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

Novel Nano-Engineered Biomaterials for Bone Tissue Engineering

This Special Issue of Nanomaterials explores the recent advances relating to nano-engineered strategies for biomaterials and implants in bone tissue engineering [...

Air jet spray of nylon 6 membrane structures for bone tissue engineering

A novel porous nylon 6 (N6) scaffold with high and low porosity was designed using a facile, one-step approach. The scaffold samples were prepared using air jet spray (AJS) to obtain high production rates as an alternative low cost, effective technique with precise thickness control. The present results show that AJS adequately produced interconnected porous networks ranging from micron to submicron scales that were observed using a scanning electron microscope. The effect of AJS on the secondary structure of N6 was examined to identify and quantify conformational changes that occurred due to processing. The mechanical properties of the fabricated samples were tested. The results of tensile tests indicated higher tensile strength of AJS scaffold than that of electrospun scaffold

Biocorrosion and osteoconductivity of PCL/nHAp composite porous film-based coating of magnesium alloy

The present study was aimed at designing a novel porous hydroxyapatite/poly(epsilon-caprolactone) (nHAp/PCL) hybrid nanocomposite matrix on a magnesium substrate with high and low porosity. The coated samples were prepared using a dip-coating technique in order to enhance the bioactivity and biocompatibility of the implant and to control the degradation rate of magnesium alloys. The mechanical and biocompatible properties of the coated and uncoated samples were investigated and an in vitro test for corrosion was conducted by electrochemical polarization and measurement of weight loss. The corrosion test results demonstrated that both the pristine PCL and nHAp/PCL composites showed good corrosion resistance in SBF. However, during the extended incubation time, the composite coatings exhibited more uniform and superior resistance to corrosion attack than pristine PCL, and were able to survive severe localized corrosion in physiological solution. Furthermore, the bioactivity of the composite film was determined by the rapid formation of uniform CaP nanoparticles on the sample surfaces during immersion in SBF. The mechanical integrity of the composite coatings displayed better performance (similar to 34% higher) than the uncoated samples. Finally, our results suggest that the nHAp incorporated with novel PCL composite membranes on magnesium substrates may serve as an excellent 3-D platform for cell attachment, proliferation, migration, and growth in bone tissue. This novel as-synthesized nHAp/PCL membrane on magnesium implants could be used as a potential material for orthopedic applications in the future. (C) 2012 Elsevier Masson SAS. All rights reserved

Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants. Crown Copyright (C) 2012 Published by Elsevier B. V. All rights reserved

An in situ hydrothermal fabrication process of poly (vinyl alcohol)/apatite-like nanocomposites with improved thermal and mechanical properties

In this communication, a novel poly(vinyl alcohol) (PVA)/apatite-like nanocomposite films were successfully synthesized using an in situ hydrothermal process at low temperatures and a solution casting method for a facile and effective fabrication process. One step in situ process, comprising nucleation and precipitation of apatite-like nanoparticles in the presence of PVA molecules of obtained PVA/apatite-like nanocomposites. The morphological, structural, thermal, and mechanical properties of the nanocomposites were studied. The morphological analysis confirmed that this process produced amorphous apatite-like nanoparticles in the PVA solution that were homogenously distributed with controlled particle sizes of less than 20 nm in diameter. The incorporation of low quantities of apatite-like nanoparticles into the PVA matrix could significantly improve the mechanical strength of the resultant biocomposite film, which suggests an excellent load transfer between the apatite and the PVA matrix. This improvement in mechanical strength is due to the effective bonding of the filler nanoparticles in the PVA matrix during the hydrothermal reaction, which is supported by the FTIR and TGA/DSC data. This proposed process offers the possibility of using these synthesized nanocomposite materials in biomedical applications. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved

In vitro bioactivity of titanium implants coated with bicomponent hybrid biodegradable polymers

In order to improve the bioactivity and biocompatibility of titanium (Ti) implants, we designed a novel biodegradable hybrid (polycaprolactone/polylactic acid, PCL/PLA) membrane to coat Ti surfaces. The bicomponent PCL/PLA membrane was applied to a Ti substrate starting with the coating of Ti samples with a porous PLA film layer using a dip-coating technique. This was followed by deposition of electrospun PCL nanofibers onto the Ti substrate, resulting in a PCL/PLA bicomponent hybrid coating layer. The cytocompatibility, bioactivity and corrosion performance of PCL/PLA-coated Ti samples was compared to PLA-coated Ti samples and untreated Ti samples. When placed in Hanks' solution, apatite formed on the treated Ti samples but not on untreated Ti samples. When assessing Ti cytocompatibility and MC3T3-E1 osteoblast adherence, proliferation, and survival, our results showed superior performance by polymer-treated Ti samples compared to untreated Ti samples, and maximal osteoblast cell viability was achieved with the bicomponent PCL/PLA hybrid coating layer. Furthermore, during the potentiodynamic polarization test in simulated body fluid, the polymer-coated Ti samples showed corrosion resistance. Therefore, the approach described herein may serve as a basis for the development of polymer-coated Ti surfaces that can be used in dental or orthopedic implants