Processing of gelatin-based cryogels with improved thermomechanical resistance, pore size gradient, and high potential for sustainable protein drug release

Porous gelatin (GEL) cryogels were processed by spatiotemporal and temperature-controlled gelation and freezing-lyophilizaton process, followed by zero-length crosslinking, using different molarities of reagents (EDC and NHS) and reaction media (100% PBS or 20/80% PBS/EtOH mixture) for variable time extensions (1-24 h). In this way, tuneable cryogels with gradient microporosity (from 100 mu m to 1000 mu m) were formed, being mainly influenced by crosslinkers' concentration and EtOH addition. Later affect the pore morphology (from round to ellipsoid), consequently modulating the steady-state physiological swelling profile toward twice lower values (approximate to 600%) comparing to stepwise swelling of in 100% PBS media crosslinked cryogels. While the presence of EtOH decelerate the crosslinking kinetic by retaining cryogels' microstructure formed during freezing, the 100% PBS and higher EDC molarity resulted in approximately 40% crosslinking degree, being expressed as a thermal resistance of cryogels up to approximately 73 degrees C. Finally, the tuneable enzymatic resistance allow time-dependent poly-l-Lysine (pL) release profile in up to month period. The processed GEL cryogels have potential in broad range biomedical applications, especially as sustainable, protein-based drug delivery systems. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1119-1130, 2015.