JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS 4 (2011) 331–339 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jmbbm Research paper Reinforcement of calcium phosphate cement with multi-walled carbon nanotubes and bovine serum albumin for injectable bone substitute applications Kean-Khoon Chew a , Kah-Ling Low a , Sharif Hussein Sharif Zein a,∗ , David S. McPhail b , Lutz-Christian Gerhardt b,1 , Judith A. Roether b,2 , Aldo R. Boccaccini b,c a School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang, Malaysia b Department of Materials, Imperial College London, Prince Consort Road, London SW7 2AZ, UK c Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany ARTICLE INFO Article history: Received 11 August 2010 Received in revised form 28 October 2010 Accepted 31 October 2010 Published online 12 November 2010 Keywords: Calcium phosphate cement (CPC) Carbon nanotubes (CNTs) Bovine serum albumin (BSA) Compressive strength Injectability ABSTRACT This paper presents the development of novel alternative injectable calcium phosphate cement (CPC) composites for orthopaedic applications. The new CPC composites comprise β-tri-calcium phosphate (β-TCP) and di-calcium phosphate anhydrous (DCPA) mixed with bovine serum albumin (BSA) and incorporated with multi-walled carbon nanotubes (MWCNTs) or functionalized MWCNTs (MWCNTs–OH and MWCNTs–COOH). Scanning electron microscopy (SEM), compressive strength tests, injectability tests, Fourier transform infrared spectroscopy and X-ray diffraction were used to evaluate the properties of the final products. Compressive strength tests and SEM observations demonstrated particularly that the concomitant admixture of BSA and MWCNT improved the mechanical properties, resulting in stronger CPC composites. The presence of MWCNTs and BSA influenced the morphology of the hydroxyapatite (HA) crystals in the CPC matrix. BSA was found to act as a promoter of HA growth when bounded to the surface of CPC grains. MWCNT–OH- containing composites exhibited the highest compressive strengths (16.3 MPa), being in the range of values for trabecular bone (2–12 MPa). c ⃝ 2010 Elsevier Ltd. All rights reserved. 1. Introduction The improved life expectancy in developed countries has led to a significant rise in the number of musculoskeletal disorders, such as osteoporosis and osteoarthritis (Bohner, 2000). Minimally invasive surgical techniques have been ∗ Corresponding author. Tel.: +60 4 599 6442; fax: +60 4 594 1013. E-mail address: chhussein@eng.usm.my (S.H. Sharif Zein). 1 Present address: Technische Universiteit Eindhoven, Biomedical Engineering, PO Box 513, 5600 MB Eindhoven, The Netherlands. 2 Present address: Department of Materials Science and Engineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany. shown to have important clinical potential for stabilizing such disorders (Mermelstein et al., 1998). Bio-resorbable calcium phosphate cements (CPCs) represent an interesting alternative to traditional bone graft materials. Moreover, CPC is a highly desirable material for orthopaedic applications due to its mouldability, in situ self-hardening ability, excellent 1751-6161/$ - see front matter c ⃝ 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jmbbm.2010.10.013