Preparation of nanoparticles with a membrane contactor

Nanoparticles have known recently an increasing interest because of their potential use as drug carriers. In this paper, we describe a membrane contactor for the preparation of nanoparticles. The organic phase is pressed through the membrane pores via the filtrate side. The aqueous phase circulates inside the membrane module, and sweeps away the nanoparticles forming at the pore outlets. Two methods for the formation of nanoparticles are investigated: the nanoprecipitation and the interfacial polymerization methods. The influence of process parameters (membrane pore size, flowrate and organic phase pressure) on organic phase flux and on nanoparticles size is investigated. It is shown that nanoparticles as small as 260 nm are obtained with the 1000 Da nanofiltration membrane, a transmembrane pressure of 3 × 105 Pa (3 bar) and a crossflow rate of 1.7 m s−1. Very high fluxes are obtained with the 0.1 μm pore size microfiltration membrane (1.6 m3/h m2), leading to the preparation of 1.8 × 10−3 m3 nanoparticles, with an average diameter of 360 nm, in 4 min. The advantages of this membrane contactor compared to other processes for nanoparticles preparation are its scale-up ability, and the possibility to control nanoparticles size by an appropriate choice of the membrane.