The effect of Poisson’s ratio and cellulose nanocrystals on mouse pre-osteoblasts
F. Mule' (TU Delft - Mechanical Engineering)
M. J. Mirzaali – Mentor (TU Delft - Mechanical Engineering)
A. Accardo – Mentor (TU Delft - Mechanical Engineering)
E.L. Fratila-Apachitei – Mentor (TU Delft - Mechanical Engineering)
A.M.A.A.A. Al-Sanea – Mentor (TU Delft - Mechanical Engineering)
R.P. Tas – Graduation committee member (TU Delft - Mechanical Engineering)
A. Savva – Graduation committee member (TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
The mechanical and topographical properties of the cellular micro environment play a crucial role in regulating bone cell behavior through mechano transduction. In this thesis, the synergistic influence of 3D-printed meta-biomaterial scaffolds with controlled Poisson’s ratio, and cellulose nano crystals (CNCs) surface coating, on the proliferation, osteogenic differentiation, and mineralization of MC3T3-E1 pre-osteoblasts was investigated. Auxetic and non-auxetic micro-architectures were fabricated via two-photon polymerization (2-PP), expressing similar morphological and mechanical properties, except for the Poisson's ratio. Scaffold surfaces were further functionalized with CNCs coatings at different concentrations to assess the contribution of nano-topographical, biochemical and mechanical cues.
Morphological characterization confirmed fabrication of the scaffolds, with dimensions within the 15\% variation from the designed structures, and homogeneous coating deposition. Cellular responses were evaluated over time period of 19 days performing various cellular staining, fluorescence imaging and scanning electron microscopy (SEM). The time steps considered were days 3, 7, 9 and 19. Results demonstrated that scaffold geometry alone significantly influenced cell organization and proliferation. Significant differences (p<0.05) were in the number of cells between the auxetic and non-auxetic structures at day 3, across all conditions. The introduction of CNCs coating enhanced cell adhesion and modulated osteogenic outcomes. Notably, coated auxetic scaffolds showed increased Alizarin red staining (ARS) expression compared to coated non-auxetic structures, indicating that auxetic mechanics combined with nano-topographical cues can enhance mineralization of pre-osteoblasts.
Overall, the findings reveal that osteogenic behavior is governed by a synergistic interaction between mechanical architecture and surface topography rather than by a single parameter. This work highlights the potential of mechanically tunable meta-biomaterials integrated with bioactive coatings to engineer microenvironments for bone tissue regeneration and advanced biomaterial design.
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