Simple functionalization of cellulose beads with pre-propargylated chitosan for clickable scaffold substrates

Concerning the increased market for bio-based materials and environmentally safe practices, cellulose-based beads are one of the more attractive alternatives. Thus, this work focuses on the generation of functional cellulose-based beads with a relatively simple and direct method of blending a pre-modified chitosan bearing the targeted functional groups and cellulose, prior to the formation of the beads, as a mean to have functional groups in the formed structure. To this end, chitosan was chemically modified with propargyl bromide in homogenous reaction conditions and then combined with cellulose in sodium hydroxide/urea solution and coagulated in nitric acid to produce spherical shaped beads. The successful chemical modification of chitosan was assessed by elemental analysis, as well as by Fourier-transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The alkynyl moieties from the chitosan derivative, served as reactive functional groups for click-chemistry as demonstrated by the tagging of the commercial fluorophore Azide-Fluor 488 via CuI-catalysed alkyne-azide cycloaddition reaction, in aqueous media. This work demonstrates the one-step processing of multiple polysaccharides for functional spherical beads as a template for bio-based scaffolds such as enzyme immobilization for stimuli-response applications and bioconjugations.