CONICET | Buscador de Institutos y Recursos Humanos

Department of Interfaces and Colloids (Institute of Physical Chemistry, BAS) and the Department of Physical Chemistry (Faculty of Chemistry and Pharmacy, SU)

Resumen:

Nano- and microcapsules are important as delivery systems as well as microreactors. [1] It has been frequent to make the by using a particle as template, coating it with polymers, and finally dissolving the template. In the case of inorganic templates the last step implies to work under chemically aggressive conditions (e.g. use of HF for silica particles). In the case of polymer templates it cannot be ensured that all the polymer chains have diffused out of the capsule.[2] In this communications we describe a simple method to coat liposomes (neutral or charged) with polymers and/or particles using the layer-by-layer method. Figure 1 illustrates the coating procedur.  Different pairs of polyelectrolytes (PAH, PSS, PGA, PLL) and also charged latex particles have been used for building the multilayers. Mixtures of phospholipids (DOPC, DPPC) and a cationic (DODAB) have allowed us to use both cationic liposomes (DOPC+DODAB) over a broad surface charge density range, and zwitterionic liposomes. The number of layers and the nature of the polymers determine the diffusion through the wall of the capsule, as well as its stability. Capsules with up to ten polymer layers have been produced that remained stable for months, and resisted centrifugation. The diffusion of a dye through the capsule wall has been studied.