove Alzheimer's disease-related pathological plaques and exert a desirable amyloid-modifying effect. We tested engineered nanocarriers composed of diverse core-shell architectures to modulate Cu levels under physiological conditions through bypassing the cellular Cu uptake systems. Two different nanocarrier systems were able to transport Cu across the plasma membrane of yeast or higher eukaryotic cells, CS-NPs (core-shell nanoparticles) and CMS-NPs (core-multishell nanoparticles).

Development of pH-responsive core-shell nanocarriers for delivery of therapeutic and diagnostic agents.

In this paper new dendritic core-shell architectures with pH-labile linkers based on hyperbranched polyglycerol cores and biocompatible poly(ethylene glycol) shells were synthesized which encapsulate the anticancer agent doxorubicin and a dye for near-infrared imaging, an indotricarbocyanine. Acid-sensitive properties of the new nanocarriers and in vitro cytotoxicity of the doxorubicin-nanocarrier are presented as well as preliminary data regarding their toxicity and tumor targeting potential in nude mice.

A novel green template for the synthesis of mesoporous silica.

Mesoporous pure silicas and functionalized silica with a narrow pore size distribution centered at 3.8 nm were prepared by a novel template, amphiphilic dendritic polyglycerol. The resulting silica materials were characterized by electron microscopy; nitrogen adsorption; (1)H, (13)C, and (29)Si solid-state cross-polarization magic-angle spinning NMR spectroscopy.

Water-soluble pH-responsive dendritic core-shell nanocarriers for polar dyes based on poly(ethylene imine).

A simple general synthetic concept to build dendritic core-shell architectures with pH-labile linkers based on hyperbranched PEI cores and biocompatible PEG shells is presented. Using these dendritic core-shell architectures as nanocarriers, the encapsulation and transport of polar dyes of different sizes is studied. The results show that the acid-labile nanocarriers exhibit much higher transport capacities for dyes than unfunctionalized hyperbranched PEI.

pH-Responsive dendritic core-shell architectures as amphiphilic nanocarriers for polar drugs.

In this paper a simple general synthetic concept was used to generate dendritic core-shell architectures based on hyperbranched poly(ethylene imine) cores and different shells which contain aliphatic chains and poly(ethylene glycol) chains, respectively. Using these dendritic core-shell architectures as nanocarriers we studied the encapsulation and transport of polar drugs, such as congo red. The results showed that the acid labile nanocarriers exhibited much higher transport capacities for congo red than the bare poly(ethylene imine).

Steric effects in the uncatalyzed and DMAP-catalyzed acylation of alcohols-quantifying the window of opportunity in kinetic resolution experiments.

The kinetics of the reaction of several alcohols (benzyl alcohol, ethanol, 1-phenylethanol, cyclohexanol, and 1-methyl-1-phenylethanol) with a selection of anhydrides (acetic anyhydride, propionic anhydride, isobutyric anhydride, isovaleric anhydride, and pivalic anhydride) as catalyzed by 4-(N,N-dimethylamino)pyridine (DMAP)/triethyl amine have been studied in CH(2)Cl(2) at 20 degrees C. In all cases the reaction kinetics can be described by rate laws containing a DMAP-catalyzed term and an uncatalyzed (background) term. The rate constants for the background reaction respond sensitively to changes in the steric demand of the alcohol and the anhydride substrates, making the reaction of cyclohexanol with acetic anhydride 526 times faster than the reaction with pivalic anhydride.

The DMAP-catalyzed acetylation of alcohols--a mechanistic study (DMAP = 4-(dimethylamino)pyridine).

The acetylation of tert-butanol with acetic anhydride catalyzed by 4-(dimethylamino)pyridine (DMAP) has been studied at the Becke3 LYP/6-311 + G(d,p)//Becke3 LYP/6-31G(d) level of theory. Solvent effects have been estimated through single-point calculations with the PCM/UAHF solvation model. The energetically most favorable pathway proceeds through nucleophilic attack of DMAP at the anhydride carbonyl group and subsequent formation of the corresponding acetylpyridinium/acetate ion pair.

The fluorescence properties of hypocrellin B and its amino-substituted derivative: photoinduced intramolecular proton transfer and photoinduced intramolecular electron transfer.

We report on the emission spectra and emission quantum yields of a newly synthesized hypocrellin dye, 2-demethoxy-2,3-ethylenediamino hypocrellin B (EDAHB), and its parent HB in different solvents of varying polarity. Our results demonstrate that EDAHB is one of the few dyes that exhibit highly solvent polarity-dependent fluorescence in the useful region (680-730 nm). Therefore, it offers some applications in the biomedical field as a fluorescent probe molecule.

Synthesis, characterization and photodynamic activity of phenmethylamino-demethoxy-hypocrellin B.

Two phenmethylamino hypocrellin B derivatives are novel photodynamic agents synthesized by a mild reaction between hypocrellin B and phenmethylamine. The red absorption of the photosensitizers is enlarged distinctly and the peri-hydroxylated perylenequinone structure of the parent HB is preserved. 9,10-diphenyl-anthracene (DPA) bleaching and electron paramagnetic resonance (EPR) spin trapping techniques were used to study the photodynamic activities of the phenmethylamino hypocrellin B derivatives in the presence of oxygen.

EPR studies of the photodynamic properties of a novel potential photodynamic therapeutic agent: photogeneration of semiquinone radical anion and active oxygen species (O2*-, OH*, H2O2 and 1O2).

Cyclohexylamino-substituted hypocrellin B (CHAHB) has been synthesized with the aim of improving the red absorption and specific affinity for malignant tumors over those of the parent compound. Irradiation of a deoxygenated DMSO solution of CHAHB generates a strong electron paramagnetic resonance (EPR) signal, which is assigned to the semiquinone radical anion of CHAHB with the aid of a series of experimental results. In the presence of oxygen, superoxide radical anions (O2*-) are generated via electron transfer from CHAHB*-, the precursor, to ground-state molecular oxygen.

First synthesis of methylated hypocrellin and its fluorescent excited state: a cautionary tale.

Methylated hypocrellins were obtained and characterized by satisfactory 1HNMR, UV-vis, IR, and mass data, and their absorption and fluorescence emission spectra were studied. A previous report of methylated hypocrellin (J. Phys.

Investigation of photobleaching of hypocrellin B in non-polar organic solvent and in liposome suspension.

Hypocrellin B (HB) is a natural pigment with a promising application in the photodynamic therapy (PDT) for anticancer treatment. The photobleaching of HB in non-polar organic solvents and in liposomes in aqueous solution were investigated by the measurements of absorption spectra, quenching experiments and determination of photoproducts. Control experiments indicated that the sensitizer, oxygen and light were all essential for the photobleaching of HB, which suggested that it was mainly self-sensitized photooxidation.

Active oxygen species (1O2, O2*-) generation in the system of TiO2 colloid sensitized by hypocrellin B.

TiO2 semiconductor colloids have been successfully employed in environmental clean-up, antibacterial and bactericidal action under ultraviolet light due to its strong redox ability and high yield of active oxygen species (1O2, O2*-), *OOH) generation. Hypocrellin B, isolated from Hypocrella bambusae (B.et.