Porous chitosan by crosslinking with tricarboxylic acid and tuneable release

Abstract

Chitosan hydrogels crosslinked with 1,3,5-benzene tricarboxylic acid (BTC) are readily prepared at room temperature by adding aqueous chitosan solution dropwise into BTC-ethanol solution. Highly interconnected porous chitosan materials are subsequently prepared by freeze-drying the chitosan hydrogels. These chitosan materials show porous structures with smaller pores than conventionally prepared chitosan hydrogels via crosslinking with NaOH, genipin or sodium triphosphate. This method of forming chitosan hydrogels with BTC provides the advantage of facile encapsulation of both hydrophobic and hydrophilic compounds, as demonstrated with the model dyes (Oil Red O and Rhodamine B). The release of the hydrophilic dye from the chitosan hydrogels is demonstrated and can be tuned by BTC/chitosan concentrations and the hydrogel drying methods. However, the release of encapsulated hydrophobic dye is negligible.