NIR and Oxidative Stress-Modulated Intestinal Peristalsis Motion of Tubular Conductive Thermo-Hydrogel Actuator

Actuators for soft bionic robotics, utilizing disease microenvironment-responsive and mechanically flexible materials, are influenced by intra- and intermolecular structures of hydrogels. However, they lack the required endogenous stimuli responsiveness necessary for applications like gastrointestinal-targeted drug screening and liquid/mass transport. Herein, a tubular conductive, reactive oxygen species (ROS)- and an near infrared (NIR)-responsive thermo-hydrogel actuator (THA) was fabricated for viscous liquid and solid transport. The presence of diselenide-crosslinked polymer dots (PDs) loaded onto polydopamine (PDA) nanoparticles (PD@PDA) in a poly(N-isopropylacrylamide) and polyvinyl alcohol (PNIPAM/PVA) matrix provided the necessary LCST alongside ROS- and NIR-responsive behavior. In the presence of high ROS, the diselenide bonds cleaved, resulting in release of PDA, generating NIR-specific actuation. The actuation process was confirmed by the directional movement of silicone oil (MR-200) and a small glass ball, which were selective to high ROS levels. The THA also demonstrated changes in electrical resistance (decrease in ΔR: ~ 14.60 kΩ), and stretchability (~ 127% increase in breaking strain), which may be used for screening-based applications. The THA demonstrated remarkable biocompatibility with Caco-2 (colon cancer) cells, alongside ROS scavenging and downregulation of TNF-α and IL-1β. Hence, this platform provides a viable pathway for fabricating bionic and biomimetic actuators for viscous liquid and solid transport.