Construction of nanocellulose-based composite hydrogel with a double packing structure as an intelligent drug carrier

Intelligent hydrogels with multifunctions including biocompatibility, good mechanical property, photothermal property, sustained drug delivery ability, and antibacterial property are urgently needed in the biomaterial fields. Herein, mesoporous polydopamine (MPDA) nanoparticles were wrapped by polyethyleneimine-modified cellulose nanocrystals (PCNC) and then physically crosslinked in cellulose nanofibrils (CNFs) hydrogel, obtaining a novel MPDA@PCNC/CNFs composite hydrogel with a double packing structure for controlled drug release. Tetracycline hydrochloride (TH) was selected as the drug model and it was loaded on MPDA nanoparticles. PCNC was warped outside surface of MPDA nanoparticle, which was used to prolong drug release time and reinforce the mechanical strength of MPDA@PCNC/CNFs composite hydrogel. Results presented that the mechanical strength of MPDA@PCNC/CNFs composite hydrogel was 3.5 times stronger than that of pure CNFs hydrogel. Burst release was reduced and drug delivery time of MPDA@PCNC/CNFs composite hydrogel was 3 times and 1.25 times longer than that of CNFs hydrogel and polydopamine/CNFs composite hydrogel, respectively. The drug delivery behavior of the MPDA@PCNC/CNFs composite hydrogel could be controlled by near infrared (NIR) light irradiation and acidic pH condition. Korsmeyer-Peppas model could be used to describe the drug delivery kinetics of the MPDA@PCNC/CNFs composite hydrogel. Fick’s diffusion was the main drug delivery mechanism. Moreover, MPDA@PCNC/CNFs composite hydrogel was found to have good biocompatibility. The as-fabricated composite hydrogel with a double encapsulation structure and unique pH and NIR responsiveness can be applied as a promising drug release carrier, and it may also has potential applications in the fields of physical and chemical therapies.