Reversible photo-controlled release of bovine serum albumin by azobenzene-containing cellulose nanofibrils-based hydrogel

Development of biomass-based and some other sustainable biomedical materials is a key subject and effective approach to biomass high-value utilization. In this work, we used cellulose resources to develop a photoresponse hydrogel (PR-gel) by integrating 4arm-PEG and azobenzene into cellulose nanofibrils (CNFs). This novel PR-gel exhibited good mechanical strength (storage modulus over 103 Pa), structure stability, reversible recoverability between sustained step strain of 1% and 1000%, and excellent biocompatibility. Under UV irradiation (λ = 365 nm, 10 mW/cm2, 10 min), the azobenzene cross-linker in PR-gel as photoswitch can cause the trans-cis isomerism and a softening effect of the hydrogel, thus realized the photo-controlled release of bovine serum albumin (BSA) (5-fold higher release rate under UV light irradiation). This work provided a new approach to design cellulose-based photoresponsive hydrogels. It is also can expand the application of cellulose-based hydrogels and some other sustainable materials in the biomedical field.