Physically and chemically cross-linked cellulose cryogels: Structure, properties and application for controlled release

• Physical and chemical cross-linked cellulose hydrogels and cryogels have been obtained.
• NMR, XRD and DSC studies confirmed cellulose cross-linking.
• Gel and cryogels swelling depends on cellulose and ECH concentration in solution.
• The potential of cellulose cryogels for controlled drug release was evidenced.

Porous cellulose matrices were prepared via cellulose dissolution in 8 wt% NaOH-water, physical gelation and chemical cross-linking with epichlorohydrin (ECH), coagulation in water and lyophilisation. Cellulose and cross-linker concentration were varied. The behaviour of gels upon coagulation and the swelling of cryogels in water were analysed. An anomalous high swelling at cross-linker concentration around stoichiometric molar ratio with cellulose was observed. Cellulose cryogel morphology, crystallinity and density were studied. The influence of chemical cross-linking on cellulose swelling was explained by suggesting that ECH acts as a spacer preventing cellulose chains tight packing during coagulation. Cellulose was loaded with a model drug, procaine hydrochloride, and the kinetics of its release was investigated.