Chemistry of Chitosan Aerogels: Three‐Dimensional Pore Control for Tailored Applications

Abstract

Chitosan is an abundant biopolymer derived from food waste with attractive properties, particularly its high biocompatibility and easy chemical processability. Here, we review the rapidly expanding literature on chitosan‐based porous materials with a focus on the gelation mechanisms, the three‐dimensional multiscale structural control, and the diverse chemical functionality not accessible by other biopolymers. The properties vary widely: from supercritically dried, mesoporous chitosan aerogels to very light, freeze‐dried macroporous scaffolds. Porous chitosan displays impressive performance at the laboratory scale, but the highly (meso)porous nature amplifies not only the beneficial functionality of chitosan, but also its drawbacks, resulting in serious barriers to industrialization. In order to facilitate technology transfer, we critically discuss the practical feasibility of chitosan aerogels in potential applications compared to conventional and other biopolymer‐based porous or nonporous materials.

Polysaccharide-Based Aerogel Production for Biomedical Applications: A Comparative Review

“…However, a more homogeneous pore size distribution was achieved using SC-CO 2 drying. Takeshita et al [ 17 ] performed a comparison between aerogels, xerogels and cryogels. According to SEM observation, CS aerogels consisted of three-dimensionally entangled nanofibers with a diameter of approximately 0.005–0.03 μm.…”

“…There are three kinds of solid materials that can be formed after drying, i.e., xerogel, cryogel and aerogel, as shown in Figure 1 . The solid material can be termed as xerogel when drying is carried out under ambient pressure and at room temperature, generally, for several days [ 17 , 18 ]. When water (ice) inside the hydrogel is sublimated by freeze-drying, the resultant materials are called cryogels.…”

Agarose, Alginate and Chitosan Nanostructured Aerogels for Pharmaceutical Applications: A Short Review

“…However, the final porous structure of these gels, required for drug release, depends on the kind of drying technique used. In particular, gels can be termed as “xerogel” when sample drying is carried out under ambient pressure and at room temperature, for some days ( Conzatti et al, 2017 ; Takeshita et al, 2020b ). Despite the energy-saving advantage of this technique, it leads to the formation of a condense structure that may have low porosity values and large shrinkage ( Mirzaei et al, 2013 ; Buchtová and Budtova, 2016 ; Sukhodub et al, 2018 ; López-Iglesias et al, 2019 ).…”

Heparanized chitosans: towards the third generation of chitinous biomaterials

“…of these polysaccharides and their derivatives, making chitosan an exciting and promising biopolymer for biomedical applications. [6][7][8][9][10] However, it should be taken into account that the term "chitosan" represents a large group of structurally different chemicals that may not only demonstrate various biological activities, but also different functionalities (i.e. non-toxicity, biodegradability, up-take…).…”