Oren Regev - Academia.edu (original) (raw)

Papers by Oren Regev

Journal of Pharmaceutical Sciences, 2000

Microencapsulated liposome systems (MELs) were investigated as a potential immunization carrier f... more Microencapsulated liposome systems (MELs) were investigated as a potential immunization carrier for a recombinant 22-nm hepatitis B surface antigen (HBsAg) particle. MELs were prepared by first entrapping the HBsAg particles within liposomes composed of phosphatidylcholine:cholesterol (1:1 molar ratio), which were then encapsulated within alginate-poly(L-lysine) (PLL) hydrogel microspheres. The entrapped HBsAg particles retained immunoreactivity, as judged by an enzyme-linked immunosorbent assay (ELISA). Direct imaging of HBsAg particles and HBsAg incorporated into liposomes by cryo-transmission electron microscopy (cryo-TEM) indicated that HBsAg is embedded in the liposomal membrane. The antigenic particles were released from MELs mainly within the context of liposomes. The release rates in vitro and in vivo depended on the molecular weight of PLL used for MEL coating; MELs-214, coated with 214 kDa PLL, released the liposomal HBsAg at much higher rates than MELs-25, which was coated with 25 kDa PLL. Concomitantly, the specific anti-HBsAg titers in mice receiving HBsAg in MELs-214 were higher than those induced by MELs-25. MELs-214 were more efficient than conventional liposomes or alum in eliciting higher and prolonged antibody levels in mice. The ability of MELs to provide an HBsAg depot as well as a sustained release of liposomal HBsAg suggests that these carriers may be an ideal immunoadjuvant.

Journal of Physical Chemistry B, 1999

... Wei Wang, † Shlomo Efrima,* † and Oren Regev ‡. Departments ... respectively. The structural ... more ... Wei Wang, † Shlomo Efrima,* † and Oren Regev ‡. Departments ... respectively. The structural characteristics of the phase can be derived from SAXS, as the position (q max ) of the firstBragg peak is related to the lamellar spacing, d l = 2π/q max . ...

Langmuir, 1998

Nanosized hydrophobic, oleate stabilized silver organosols in various organic solvents are obtain... more Nanosized hydrophobic, oleate stabilized silver organosols in various organic solvents are obtained using a solvent exchange method. The silver particles are initially prepared as a hydrosol in the presence of sodium oleate (surfactant). Then a transfer of the colloid to an ...

Analytical Chemistry, 2015

The rapid increase in graphene-based applications has been accompanied by novel top-down manufact... more The rapid increase in graphene-based applications has been accompanied by novel top-down manufacturing methods for graphene and its derivatives (e.g., graphene nanoplatelets (GnPs)). The characterization of the bulk properties of these materials by imaging and surface techniques (e.g., electron microscopy and Raman spectroscopy) is only possible through laborious and time-consuming statistical analysis, which precludes simple and efficient quality control during GnP production. We report that thermogravimetry (TG) may be utilized, beyond its conventional applications (e.g., quantification of impurities or surfactants, or labile functional groups) to characterize bulk GnP properties. We characterize the structural parameters of GnP (i.e., defect density, mean lateral dimension, and polydispersity) by imaging and surface techniques, on one hand, and by a systematic TG, on the other. The combined data demonstrate that the combustion temperature of commercially available and laboratory-prepared GnPs is correlated with their mean lateral dimension and defect density, while the combustion temperature range is proportional to their polydispersity index. Mapping all these parameters allows one to evaluate the GnPs&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; structure following a simple thermogravimetric experiment (without necessitating further statistical analysis). Finally, TG is also used to detect and quantify different GnP constituents in powder and to conduct rapid quality-control tests during GnP production.

Current Opinion in Colloid & Interface Science, 2005

Rapid strides realized in the field of ordered mesoporous silica (OMS) with a well-defined pore s... more Rapid strides realized in the field of ordered mesoporous silica (OMS) with a well-defined pore shape and nanometric sizes, provide new gateways for the preparation of nanostructured materials having controlled shape and size with a very narrow distribution. The focus of the current review is on the synthesis of nanostructures templated by OMS either in bulk or in thin film

The Journal of Physical Chemistry B, 1999

... Niklas Hedin, Ruslan Sitnikov, István Furó,* Ulf Henriksson, and Oren Regev . Divisi... more ... Niklas Hedin, Ruslan Sitnikov, István Furó,* Ulf Henriksson, and Oren Regev . Division of Physical Chemistry, Department of Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden, and Department ...

Microporous and Mesoporous Materials, 2000

Journal of the American Chemical Society, 2003

Journal of Controlled Release, 1997

This paper describes the preparation and characterization of microencapsulated liposome systems (... more This paper describes the preparation and characterization of microencapsulated liposome systems (MELs) for the controlled delivery of liposome-associated macromolecules. Liposomes were encapsulated within microspheres of calcium-crosslinked alginate, with ...

Journal of Colloid and Interface Science, 2008

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2009

... b Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105, I... more ... b Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel. c The Ilse Katz Center for Meso and Nanoscale Science and Technology,Ben-Gurion University of the Negev, Beer Sheva 84105, Israel. ...

Chemical Communications, 2008

Journal of Nanoscience and Nanotechnology, 2013

The principles, occurrence, structure and properties of worm-like micellar solutions in nonionic ... more The principles, occurrence, structure and properties of worm-like micellar solutions in nonionic surfactant systems is reviewed, with focus in certain experimental methods used to characterize such soft nanostructured systems. Formulation plays a critical role in the design of worm-like micellar systems and derived viscoelastic networks. Micellar growth in one dimension, and hence formation of worm-like aggregates, is favoured by an increase in the average surfactant molecular packing parameter. Such an increase can be induced by addition of cosurfactant or amphiphilic oil that tends to penetrate in the surfactant palisade layer and reduce the specific surface area. On the other hand, long and bulky oils prone to be solubilized in the micellar core, cause a rod-sphere transition and therefore a decrease in viscosity. Salts have a small effect on the behaviour of nonionic worm-like micelles, contrary to what is found for ionic surfactant systems. The effect of raising temperature on worm-like micellar solutions is the result of a balance between the dehydration of the surfactant head groups, which favors elongation, the kinetics of micellar disruption and the formation of structures with nearly zero curvature. Therefore, a viscosity maximum as a function of temperature is found in many systems. Reverse worm-like micelles with a hydrophilic core can also be formed in organic solvents, even in the absence of ionic components or water. Worm-like micelles are useful as templates for the formation of ordered mesoporous oxides. The interaction of micelles with silica species results in the formation of silica-surfactant complexes that later precipitate as hexagonal phase via a cooperative mechanism.