Chemical and Photochemical-Driven Dissipative Fe³⁺/Fe²⁺-Ion Cross-Linked Carboxymethyl Cellulose Gels Operating Under Aerobic Conditions: Applications for Transient Controlled Release and Mechanical Actuation

A Fe³⁺-ion cross-linked carboxymethyl cellulose, Fe³⁺-CMC, redox-active gel exhibiting dissipative, transient stiffness properties is introduced. Chemical or photosensitized reduction of the higher-stiffness Fe³⁺-CMC to the lower-stiffness Fe²⁺-CMC gel, accompanied by the aerobic reoxidation of the Fe²⁺-CMC matrix, leads to the dissipative, transient stiffness, functional matrix. The light-induced, temporal, transient release of a load (Texas red dextran) and the light-triggered, transient mechanical bending of a poly-N-isopropylacrylamide (p-NIPAM)/Fe³⁺-CMC bilayer construct are introduced, thus demonstrating the potential use of the dissipative Fe³⁺-CMC gel for controlled drug release or soft robotic applications.