Effect of molecular mass on the properties of chitosan/hydroxypatite biocomposites incorporated with niobium

Full text: Chitosan (Chi) is used for the reconstruction and replacement of bone tissues due to its biocompatibility, biodegradability and bioactivity [1]. However, some properties of chitosan should be improved to be effectively used as biomaterial in bone repair. Thus, biocomposites based on Chi with inorganic components such as hydroxyapatite (HAp) may significantly improve of the properties. Besides, it is feasible to add small contents of cations to HAp such as Zn²⁺, Sr²⁺, Nb⁵⁺ aiming at further improvements on their properties [2]. In this study, it is reported the synthesis and characterization of biocomposites based on Chi with different polymer chain length and HAp partially incorporated with niobium (Chi/HApNb).The HAp modified Nb⁵⁺ was prepared by the co-precipitation method in alkaline aqueous media based on the procedure previously reported by our group [3]. Membranes were produced by cast method of Chi solutions prepared in water concentration at 0.5% in acetic acid, followed by the incorporation of HAp modified Nb⁵⁺. The biocomposites were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD), and swelling assays. The results revealed the presence of Nb incorporated to HAp, which has partially replaced Ca²⁺ sites in the apatite structure. In XRD results it was observed the main peaks associated with crystalline phases. The FTIR spectra of Chi showed the presence of major chemical functional groups (amines, hydroxyls and acetyls). The morphological characteristics and swelling of Chi/HApNb were affected by the molecular mass of the biopolymer (Chi). Thus, the Chi/HApNb may be considered as potential alternatives as biomaterials for bone repair and substitutes. References: [1] Costa-Jr E.Z. and MANSUR H.S. Quím. Nova. 31,2008. [2] Costa E. et al. Rev. Biot.Ciência e Desenvolvimento. 6(30), 2003. [3] Santos M. et al. Mat. Res. 7(4):625-630,2004. (author)