Preparation of solid lipid nanoparticles using a membrane contactor.

Solid lipid nanoparticles (SLN) were introduced at the beginning of the 1990s, as an alternative to solid nanoparticles, emulsions and liposomes in cosmetic and pharmaceutical preparations. The present study investigates a new process for the preparation of SLN using a membrane contactor. The lipid phase is pressed, at a temperature above the melting point of the lipid, through the membrane pores allowing the formation of small droplets. The aqueous phase circulates inside the membrane module, and sweeps away the droplets forming at the pore outlets. SLN are formed by the following cooling of the preparation to room temperature. The influence of process parameters (aqueous phase and lipid phase temperatures, aqueous phase cross-flow velocity and lipid phase pressure, membrane pore size) on the SLN size and on the lipid phase flux is investigated. It is shown that the membrane contactor allows the preparation of SLN with a lipid phase flux between 0.15 and 0.35 m3/h m2, and a mean SLN size between 70 and 215 nm. The advantages of this new process are its facility of use, the control of the SLN size by an appropriate choice of process parameters, and its scaling-up abilities.