Electrospun polyurethane/hydroxyapatite bioactive Scaffolds for bone tissue engineering: The role of solvent and hydroxyapatite particles

Abstract

Polyurethane (PU) is a promising polymer to support bone-matrix producing cells due to its durability and mechanical resistance. In this study two types of medical grade poly-ether urethanes Z3A1 and Z9A1 and PU-Hydroxyapatite (PU-HA) composites were investigated for their ability to act as a scaffold for tissue engineered bone. PU dissolved in varying concentrations of dimethylformamide (DMF) and tetrahydrofuran (THF) solvents were electrospun to attain scaffolds with randomly orientated non-woven fibres. Bioactive polymeric composite scaffolds were created using 15 wt% Z3A1 in a 70/30 DMF/THF PU solution and incorporating micro- or nano-sized HA particles in a ratio of 3:1 respectively, whilst a 25 wt% Z9A1 PU solution was doped in ratio of 5:1. Chemical properties of the resulting composites were evaluated by FTIR and physical properties by SEM. Tensile mechanical testing was carried out on all electrospun scaffolds. MLO-A5 osteoblastic mouse cells and human embryonic mesenchymal progenitor cells, hES-MPs were seeded on the scaffolds to test their biocompatibility and ability to support mineralised matrix production over a 28 day culture period. Cell viability was assayed by MTT and calcium and collagen deposition by Sirius red and alizarin red respectively. SEM images of both electrospun PU scaffolds and PU-HA composite scaffolds showed differences in fibre morphology with changes in solvent combinations and size of HA particles. Inclusion of THF eliminated the presence of beads in fibres that were present in scaffolds fabricated with 100% DMF solvent, and resulted in fibres with a more uniform morphology and thicker diameters. Mechanical testing demonstrated that the Young׳s Modulus and yield strength was lower at higher THF concentrations. Inclusion of both sizes of HA particles in PU-HA solutions reinforced the scaffolds leading to higher mechanical properties, whilst FTIR characterisation confirmed the presence of HA in all composite scaffolds. Although all scaffolds supported proliferation of both cell types and deposition of calcified matrix, PU-HA composite fibres containing nano-HA enabled the highest cell viability and collagen deposition. These scaffolds have the potential to support bone matrix formation for bone tissue engineering.

A Study of Hybrid Composite Hydroxyapatite (HA)-Geopolymers as a Material for Biomedical Application

“…The results indicate that the magnitude of samples capacitance is directly proportional to the weight of HA and hence the thickness of the samples. This results prove that the hybrid composite HA-geopolymer exhibit a bioactive properties [17,18]. The results also suggest that use of geopolymers to bind HA do not reduce the bioactive properties of HA and therefore can be applied as biosensor [19,20].…”

Enhancing the proliferation of MC3T3-E1 cells on casein phosphopeptide-biofunctionalized 3D reduced-graphene oxide/polypyrrole scaffolds

“…With these guidelines in mind, in a few recent studies, several scaffolds have been successfully developed, such as polyurethane, (PU), 5 biphasic calcium phosphate (BCP), 6 polyethylene glycol (PELA), 7 and 3D rGO/PPY. 8 On the whole, these scaffolds can function as alternative 3D matrixes for bone tissue engineering.…”

“…However, these scaffolds are usually hydrophobic and lack bioactivity, preventing cell adhesion and proliferation. [5][6][7][8][9] Some reports also claim that the implant materials without bioactivity cannot ultimately form a good osseointegration with new bone, and angular absorption, prolonging the healing time and even implant failure are generally involved. 10,11 Therefore, plenty of experimental methods, such as plasma treatment, ozone or photo-induced graing, and surface oxidation strategies are generally needed to introduce some hydrophilic/bioactivity components onto the surfaces of the matrix.…”

Electrospun Nanocomposite Materials, A Novel Synergy of Polyurethane and Bovine Derived Hydroxyapatite

“…Previous research has been investigated for electrospun polyurethane/hydroxyapatite scaffolds [11], development and characterization of Polyurethane-Hydroxyapatite bio nanocomposites [12], Polyurethane/fluorhydroxyapatite nanocomposite scaffolds [13], investigation of PU and HA [14].…”