Delivery of Growth Factors Using a Smart Porous Nanocomposite Scaffold to Repair a Mandibular Bone Defect

Abstract

Implantation of a porous scaffold with a large volume into the body in a convenient and safe manner is still a challenging task in the repair of bone defects. In this study, we present a porous smart nanocomposite scaffold with a combination of shape memory function and controlled delivery of growth factors. The shape memory function enables the scaffold with a large volume to be deformed into its temporal architecture with a small volume using hot-compression and can subsequently recover its original shape upon exposure to body temperature after it is implanted in the body. The scaffold consists of chemically cross-linked poly(ε-caprolactone) (c-PCL) and hydroxyapatite nanoparticles. The highly interconnected pores of the scaffold were obtained using the sugar leaching method. The shape memory porous scaffold loaded with bone morphogenetic protein-2 (BMP-2) was also fabricated by coating the calcium alginate layer and BMP-2 on the surface of the pore wall. Under both in vitro and in vivo environmental conditions, the porous scaffold displays good shape memory recovery from the compressed shape with deformed pores of 33 μm in diameter to recover its porous shape with original pores of 160 μm in diameter. In vitro cytotoxicity based on the MTT test revealed that the scaffold exhibited good cytocompatibility. The in vivo micro-CT and histomorphometry results demonstrated that the porous scaffold could promote new bone generation in the rabbit mandibular bone defect. Thus, our results indicated that this shape memory porous scaffold demonstrated great potential for application in bone regenerative medicine.

Shape Memory Polymer–Inorganic Hybrid Nanocomposites

“…For example, when researchers added the bone mineral-mimicking hydroxyapatite (HA) to a poly(D,L-lactide) (PDLLA) network, they not only validated a SMPINC with fully explored biocompatibility but also showed a network with significantly increased shape recovery ratios of up to 99.5%, depending on the ratio of HA to PDLLA [99,100]. HA has also been used in a growth factor delivery system, where the HA loading of the chemically crosslinked poly(ε-caprolactone) (c-PCL) was used to create uniform pore sizes in the smart network [101]. The process described in Fig.…”

Responsive Biomaterials: Advances in Materials Based on Shape‐Memory Polymers

“…Critically, when implanted in a rabbit mandibular bone defect this material was shown to promote new bone generation after 8 weeks. [59] …”

Polymeric nanobiocomposites for biomedical applications

“…As an earliest initiative, Usuki et al 84,85 used compatibilizing/coupling agent (i.e., amino acid) while developing polyamide 6-clay nanobiocomposites. Similarly, Lopez et al 102 studied the performance of polypropylene grafted maleic anhydride (MAH) and polypropylene grafted diethyl maleate as compatibilizing agents.…”

“…One of the most noticeable advantages of the shape memory polymers is their ability to be used for minimally invasive surgery; the mechanism is that the shape memory polymers can be designed to fit into small incisions and upon deployment into the body they reach their functional shapes. 84 Exploiting this mechanism, Liu et al 85 developed new type of composites which were able to deliver of growth factors along with shape memory function. The poly (e-caprolactone) (c-PCL) and hydroxyapatite nanoparticles scaffolds were chemically fabricated; and the volume of scaffolds was reduced by using hot compression, and these compressed scaffolds attained their functional shape upon exposure to the body temperature.…”