A Sandwich-Structured Silk Fibroin Mesh with ROS-Responsive and Immunoregulatory Functions for Pelvic Floor Repair

Current biodegradable meshes for pelvic floor repair are constrained by a limited ability to actively modulate the hostile immune microenvironment following implantation. To address these challenges, we developed a functionalized degradable silk fibroin mesh (SFM) integrated with a reactive oxygen species (ROS)-responsive nanocomposite hydrogel. The resulting composite mesh, SFM@Gel-NP, features a "hydrogel-mesh-hydrogel" sandwich structure, wherein the hydrogel layers are loaded with self-assembled nanoparticles (NP-H-CRFP) for the co-delivery of the STING inhibitor H-151 and the ROS-scavenging agent catechin. This design provides immediate mechanical reinforcement while enabling microenvironment-triggered drug release. In vitro, NP-H-CRFP demonstrated efficient cellular uptake, significant ROS clearance, and effective attenuation of macrophage inflammation and apoptosis. In vivo, SFM@Gel-NP remodeled the local immune milieu by inhibiting the ROS/cGAS-STING/NF-{kappa}B axis, thereby promoting a shift from pro-inflammatory M1 toward pro-regenerative M2 macrophage polarization. This immunomodulatory effect, coupled with enhanced and well-organized collagen deposition--particularly of early type III collagen--resulted in improved tissue integration and repair. This work presents a novel strategy that combines structural reinforcement with active immune regulation, offering a promising next-generation solution for durable and functional pelvic floor reconstruction.