An injectable hemostatic PEG-based hydrogel with on-demand dissolution features for emergency care.

Uncontrolled bleeding from internal noncompressible wounds is a major cause of prehospital death in military personnel and civilian populations. An ideal hemostatic sealant for emergency care should quickly control blood loss and be removed without debridement for the follow-up treatment in the operating room, yet the lack of suitable materials to meet both requirements is the bottleneck. Herein, we suggest an injectable and dissolvable hydrogel sealant for hemorrhage management of noncompressible wounds. To this end, a 4-arm poly(ethylene glycol) (PEG) crosslinker modified with thioester linkages and terminated with aldehyde groups is designed and synthesized, and to modulate the gel properties and make it suitable as a hemostatic sealant, a mixed amino component composed of poly(ethylene imine) and adipic dihydrazide is employed to react with the PEG crosslinker to form the adhesive and elastic sealant for the first time. The aldehyde groups provide the adhesion to the tissues, and the amino component affords the procoagulant ability. More importantly, the thioester moieties allow the on-demand dissolution of sealant via a thiol-thioester exchange reaction upon exposure to an exogenous thiolate solution. In the rat femoral artery puncture and liver injury models, the administration of the hydrogel sealant dramatically reduces blood loss, and its subsequent removal does not induce rebleeding. Consequently, this hydrogel sealant with the unique feature of on-demand dissolution can not only efficiently control bleeding in emergent scenarios, but also allow non-traumatic re-exposure of wounds during subsequent surgical care. STATEMENT OF SIGNIFICANCE: Sealants, adhesives or hemostatic dressings currently used in emergency situations not only require manual pressure to control bleeding, but also face removal by cutting and mechanical debridement to enable eventual surgical treatment. In this study, we design and develop an injectable and adhesive hydrogel sealant with good procoagulant capacity and on-demand dissolution feature. The application of the hydrogel sealant substantially reduces bleeding from internal noncompressible wounds without the need for direct pressure, and demonstrates for the first time that its controlled removal without debridement does not cause rebleeding. Considering that there are currently no commercial wound sealant systems with the feature of on-demand dissolution, the hydrogel sealant developed by us is expected to address an unmet clinical need.

Fabrication of porous carbon derived from cotton/polyester waste mixed with oyster shells: Pore-forming process and application for tetracycline removal.

Porous carbon was fabricated from cotton/polyester-based textile wastes as a carbon source coupled with oyster shells for tetracycline removal. The preparation conditions were optimized and detailed characterization was conducted to study the effects of oyster shells on cotton/polyester pyrolysis. The optimal pyrolysis temperature (900 °C), pyrolysis time (1 h) and mass ratio (OS/CPW of 1:1) were determined using the Box-Behnken experiment. The best porous carbon reached a surface area of 645.05 m2/g. Oyster shells acted as templates to produce cotton/polyester-based porous carbon and a possible pore-forming process was proposed. CaO was converted from CaCO3, which played the dominant role in developing the mesoporous structure. CO2 gas released from CaCO3 promoted the creation of micropore structure. In addition, the impurites of oyster shells acted as the dispersing agent inhibiting CaCO3 and CaO aggregation and growth. Fe2O3 and K2O from impurities reacted with the carbon skeleton to increase microporosity. Finally, the well-developed and uniform porous carbon was obtained. The first-pseudo order model and Langmuir isotherms were suitable. The maximum adsorption capacity of PC-OS-900 was 515.17 mg/g which competed with other waste-based adsorbents. The TET adsorption mechanism was related to pore distribution, hydrogen bonds, π-π EDA interactions and electrostatic interactions.