title: High-strength, in situ-setting calcium phosphate composite with protein release.
abstract: The aim of this study was to develop a mechanically-strong calcium phosphate cement (CPC) with protein release. Chitosan was used to strengthen CPC and control protein release. Mass fraction of protein release = mass of released protein/mass of total protein incorporated into the specimen. Flexural strength (mean +/- sd; n = 6) of CPC containing 100 ng/mL of protein increased from 8.0 +/- 1.4 MPa with 0% chitosan, to 19.8 +/- 1.4 MPa with 15% chitosan (p < 0.05). The latter exceeded the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. When the chitosan mass fraction was increased from 0% to 10% and 15%, protein release varied from 0.60 +/- 0.03 to 0.41 +/- 0.04, and to 0.23 +/- 0.07, respectively (p < 0.05). When powder:liquid ratio increased from 2:1 to 3:1 and 4:1, protein release changed from 0.89 +/- 0.10 to 0.41 +/- 0.04, and to 0.23 +/- 0.07, respectively p < 0.05. Therefore, chitosan content and powder:liquid ratio successfully controlled the protein release. The protein release mass fraction, M, was related to CPC porosity P by: M = 16.9 P(4.5). In summary, a mechanically-strong CPC with controlled protein release was formulated. Protein release was proportional to CPC porosity. The in situ-hardening, nano-apatite composite may have potential for bone tissue engineering, especially when both mechanical strength and controlled release of therapeutic/bioactive agents are needed.
authors: Paffenbarger Research Center, American Dental Association Foundation, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8546, USA.
authors: Michael D
authors: MD
authors: Weir
authors: Hockin H K
authors: HH
authors: Xu
mesh_terms: D001843:Bone Cements / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D003692:Delayed-Action Preparations; D016062:Porosity; D013205:Staphylococcal Protein A / Q000737:chemistry*; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; D003692:Delayed-Action Preparations; D013205:Staphylococcal Protein A; D048271:Chitosan; C020243:calcium phosphate
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