Pore volume distribution of artificial skin by liquid extrusion analysis

Abstract

AbstractLiquid extrusion pore volume analysis was used to characterize the pore structure of the collagen‐based artificial skin material developed by Yannas and Burke.1 This technique is based on following the liquid loss from a saturated porous material as the pressure gradient across the material is increased. From the measured increments of volume of liquid drained at successively increasing pressures, each of which corresponds to a given pore radius, one obtains a cumulative pore volume curve as a function of pore radius from which pore volume distributions can be calculated. Using a nonswelling liquid (hexadecane) and a swelling liquid (aqueous surfactant solution), the effects of crosslinking and the method of drying were examined. In hexadecane, the median pore size of the uncrosslinked material is 25 μm, while for the crosslinked material, it is 115 μm. In water, the free volume of the crosslinked material is 36 mm3/mg, while for the uncrosslinked material it is an order of magnitude less. Sublimative drying provides a material with a total free volume of 55 mm3/mg, while evaporative drying collapses the porous structure to give a material with a total free volume of 8 mm3/mg. The liquid extrusion technique is relatively simple and allows pores to be measured in swollen materials in terms of their accessibility to skin cells. This method of pore characterization is considered more relevant for artificial skin than is a purely geometric characterization of pore dimensions.