Enhanced mechanical strength and biocompatibility of electrospun polycaprolactone-gelatin scaffold with surface deposited nano-hydroxyapatite A.K. Jaiswal a, 1 , H. Chhabra b, 1 , V.P. Soni a , J.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 3 December 2012 Received in revised form 23 January 2013 Accepted 2 February 2013 Available online 9 February 2013 Keywords: Electrospinning Biocompatibility Alternate soaking Cell proliferation Alkaline phosphatase activity In this study for the first time, we compared physico-chemical and biological properties of polycaprolactone- gelatin-hydroxyapatite scaffolds of two types: one in which the nano-hydroxyapatite (n-HA) was deposited on the surface of electrospun polycaprolactone-gelatin (PCG) fibers via alternate soaking process (PCG-HA AS ) and other in which hydroxyapatite (HA) powders were blended in electrospinning solution of PCG (PCG-HA B ). The microstructure of fibers was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which showed n-HA particles on the surface of the PCG-HA AS scaffold and embedded HA particles in the interior of the PCG-HA B fibers. PCG-HA AS fibers exhibited the better Young's moduli and tensile strength as compared to PCG-HA B fibers. Biological properties such as cell proliferation, cell attachment and alkaline phosphatase activity (ALP) were determined by growing human osteosarcoma cells (MG-63) over the scaffolds. Cell proliferation and confocal results clearly indicated that the presence of hydroxyapatite on the surface of the PCG-HA AS scaffold promoted better cellular adhesion and proliferation as compared to PCG-HA B scaffold. ALP activity was also observed better in alternate soaked PCG scaffold as compared to PCG-HA B scaffold. Mechanical strength and biological properties clearly demonstrate that surface deposited HA scaffold prepared by alternate soaking method may find application in bone tissue engineering. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The limitations associated with autograft and allograft approach have drawn researcher's interest to develop synthetic grafts to cure bone defects [1–4]. The advancement in nanotechnology has enabled the use of nanofibrous scaffold for bone tissue constructs. Of the vari- ous methods available for fabrication of scaffold [5], electrospinning is a simple technique by which fibers of varying dimension from micron to nano range can be prepared by controlling the various parameters such as solution viscosity, voltage, and flow rate [6]. The scaffold material as well as its architecture and topography greatly influence the cellular response of scaffold [7,8]. Electrospun fibers mimic the extracellular (ECM) matrix of bone which provide support to cells and guide cellular behavior [9]. There are various synthetic polymers which have been successfully electrospun into nanofibrous scaffold [10]. To increase the biomimeticity of synthetic polymers, natural polymers such as collagen [11], gelatin [12] and chitosan [13] have been blended with them and composites have the advantages of both, with improved biocompatibility, tunable mechanical properties and degradability. For this study, we have chosen two widely used FDA approved materials; polycaprolactone and gelatin. PCL was selected as the synthetic polymer due to its biocompatibility, stability, better shelf life and low cost [14–16]. Another advantage of PCL is its slow degradation rate in in vivo environment and degradation products do not generate acidic environment in surrounding [17]. To provide the biomimeticity to PCL, gelatin was mixed as a natural polymer because of its well known biocompatibility, biodegradability and low cost in comparison to collagen [18]. Hydroxyapatite (HA), the major inorganic component present in human bone has been widely used as filler material, as coating on bone implants and to functionalize polymeric scaffolds which lack cel- lular recognition sites. HA coatings improve biocompatibility as well as provide osteophilic surface to implants for bonding with natural bone after implantation [19]. The presence of HA on the surface of polymeric scaffold offers several benefits: it furnishes synthetic poly- mer scaffolds bioactive and osteoconductive; it changes the chemistry and as well as topography at the surface [20]; HA functionalized scaffold has shown better attachment and proliferation of osteoblasts [21] and it facilitates differentiation of mesenchymal stem cells to- wards osteoblastic lineage [22]. Budiraharjo et al. fabricated HA coated carboxymethyl chitosan scaffold and observed better attachment, proliferation and differentiation of osteoblasts on HA coated scaffold as compared to non coated scaffold [23]. HA composited scaffolds so far as reported in literature have been mainly produced by three methods: 1 — Blending of HA into polymeric solution [24–29] in which poor dispersion and agglomeration of HA particles occur due Materials Science and Engineering C 33 (2013) 2376–2385 ⁎ Corresponding author. Tel.: +91 22 25767207; fax: +91 22 25726895. E-mail address: jb@iitb.ac.in (J.R. Bellare). 1 Equal contributors. 0928-4931/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msec.2013.02.003 Contents lists available at SciVerse ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec