Temperature-sensitive poly-NIPAm modified cellulose nanofibril cryogel microspheres for controlled drug release

In this article, we report a novel method for synthesizing temperature-sensitive polymer-modified cellulose nanofibril (CNF) cryogel microspheres. The pristine cryogel microspheres were first prepared using a spray-freeze dry method in the presence of a chemical crosslinker. Afterwards, NIPAm (N-isopropylacrylamide), a temperature-sensitive monomer, was polymerized and grafted to the cellulose cryogel microspheres through in situ free radical polymerization in the cryogel microreactor. The morphology, chemical structure, thermal sensitivity, bulk density and water uptake capacity of the hybrid microspheres were characterized. The CNF–PNIPAm hybrid microspheres exhibited a good temperature response at around 32 °C in water. The swelling behavior and drug release capability of CNF–PNIPAm hybrid microspheres were also investigated. The microspheres with PNIPAm exhibited a controllable drug release rate. The temperature effect on the drug release rate was also observed. These results indicated that porous CNF–PNIPAm hybrid microspheres could serve as a new type of material for controlled drug release.