RESEARCH A RTICLE 10.2217/17435889.3.1.45 © 2008 Future Medicine Ltd ISSN 1743-5889 Nanomedicine (2008) 3(1), 45–60 45 part of Electrospun biodegradable nanofibrous mats for tissue engineering Albana Ndreu 1 , Lila Nikkola 2 , Hanna Ylikauppila 3 , Nureddin Ashammakhi 4 & Vasif Hasirci 5† † Author for correspondence 1 BiotechnologyResearch Unit, Department of Biological Sciences, Middle East Technical University, Ankara, Turkey Tel.: +90 312 210 5189; Fax: +90 312 210 1542; Email: ndreualbana@ yahoo.com 2 Tampere University of Technology, Department of Biomedical Engineering, PO Box 692, 33101 Tampere, Finland Tel.: +358 331 1511; Fax: +358 331 152 250; Email: lila.nikkola@tut.fi 3 Tampere University of Technology, Department of Biomedical Engineering, PO Box 692, 33101 Tampere, Finland Tel.: +358 331 1511; Fax: +358 331 152 250; Email: hanna.ylikauppila@ tut.fi 4 Tampere University of Technology, Department of Biomedical Engineering, PO Box 692, 33101 Tampere, Finland Tel.: +358 331 1511; Fax: +358 331 152 250; Email: nureddin.ashammakhi @tut.fi 5 BiotechnologyResearch Unit, Department of Biological Sciences, Middle East Technical University, Ankara 06531, Turkey Tel.: +90 312 210 5180; Fax: +90 312 210 1542; Email: vhasirci@metu.edu.tr Keywords: biodegradable, electrospinning, extracellular matrix, nanofibers, tissue engineering, wet spinning Aims & method: In this study, a microbial polyester, poly(3-hydroxybutyrate-co- 3-hydroxyvalerate) (PHBV), and its blends were electrospun into PHBV (10% w/v), PHBV (15% w/v), PHBV-PLLA (5% w/v), PHBV-PLGA (50:50) (15% w/v) and PHBV-P(L,DL)LA (5% w/v) fibrous scaffolds for tissue engineering. Results: Various processing parameters affected the morphology and the dimensions of beads formed on the fibers. Concentration was highly influential on fiber properties; as it increased from 5 to 15% (w/v), fiber diameter increased from 284 ± 133 nm to 2200 ± 716 nm. Increase in potential (from 20 to 50 kV) did not lead to the expected decrease in fiber diameter. The blends of PHBV with lactide-based polymers led to fibers with less beads and more uniform diameter. The surface porosities for PHBV10, PHBV15, PHBV-PLLA, PHBV-PLGA (50:50) and PHBV-P(L,DL)LA were 38.0 ± 3.8, 40.1 ± 8.5, 53.8 ± 4.2, 50.0 ± 4.2 and 30.8 ± 2.7% , respect ively. In vitro studies using human osteosarcoma cells (Saos-2) revealed that the electrospun scaffolds promoted cell growth and penetration. Surface modification with oxygen plasma treatment slightly improved the improved the results in terms of cell number increase and significantly improved spreading of the cells. Conclusion: All scaffolds prepared by electrospinning have implied significant potential for use in further studies leading to bone tissue engineering applications. The PHBV-PLLA blend appeared to yield the best results regarding cell number increase, their attachment and spreading inside and on the scaffold. Tissue engineering is an extension of the bio- materials field and aims at producing tissue sub- stitutes from a combination of biodegradable polymers and cells specific for the tissues that need to be restored. An intensive research was carried out in the last decade in this field [1–3]. One of the most important challenges in tissue engineering is the design of a 3D scaffold, which should provide a suitable environment for easy attachment, proliferation and differentiation of cells. In order to achieve this, the best approach is to develop a scaffold that can mimic the bio- logical functions and structure of the naturally existing extracellular matrix. There are some important points that should be considered when designing the scaffolds. One of these is that the polymer should have proven bio- compatibility and biodegradability. The scaffold should possess appropriate permeability and porosity to enable the entrance of required nutrients and removal of waste products. A suit- able surface chemistry that enables attachment, proliferation and differentiation of cells is also required. The formed fibrous material should have an appropriate degradation rate and good mechanical properties so that different stresses that develop during new tissue formation can be handled [4,5]. Different types of scaffolds, in the form of films [5], foams [6,7] and fibers [2–4,6], with widely differing chemistry have been tested so far and a variety of studies ranging from in situ to clinical applications have been carried out. Cells attach, grow and organize well on fibrous structures when the individual fiber diameter is smaller than that of the cells [8,9]. This was explained as being a result of the high porosity of the scaffolds and the large ratio of surface area per volume that enabled rapid transfer of nutrients and wastes and also provided a large surface for the cells to attach to. There is extensive research on fabrication of these fibrous structures and several techniques, such as electrospinning, drawing, template syn- thesis, melt blowing, phase separation and self- assembly, have been used [10,11]. Its simplicity, capability to produce continuous fibers and the fact that it is more economical when compared with the other processes has made electrospin- ning one of the most popular nanofiber-produc- ing processes. Furthermore, electrospinning results in fibers with diameters in the range of 3 nm to several micrometers, whereas other methods, such as self-assembly, template synthe- sis and phase separation, produce much larger fibers with diameters ranging from 500 nm to For reprint orders, please contact: reprints@futuremedicine.com