Thymosin β4 sustained release from poly(lactide-co-glycolide) microspheres: synthesis and implications for treatment of myocardial ischemia.

A sustained release formulation for the therapeutic peptide thymosin β4 (Tβ4) that can be localized to the heart and reduce the concentration and frequency of dose is being explored as a means to improve its delivery in humans. This review contains concepts involved in the delivery of peptides to the heart and the synthesis of polymer microspheres for the sustained release of peptides, including Tβ4. Initial results of poly(lactic-co-glycolic acid) microspheres synthesized with specific tolerances for intramyocardial injection that demonstrate the encapsulation and release of Tβ4 from double-emulsion microspheres are also presented.

Accurate determination of the dielectric parameters of spherical shells in suspension.

A novel, self-consistent, algebraic method is developed within the framework of Maxwell-Wagner theory (i.e., 'mixture formula' and single shell model) for obtaining the dielectric parameters, such as epsilon(s), kappa(s) and f(Q) of spherical shells.

Cluster precursors of uncapped CdS quantum dots via electroporation of synthetic liposomes. Experiments and theory.

Subnanometer size cluster precursors of uncapped CdS quantum dots were produced via the electroporation of synthetic dioleoylphosphatidylcholine (DOPC) unilamellar bilayer vesicles of mean hydrodynamic diameter Dh = 175 nm. During electroporation, Cd2+ ions are ejected from the interior compartments of the vesicles into the bulk solution where they react with S(2-) ions to form CdS monomers. The monomers adsorb on the exterior surface of the vesicles, where their spontaneous self-aggregation to (CdS)n clusters occurs on the hour and day time scale.

Structures of silver pyrazolates in hydrocarbon solutions via vapor-pressure osmometry.

Molecular weights of {[3,5-(CF 3) 2Pz]Ag} 3, {[3-(C 3F 7),5-( t-Bu)Pz]Ag} 3, and {[3,5-( i-Pr) 2Pz]Ag} 3 at various solution concentrations have been investigated using vapor-pressure osmometry. Depending on the concentration, the trinuclear {[3,5-(CF 3) 2Pz]Ag} 3 either dissociates into mono- and dinuclear moieties or remains trinuclear or aggregates to hexanuclear species in toluene. In contrast, {[3-(C 3F 7),5-( t-Bu)Pz]Ag} 3, which has a bulky and relatively electron-rich pyrazolate, retains the trinuclear form even at low concentrations in toluene.

Oscillation of absorption bands of Zn(1-x)Mn(x)S clusters: an experimental and theoretical study.

Electroporation of synthetic vesicles is utilized for the preparation of molecular size uncapped Zn(1-x)Mn(x)S clusters. The absence of caps permits (i) continued growth of the Zn(1-x)Mn(x)S clusters formed, (ii) the assessment of their true absorption spectra unaltered by stabilizing ligands, and (iii) the previously inaccessible live observation of the growth of the clusters in the molecular size regime. Upon cluster growth, the UV spectra exhibit novel, time-dependent, oscillation of red and blue shifts of the characteristic absorption band.

Subnanometer size uncapped quantum dots via electroporation of synthetic vesicles.

The very rapid, usually diffusion-controlled, self-aggregation of nascent molecules of semiconductors (MX) or metals (M) in solution represents an experimental challenge for arresting the growth of the particles at a desired size. Unfortunately, the typical remedy used, namely capping of the clusters with a protective coating, alters their intrinsic electronic and optical properties. An additional defect of capping's virtue is that it prevents the observation of further cluster growth--which is especially important in the subnanometer (molecular) size regime, where particle growth is associated with dramatic changes in structure, surface states, and transition energy.

Synthesis and bandgap oscillation of uncapped, ZnO clusters by electroporation of vesicles.

A convenient preparation is reported for subnanometre size uncapped ZnO quantum dots, which permits the previously inaccessible live observation of the growth of the clusters in the molecular size regime. The preparation method utilizes electric field-induced transient pore formation (electroporation) in synthetic unilamellar vesicles. This condition allows for facile monitoring of the time-dependent UV spectra associated with the growth of the clusters which are found to initially exhibit novel, oscillating red and blue shifts of the characteristic absorption band, ultimately followed by a monotonic red shift-the latter reflecting cluster growth beyond a size of ∼10 Å.

Growth of uncapped, subnanometer size gold clusters prepared via electroporation of vesicles.

Electric-field-induced transient pore formation (electroporation) in synthetic unilamellar vesicles is utilized for the preparation of subnanometer size uncapped gold quantum dots. With the precursor AuCl4(-) placed in the aqueous bulk solution and the reducing agent BH4(-) originally entrapped in the vesicles' compartments, the redox reaction--that occurs in the bulk--is initiated by the opening of transient pores in the vesicles' bilayers. The absence of caps permits (i) continued growth of the Au clusters formed, (ii) the assessment of their true absorption spectra unaltered by stabilizing ligands, and (iii) the previously inaccessible live observation of the growth of the clusters in the molecular size regime.

Density functional study of the structures of lead sulfide clusters (PbS)n (n = 1-9).

The structures of (PbS)n (n = 1-9) clusters are investigated with density functional theory at the B3LYP level. Various pseudopotential basis sets on lead and the 6-31+G basis set on sulfur were employed. Full geometry optimization and extensive searches of the potential energy surface were carried out for clusters with n = 1-6.

Preparation of ultrasmall, uncapped PbS quantum dots via electroporation of vesicles.

Electric-field-induced transient pore formation (electroporation) in synthetic unilamellar dioleoylphosphatidylcholine vesicles of 178-nm diameter is utilized for the preparation of subnanometer-size PbS quantum dots. With Pb2+ ions originally entrapped in the vesicles and S2- ions placed in the bulk, their reaction is initiated by the opening of pores and occurs in the bulk. The ensuing self-aggregation of PbS is slowed to the hour and day time scales by its adsorption at the exterior surface of the vesicles.