Fabrication of 3D Hierarchically Porous Chitosan Monoliths by Thermally Induced Phase Separation of Chemically Modified Chitin

Abstract

Chitosan (CS), an amino-polysaccharide, has applications in various areas such as drug delivery, biotechnology, food technology, and numerous industrial applications. Monoliths have been developed continuously for several decades, and today, they hold an impressively strong position in highly efficient separation, ion exchange, catalysis, and chromatography. In our previous study, a hierarchical chitin (CT) monolith was fabricated using chemically modified CT through the thermally induced phase separation (TIPS) method. This report generated a template-free approach to prepare highly effective, stable, and reusable hierarchically porous CS monoliths by deacetylation of CT monoliths. The acquired CS monoliths exhibited a high surface area at 144.1 m 2 g −1 owing to the presence of hierarchical macro-and mesopores. The monoliths demonstrated efficient removal of metal ions from an aqueous solution in a flow system (adsorption capacity at 92.1 mg g −1 ). To gain durability of CS monoliths in acidic and basic environments, epichlorohydrin (ECH) was used as a cross-linking agent. The cross-linked monoliths also exhibited excellent performance in the adsorption of Cu(II) ions from the solution (64.4 mg g −1 ) and good reusability in multiple adsorption−desorption cycles without losing significant performance (with 90.7 ± 6.1% adsorption efficiency and 88.5 ± 7.2% desorption efficiency). The fabricated CS monolith can be modified and applied to various fields such as protein separation, catalysis, and drug delivery.

Application of Hierarchically Porous Chitosan Monolith for Enzyme Immobilization

“…CS monoliths were fabricated using a thermally induced phase-separation method, as described in our previous study. , The monoliths were fabricated as follows. Five g CT powder was mixed with a solution of 95 mL of butyric anhydride and 2.2 mL of 70% perchloric acid and stirred for 3 h at 20 °C.…”

“…This study introduces a novel and practical method for immobilizing α-amylase on a hierarchically porous CS monolith. Expanding upon previous research on the fabrication of CS monoliths using chemically modified CT and thermally induced phase separation, 36 we optimized the morphology of the monolith to achieve optimum α-amylase activity. The immobilization technique integrates physical adsorption and covalent bonding to enhance the stability of α-amylase at different pH levels and temperatures compared to its soluble form.…”

Nanofiber Scaffolds as Drug Delivery Systems Promoting Wound Healing

“…Chitosan is an alkaline natural polysaccharide substance; in particular, it is a large molecular viscous polysaccharide formed by the partial deacetylation of chitin [ 115 ]. The amino groups on the chitosan molecular chain are easily protonated and carry a positive charge, endowing chitosan with a wide range of antibacterial properties and hemostatic effects [ 116 ].…”

Mesoporous degradable chitosan-based monoliths: synthesis and applications toward water purification

“…Very recently, Hajili et al reported a hierarchically porous chitosan monolith fabricated via a thermally induced phase separation approach, resulting in a porous structure with a total surface area of 144 m 2 g −1 . 52 In the recent past, the use of suitable crosslinkers and changing the crosslinking density has evolved as an established mechanism to develop porous polymers, but such a process has never been well explored in the context of chitosan. Here, we use PEG diacrylate as a macro crosslinker, which is hydrophilic and soluble in water, thereby allowing us to prepare materials with wide-ranging crosslinking densities.…”