Layer-by-layer assembly of 3D alginate-chitosan-gelatin composite scaffold incorporating bacterial cellulose nanocrystals for bone tissue engineering

[Display omitted] •HAP-GDL mixture was used as the gelling system for the preparation of homogeneous hydrogel.•BCNs was applied to enhance the porous structure, desired mechanical and biological activity.•LBL electrostatic assembly was proposed to promote the stability and cytocompatibility.•Alg/BCNs-CS-GT composite scaffold exhibited good 3D architecture and cytocompatibility. Alginate hydrogel undergoes the poor and unstable mechanical strength, and the lack of cell recognition sites for bone tissue engineering. For this reason, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffold by the combined method involving the incorporation of bacterial cellulose nanocrystals (BCNs) in alginate matrix, internal gelation by hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex and layer-by-layer (LBL) electrostatic assembly of positively charged chitosan (CS) and negatively charged gelatin (GT). The characterization results revealed that Alg/BCNs-CS-GT composite scaffold exhibited good 3D architecture with well-defined porous structure, improved compressive strength and regulated biodegradation. In particular, the excellent biocompatibility and the reinforcing effect of BCNs, and the outer GT chains containing repetitive motifs of arginine-glycine-aspartic (RGD) sequences favored the attachment, proliferation and differentiation of osteoblastic MC3T3-E1 cells.