Effects of nozzle type atmospheric dry air plasma on L929 ﬁbroblast cells hybrid poly (ε-caprolactone)/chitosan/poly (ε-caprolactone) scaffolds interactions Ozan Ozkan and Hilal Turkoglu Sasmazel * Department of Metallurgical and Materials Engineering, Atilim University, Incek, Golbasi 06836, Ankara, Turkey Received 20 October 2015; accepted 6 January 2016 Available online xxx In the study presented here, in order to improve the surface functionality and topography of poly (ε-caprolactone) (PCL)/chitosan/PCL hybrid tissue scaffolds fabricated layer by layer with electrospinning technique, an atmospheric pressure nozzle type plasma surface modiﬁcation was utilized. The optimization of the plasma process parameters was carried out by monitoring the changes in surface hydrophilicity by using contact angle measurements. SEM, AFM and XPS analyses were utilized to observe the changes in topographical and chemical properties of the modiﬁed surfaces. The results showed that applied plasma modiﬁcation altered the nanotopography and the functionality of the surfaces of the scaffolds. The modiﬁcation applied for 9 min from a distance of 17 cm was found to provide the possible contact angle value (75.163 ±0.083) closest to the target value which is the value of tissue culture polystyrene (TCPS) petri dishes (w49.7  ), compared to the unmodiﬁed samples (84.46 ± 3.86). In vitro cell culture was carried out by L929 mouse ﬁbroblast cell line in order to examine the effects of plasma surface modiﬁcation on cellematerial interactions. Stan- dard MTT assay showed improved cell viability on/within modiﬁed scaffolds conﬁrmed with the observations of the cell attachment and the morphology by means of SEM, ﬂuorescence and confocal imaging. The experiments performed in the study proved the enhanced biocompatibility of the nozzle type dry air plasma modiﬁed scaffolds. Ó 2016, The Society for Biotechnology, Japan. All rights reserved. [Key words: Nozzle type atmospheric plasma; Dry air; Electrospun poly (ε-caprolactone); Electrospun chitosan; L929 ﬁbroblast cells] It has been widely accepted that using polymeric materials individually, whether natural or synthetic, has its limits in terms of supporting cellular interactions, because almost every single polymer has some disadvantages that prevent it from being an ideal candidate for meeting the complex requirements of tissue scaffold applications. Therefore, hybrid materials that consist of two or more types of polymers have been adopted for next generation tissue scaffolds. By this means, it is possible to achieve an advance material with several different advantages that come from several different materials in which the disadvantages are eliminated (1). Natural polymer, chitosan and synthetic polymer, poly (ε-capro- lactone) (PCL) have raised a considerable interest in the literature and in the industry for tissue engineering applications (2,3). The electrospinning technique is one of the most promising hybrid scaffold fabrication methods that can meet most of the re- quirements with no hassle. The ﬁbrous and porous nature of the electrospun scaffolds can be adjusted so that one can achieve relatively cheap, natural tissue mimicking scaffolds easily by uti- lizing most of the polymers. Furthermore, it is possible to obtain hybrid materials with different structural design by using several different instrumental setups. Therefore, in recent years, electro- spinning has become a widely studied fabrication method in terms of achieving tissue scaffolds with several desired properties (4e6). In recent years, the use of atmospheric pressure plasma surface modiﬁcation has become attractive because of its several advan- tages, such as feasibility due to the required low energy levels ob- tained without expensive vacuum instruments, and versatility due to the opportunity of using several different reactive gas or gas mixtures for modiﬁcation (7,8). The nozzle type atmospheric plasma system is a versatile, commercial-ready plasma system that can generate plasma with radio frequency (RF) power or microwave power (9). The handheld pen-like design of the instrument enables the equipment to be adapted to commercial process lines. The ionized gas from the plasma jet ﬂows out through a nozzle, where it is directed onto a substrate, located a few millimeters to a few cm away from the nozzle tip (10,11). The aim of the present work was to improve the cellular in- teractions of PCL/chitosan/PCL layer by layer ﬁbrous scaffolds developed and characterized in our previous study (12) for espe- cially connective tissue engineering applications. By using nozzle type atmospheric dry air plasma modiﬁcation, it was aimed to introduce/enhance reactive functional groups and/or topographical alterations to the surface in order to improve cellematerial in- teractions. It was considered that modiﬁed ﬁber surfaces would act as anchorage points for cells helping the overall attachment, pro- liferation and growth. The plasma modiﬁcation parameters were optimized initially according to the wettability data obtained with contact angle measurements. The physical and chemical charac- terizations of the modiﬁed samples were carried out with the emphasis on several important aspects such as surface functional group concentration, nanotopographical changes on the surfaces of * Corresponding author. Tel.: þ90 312 586 88 44; fax: þ90 312 5868091. E-mail address: hilal.sasmazel@atilim.edu.tr (H. Turkoglu Sasmazel). www.elsevier.com/locate/jbiosc Journal of Bioscience and Bioengineering VOL. xx No. xx, 1e8, 2016 1389-1723/$ e see front matter Ó 2016, The Society for Biotechnology, Japan. All rights reserved. http://dx.doi.org/10.1016/j.jbiosc.2016.01.004 Please cite this article in press as: Ozkan, O., and Turkoglu Sasmazel, H., Effects of nozzle type atmospheric dry air plasma on L929 ﬁbroblast cells hybrid poly (ε-caprolactone)/chitosan/poly (ε-caprolactone)..., J. Biosci. Bioeng., (2016), http://dx.doi.org/10.1016/j.jbiosc.2016.01.004