Complexation between chitosan and carboxymethyl cellulose in weakly acidic, neutral, and weakly alcaline media.

The interaction between carboxymethyl cellulose and partially reacetylated chitosan soluble in acidic and alkaline aqueous media is studied by light scattering and isothermal titration calorimetry in a wide pH range. It is shown that the formation of polyelectrolyte complexes (PEC) can occur in the pH range of 6-8, while this pair of polyelectrolytes loses the ability to complexation upon transition to a more alkaline medium. The revealed dependence of the observed enthalpy of interaction on the ionization enthalpy of the buffer indicates the participation of proton transfer from the buffer substance to chitosan and its additional ionization in the binding process. This phenomenon is first observed in a mixture of a weak polybase chitosan and a weak polyacid. The possibility to obtain soluble nonstoichiometric PEC by a direct mixing of the components in a weakly alkaline medium is shown. The resulting PECs are polymolecular particles in shape close to homogeneous spheres with a radius of about 100 nm. The obtained results are promising for creating of biocompatible and biodegradable drug delivery systems.

Peculiarities of the interaction of sodium dodecyl sulfate with chitosan in acidic and alkaline media.

In this work, the interaction between the negatively charged surfactant sodium dodecyl sulfate (SDS) and partially N-reacetylated chitosan (RA-CHI), which is soluble at pH range up to pH 12, is studied in a wide pH range including alkaline media by light scattering (LS) and isothermic titration calorimetry (ITC). It is shown that in the weakly alkaline medium (pH 7.4), RA-CHI/SDS interaction is exothermic and cooperative. This interaction is found to be coupled with proton transfer from the buffer substance to chitosan as it is revealed by the dependence of the measured heat release on the ionization enthalpy of the buffer. At higher pH values (pH > 8), another mechanism of interaction is observed that include SDS micellization induced by hydrophobic interactions with polymer segments, so that no phase separation occurred in these mixtures. The results obtained can contribute to expand the knowledge about application of chitosan for preparation of pharmaceutical and cosmetic compositions containing anionic surfactants.

Nanobiology for the pharmacology of cellular ion channels.

Writing this editorial is especially pleasing. First, it provides us an opportunity to introduce new directives to the field of Neuroimmune Pharmacology and to explain why the field of nanomedicine is likely an important part of its future growth and development. Second, it is an opportunity to showcase research in this area currently operative in Russia that may not be readily accessible to the readership. Third, it is a platform to better explain why the Journal Editorial leadership was enthusiastic about the science and its relationship to the Society on NeuroImmune Pharmacology strategic goals. All are brought to bear in this issue of the Journal of Neuroimmune Pharmacology. The issue includes articles presented at a recent joint US-Russian workshop entitled, "Health in the 21st Century: Nanomedicine and Self-Organization of Biological Systems" held at M.V. Lomonosov Moscow State University (MSU), Moscow, Russia, December 10-11, 2007. The conjoint meeting was organized through the Departments of Biology, Chemistry, and Physics, MSU and by the Center for Drug Delivery and Nanomedicine and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center (Omaha, NE). The speakers included established internationally regarded scientists from these institutions as well as graduate students and faculties at MSU. In addition to selected papers by workshop contributors, we have included several papers closely aligned to the theme of nanomedicine and nanopharmacology of the central nervous system in order to provide a biological anchor for this research. We understand that such works are new to many but hope that its organization and interdisciplinary approaches will appeal to this audience. All together, it is our hope that, by gathering basic and clinical scientists with the common interest of using nanotechnology in the delivery of therapeutic agents with a focus on nanopharmacology and complex supramolecular biological assembly, the papers included will provide a platform for thought, discussion, and future translational research.