Processing and Scale-up of Polymeric Nanoparticles - Intracellular Delivery: Fundamentals and Applications - page 441

Other methods consist in reducing size of the droplets of a rough emulsion using
special machines including colloidal mills, microfluidizer and high pressure
homogeniser (Table 2 ) (Urban et al. 2006 ; Anton et al. 2008 ). By using a microflu-
idizer, the diameter of the droplets, D , formed in the final emulsion depends on the
viscosity of the organic solution of polymer as indicated by the Eq. 1 (Koshy et al.
1988 ; Walstra 1983 ).

(1)

D = h

a

In this equation, h corresponds to the viscosity of the polymer solution, a is a coef-
ficient which depends on many parameters of the system including the nature of the
polymer. The alpha coefficients were determined for ethylcellulose and poly(lactic
acid) using ethylacetate as the organic solvent. The values were 0.05 and 0.28
respectively (Desgouilles et al. 2003 ).

Table 2 Apparatus used to reduce size of emulsion droplets from a rough emulsion (Adapted
from Urban et al. 2006 )
Microfluidizer
(Bodmeier and
Huagang 1990 ;
Desgouilles et al.
2003 )

Colloidal mill (Stork
et al. 2003 ;
Mabile et al.
2003 )

High pressure
homogenizer
( Shegokar et al.
2010 )