A B S T R A C T
Tissue engineering, particularly the recreation of the three-dimensional hierarchical structure of the extracellular
matrix, demands advanced biomaterials. These biomaterials can be electrospun to create microporous scaffolds
with tailored properties. In this study, three natural polymers were combined to develop a novel nanocomposite
scaffold designed to integrate multiple desirable functionalities and to provide sufficient cellular activity while
enhancing the strength required for bone tissue. Incorporating cellulose nanocrystals (CNCs) into a polyhydroxybutyrate
(PHB) and chitosan matrix led to significant improvements. Specifically, scaffold diameter was
reduced by 26.44 %, surface roughness increased by 10.45 %, hydrophilicity improved by 12.05 %, modulus
increased by 16.49 %, tensile strength was enhanced by 33.43 %, and crystallinity was modified by 56.8 %
compared to the PHB-chitosan scaffold. The addition of CNCs also slightly decreased crystal sizes and influenced
the degradation behavior. This nano-additive enhanced mineralization, promoted cell growth, and increased the
viability of MG-63 osteoblast cells to 91.5 %. Furthermore, scaffolds containing 3 wt% CNCs significantly
upregulated the expression of osteogenic markers, including a 10.7-fold increase in osteopontin and a 4.1-fold
increase in alkaline phosphatase, highlighting their promise for bone tissue engineering. These findings
demonstrate that PHB-chitosan/CNC scaffolds, with improved mechanical properties, possess considerable potential
for trabecular bone tissue repair and regeneration.

Keywords:
Polyhydroxybutyrate (PHB)
Bone tissue engineering (BTE)
Nanocomposite