Urchin-inspired spiky microparticles for enhanced mild photothermal antibacterial therapy and wound healing

The widespread use of antibiotics to combat bacterial infections has now introduced significant new risks, particularly the continuous evolution of antibiotic-resistant strains. Consequently, the development of non-antibiotic antibacterial materials with high efficacy has become a major focus of research. Inspired by the morphology of sea urchins, we developed novel spiky microparticles (SMPs) fabricated using a natural fatty acid mixture (lauric acid and stearic acid) loaded with hemin chloride and silver nanoparticles (Ag NPs). The SMPs exhibited excellent photothermal and photodynamic properties. Under mild photothermal conditions (<45 °C), the SMPs achieved bactericidal rates exceeding 99.999% against <i>Escherichia coli</i> (<i>E. coli</i>) and over 99.9% against tetracycline-resistant enteroinvasive <i>Escherichia coli</i> (<i>E. coli</i> EIEC) within 10 min. Under near-infrared (NIR) light irradiation, there was a significant increase in the production of reactive oxygen species (ROS), ultimately achieving rapid and highly efficient bacterial eradication. Thus, we propose that SMPs synergistically disrupt bacterial cell membranes due to their urchin-inspired spiky structure and photothermal effects. Moreover, in a mouse model of bacterial wound infection, the SMPs demonstrated outstanding antibacterial efficacy. SMPs promoted wound tissue healing and suppressed the production of inflammatory cytokines, without inducing significant cytotoxicity. Therefore, this study presents a novel non-antibiotic tool for antibacterial therapy that offers a promising alternative approach for future clinical applications in treating bacterial infections.