On‐Off Phagocytosis and Switchable Macrophage Activation Stimulated with NIR for Infected Percutaneous Tissue Repair of Polypyrrole‐Coated Sulfonated PEEK.

Intelligent control of the immune response is essential for obtaining percutaneous implants with good sterilization and tissue repair abilities. In this study, polypyrrole (Ppy) nanoparticles enveloping a 3D frame of sulfonated polyether ether ketone (SP) surface are constructed, which enhance the surface modulus and hardness of the sulfonated layer by forming a cooperative structure of simulated reinforced concrete and exhibit a superior photothermal effect. Ppy‐coated SP could quickly accumulate heat on the surface by responding to 808 nm near‐infrared (NIR) light, thereby killing bacteria, and destroying biofilms. Under NIR stimulation, the phagocytosis and M1 activation of macrophages cultured on Ppy‐coated SP are enhanced by activating complement 3 and its receptor, CD11b. Phagocytosis and M1 activation are impaired along with abolishment of NIR stimulation in the Ppy‐coated SP group, which is favorable for tissue repair. Ppy‐coated SP promotes Collagen‐I, vascular endothelial growth factor, connective tissue growth factor, and α‐actin (Acta2) expression by inducing M2 polarization owing to its higher surface modulus. Overall, Ppy‐coated SP with enhanced mechanical properties could be a good candidate for clinical percutaneous implants through on‐off phagocytosis and switchable macrophage activation stimulated with NIR. [ABSTRACT FROM AUTHOR]