Liposome-functionalized biocompatible polyurethane microspheres with bacteria-capturing traps for comprehensive management of bacterial infections

Bacterial infections pose a significant threat to public health, as pathogens and their secreted toxins jointly activate immune responses, and severe cases may develop into sepsis. Effective anti-infective treatment requires comprehensive eradication of pathogens, involving not only bacterial clearance but also neutralization of virulence factors. Traditional adsorbents in blood purification often face a trade-off between efficacy and biosafety. Herein, we develop a graded modified hemoperfusion adsorbent for full-cycle sepsis management. Cationic diallyl dimethylammonium chloride (DDA)-modified carbon nanotubes (CNTs) are embedded within polyurethane precursors, and liposomes (Lipo) are anchored onto the surface of microspheres through polymer chain entanglement and electrostatic interactions during phase separation, resulting in polyurethane-CNT-DDA-Lipo (PUD-L) porous microspheres. This hierarchical modification strategy enables spatial partitioning, effectively balancing the material functionality with biosafety and achieving the simultaneous removal of bacteria and toxins. The porous surface of PUD-L matches the size of the bacteria, serving as a bacterial trap that removes 98.2% of <i>Staphylococcus aureus</i> (<i>S. aureus</i>) and 97.2% of <i>Escherichia coli</i> (<i>E. coli</i>) within 3 h. Additionally, PUD-L significantly decreases hemolysis induced by exotoxins (from 49.49% to 0.22%) and reduces endotoxin levels (from 236.08 EU per mL to 38.15 EU per mL), primarily through adsorption. In a sepsis blood model, treatment with PUD-L reduces pro-inflammatory cytokine concentrations to normal physiological levels. Overall, this work highlights that both pathogens and their toxins are key triggers of excessive inflammation. The PUD-L microspheres represent a promising strategy that integrates antibacterial activity and virulence factor adsorption in a hierarchical method while maintaining great biocompatibility, providing a novel platform for the comprehensive management of bacterial infections.