International Journal of Nanomedicine (Nov 2018)
Reinforcement of calcium phosphate cement using alkaline-treated silk fibroin
Abstract
Muli Hu,1,2,* Zhiwei He,2,3,* Fengxuan Han,1,2 Chen Shi,4 Pinghui Zhou,2 Feng Ling,1,2 Xuesong Zhu,2 Huilin Yang,2 Bin Li2,5 1Department of Polymer Science, College of Chemistry, Chemical Engineering and Materials Science, Orthopaedic Institute, Soochow University, Suzhou, China; 2Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, Suzhou, China; 3Department of Orthopaedics, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, China; 4Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore; 5China Orthopaedic Regenerative Medicine Group (CORMed), Hangzhou, China *These authors contributed equally to this work Background: Bone cement plays an important role in the treatment of osteoporotic vertebral compression fractures. Calcium phosphate cement (CPC) is a potential alternative to poly(methyl methacrylate), currently the gold standard of bone cements. However, the poor mechanical properties of CPCs limit their clinical applications. The objective of this study was to develop reinforced CPCs for minimally invasive orthopedic surgeries by compositing silk fibroin (SF) with α-tricalcium phosphate.Methods: SF solution was treated with calcium hydroxide and characterized by Zeta potential analyzer and Fourier transform infrared spectroscopy. The alkaline-treated SF (tSF) was composited with α-tricalcium phosphate to obtain tSF/CPC composite, which was characterized using mechanical tests, scanning electron microscopy, handling property and biocompatibility tests, and sheep vertebral augmentation tests.Results: Upon treatment with calcium hydroxide, larger SF particles and more abundant negative charge appeared in tSF solution. The tSF/CPCs exhibited a compact structure, which consisted of numerous SF -CPC clusters and needle-like hydroxyapatite (HAp) crystals. In addition, high transition rate of HAp in tSF/CPCs was achieved. As a result, the mechanical property of tSF/CPC composite cements was enhanced remarkably, with the compressive strength reaching as high as 56.3±1.1 MPa. Moreover, the tSF/CPC cements showed good injectability, anti-washout property, and decent biocompatibility. The tSF/CPCs could be used to augment defected sheep vertebrae to restore their mechanical strength.Conclusion: tSF/CPC may be a promising composite bone cement for minimally invasive orthopedic surgeries. Keywords: bone cement, silk fibroin, calcium phosphate, calcium hydroxide, reinforcement
