Nanocomposite scaffolds of bioactive glass ceramic nanoparticles disseminated chitosan matrix for tissue engineering applications

Abstract

A novel nanocomposite scaffold of chitosan (CS) and bioactive glass ceramic nanoparticles (nBGC) was prepared by blending nBGC with chitosan solution followed by lyophilization technique. The particle size of the prepared nBGC was found to be 100 nm. The prepared composite scaffolds were characterized using techniques such as Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD). The SEM studies showed that the bioactive nBGC were homogenously distributed within the chitosan matrix. The swelling, density, degradation and in-vitro biomineralization studies of the composite scaffolds were also studied. The composite scaffolds showed adequate swelling and degradation properties. The in-vitro biomineralization studies confirmed the bioactivity nature of the composite scaffolds. Cytocompatability of the composite scaffolds were assessed by MTT assay, direct contact test and cell attachment studies. Results indicated no toxicity, and cells attached and spread on the pore walls offered by the scaffolds. These results indicate that composite scaffolds developed using nBGC disseminated chitosan matrix as potential scaffolds for tissue engineering applications.

Introduction

Bone tissue engineering is gaining popularity as alternative method for treatment of osseous defects. A number of biodegradable polymers have been explored for tissue engineering purposes. These include synthetic polymers like poly(caprolactone), poly(lactic-co-glycolic acid), poly(ethylene glycol), poly(vinyl alcohol) and natural polymers like alginate, collagen, gelatin, chitin, chitosan etc. (Hirano et al., 1990). Chitosan is a biopolymer derived from partial deacetylation of chitin. Chitosan is considered as an appropriate functional material for biomedical applications because of its high biocompatibility, biodegradability, non-antigenicity and protein adsorption properties (Gupta et al., 2006, Jayakumar et al., 2007, Jayakumar et al., 2005, Jayakumar et al., 2006, Jayakumar et al., 2008, Muzzarelli et al., 1988, Muzzarelli, 2009). CS favour cell adhesion due to its chemical backbone, which resembles glycosaminoglycans, a major component of bone and cartilage. However, continuous efforts are being made to improve the bioactivity & compatibility of chitosan along with better mechanical properties. Many inorganic materials are in the literature, like hydroxyapatite (Jayakumar and Tamura, 2006, Jiang et al., 2006, Kong et al., 2005, Zhang et al., 2008, Zhao et al., 2006), β-TCP (Takahashi et al., 2005, Yin et al., 2003) and montmorillonite (Zheng et al., 2007), which are added to improve the properties of chitosan.

Bioactive glass ceramic is a group of osteoconductive biomaterial used as bone repair materials. They are silicate glasses containing SiO₂–CaO–P₂O₅ networks. This ceramic is known to bond to hard and soft tissues by the formation of surface hydroxy carbonate apatite (HCA) layer (Cao & Hench, 1996). Reports also suggest that bioactive glass ceramic influences the cell adhesion, proliferation, differentiation and colonization on surface of implants (Bosetti and Cannas, 2005, Verrier et al., 2004, Xynos et al., 2000). Bioactive glass also allows the expression of peculiar osteoblast differentiation marker, namely osteocalcin (Foppiano et al., 2007, Oliva et al., 1998).

Nanosurface and nanoparticles are known to influence cell behaviour including attachment & spreading (Dalby et al., 2006, Lauer et al., 2001, Linez-Bataillon et al., 2002). Significantly enhanced cell–material interactions are reported on nanophase ceramics compared to microphase ceramics (Webster, Ergun, Doremus, Siegel, & Bizios, 2000). Therefore, continuous efforts are being made to engineer biomaterials/particles in nanoscale topography/size. Recently, bioactive glass ceramic has been synthesized as nanoparticles (nBGC) by sol–gel process (Xia & Chang, 2007). Hence it is interesting to investigate the possibility of preparing a scaffold using chitosan matrix disseminated with nBGC to evaluate the influence of nBGC addition in scaffold properties for tissue engineering applications. Therefore in this paper, we address the preparation of chitosan/nBGC composite scaffolds and its properties relevant to tissue engineering applications.