Development and characterization of non-sintered blocks of HAp91®/silk fibroin dissolved with formic acid

Reference	Presenter	Authors (Institution)	Abstract
03-011	Sergio Akinobu Yoshioka	Yoshioka, S.A.(Universidade de São Paulo); Restrepo, S.G.(Universidade de São Paulo); Vieira, D.(Programa de Pós-Graduação Interunidades em Bioengenharia (EESC/FMRP/IQSC) - USP São Carlos); Castro Máximo Bicalho, S.M.(JHS Biomateriais);	Biomaterials for bone tissue regeneration represent a major focus of orthopedic research. However, only a few materials are used today because of their low compressive strength. The use of porous composites scaffolds with ceramic and polymer components supports cell and tissue growth. The challenge is to find a biomaterial that can biomimetic the mechanical and biological bone tissue matrix. As a fibrous protein, silk fibroin (SF), from Bombyx mori, is used as biomedical material due to its excellent properties, like biocompatibility, biodegradability, minimal inflammatory reaction, and high thermal properties (degradation temperature >150ºC). Synthetic hydroxyapatite (HAp91®) has a similar composition to human bone, excellent biocompatibility, affinity to biopolymers, and high osteogenic potential. The silk and hydroxyapatite composite had been studied due they efficient biocompatibility and bone-mimicking properties. In the present study, the SF was degummed using sodium carbonate and dissolved with formic acid, and then blocks of HAp91® and silk fibroin were made in a weight ratio of 75/25, closest to the inorganic/organic natural bone (70/30). In order to improve porosity, granular sugar was added to the blocks and then compare with nom sugar ones. The morphological and physical analysis showed that the mechanical strength and porosity was mimetic to the porous bone. Scanning electron microscopy (SEM) showed structures with macro and micro porous. A qualitative Ca/P ratio, measure with energy dispersive X-ray spectrum (EDS), was bigger than the natural bone, 1.67. The results provides a potential material that might be useful as replaceable bone tissue grafts.
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