Abstract
Polycaprolactone (PCL) fiber mats with defined pore architecture were shown to provide sufficient support for a premixed calcium phosphate cement (CPC) paste to serve as a flat and flexible composite material for the potential application in 2-dimensional, curved cranial defects. Fiber mats were fabricated by either melt electrospinning writing (MEW) or solution electrospinning (SES) with a patterned collector. While MEW processed fiber mats led to a deterioration of the cement bending strength by approximately 50%, due to a low fiber volume content in conjunction with a weak fiber-matrix interface, fiber mats obtained by solution electrospinning resulted in a mechanical reinforcement of the cement matrix in terms of both bending strength and absorbed fracture energy. This was attributed to a higher fiber volume content and a large contact area between nanosized fibers and cement matrix. Hydrophilization of the PCL scaffolds prior to lamination further improved composite strength and preserved the comparably higher fracture energy of 1.5 to 2.0 mJ/mm2. The laminate composite approach from this study was successful in demonstrating the limitations and design options of such novel composite materials. However, fiber-cement compatibility remains an issue to be addressed, since a high degree of hydrophilicity does not necessarily provoke a stronger interface.
Highlights
Mineral bone cements mainly consisting of calcium phosphate phases are clinically well-established materials for bone replacement
The demand for a low melting point and a high thermal stability restricts the application of melt electrospinning writing (MEW) technique to thermoplastic polymers, whereas PCL
Macroporous solution electrospinning (SES) fiber mats can be produced by either using porogens [23,24] or a patterned collector. The latter allows a disturbance of the electric field so that the deposited fiber mat mimics this pattern in order to control SES scaffold porosity [22,25]
Summary
Mineral bone cements mainly consisting of calcium phosphate phases are clinically well-established materials for bone replacement. Flat defects (e.g., in cranioplasty) are mostly treated with intraoperatively moulded polymethylmethacrylate (PMMA) cement implants [3,4], custom made titanium, polyethylene (PE) or polyetheretherketone (PEEK) implants, titanium meshes as a support for cementitious pastes or preformed solid calcium phosphate implants [5]. The former are known for damaging native tissue due to their heat development and monomer release, while metal implants suffer from their high thermal conductivity [6] and low malleability [7]. All implants share a certain risk for post-treatment infection, Materials 2019, 12, 834; doi:10.3390/ma12050834 www.mdpi.com/journal/materials
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