RESEARCH ARTICLE Biomimetic apatite layer formation on a novel citrate starch scaffold suitable for bone tissue engineering applications Jhamak Nourmohammadi 1 , Sepideh Shahriarpanah 1 , Negin Asadzadehzanjani 1 , Shila Khaleghpanah 2 and Shafagh Heidari 3 1 Faculty of New Sciences and Technologies, Department of Life Science Engineering, University of Tehran, Tehran, Iran 2 Department of Material Science, Sharif University, Tehran, Iran 3 National Cell Bank, Pasteur Institute, Tehran, Iran The formation of biomimetic bone-like apatite layers throughout the biopolymer-based hydrogel scaffold is an attractive approach in bone tissue engineering. Here, the starch scaffold was prepared using a combination of particulate leaching and freeze-drying techniques. The fabricated structures were then modified by citric acid to investigate the formation of bone-like apatite layer on the porous citrate-based scaffold after soaking in simulated body fluid (SBF). The Fourier Transform Infrared (FTIR) spectra and X-ray diffraction (XRD) patterns revealed that the B-type carbonated apatite has successfully deposited on the scaffold after immersing in SBF for 28 days. Indeed, high chemical affinity of carboxyl group in citrate starch resulted in primary heterogeneous nucleation of apatitic calcium phosphate throughout the starch hydrogel. Moreover, the biological activity of MG63 osteoblast-like cells cultured on the scaffold was assessed using indirect MTT assay and cell attachment experiment. The results indicated that the cells show significant biocompatibility and cell attachment. Received: August 10, 2015 Revised: December 31, 2015 Accepted: January 8, 2016 Keywords: Apatite deposition / Biomimetic method / Bone tissue engineering / Citrate starch / Scaffold : Additional supporting information may be found in the online version of this article at the publisher’s web-site. 1 Introduction These days, starch-based materials have become popular in the field of biomedical engineering due to their low cost, availability, biocompatibility, biodegradability, and ease of processability. As a polysaccharide, starch consists of two biomacromolecules: 20% amylose (linear; a-1,4-glycosidic linkage) and 80% amylopectin (branched; a-1,4 and a-1,6- glycosidic linkage) [1]. The preparation of porous starch-based structures has been investigated in many reports. Nasri- Nasrabadi et al. [2] prepared a porous starch/cellulose nanofibers composite that could potentially be used in cartilage tissue engineering. Moreover, as mentioned by Salgado et al. [3], the scaffold fabricated by the blend of corn starch with ethylene–vinyl alcohol demonstrates appropriate properties for bone regeneration. Nevertheless, the lack of osteo-coductivity and -inductivity of these materials limit their application as bone substitutes [3, 4]. To examine the bioactivity of such scaffolds, researchers incorporate hydroxyapatite, bioactive glass, and bioactive glass-ceramics into the starch matrix [5–7]. However, the lack of homogeneity during the distribution of ceramic fillers into polymer matrix and the weak bonding between ceramic and polymer matrix were observed in such reports. Fortunately, the intrinsic nature of apatite deposition on the surface of CaO–SiO 2 glasses has developed an effective approach in coating bone-like apatite layer on a variety of materials such as metals, ceramics, and polymers [8]. Reportedly, negatively charged functional groups such as carboxyl (COOH) are also considered as nucleation sites for Colour Online: See the article online to view figures in colour. Correspondence: Dr. Jhamak Nourmohammadi, Faculty of New Sciences and Technologies, Department of Life Science Engineering, University of Tehran, P.O.Box: 14395-1561,Tehran, Iran E-mail: j_nourmohammadi@ut.ac.ir Fax: þ98 2188497324 Abbreviations: EDS, energy dispersive spectroscopy; PLA, polylactic acid; SBF, simulated body fluid DOI 10.1002/star.201500216 Starch/Stärke 2016, 68, 1275–1281 1275 ß 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.starch-journal.com