Towards functional 3D-stacked electrospun composite scaffolds of PHBV, silk fibroin and nanohydroxyapatite: Mechanical properties and surface osteogenic differentiation

Abstract

Bone tissue engineering scaffolds have two challenging functional tasks to fulfil: to encourage cell proliferation, differentiation and matrix synthesis and to provide suitable mechanical stability upon implantation. Composites of biopolymers and bioceramics combine the advantages of both types of materials, resulting in better processability and enhanced mechanical and biological properties through matrix reinforcement. In the present study, novel thick bone composite scaffolds were successfully fabricated using electrospun flat sheets of polyhydroxybutyrate-polyhydroxyvalerate/nanohydroxyapatite/silk fibroin essence (2% nanohydroxyapatite - 2% silk fibroin essence and 5% nanohydroxyapatite - 5% silk fibroin essence, respectively). Their potential asin vitrobone regeneration scaffolds was evaluated using mouse calvarian osteoblast cells (MC3T3-E1), in terms of morphology (scanning electron microscope), cell attachment, cell proliferation, Col type I, osteopontin and bone alkaline phosphatase activity (Quantitative Real Time Polymerase Chain Reaction [qRT-PCR], enzyme-linked immunosorbent assay, immunocytochemistry). Electrospun polyhydroxybutyrate-polyhydroxyvalerate scaffolds were used as reference constructs. The results showed that the compressive and tensile mechanical properties of the scaffolds are dependent on the change in their composition, and the treatment these underwent. Furthermore, methanol-treated and autoclaved (MA) P2 (2% nanohydroxyapatite, 2% silk fibroin essence) samples appeared to exhibit more promising tensile properties. Additionally, the compressive tests results confirmed that the methanol pre-treatment and the autoclaving step lead to an increase in the P2 secant modulus when compared to the non-methanol-treated ones, P2 and P5 (5% nanohydroxyapatite, 5% silk fibroin essence), respectively.Both formulations of polyhydroxybutyrate-polyhydroxyvalerate/nanohydroxyapatite/silk fibroin essence composite promoted greater cell adhesion and proliferation than the corresponding polyhydroxybutyrate-polyhydroxyvalerate control ones. Cells seeded on the composite fibrous scaffolds were extensively expanded and elongated on the fibre surface after one day in culture, whereas those seeded on the polyhydroxybutyrate-polyhydroxyvalerate scaffolds were not completely elongated. In addition, cells grown on P2 and P5 scaffolds had higher alkaline phosphatase activity when compared to those containing no nanohydroxyapatite/silk fibroin essence.

Poly(ε-caprolactone) Scaffolds Fabricated by Melt Electrospinning for Bone Tissue Engineering

“…In our study, scaffolds were produced by melt electrospinning a pure polymer and cultured with typical bone forming cells, osteoblasts. Recently published articles follow a more complex approach to produce scaffolds for bone TE [42,43]. Paşcu et al melt electrospun silk fibroin and nanohydroxyapatite to produce biodegradable and biocompatible scaffolds for bone TE [42].…”

“…Recently published articles follow a more complex approach to produce scaffolds for bone TE [42,43]. Paşcu et al melt electrospun silk fibroin and nanohydroxyapatite to produce biodegradable and biocompatible scaffolds for bone TE [42]. Pasuri et al used electrospun hydroxyapatite fibres embedded in Matrigel and cultured osteoclasts and macrophages, giving credit to the complex cell–cell interactions between osteoblasts, osteoclasts and macrophages necessary to promote bone formation [43].…”

A Charge-Based Mechanistic Study into the Effects of Process Parameters on Fiber Accumulating Geometry for a Melt Electrohydrodynamic Process

“…Melt electrowriting processes, as an emergent technology utilizing the principle of electro-hydrodynamics and additive manufacturing [1,2], have aroused wide interest due to its ability to produce polymeric scaffold with tunable microarchitecture [3][4][5][6] and morphology [7][8][9][10][11]. Moreover, the solvent-free characteristic of the process makes it amenable for a broad application scope for engineered tissues [12][13][14][15][16][17][18]. However, the printing fidelity of the engineered scaffold notably deteriorates when the printing toolpath is designed for larger layering dimensions [19] or smaller feature pore sizes [20].…”

Effects of polyethylene glycol content on the properties of a silk fibroin/nano-hydroxyapatite/polyethylene glycol electrospun scaffold

“…3 Silk broin (SF) has been widely used in BTE research, 4,5 but its lack of mechanical strength and long period of degradation limit its clinical applications in bone regeneration. 6 Promoting the protein's secondary structure transformation, especially an increase in the b-sheet structure of SF, will improve its mechanical strength, 7,8 but inhibits its degradation at the same time. 9,10 Adding 20 wt% nano-hydroxyapatite (nHAP) into SF scaffolds results in better mechanical properties and even osteoconduction.…”