Hardystonite improves biocompatibility and strength of electrospun polycaprolactone nanofibers over hydroxyapatite: A comparative study Amit K. Jaiswal a , Hemlata Chhabra b , Sachin S. Kadam b , Kishore Londhe a , Vivek P. Soni a , Jayesh R. Bellare b, ⁎ a Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India b Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India abstract article info Article history: Received 13 September 2012 Received in revised form 19 January 2013 Accepted 12 March 2013 Available online 21 March 2013 Keywords: Hardystonite Hydroxyapatite Cell proliferation Cellular infiltration Electrospinning Mineralization The aim of this study was to compare physico-chemical and biological properties of hydroxyapatite (HA) and hardystonite (HS) based composite scaffolds. Hardystonite (Ca 2 ZnSi 2 O 7 ) powders were synthesized by a sol– gel method while polycaprolactone–hardystonite (PCL–HS) and polycaprolactone–hydroxyapatite (PCL–HA) were fabricated in nanofibrous form by electrospinning. The physico-chemical and biological properties such as tensile strength, cell proliferation, cell infiltration and alkaline phosphatase activity were determined on both kinds of scaffolds. We found that PCL–HS scaffolds had better mechanical strength compared to PCL–HA scaffolds. Addition of HA and HS particles to PCL did not show any inhibitory effect on blood biocompatibility of scaffolds when assessed by hemolysis assay. The in vitro cellular behavior was evaluated by growing murine adipose-tissue-derived stem cells (mE-ASCs) over the scaffolds. Enhanced cell proliferation and improved cellu- lar infiltrations on PCL–HS scaffolds were observed when compared to HA containing scaffolds. PCL–HS scaffolds exhibited a significant increase in alkaline phosphatase (ALP) activity and better mineralization of the matrix in comparison to PCL–HA scaffolds. These results clearly demonstrate the stimulatory role of Zn and Si present in HS based composite scaffolds, suggesting their potential application for bone tissue engineering. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Scaffold mediated bone regeneration offers an exciting approach to cure bone defects that occurred due to trauma, tumor, disease and biochemical disorders. Synthetic bone grafts have gained popu- larity as a bone defect treatment due to the limited availability of au- tograft tissue and also the associated adverse immune reactions that can occur with allograft approach. The ideal bone graft should possess adequate mechanical properties, porosity, biocompatibility, degrad- ability and be osteoconductive [1,2]. Unfortunately, available plans to treat bone defects do not meet all the desired requirements, there is still a need to develop a suitable synthetic bone graft for bone tissue engineering that meets all of the above success criteria. Important considerations for scaffold preparation are material se- lection and fabrication technology. There are several methods for scaffold fabrication such as phase separation, solvent casting, particu- late leaching and fiber bonding [3]. Electrospinning has also emerged as an efficient technique to form nanofibrous scaffolds which closely mimic the nanometer scale feature of the extracellular matrix [4]. The large surface area to volume ratio, high porosity and nano-sized features of electrospun scaffolds provide better cell–biomaterial in- teraction as compared to macroporous scaffolds [5]. Hydroxyapatite (HA) is the most investigated ceramic material for creating bone tissue scaffolds as it is the major inorganic component of natural bone. Several polymers with HA have been studied for bone tissue engineering including poly-L-lactic acid/HA (PLLA/HA) [6], poly-L-glycolicacid/HA (PLGA/HA) [7], Poly(3-hydroxybutyrate)/ nano-hydroxyapatite (PHB/nHA) [8],cellulose/HA [9], and PCL/HA [10]. HA mainly contains calcium and phosphate ions which are pre- dominantly present under in vivo conditions but multiple ions such as silicon, magnesium and zinc are also present in varying concentra- tions [11]. There are various reports available in the literature which show the promising role of ion substituted HA in bone metabolism such as Mg–HA [12], Si–HA [13], Sr–HA, and Zn–HA [14]. The promoting role of silicon [Si] in bone metabolism was first ob- served by Carlisle [15] and Schwarz et al. [16]. The addition of Si to cell culture media has been shown to enhance cell proliferation, dif- ferentiation and increased ALP activity and collagen synthesis was ob- served [17]. Kim et al. reported enhanced bone mineral density when silicon was supplemented to ovariectomized rats [18]. Bioglass containing silicon has been used as a synthetic bone graft for the last 10 years in the US, Europe and China. In 2005, the US Food and Drug Administration (FDA) has cleared bioglass products for osteostimulation [19]. Researchers synthesized Si substituted ce- ramics such as Si–TCP [20] and Si–HA [13] and observed better Materials Science and Engineering C 33 (2013) 2926–2936 ⁎ Corresponding author at: Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, India. Tel.: +91 22 25767207; fax: +91 22 25726895. E-mail address: jb@iitb.ac.in (J.R. Bellare). 0928-4931/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msec.2013.03.020 Contents lists available at SciVerse ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec