Polydopamine-coated cellulose nanocrystal as functional filler to fabricate nanocomposite hydrogel with controllable performance in response to near-infrared light

Near-infrared (NIR) light-responsive materials had attracted much attention by virtue of their ability to employ abundant light sources to adapt their properties remotely and spatially in which development of novel NIR light-responsive fillers was the key factor. In this work, cellulose nanocrystals (CNCs) were coated with polydopamine (PDA) to endow these plant-derived nanofillers with good light absorption properties. In this work, PDA@CNC was incorporated into the poly(N-isopropylacrylamide) (PNIPAM) matrix to fabricate PDA@CNC/PNIAPM nanocomposite hydrogels with controllable performance in response to NIR stimuli. The PDA@CNC would not only serve as a reinforcement agent to mechanically toughen the hydrogels but also integrate considerable photothermal effect into the same system. As a result of fast NIR responsiveness and easily tailored photothermal properties, the 5-Fluorouracil (5-Fu) release behavior of the nanocomposite hydrogels could be remotely controlled with the assistance of a NIR laser. Besides, the nanocomposite hydrogel with Ag nanoparticles immobilized PDA@CNC (Ag/PDA@CNC) was demonstrated as a novel catalyst to tune the reduction rate of 4-nitrophenol (4-NP) upon NIR irradiation. Taken together, the modified CNCs would be alternative functional nanofillers for the construction of NIR light-responsive materials with controllable performance.