β-Sheet-Stabilized, MMP-9-Responsive Resveratrol-Loaded Gelatin/Silk Fibroin Nanoparticles for Coordinated Neuroinflammation Modulation and Neural Differentiation

Spinal cord injury (SCI) is accompanied by sustained neuroinflammation and limited neural repair. Nanosized protein carriers offer a promising strategy for improving the delivery of poorly soluble therapeutics, but some protein nanoparticle systems require chemical cross-linkers to maintain structural integrity. Here, β-sheet-stabilized, matrix metalloproteinase-9 (MMP-9)-responsive resveratrol-loaded gelatin/silk fibroin nanoparticles (RESV-loaded Gel/SF NPs) were prepared by ethanol-induced coassembly. In this design, silk fibroin provides β-sheet-rich physical cross-linking domains, gelatin confers MMP-9-sensitive degradability, and resveratrol (RESV) supplies anti-inflammatory and neuroprotective activity. The formulation yielded stable nanoparticles that retained RESV within the protein matrix and exhibited MMP-9-triggered drug release in an SCI-mimetic protease environment. In vitro, RESV-loaded Gel/SF NPs showed favorable cytocompatibility with neural stem cells (NSCs), attenuated lipopolysaccharide (LPS)-induced pro-inflammatory activation of BV2 microglia, reduced M1-associated features, and increased M2-associated features within the measured marker panel. The formulation increased TUBB3 (Tuj-1) and MAP2 expression, enhanced βIII-tubulin-positive neurite extension and branching, and reduced the astrocyte-associated marker GFAP under serum-free differentiation conditions. Collectively, as a cross-linker-free, MMP-9-responsive protein nanocarrier, β-sheet-stabilized Gel/SF NPs enable responsive RESV delivery and provide a potential strategy for coordinating neuroinflammation modulation with neural differentiation-associated responses in vitro.