Mineralized self-assembled silk fibroin/cellulose interpenetrating network aerogel for bone tissue engineering.

The preparation of bioactive materials with biomolecules as templates to control the nucleation and growth of nano-hydroxyapatite (n-HA) crystals is a vital research field in bone tissue engineering. However, meeting the performance requirements of possessing appropriate surface roughness, high porosity, structural stability, adequate mechanical strength, biodegradability and biocompatibility at the same time is the core issue that restricts the development of these biomimetic materials in biosciences as well as medical clinical translation. In this work, a mineralized self-assembled silk fibroin (SF)/cellulose interpenetrating network composite aerogel (M-S-C) material was prepared by freeze-drying using sol-gel and in situ mineralization strategy. The effects of the main factors, such as the surface properties of SF macromolecules and the change of mineralization time, on the n-HA self-assembly process and the property of M-S-C under defined conditions were explored. The properties of M-S-C, including the physicochemical properties, morphology, mechanical property, degradation behavior and in vitro cytotoxicity, were investigated to evaluate its application prospects in bone tissue engineering. M-S-C exhibits the microstructure required for an ideal cancellous bone repair material, porosity up to 99.2%, high thermal stability, moderately adjustable compressive strength (12.7-22.4 MPa), and appreciable in vitro degradation rate. Moreover, M-S-C extracts can significantly accelerate the proliferation of human embryonic kidney cells. This mineralized interpenetrating polymer network aerogel material with excellent comprehensive performance shows potential for application in bone repair and regeneration.

A new cancellous bone material of silk fibroin/cellulose dual network composite aerogel reinforced by nano-hydroxyapatite filler.

Composites materials comprised of biopolymeric aerogel matrices and inorganic nano-hydroxyapatite (n-HA) fillers have received considerable attention in bone engineering. Although with significant progress in aerogel-based biomaterials, the brittleness and low strengths limit the application. The improvements in toughness and mechanical strength of aerogel-based biomaterials are in great need. In this work, an alkali urea system was used to dissolve, regenerate and gelate cellulose and silk fibroin (SF) to prepare composite aerosol. A dual network structure was shaped in the composite aerosol materials interlaced by sheet-like SF and reticular cellulose wrapping n-HA on the surface. Through uniaxial compression, the density of the composite aerogel material was close to the one of natural bone, and mechanical strength and toughness were high. Our work indicates that the composite aerogel has the same mechanical strength range as cancellous bone when the ratio of cellulose, n-HA and SF being 8:1:1. In vitro cell culture showed HEK-293T cells cultured on composite aerogels had high ability of adhesion, proliferation and differentiation. Totally, the presented biodegradable composite aerogel has application potential in bone tissue engineering.