Interpenetration of Natural Polymer Aerogels by Supercritical Drying

Abstract

Natural polymers, such as alginate and gelatin, can be used to produce scaffolds for tissue engineering applications; but, their mechanical and biochemical performance should be improved. A possible solution to obtain this result, is the generation of multi-component scaffolds, by blending two or more polymers. One way to realize it, is the formation of an interpenetrating polymer network (IPN). In this work, the interpenetration of alginate and gelatin hydrogels has been successfully obtained and preserved by supercritical CO 2 (SC-CO 2 ) drying performed at 200 bar and 35˝C, using different blend compositions: from alginate/gelatin = 20:80 v/v to alginate/gelatin = 80:20 v/v. The process allowed modulation of morphology and mechanical properties of these blends. The overall result was made possible by the supercritical drying process that, working at zero surface tension, allows preserving the hydrogels nanostructure in the corresponding aerogels.

Synthesis and Characterization of a New Collagen-Alginate Aerogel for Tissue Engineering

“…Compared to other drying methods, supercritical drying is a more effective method for preventing the shrinkage or collapse of mesopores [25]. The synthetized aerogel-based scaffold in this study showed a highly porous network and no collapse of the structure, in which the pores range from 2-10 micrometres; a similar structure is reported by Baldino et al [36], who synthetized an alginate-gelatine aerogel by CO 2 supercritical method; they reported a nanofibrous structure, in which the nanofibers have a diameter lower than 100 nm. The similarity in the three-dimensional structure of the alginate-gelatine aerogel and the collagenalginate-GO aerogel in this study could be due to the fact that gelatine is a protein compound obtained by partial hydrolysis of collagen and maintains most of its structure and amino groups [38].…”

“…Nevertheless, it has been reported that the Journal of Nanomaterials gelatine gelation mechanism, as well as the formed gel network structure, differs considerably from collagen, as described by Gomez-Guillen et al [38]; despite this, the three-dimensional structure obtained by CO 2 supercritical method is similar in both combinations carried out in this study, probably because of the crosslinking performed previously in the hydrogel phase. Baldino et al [36] also confirmed that the supercritical process does not modify the gel organization and avoids gel collapse during drying. Martins et al [35] reported an alginate-based aerogel for TE; to obtain an adequate porosity in the structure, Martins et al proposed different pressuring and depressurizing rates.…”

“…Nowadays, there has been considerable interest in carbon-based nanomaterials to fabricate a new class of materials with unique properties [20]. In this study, a method to improve the mechanical and biological properties of the scaffold by the incorporation of alginate and GO was used, since it has been previously reported as successful [6,28,[35][36][37]. Even though it has been established that both materials could be employed to improve general properties of biomaterials, results in this study showed that the incorporation of GO could negatively affect cell attachment, proliferation, and response.…”

PCL/Mesoglycan Devices Obtained by Supercritical Foaming and Impregnation

“…Moreover, post-processes for solvent separation are not necessary, since scCO 2 is easily removed by depressurization, and it is possible to process also thermosensible compound without degradation, thanks to the scCO 2 moderate critical conditions (Tc = 31.1 • C, Pc = 7.38 MPa). [16] In some previous studies, one-step procedures for the simultaneous PCL foaming and impregnation via supercritical CO 2 were developed [17][18][19]. For example, Campardelli et al [18] optimized the foaming conditions of PCL granules and, then, studied the one-step foaming and impregnation process to obtained medical patches loaded with nimesulide, a non-steroidal anti-inflammatory drug.…”

Development of barley and yeast β-glucan aerogels for drug delivery by supercritical fluids

“…To fulfill the requirements of low toxicity, biodegradability and stability for drug delivery applications, polysaccharides are a good option as carriers [8]. Many works report the production of aerogels using starch, alginate or chitin [8][9][10][11][12][13][14]. However, β-glucans have been barely studied for this purpose.…”