Synthesis and Properties of Cationic Photocurable Polymethylsiloxane/Eugenol-Modified Oxetane Monomers

Construction of near-infrared gradient hydrogel actuators using self-floating induction and LED photopolymerization

Creating gradient hydrogels for remote control of bionic systems continues to be challenging due to the complexity of the preparation process. Herein, we have proposed a strategy to prepare near-infrared photothermal conversion gradient hydrogel featuring self-floating-induced gradient structures through fast LED light-triggered photopolymerization. A judiciously designed polysiloxane acrylate crosslinker (PA-Si) possesses the self-floating, crosslinking, and initiating properties. The self-floating ability of the PA-Si enables the autonomous formation of compositional and crosslinking gradients within the hydrogel, resulting in top-down variations in contraction stress. The gradient hydrogel demonstrates excellent NIR light-driven response (50°/s), cyclic stability, and mechanical properties (4392.84 kJ/m3). Cargo four times its mass is grasped and lifted by the gradient hydrogel actuator under the NIR light irradiation, displaying impressive performance in light-driven bionics. This study delivers a convenient strategy for manufacturing gradient hydrogels with actuation capabilities and shows potential for application in soft actuators.

Poloxamer-Based Mixed Micelles Loaded with Thymol or Eugenol for Topical Applications

Poloxamers (P184, P188, and P407) have been investigated as the carrier system for eugenol or thymol. A synergic effect of mixed Poloxamers was proved by enhanced micellar parameters, with a lower critical micelle concentration (about 0.06 mM) and the highest surface adsorption of 9 × 10-7 mol m-2 for P188/P407. Dynamic light scattering revealed a decrease in micellar size after loading with biomolecules. Three mathematical models were applied to study the release kinetics, of which Korsmeyer-Peppas was the best fitted model. Higher relative release was observed for Poloxamer/eugenol samples, up to a value of 0.8. Poloxamer micelles with thymol were highly influential in bacterial reduction. Single P407/eugenol micelles proved to be bacteriostatic for up to 6 h for S. aureus or up to 48 h for E. coli. Mixed micelles were confirmed to have prolonged bacteriostatic activity for up to 72 h against both bacteria. This trend was also proven by the modified Gompertz model. An optimized P188/P407/eugenol micelle was successfully used as a model system for release study with a particle size of less than 30 nm and high encapsulation efficiency surpassing 90%. The developed mixed micelles were proved to have antibiofilm activity, and thus they provide an innovative approach for controlled release with potential in topical applications.