Adhesion force measurement of a DPI size pharmaceutical particle by colloid probe atomic force microscopy

Characterisation of dry powder inhaler formulations using atomic force microscopy

“…When compared directly, colloidal probe AFM proved to be superior to the tensile strength technique as the distribution of results was considerably narrower. A number of similar colloidal probe experiments carried out by other groups also confirmed the dominance of capillary forces between particles over electrostatic interactions at increasing levels of humidity (Berard et al, 2002a;Tsukada et al, 2004;Young et al, 2003). These experiments were carried out at different RH and with different API and carrier materials.…”

“…This is particularly true for surface analyses, e.g. the evaluation of surface morphology, surface rugosity or surface energetics (Wu et al, 2010) and for determining the interparticulate forces between the API and/or carrier particles (Tsukada et al, 2004). For a number of decades, one technique in particular has proven to be extremely valuable for measuring such forces: atomic force microscopy (AFM).…”

“…3) to evaluate both the cohesive and adhesive interactions between materials used in drug delivery (Adi et al, 2007;Beilmann et al, 2007;De Boer et al, 2003a,b;Eve et al, 2002;James et al, 2008;Karner et al, 2014;Louey et al, 2001;Price et al, 2002;Sindel and Zimmermann, 2001;Tsukada et al, 2004;Young et al, 2009) and, quite recently, the mechanism of particle detachment (Cui and Sommerfeld, 2015). While three different scenarios describing the process of particle detachment-lift-off, sliding and rolling-are possible, a combination of colloidal probe measurements, simulations and computational modelling identified the rolling mechanism, closely followed by sliding, as the main mechanisms of particle detachment.…”

“…The adhesive interactions between APIs/ excipients and different container materials have been evaluated and correlated with the performance of the respective formulations. Typical container materials include, but are not limited to, aluminium (Ashayer et al, 2004;Traini et al, 2006), polytetrafluoroethylene (Traini et al, 2006) and steel (Tsukada et al, 2004). Knowledge of these interactions is particularly relevant for processing and storing DPI formulations.…”

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…The adhesion of steroid type drug particles decreased with increasing roughness of the lactose substrate. Adhesion was higher on stainless steel, and increased with humidity [633]. Young et al used beclometasone dipropionate probes to test the effect of different surface modifications of the lactose carrier surface on the adhesion force.…”