Biodegradable Elastic Sponge from Nanofibrous Biphasic Calcium Phosphate Ceramic as an Advanced Material for Regenerative Medicine

Yonggang Zhang,Pamela Habibovic,Roman Truckenmüller,Francesca Giacomini,Mohammad Soleimani,Heiner Friedrich,Jiaping Li

doi:10.1002/adfm.202102911

Abstract

AbstractBiodegradable porous calcium phosphate (CaP) ceramics are widely used as synthetic graft substitutes for bone regeneration, owing to their chemical and structural similarity to bone and associated bioactivity in terms of bone‐bonding, osteoconductive, and even osteoinductive properties. Nevertheless, the intrinsic brittleness and poor processability of porous CaP ceramics strongly impair their clinical applicability. Herein, a biphasic calcium phosphate (BCP) sponge is developed that consists of a self‐supporting network of seamlessly interwoven hydroxyapatite nanowires and β‐tricalcium phosphate nanofibers and possesses a highly interconnected porous structure with open cell geometry and ultrahigh porosity. Owing to its unique properties, the ceramic sponge can be easily processed into various shapes and dimensions, such as cylindrical scaffolds and thin, flexible membranes. Moreover, the BCP sponge can be introduced into a bone defect in a compacted or folded state from a syringe and, upon wetting, expand to its original shape, thereby filling the cavity. The nanofibrous sponge gradually degrades in vitro and rapidly mineralizes when immersed in simulated body fluid. Moreover, it adsorbs significantly more proteins than a conventional porous BCP ceramic. Finally, the nanofibrous sponge supports the attachment, proliferation, and osteogenic differentiation of human mesenchymal stromal cells comparable to the conventional porous BCP ceramic.

Highlights

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Β-TCP nanofibers were prepared by sintering the precursor ceramic consisting of octacalcium phosphate (OCP) and calcium-deficient HA (CDHA) at 800 °C for 3 h (Figure S1D–F, Supporting Information)
We propose the following mechanism for the water-triggered shape-memory mechanism: 1) during compression, the flexible HA nanowires and β-TCP nanofibers around the pore walls transform from relaxed state to bent state and a certain amount of energy is stored inside the sponge, like in the case of a compressed spring; 2) when the load is removed, the energy stored within the BCP ceramic sponge is not sufficient to overcome the internal material system resistance to return to the relaxed state; 3) when the BCP sponge is placed in water, the inflow of water aids in overcoming the resistance, resulting in the recovery of the original shape of the BCP sponge

Summary

Introduction

Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal. Biodegradable porous calcium phosphate (CaP) ceramics are widely used bone graft substitutes, and cell- and/or growth factor-based tissue-engineered conas synthetic graft substitutes for bone regeneration, owing to their chemical structs. 3D porous scaffold materials play and structural similarity to bone and associated bioactivity in terms of bonebonding, osteoconductive, and even osteoinductive properties. The nanofibrous sponge gradually degrades in vitro and rapidly mineralizes when immersed in simulated body fluid. It adsorbs significantly more proteins than a conventional porous BCP ceramic. Besides being bone-bonding and the nanofibrous sponge supports the attachment, proliferation, and osteofacilitating new bone deposition on the genic differentiation of human mesenchymal stromal cells comparable to the surface (osteoconduction), a family of CaP conventional porous BCP ceramic. In the past three decades, a variety of strategies has been inves- tional advantages of CaP-based bone graft substitutes are that tigated for treating large, clinically relevant bone defects that do they, unlike natural bone grafts, do not impose risks of mornot heal spontaneously, including natural bone grafts, synthetic bidity or infection of the donor site, they can be produced in

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