Novel polycaprolactone/hydroxyapatite nanocomposite fibrous scaffolds by direct melt-electrospinning writing

Melt electrospinning writing (MEW) using an automated stage has recently been developed as a direct additive manufacturing method for the fabrication of orderly, precise and complex porous 3D fibrous structures that can promote cell infiltration and growth. The further incorporation of inorganic particles within fibrous scaffolds is desirable in order to enhance bioactivity, however this remains challenging with the MEW fabrication process. To address this challenge, flexible, osteoconductive, medical grade polycaprolactone (m-PCL) - hydroxyapatite (HAp) composite 3D fibrous structures with high porosity (96–98%) and fully interconnected pore architectures were fabricated using MEW under precisely controlled parameters. The physical properties of these 3D fibrous composite scaffolds including fibre size, mechanical characteristics, and in vitro degradation rate were investigated. The results showed that the composite m-PCL/HAp fibrous scaffolds degraded in an alkaline environment at 37 °C faster than plain m-PCL and provided a favourable platform for the infiltration and growth of human osteoblasts. Moreover, confocal imaging confirmed that the scaffolds contained HAp nano-particles (NPs) which induced a more homogeneous distribution of cells within the scaffold particularly after 7 days of culture. Osteoblast activity and viability in the m-PCL/HAp composite scaffolds indicated a favourable cell/material interaction, suggesting great potential for use in mineralised tissue reconstruction / regeneration applications

Optimising degradation and mechanical performance of additively manufactured biodegradable Fe–Mn scaffolds using design strategies based on triply periodic minimal surfaces

Additively manufactured lattices based on triply periodic minimal surfaces (TPMS) have attracted significant research interest from the medical industry due to their good mechanical and biomorphic properties. However, most studies have focussed on permanent metallic implants, while very little work has been undertaken on manufacturing biodegradable metal lattices. In this study, the mechanical properties and in vitro corrosion of selective laser melted Fe–35%Mn lattices based on gyroid, diamond and Schwarz primitive unit-cells were comprehensively evaluated to investigate the relationships between lattice type and implant performance. The gyroid-based lattices were the most readily processable scaffold design for controllable porosity and matching the CAD design. Mechanical properties were influenced by lattice geometry and pore volume. The Schwarz lattices were stronger and stiffer than other designs with the 42% porosity scaffold exhibiting the highest combination of strength and ductility, while diamond and gyroid based scaffolds had lower strength and stiffness and were more plastically compliant. The corrosion behaviour was strongly influenced by porosity, and moderately influenced by geometry and geometry-porosity interaction. At 60% porosity, the diamond lattice displayed the highest degradation rate due to an inherently high surface area-to-volume ratio. The biodegradable Fe–35Mn porous scaffolds showed a good cytocompatibility to primary human osteoblasts cells. Additive manufacturing of biodegradable Fe–Mn alloys employing TPMS lattice designs is a viable approach to optimise and customise the mechanical properties and degradation response of resorbable implants toward specific clinical applications for hard tissue orthopaedic repair

Development of lyophilized spherical particles of poly(epsilon-caprolactone) and examination of their morphology, cytocompatibility and influence on the formation of reactive oxygen species

A common limitation of using polymeric micro- and nanoparticles in long-term conservation is due to their poor physical and chemical stability. Freeze-drying is one of the most convenient methods that enable further reconstitution of micro- and nanoparticles for therapeutical use. Nevertheless, this process generates various stresses during freezing and desiccation steps. This paper underlines the combined outcomes of freeze drying method and physicochemical solvent/non-solvent approach to design biocompatible poly(epsilon-caprolactone) (PCL) nanospheres and evaluate influence of different cryoprotectants (glucose, saccharose, polyvinyl alcohol or polyglutamic acid) on the outcome of freeze-dried PCL particles. Samples were characterized using Fourier transform infrared spectroscopy (FT-IR). scanning electron microscopy (SEM) and dynamic light scattering method (DLS). In vitro studies used, include MTT assay (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). testing cytotoxicity as the quality of being toxic to cells, and DCFH-DA assay (2',7'-dichlordihydrofluorescein-diacetate), testing the possible increase in ROS levels. It was found that cryoprotection with 1% glucose solution is an optimal for obtaining uniform, spherical but also biocompatible PCL nanoparticles for biomedical purposes

In vitro bioactivity of implantable Ti materials coated with PVAc membrane layer

A novel, simple and efficient approach for designing a 3-D structure of poly(vinyl acetate) (PVAc) fibers layer coated on chemically treated Ti coupons by means of air jet spinning (AJS) approach has been developed. The effects of the PVAc AJS membrane mats on apatite formation were evaluated in vitro with immersion in simulated physiological Hank's balanced salt solution. The MC3T3-E1 pre-osteoblast cell-line has been utilized for measuring the bone cell response. The results suggest that the AJS produces a distinct porous layer of 3-D interconnected fibers on Ti with strong adhesion which offers a suitable surface structure for cell attachment. A significant amount of apatite-like formation and cell spread with strong local adhesion were identified on the PVAc fibers compared to the neat samples. © 2014 Elsevier B.V

Fabrication and characterization of silver nanostructures conformal coating layer onto electrospun N6 nanofibers with improved physical properties

In this communication, colloidal silver (Ag) nanostructures were synthesized and deposited directly onto electrospun nylon 6 (N6) fibers without using surface modifier in the form of an ultrathin conformal coating layer via a hydrothermal treatment. The morphological, structural, and thermal properties of the Ag/N6 nanocomposite membranes were analyzed by field-emission scanning electron microscopy (FESEM), X-ray diffraction, X-ray photoelectron spectroscopy, and differential scanning calorimetry (DSC). FESEM imaging showed that the Ag coating on individual N6 nanofibers was continuous, uniform, and compact. A DSC study of the nanocomposites illustrated a strong interfacial adhesion of the Ag layer with N6 nanofiber surfaces via strong hydrogen bonds. A possible mechanism for hydrogen bond formation during the hydrothermal process was proposed. Further, it was found that the transition of the meta-stable ?-form into the thermodynamically more stable ?-form of N6 structure was achieved; therefore, the hydrothermal process did not cause chain degradation. © 2014 Springer Science+Business Media New York