Contents lists available at ScienceDirect Materials Science & Engineering C journal homepage: www.elsevier.com/locate/msec Fabrication of chitosan-coated porous polycaprolactone/strontium- substituted bioactive glass nanocomposite scaffold for bone tissue engineering M. Shaltooki a , G. Dini a, ⁎ , M. Mehdikhani b a Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441, Iran b Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan 81746-73441, Iran ARTICLE INFO Keywords: Porous nanocomposite scaffold Polycaprolactone Bioactive glass nanoparticles Chitosan Bone tissue engineering ABSTRACT In the present study, porous (about 70 vol%) nanocomposite scaffolds made of polycaprolactone (PCL) and different amounts (0 to 15 wt%) of 45S bioactive glass (BG) nanoparticles (with a particle size of about 40 nm) containing 7 wt% strontium (Sr) were fabricated by solvent casting technique for bone tissue engineering. Then, a selected optimum scaffold was coated with a thin layer of chitosan containing 15 wt% Sr-substituted BG nanoparticles. Several techniques such as X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), tensile test, and water contact angle measurement were used to characterize the fabricated samples. In vitro experiments including degradation, bioactivity, and biocompatibility (i.e., cytotoxicity, alkaline phosphate activity, and cell adhesion) tests of the fabricated scaffold were performed. The biomedical behavior of the fabricated PCL-based composite scaffold was interpreted by considering the presence of the porosity, Sr-sub- stituted BG nanoparticles, and the chitosan coating. In conclusion, the fabricated chitosan-coated porous PCL/BG nanocomposite containing 15 wt% BG nanoparticles could be utilized as a good candidate for bone tissue en- gineering. 1. Introduction Bone has a high regeneration capacity, but large defects need repair treatments with grafts such as autografts, allografts, xenografts, and synthetic grafts to promote bone restoration. Nonetheless, autografts, allografts, and xenografts involve some problems, including the pain, infection, immune rejection, as well as the lack of connective tissue quantities. Consequently, synthetic grafts in the form of scaffolds have been gained great interest in bone regeneration. In fact, biocompatible and biodegradable scaffolds serve as a suitable substrate for cell ad- hesion, growth, proliferation, and formation of new bone in defect areas [1–10]. Suitable porous and manipulative scaffolds with minimum impaired mechanical properties utilized for bone tissue engineering are the main characteristics of such constructs. As a matter of fact, interconnected porosities with sufficient size in the scaffolds provide a satisfactory environment for cell nutrition, tissue in-growth, vascularization, me- tabolic products transportation, and consequently bone formation en- hancement [11,12]. Among different techniques for scaffolds preparation, solvent casting/particulate leaching presents an efficient method to fabricate a foam-like structured scaffold with desired por- osities. Unfortunately, this procedure needs a long time for particulate leaching and porosities creation [13,14]. Therefore, in our study, a novel method was used to accelerate the particulate leaching phe- nomenon and as a result, the time required for samples preparation was reduced. Researches have been depicted that exploitation of individual characteristics of porous scaffolds components can raise physicochem- ical, mechanical, as well as biological properties of them [15]. Ac- cordingly, solid and flexible composites made by biodegradable poly- mers and bioactive fillers have been received a growing tendency to fabricate bone tissue engineering scaffolds due to their compositional and structural similarities with natural bone [5,6,16–18]. Bioactive glasses (BGs) have been acquired widespread applications in bone tissue augmentation and reconstruction. Furthermore, they can provide a firm attachment with the implants coated with them to the surrounding living host tissues [19–22]. It is noteworthy that BGs are exceptionally more bioactive than calcium phosphates and they https://doi.org/10.1016/j.msec.2019.110138 Received 23 May 2019; Received in revised form 24 August 2019; Accepted 25 August 2019 ⁎ Corresponding author. E-mail address: g.dini@sci.ui.ac.ir (G. Dini). Materials Science & Engineering C 105 (2019) 110138 Available online 26 August 2019 0928-4931/ © 2019 Elsevier B.V. All rights reserved. T