Polydopamine Nanoparticles Modulating Stimuli-Responsive PNIPAM Hydrogels with Cell/Tissue Adhesiveness

TLDR

Stimuli‑responsive hydrogels, including NIR‑responsive variants, can undergo precise phase or volume changes by adjusting radiation intensity, exposure time, and irradiation sites. The study aims to fabricate a PDA‑NPs/PNIPAM hydrogel that is NIR‑responsive, self‑healing, and cell/tissue adhesive. PDA‑NPs were incorporated into a PNIPAM network, combining PNIPAM’s thermosensitivity with PDA‑NPs’ catechol chemistry to produce a hydrogel that responds to NIR, self‑heals, and adheres to cells and tissues. The resulting hydrogel displayed NIR‑induced phase transitions and volume changes, enabling pulsatile drug release, actuation, and healing; it also exhibited strong cell affinity, 90 kPa tissue adhesion, and accelerated wound healing in vivo when paired with immobilized growth factor.

Abstract

Stimuli-responsive hydrogels can respond to stimuli by phase transformation or volume change and exhibit specific functions. Near-infrared (NIR)-responsive hydrogel is a type of stimuli-responsive hydrogel, which can be precisely controlled by altering the radiation intensity, exposure time of the light source, and irradiation sites. Here, polydopamine nanoparticles (PDA-NPs) were introduced into a poly(N-isopropylacrylamide) (PNIPAM) network to fabricate a PDA-NPs/PNIPAM hydrogel with NIR responsibility, self-healing ability, and cell/tissue adhesiveness. After incorporation of PDA-NPs into the hydrogel, the PDA-NPs/PNIPAM hydrogel showed phase transitions and volume changes in response to NIR. Thus, the hydrogel can achieve triple response effects, including pulsatile drug release, NIR-driven actuation, and NIR-assisted healing. After coating PDA-NPs onto hydrogel surfaces, the hydrogel showed improved cell affinity, good tissue adhesiveness, and growth factor/protein immobilization ability because of reactive catechol groups on PDA-NPs. The tissue adhesion strength to porcine skin was as high as 90 KPa. In vivo full-skin defect experiments demonstrated that PDA-NPs coating on the hydrogel and an immobilized growth factor had a synergistic effect on accelerating wound healing. In summary, we combined thermosensitive PNIPAM and mussel-inspired PDA-NPs to form a NIR-responsive hydrogel, which may have potential applications for chemical and physical therapies.