PAA-PU Janus Hydrogels Stabilized by Janus Particles and its Interfacial Performance During Hemostatic Processing.

Hydrogel is a very promising dressing for hemostasis and wound healing due to its good adhesion and long-term moist environment. However, secondary injury caused by tissue adhesion due to homogeneous hydrogel cannot be ignored. The obvious interface existing in Janus hydrogel will weaken its asymmetric function. Here, a hierarchical adhesive polyacrylic acid-polyurushiol water-oil Janus hydrogel (JPs@PAA-PU) without adhesive layer is fabricated by one-pot method in the stabilization of polystyrene@silica-siliver Janus particles (JPs). The morphological structure, mechanical properties, anisotropic chemical composition, and adhesion performance, in vivo, and in vitro hemostatic properties of Janus hydrogel are investigated. Result shows that the obtained Janus hydrogel possesses obvious compartmentalization in microstructure, functional groups, and chemical elements. Janus hydrogel is provided with asymmetric interfacial toughness with top 52.45 ± 2.29 Kpa and bottom 7.04 ± 0.88 Kpa on porcine liver. The adhesion properties of PAA side to tissue, red blood cells and platelets, promoting effect of PU side on coagulation cascade reaction and its physical battier endow Janus hydrogel with shorter hemostatic time and less blood loss than control group. It also exhibits excellent antibacterial effects against Escherichia coli and Staphylococcus aureus (>90%). Janus hydrogel possesses biosafety, providing safety guarantee for clinical applications in the future.

Sheet-like Janus hemostatic dressings with synergistic effects of cardanol hemostasis and quaternary ammonium salt antibacterial action.

It is of utmost importance that bleeding should be stopped and infection be prevented in people with trauma. In this study, an anisotropic Janus mesoporous silica nanosheet (MSNS) with different functional groups was designed and prepared. In order to endow both sides of the MSNS with independent fast hemostasis and effective antibacterial action, the MSNS was modified with cardanol (CA) and 2,3-epoxypropyltrimethylammonium (GTA). The addition of CA significantly improved the hemostatic property of the MSNS. In a SD rat femoral artery injury model, the hemostatic time of CA-MSNS-GTA was 47% shorter than that of the MSNS, attributed to the sealing of the hydrophobic alkyl side chain and the adhesion of phenolic hydroxyl groups in CA. CA-MSNS-GTA could form a three-dimensional network with fibrin to further accelerate the coagulation process. This Janus material exhibited excellent antibacterial effects (∼90%) against Gram-positive bacteria (S. pneumoniae) and Gram-negative bacteria (E. coli) due to the presence of GTA. The cytotoxicity test showed that CA-MSNS-GTA exhibited biosafety, which provided safety guarantee for clinical applications in the future. This Janus dressing with different functions on two opposite sides provides synergetic multifunctional effects during wound healing.

Superelastic, Antifreezing, Antidrying, and Conductive Organohydrogels for Wearable Strain Sensors.

Sensors based on conductive hydrogels have received extensive attention in various fields, such as artificial intelligence, electronic skin, and health monitoring. However, the poor resilience and fatigue resistance, icing, and water loss of traditional hydrogels greatly limit their application. Herein, an ionic conductive organohydrogel (PAC-Zn) was prepared for the first time by copolymerization of cardanol and acrylic acid in water/1,3-butanediol as a binary solvent system. A very small amount of cardanol (1% cardanol of total monomers) could not only significantly improve the tensile strength (∼4 times) and toughness (∼3 times) of PAA but also improve its extensibility. Due to the presence of 1,3-butanediol, PAC-Zn showed outstanding tolerance for freezing (-45 °C) and drying (over 85% moisture retention after 15 days of storage in a 37 °C oven). Compared with ethylene glycol and glycerol as antifreeze agents used in organohydrogels, the addition of 1,3-butanediol endowed the organohydrogel with not only similar frost resistance but also better mechanical performance. Besides, PAC-Zn exhibited fast resilience (almost no hysteresis loop) and excellent antifatigue ability. More importantly, a PAC-Zn organohydrogel-based sensor could detect human motion in real time (wrist, elbow, finger, and knee joints), revealing its fast response, good sensitivity, and stable electromechanical repeatability. In conclusion, the multifunctional PAC-Zn organohydrogel is expected to become a potential and promising candidate in the field of strain sensors under a broad range of environmental temperatures.