Production Techniques - Lipid Nanoparticles: Production, Characterization and Stability - page 36

Step 1: Pressing of
lipid melt through
membrane pores
Membrane with pores
Membrane contactor
Step 2: Passage of aq.
phase tangentially
Step 3: Collection of
solid lipid nanoparticles
Fig. 3.10 Schematic steps involved in the membrane contactor technique
lipid flux (Charcosset et al. 2005 ). The dispersed lipid flux is calculated as the vol-
ume of the lipid phase divided by the reaction time and membrane surface area.
The cross flow velocity and temperature of the aqueous phase also influence the
size of the nanoparticles produced and the lipid flux (Charcosset and Fessi 2005 ).
The choice of emulsifiers and their concentration affects the lipid flux and the size
of nanoparticles (El-Harati et al. 2006 ).
3.2.10 Supercritical Fluid Extraction of Emulsions
Supercritical fluid (SCF) technology has been used in the production of micro-
particles and drugs (Yasuji et al. 2008 ). SCF technology is based on the princi-
ple of precipitation of drug or microparticles using a compressed anti-solvent such
as supercritical carbon dioxide. The solutes are dissolved in a solvent. The super-
critical fluid chosen here has complete or partial miscibility with the solvent, but
acts as the anti-solvent to the solutes. The micron-sized solute particles precipitate
upon spraying the solution into flowing SCF (Byrappa et al. 2008 ).
The process of preparing lipid nanoparticles from emulsions using SCF
technology is referred to as “supercritical extraction of emulsions” (SFEE)
(Chattopadhyay et al. 2006 , 2007 ). Figure 3.11 is a schematic depiction of the
preparation of lipid nanoparticles by the SFEE process. The organic solution
is prepared by solubilizing the lipid material and the drug in an organic solvent
such as chloroform with the addition of a suitable surfactant. The organic solu-
tion is dispersed into an aqueous solution (which may contain a co-surfactant) and
the mixture is subsequently passed through a high pressure homogenizer to form
an o/w emulsion. The o/w emulsion is introduced from one end of the extraction