An alternative technique to shape scaffolds with hierarchical porosity at physiological temperature.

The method described in this work, termed GELPOR3D, is characterised by its simplicity of use, low-cost equipment, compositional flexibility, and lack of aggressive or toxic solvents or other thermal treatment. This technique ensures the generation of a three-dimensional network of interconnected pores (300-900 microm); in addition, a random and not necessarily connected porosity is generated, yielding a hierarchical porous architecture from the macro to the molecular scale. The interconnected pores, large enough to ensure an adequate vascularization and new tissue ingrowth, can be obtained by pouring a slurry containing a biodegradable thermogel (such as agarose and gellan) and a ceramic into a mold consisting of a three-dimensional network of rigid filaments. Additional pore distributions in the macropore region can be tailored as a function of the drying/preservation technology (10-100 microm) or the interaction between the inorganic particles coated by the polymeric components (0.1-1 microm). Moreover, porosity in the mesopore range can be created by shaping ceramics such as mesoporous silica or nanocrystalline carbonatehydroxyapatite. In addition to the various bioceramics that have been successfully shaped, this method is flexible enough to allow the introduction of certain substances whose controlled release may help to avoid some negative effects that usually appear with the implantation of a material, i.e. infection, inflammation, etc., or to simplify some of the many steps required for the successful integration of a graft.