Engineering macromolecular crowding-driven amyloid-mineral hybrid scaffolds for enhanced bone regeneration

The extracellular matrix (ECM) of native bone features a densely crowded, hierarchically organized architecture composed of collagen fibrils and hydroxyapatite (HAp) nanocrystals, which together confer mechanical strength and biological functionality. However, faithfully replicating this complex organic-inorganic interface in synthetic scaffolds remains a significant challenge. Here, we report a macromolecular crowding (MMC)-driven strategy to construct ECM-mimetic scaffolds using phase-transited lysozyme (PTL) as an amyloid-based protein matrix. By employing a reverse dialysis process to mimic the crowded microenvironment, amyloid proteins undergo aggregation, conformational rearrangement, and a liquid-crystalline-like phase transition, accompanied by reconstruction of the organic-inorganic interface and energetic reorganization, thereby promoting biomineralization. The resulting amyloid-mineral hybrid scaffold exhibits excellent structural stability, mechanical robustness, and bioactivity, supporting bone regeneration comparable to mineralized collagen in vitro and in vivo. Collectively, this study demonstrates that, unlike conventional water-rich and dilute scaffolds, the MMC-driven strategy provides a more biomimetic and functionally versatile platform, highlighting the feasibility of using structurally stable amyloid proteins as substitutes for collagen and offering a powerful design paradigm for next-generation bone tissue engineering scaffolds.