ECM-inspired calcium/zinc laden cellulose scaffold for enhanced bone regeneration

Cellulose-based polymer scaffolds are highly diverse for designing and fabricating artificial bone substitutes. However, realizing the multi-biological functions of cellulose-based scaffolds has long been challenging. In this work, inspired by the structure and function of the extracellular matrix (ECM) of bone, we developed a novel yet feasible strategy to prepare ECM-like scaffolds with hybrid calcium/zinc mineralization. The 3D porous structure was formed via selective oxidation and freeze drying of bacterial cellulose. Following the principle of electrostatic interaction, calcium/zinc hybrid hydroxyapatite nucleated, crystallized, and precipitated on the 3D scaffold in simulated physiological conditions, which was well confirmed by morphology and composition analysis. Compared with alternative scaffold cohorts, this hybrid ion-loaded cellulose scaffold exhibited a pronounced elevation in alkaline phosphatase (ALP) activity, osteogenic gene expression, and cranial defect regeneration. Notably, the hybrid ion-loaded cellulose scaffold effectively fostered an M2 macrophage milieu and had a strong immune effect in vivo. In summary, this study developed a hybrid multifunctional cellulose-based scaffold that appropriately simulates the ECM to regulate immunomodulatory and osteogenic differentiation, setting a measure for artificial bone substitutes.