Highly porous poly(3-hydroxybutyrate) (PHB) scaffolds were fabricated using non-solvent-induced phase separation with chloroform as the solvent and tetrahydrofuran as the non-solvent. The microporosity, nanofiber morphology, and mechanical strength of the scaffolds were adjusted by varying the fabrication parameters, such as the polymer concentration and solvent composition. The influence of these parameters on the structure and morphology of PHB organogels and scaffolds was elucidated using small-angle neutron scattering and scanning electron microscopy. The organogels and scaffolds in this study have a complex hierarchical structure, extending over a wide range of length scales. In vitro viability assays were performed using the human keratinocyte cell line (HaCaT), and all PHB scaffolds demonstrated the excellent cell viability. Microporosity had the greatest impact on HaCaT cell proliferation on PHB scaffolds, which was determined after a 3-day incubation period with scaffolds of different morphologies and mechanical properties. The superior cell viability and the controlled scaffold properties and morphologies suggested PHB scaffolds fabricated by non-solvent-induced phase separation using chloroform and tetrahydrofuran as promising biomaterials for the applications of tissue engineering, particularly of epidermal engineering.
In
this study, we fabricated nanofibrous foams of neat poly(3-hydroxybutyrate)
(PHB) and PHB/cellulose nanocrystal (CNC) nanocomposite using nonsolvent-induced
phase separation (NIPS) followed by solvent extraction. Two different
nonsolvents, tetrahydrofuran (THF) and 1,4-dioxane (Diox), in combination
with the solvent, chloroform (CF), were used for NIPS. The parameters
of NIPS-derived crystallization kinetics were calculated using Avrami
analysis of time-dependent infrared spectral measurements. The lower
viscosity and poorer PHB affinity of THF than those of Diox resulted
in rapid crystallization and gelation rate, which in turn resulted
in higher strength of the foam. The mechanical reinforcement by the
incorporation of CNCs was achieved for the composite foam prepared
in Diox/CF but not in THF/CF, owing to the relatively better dispersion
of the CNCs in Diox than that in THF. A rapid rate of NIPS-derived
crystallization and gelation was achieved in THF/CF with the incorporation
of CNCs, indicating the effective crystal nucleation of CNCs. However,
the presence of CNCs deaccelerated the crystallization in Diox/CF,
indicating that the inhibition effect of PHB mobility became more
dominant than the nucleation effect of CNCs; this was because the
CNC dispersion became more homogeneous in Diox/CF. In vitro cell viability
assays exhibited excellent cytocompatibility of the foams, thereby
showing potential for use in biomedical applications.
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