Performance of multiphase scaffolds for bone repair based on two-photon polymerized poly(d,l-lactide-co-ɛ-caprolactone), recombinamers hydrogel and nano-HA

Reda M Felfel,Dhanak Gupta,Adi Z Zabidi,Amy Prosser,Colin A Scotchford,Virginie Sottile,David M Grant

doi:10.1016/j.matdes.2018.09.035

Reda M Felfel, Dhanak Gupta + Show 5 more

Open Access

https://doi.org/10.1016/j.matdes.2018.09.035

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Abstract

Multiphase hybrids were fabricated from poly(d,l-lactide-co-ɛ-caprolactone) (PLCL) copolymer scaffolds impregnated with silk-elastin-like recombinamers (SELRs) hydrogel containing 2 wt% hydroxyapatite nanoparticles (nHA). The PLCL scaffolds, triply-periodic minimal surface geometry, were manufactured using two-photon stereolithography. In vitro degradation studies were conducted on PLCL scaffolds in inflamed tissue mimic media (pH ~ 4.5–6.5) or phosphate buffered saline (PBS) at 37 °C. Compression test revealed instant shape recovery of PLCL scaffolds after compression to 70% strain, ideal for arthroscopic delivery. Degradation of these scaffolds was accelerated in acidic media, where mass loss and compressive properties at day 56 were about 2–6 times lower than the scaffolds degraded in PBS. No significant difference was seen in the compressive properties between PLCL scaffolds and the hybrids due to the order of magnitude difference between the hydrogels and the PLCL scaffolds. Moreover, degradation properties of the hybrids did not significantly change by inclusion of SELR+/−nHA nanocomposite hydrogels. The hybrids lost approximately 40% and 84% of their initial weight and mechanical properties, respectively after 112 days of degradation. Cytotoxicity assessment revealed no cytotoxic effects of PLCL or PLCL-SELR+/−2%nHA scaffolds on bone marrow-derived human Mesenchymal Stem Cells. These findings highlight the potential of these hybrid constructs for bone and cartilage repair.

Highlights

Natural polymers such as chitosan, collagen, gelatine and synthetic polymers, e.g. polylactic acid [1], polycaprolactone (PCL), polyglycolic acid (PGA), and their copolymers have been thoroughly investigated for a range of biomedical applications [2], from sutures and soft tissue grafting to load-bearing bone fixation devices [3]
A highly controllable 3D copolymer scaffold architecture was achieved using two photon polymerization (TPP), which were infiltrated with silk-elastin-like recombinamers (SELRs) hydrogel with and without nHA particles
In order to investigate the mechanical performance of PLCL-SELR-nHA hybrids, compressive properties of PLCL scaffold, SELR and SELR-nHA were separately evaluated

Summary

Introduction

Natural polymers such as chitosan, collagen, gelatine and synthetic polymers, e.g. polylactic acid [1], polycaprolactone (PCL), polyglycolic acid (PGA), and their copolymers have been thoroughly investigated for a range of biomedical applications [2], from sutures and soft tissue grafting to load-bearing bone fixation devices [3]. Natural and synthetic polymers have been fabricated into porous structures using a variety of methods such as porogen leaching, phase separation, freeze drying and electrospinning [2,3,5]. These techniques do not offer good control over geometry, porosity, pore size and strut thickness, which can significantly affect cell behaviour and fate [6,7]. A thermoset or thermoplastic layer-by-layer approach (stereolithography) has been applied using photo-polymerization of multifunctional monomers containing photoinitiators and acrylates reactive groups [9,11] This method enables manufacturing of hierarchical polymer constructs with a well-defined geometry, porous structure and surface roughness of up to 5 μm resolution [10]. Scaffolds of PLA, PCL and polyethylene glycol (PEG) have been fabricated using 2PA stereolithography technology for biomedical purposes [10,12]

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