Preparation, mechanical properties and in vitro degradability of wollastonite/tricalcium phosphate macroporous scaffolds from nanocomposite powders Faming Zhang Æ Jiang Chang Æ Kaili Lin Æ Jianxi Lu Received: 19 January 2006 / Accepted: 27 November 2006 / Published online: 28 June 2007 Ó Springer Science+Business Media, LLC 2007 Abstract A new class of scaffolds with a gain size of 200 nm was prepared from wollastonite/tricalcium phos- phate (WT) nanocomposite powders (termed ‘‘nano-sin- tered scaffolds’’) through a two-step chemical precipitation and porogen burnout techniques. For a comparison, WT scaffolds with a grain size of 2 lm were also fabricated from submicron composite powders (termed ‘‘submicron- sintered scaffolds’’) under the same condition. The resul- tant scaffolds showed porosities between 50 ± 1.0% and 65 ± 1.0% with a pore size ranging from 100 lm to 300 lm. The WT nano-sintered scaffolds exhibited com- pressive strength and elastic modulus values that were about twice that of their submicron-sintered counterparts. The in vitro degradation tests demonstrated that the degradability could be regulated by the grain size of bioceramics. The decreased specific surface area of pores in the nano-sintered scaffolds led to their reduced degra- dation rate. The mechanical properties of the nano-sintered scaffolds exhibited less strength loss during the degradation process. The WT macroporous nano-sintered scaffolds are a promising and potential candidate for bone reconstruction applications. Introduction Bone defects that occur due to surgery, trauma, or abnor- mal development require skeletal reconstruction. Bone reconstructive methods require grafts or synthetic material to replace lost bone or enhance new bone formation [1]. Since their compositions are similar to the inorganic components of bone, calcium phosphate bioceramics, especially hydroxyapatite (HA) and b-tricalcium phosphate (b-TCP), have been extensively explored as grafts for bone regeneration applications [2]. HA possesses excellent bio- activity whereas b-TCP exhibits biodegradability. There- fore, many studies have focused on developing HA/b-TCP biphasic calcium phosphate (BCP) bioceramics because their biological performances are more effective than pure HA or b-TCP [3–5]. The bioactivity and biodegradability of BCP composites could be controlled by modulating the HA/b-TCP ratio. Recent studies revealed that wollastonite (CaSiO 3 ) ceramics are bioactive and can be used as a new bioactive material [6, 7]. Recent studies in our group showed that the wollastonite ceramics also possess better mechanical properties and more degradability than HA [8–11]. It is well known that the HA ceramics are brittle and almost not degradable. Expectedly, the mechanical properties of the grafts could be enhanced by using wollastonite instead of HA with b-TCP phase. De Aza et al. first studied the wollastonite/TCP (WT) composite and found it has good bioactivity as evidenced by deposition of a bone like apa- tite layer on the surface of the composite [12]. Huang et al. investigated the apatite formation mechanism on wollas- tonite/b-TCP surfaces [13]. The above studies mainly focused on the bioactivity of the dense WT bioceramics without consideration of the mechanical properties and degradability. Although the dense WT bioceramics could F. Zhang  J. Chang (&)  K. Lin  J. Lu Biomaterials and Tissue Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China e-mail: jchang@mail.sic.ac.cn J. Lu Institut de Recherche sur les Biomate ´rieux et les Biotechnologies, Universite ´ du Littoral Co ˆte d’Opale, Berck sur Mer Cedex 62608, France 123 J Mater Sci: Mater Med (2008) 19:167–173 DOI 10.1007/s10856-006-0056-3