Particle seeding enhances interconnectivity in polymeric scaffolds foamed using supercritical CO2

Dexamethasone-loaded poly(ɛ-caprolactone)/silica nanoparticles composites prepared by supercritical CO2 foaming/mixing and deposition

“…In general, pressure and processing time did not present comprehensible effects and tendencies, contrarily to faster depressurization rates that led to smaller average pore diameters (at all operational conditions and for all tested PCL and PCL/MCM-41 samples -as previously observed by SEM). This is mostly due to the CO 2 diffusion rate in the molten polymer and similar results were already reported in the literature (Collins et al, 2010;Fanovich and Jaeger, 2012;Jenkins et al, 2006;Kiran, 2010;Tai et al, 2007b;Xu et al, 2004;Zhai et al, 2006). In sum, the implemented SFM method enables the preparation of PCL and PCL/MCM-41 composite biomaterials with different morphological properties (density, porosity, surface area, pore volume, average pore diameter and pore diameter range) simply by changing some of the processing conditions (pressure, processing time and depressurization rate, Chen et al, 2002;Tai et al, 2007b;Teng et al, 2007;Rouholamin et al, 2013) and the MCM-41 relative composition.…”

“…The presence of dispersed inorganic particles may affect the polymer-scCO 2 interactions and favor heterogeneous nucleation (thus acting as nucleation sites). This usually leads to the formation of smaller pores and to narrow pore size distribution (Collins et al, 2008(Collins et al, , 2010Jenkins et al, 2006;Léonard et al, 2008;Shieh et al, 2009;Tsimpliaraki et al, 2011). scCO 2 -assisted impregnation/deposition method (SSID) is another advantageous method for precise incorporation of bioactive substances into polymeric, inorganic and composite materials in a short time and without the presence of harmful solvent residues (Ahern et al, 2012;Braga et al, 2011;Belhadj-Ahmed et al, 2009;Kazarian, 2000;Kikic and Vecchione, 2003;López-Periago et al, 2009;Natu et al, 2008).…”

Biodegradable shape memory polymer foams with appropriate thermal properties for hemostatic applications

“…Some undissolved particles may have acted as stress concentration points during foaming, generating holes in the pore membrane. Previously, Collins, Bridson, Leeke, and Grover () demonstrated that increasing the amount of silica microparticles during foaming increased pore interconnectivity in polymer scaffolds. Interconnectivity is a crucial property for a hemostat or for a tissue scaffold, since interconnected pores allow enhanced blood clotting, degradation rate, cellular growth, nutrient transport, and waste exchange (Collins et al, ; Tan, Chua, & Leong, ).…”

“…Some undissolved particles may have acted as stress concentration points during foaming, generating holes in the pore membrane. Previously, Collins, Bridson, Leeke, and Grover (2010) demonstrated that increasing the amount of silica microparticles during foaming increased pore interconnectivity in polymer scaffolds.…”

“…Interconnectivity is a crucial property for a hemostat or for a tissue scaffold, since interconnected pores allow enhanced blood clotting, degradation rate, cellular growth, nutrient transport, and waste exchange (Collins et al, 2010;Tan, Chua, & Leong, 2010). Formation of interconnected pores in TA(2)30, TA40, and T40TG20 foams also removes the need for a postprocessing step of reticulation, which involves mechanically punching holes on the foam membranes with floating nitinol pin array .…”