Contents lists available at ScienceDirect Biosensors and Bioelectronics journal homepage: www.elsevier.com/locate/bios Biofunctionalization of PAMAM-montmorillonite decorated poly (Ɛ- caprolactone)-chitosan electrospun nanofibers for cell adhesion and electrochemical cytosensing Fatma Ozturk Kirbay a , Esra Evrim Yalcinkaya b, ⁎ , Gozde Atik a , Gizem Evren a , Betul Unal a , Dilek Odaci Demirkol a, ⁎ , Suna Timur a a Ege University, Faculty of Science, Biochemistry Department, 35100 Bornova, Izmir, Turkey b Ege University, Faculty of Science, Chemistry Department, 35100 Bornova, Izmir, Turkey ARTICLE INFO Keywords: Electrospun nanofiber Poly(Ɛ-caprolactone) Chitosan Biofunctional surface Cyctosensing Cell adhesion ABSTRACT The construction and biofunctionalization of the poly (Ɛ-caprolactone) (PCL)-chitosan (CHIT) nanofibrous mats, which included Polyamidoamine (PAMAM) dendrimer modified montmorillonite (Mt), for the cell adhesion and electrochemical cytosensing were accomplished in this report. After the intercalation of the PAMAM generation zero dendrimer into the Mt, PAMAM-Mt decorated PCL-CHIT electrospun nanofibers were formed. The addition of PAMAM caused the decrease of contact angle of PCL-CHIT nanofibers. The covalent immobilization of a tripeptide namely Arginylglycylaspartate (RGD) on both the PCL-CHIT/Mt and PCL-CHIT/PAMAM-Mt surface was carried out. U87-MG and HaCaT (negative control) cell lines were incubated on the PCL-CHIT/Mt/RGD and PCL-CHIT/PAMAM-Mt/RGD. The proliferation studies and imaging of the cells were carried out on these fibers. Finally, electrochemical measurements were performed after each modification step by differential pulse/cyclic voltammetry and electrochemical impedance spectroscopy. U87-MG cells were grown better than HaCaT cells on the PCL-CHIT/PAMAM-Mt/RGD surfaces. To the best of our knowledge, there is no study that developed electrochemical cytosensor using electrospun nanofibers as a cell adhesion platform. 1. Introduction The selective, functional and biocompatible surfaces to design bio- medical instrument for life sciences and public health has increased attention in recent years (Khalili and Ahmad, 2015; Ku et al., 2010; Pei et al., 2013). Electrochemical detection has a consideration nowadays because of detection analytes with lower process steps, suitability to automation, lower detection limits, analysis without qualified analyst and a short analysis time etc. (Shu and Tang, 2017; Shu et al., 2017; Tang et al., 2013; Lin et al., 2017). The non-controllable thickness of immobilization materials in electrochemical sensor design causes the decreased sensitivity. Consequently, electrospun nanofibers (ENs) can be valuable alternative to these materials. Electrospinning is widely used technique to prepare nanofibers, which have different sizes in nanometer or micrometer scale, mor- phology, and functions (Xue et al., 2017; Abrigo et al., 2014). Con- sidering natural polymers, their lower mechanical stability, higher viscosity, and hydrophilicity cause a decreased potential in spinnability (Sill and von Recum, 2008). However, synthetic polymers are not suitable for selective surface design for targets and their hydrophobic nature limits biomolecule-material interactions (Wang et al., 2009). To enhance their selectivity and hydrophilicity, various polymers can be added to the synthetic polymers solution as a second structure. Montmorillonite (Mt) is favorable immobilization matrix in elec- trochemical biosensor preparation due to it providing increased me- chanical stability, higher adsorption capacity, and higher cation ex- change capacity (Mousty, 2004). The structural units of Mt consist of a sandwich of one octahedral sheet (Mg, Al and Fe cations) between two tetrahedral sheets (Si and Al cations). In many minerals an atom of lower positive valence replaces one of higher valence, resulting in a deficit of positive charge, or, in other words, an excess of negative charge. This excess negative charge is balanced by an interlayer of exchangeable, hydrated cations (Ca 2+ , Mg 2+ , Cu 2+ , Na + ,H + ). The intercalation and homogen dispersion of the clay in the polymer matrix is difficult because of the hydrophilic surface of the Mt. However, the dispersion of the nanofiller in the polymer and the interaction between nanofiller and polymer matrix significantly affect the properties of the nanofibers. Therefore, it is necessary to make the surface of the Mt less https://doi.org/10.1016/j.bios.2018.03.017 Received 23 January 2018; Received in revised form 6 March 2018; Accepted 9 March 2018 ⁎ Corresponding authors. E-mail addresses: esra.evrim.saka@ege.edu.tr (E.E. Yalcinkaya), dilek.odaci.demirkol@ege.edu.tr (D.O. Demirkol). Biosensors and Bioelectronics 109 (2018) 286–294 Available online 14 March 2018 0956-5663/ © 2018 Elsevier B.V. All rights reserved. T