Porous Gelatin Hydrogels:  1. Cryogenic Formation and Structure Analysis

• Published in: Biomacromolecules Vol. 8; no. 2; pp. 331 - 337
• Main Authors: Van Vlierberghe, Sandra, Cnudde, Veerle, Dubruel, Peter, Masschaele, Bert, Cosijns, An, De Paepe, Ilse, Jacobs, Patric J. S, Van Hoorebeke, Luc, Remon, Jean Paul, Schacht, Etienne
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-02-2007
• Subjects: Applied sciences; Biological and medical sciences; Cross-Linking Reagents; Exact sciences and technology; Freeze Drying; Freezing; Gelatin; Hydrogels - chemistry; Medical sciences; Natural polymers; Physicochemistry of polymers; Porosity; Proteins; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Technology. Biomaterials. Equipments; Temperature; Freeze drying; Tissue engineering; Cooling rate; Porous material; Protein; Colloidal gel; Structure processing relationship; Pore size; Gelatin; Morphology; Concentration effect; Biomaterial; Porosity; Framework
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm060684o

In the present work, porous gelatin scaffolds were prepared by cryogenic treatment of a chemically cross-linked gelatin hydrogel, followed by removal of the ice crystals formed through lyophilization. This technique often leads to porous gels with a less porous skin. A simple method has been developed to solve this problem. The present study demonstrates that the hydrogel pore size decreased with an increasing gelatin concentration and with an increasing cooling rate of the gelatin hydrogel. Variation of the cryogenic parameters applied also enabled us to develop scaffolds with different pore morphologies (spherical versus transversal channel-like pores). In our opinion, this is the first paper in which temperature gradients during controlled cryogenic treatment were applied to induce a pore size gradient in gelatin hydrogels. With a newly designed cryo-unit, temperature gradients of 10 and 30 °C were implemented during the freezing step, resulting in scaffolds with average pore diameters of, respectively, ±116 and ±330 μm. In both cases, the porosity and pore size decreased gradually through the scaffolds. Pore size and structure analysis of the matrices was accomplished through a combination of microcomputed tomography using different software packages (μCTanalySIS and Octopus), scanning electron microscopy analysis, and helium pycnometry.