Role of the critical micelle concentration in the electrochemical deposition of nanostructured ZnO films under utilization of amphiphilic molecules.

A detailed understanding of micelle formation that occurs above a critical micelle concentration (cmc) is a crucial point for the surfactant-assisted preparation of porous materials such as molecular sieves. However, the role of the cmc in the surfactant-assisted electrodeposition of porous oxides is widely unknown. In this study, we investigated the electrodeposition of ZnO films under utilization of alkyl sulfates and alkyl sulfonates with different chain lengths.

Capacitance and field-driven electron transport in electrochemically self-assembled nanoporous ZnO/dye hybrid films.

Electrodeposited nanoporous ZnO/eosin Y hybrid films have been investigated in view of their potential applications in dye-sensitized solar cells and supercapacitors. Intensity-modulated photocurrent spectra were measured at different electrode potentials at films of different thicknesses. It was found that the results represent either the RC constant of the cell and surface recombination of photogenerated holes with electrons or the diffusion of photogenerated electrons and are dependent on the electron concentration in the ZnO, which is influenced by the film thickness, the electrode potential, and the light intensity.

Differential reactivity of maleimide and bromoacetyl functions with thiols: application to the preparation of liposomal diepitope constructs.

The comparative reactivity of maleimide and bromoacetyl groups with thiols (2-mercaptoethanol, free cysteine, and cysteine residues present at the N-terminus of peptides) was investigated in aqueous media. These studies were performed (i) with water-soluble functionalized model molecules, i.e.

Design of highly immunogenic liposomal constructs combining structurally independent B cell and T helper cell peptide epitopes.

We have designed liposomal diepitope constructs that allow the physical combination, within the same vesicle, of B and Th epitopes as structurally separate entities. The immune response against such constructs was explored using TPEDPTDPTDPQDPSS (TPE), a B cell epitope originating from a Streptococcus mutans surface adhesin and QYIKANSKFIGITEL (QYI), a "universal" Th epitope from tetanus toxin. The two peptides were linked to the outer surface of small (diameter approximately 100 nm) unilamellar liposomes by covalent conjugation to two different anchors.

Design and synthesis of thiol-reactive lipopeptides.

Lipopeptides are potent adjuvants that trigger an immune response against covalently conjugated low molecular mass antigens. We report here the design and synthesis of thiol-reactive lipopeptides (6, 7) which can be incorporated into liposomes and react, under mild conditions, with synthetic peptides carrying a thiol function.

Immunogenicity of new heterobifunctional cross-linking reagents used in the conjugation of synthetic peptides to liposomes.

We have investigated the immunogenicity of six thiol-reactive heterobifunctional cross-linking reagents that permit the conjugation of cysteine carrying peptides to the surface of liposome containing monophosphoryl lipid A. Such constructs elicit an immune response against short synthetic peptides and our aim was to find the least immunogenic linkers to limit potential carrier-induced epitopic suppression. For that purpose the properties of three new polyoxyethylene linkers of different lengths and thiol-reactive moieties (maleimide, bromoacetyl, dithiopyridine) were compared to known derivatives obtained by reacting the classical reagents SMPB and SPDP or N-succinimidyl bromoacetate with phosphatidylethanolamine.

Synthesis of short polyoxyethylene-based heterobifunctional cross-linking reagents. Application to the coupling of peptides to liposomes.

We describe the synthesis of [2-[2-[2-[(2-bromoacetyl)amino]ethoxy]ethoxy]ethoxy acetic acid (7), [2-[2-(2,5-dioxo-2,5-dihydropyrrol-1-yl)ethoxy]ethoxy] acetic acid (11), and [2-[2-(pyridin-2-yldisulfanyl)-ethoxy]ethoxy] acetic acid (16), three new thiol-reactive heterobifunctional reagents, and the preparation of their corresponding dipalmitoylphosphatidylethanolamine derivatives (8, 12, and 17). Such phospholipid amide derivatives were aimed to be incorporated into the bilayers of liposomal constructs used for immunization with e.g.

Efficient gene delivery with neutral complexes of lipospermine and thiol-reactive phospholipids.

The presence of thiol-reactive phospholipid derivatives, such as N-4-(p-maleimidophenyl)butyryl) dipalmitoylphosphatidylethanolamine (MPB-DPPE), in electrically neutral lipospermine/DNA particles results in more than a 100-fold increased transfection efficiency of human hepatoma HepG2 cells and murine 3T3 fibroblasts. These effects could be ascribed to the presence of thiol-reactive functions, such as maleimide, bromoacetamide and dithiopyridyl linkage, on the transfecting particles. We propose that such particles react with thiol groups present at the surface of the cells, leading to their covalent anchoring, a process that is probably followed by an endocytosis of the complex.