Fig. 6. (A) Controlled release of doxorubicin from the glucosamine–boronate ester and trans-azobenzene stabilized duplex crosslinked hydrogel: (a) time-dependent release of doxorubicin upon the UV light-induced transition (λ = 365 nm) of the stiff glucosamine–boronate ester and trans-azobenzene stabilized duplex crosslinked hydrogel, into the low-stiffness hydrogel composed of glucosamine–boronate ester bridges only, and free cis-azobenzene tethers. (b) Release of the doxorubicin from the stiff hydrogel in the absence of UV light irradiation. Inset: fluorescence spectra corresponding to the released doxorubicin from the low-stiffness hydrogel crosslinked by the glucosamine–boronate ester bridges only at different time-intervals. (B) Switchable light-induced “ON” and “OFF” release of doxorubicin upon the cyclic photoisomerization of the hydrogel between the low-stiffness hydrogel crosslinked by the glucosamine–boronate ester bridges only (free cis-azobenzene tethers), λ = 365 nm (switch “ON”), and the high-stiffness hydrogel crosslinked by glucosamine–boronate ester bridges and the trans-azobenzene-stabilized duplexes as crosslinkers, λ > 420 nm (switch “OFF”).