Analysis of cellular adhesion on superhydrophobic and superhydrophilic vertically aligned carbon nanotube scaffolds M.M. Machado a,b , A.O. Lobo a , F.R. Marciano a , E.J. Corat c , M.A.F. Corat b, ⁎ a Laboratory of Biomedical Nanotechnology, Development Research Institute, University of Vale do Paraiba, Av. Shishima Hifumi, 2911, Sao Jose dos Campos, 12244-000 SP, Brazil b Transgenesis Unity, Multidisciplinary Center for Biological Investigation in Laboratory Animals Science (CEMIB), State University of Campinas (UNICAMP), Campinas 13083-877, SP, Brazil c Associated Laboratory for Sensors and Materials (LAS), National Institute for Space Research (INPE), Av. dos Astronautas 1758, Sao Jose dos Campos 12227-010, SP, Brazil abstract article info Article history: Received 15 May 2014 Received in revised form 12 November 2014 Accepted 28 November 2014 Available online 29 November 2014 Keywords: Cell adhesion Carbon nanotube Embryonic fibroblasts Transgenic mice Green fluorescent protein Superhydrophilicity We analyzed GFP cells after 24 h cultivated on superhydrophilic vertically aligned carbon nanotube scaffolds. We produced two different densities of VACNT scaffolds on Ti using Ni or Fe catalysts. A simple and fast oxygen plas- ma treatment promoted the superhydrophilicity of them. We used five different substrates, such as: as-grown VACNT produced using Ni as catalyst (Ni), as-grown VACNT produced using Fe as catalyst (Fe), VACNT-O pro- duced using Ni as catalyst (Ni\O), VACNT-O produced using Fe as catalyst (Fe\O) and Ti (control). The 4′,6- diamidino-2-phenylindole reagent nuclei stained the adherent cells cultivated on five different analyzed scaf- folds. We used fluorescence microscopy for image collect, ImageJ® to count adhered cell and GraphPad Prism 5® for statistical analysis. We demonstrated in crescent order: Fe, Ni, Ni\O, Fe\O and Ti scaffolds that had an improved cellular adhesion. Oxygen treatment associated to high VACNT density (group Fe\O) presented signif- icantly superior cell adhesion up to 24 h. However, they do not show significant differences compared with Ti substrates (control). We demonstrated that all the analyzed substrates were nontoxic. Also, we proposed that the density and hydrophilicity influenced the cell adhesion behavior. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Biomedical industries of implants use for several decades carbon structures (pyrolytic carbon) for production of prosthetic heart valves [1]. Chemical vapor deposition (CVD) produced numerous carbon struc- tures, especially in the form of nanosized tubes encouraging their appli- cation on biomedicine [2]. Carbon nanotubes (CNTs) presented a great potential for biomedical applications because of their versatile proper- ties, such as high electrical conductivity, chemical stability and mechan- ical strength. These characteristics may facilitate their interaction with cells and living tissues [3,4]. Vertically-aligned CNT (VACNT) grown on Ti has a similar nanoarchitecture with physiological components of the extracellular matrix (ECM). Besides this, it plays a fundamental role in the survival, proliferation, and cell spreading, making them po- tentially attractive for use in biomaterials [4,5]. Generally, as-grown CNT presents superhydrophobic behavior, lim- iting it as a biomaterial. Despite some evidence of cytotoxicity, studies support the idea of the biocompatibility of CNT applied with scaffolds to grown cell such as neuronal cells, osteoblasts, fibroblasts, antibodies, immune system, DNA and drug delivery, among others [6]. To increase this success, the authors suggested covalent or non-covalent treatments to improve affinity of CNTs with biological media. It was applied to break the strong hydrophobic character, making them more hydrophil- ic. Functionalization promoted better solubility and biocompatibility of CNT films and powders, respectively [4,7,8]. Biomaterial application studies showed a strong correlation between surface nanotopography and cellular adhesion. These demonstrated that the nanotopography can affect positively or negatively the response of cell adhesion. All these characteristics influenced in correlation between cell and substrate surfaces besides of spatial domains, structural composi- tion, and mechanical forces in micro and nano-scale [9–11]. The physical and physicochemical modification of biomaterial surface properties can improve its interaction with cells [12]. Therefore, our group showed a simple and fast method to promote a superhydrophilicity of CNT using oxygen plasma treatment. It occurs because of the surface change that promotes the inclusion of highly polar carboxylic groups (COH, OH, C_O, and COOH) on them [13,14]. Superhydrophilic biomaterials possess a great interest in biomedical applications because of cellular affinity. Their surface plays several biological phenomena that can significantly af- fect events at the sub-cellular and cellular levels, such as: protein adsorp- tion, cell adhesion and cell spreading [5]. Cellular behavior, viability, proliferation, and programmed cell death are strong dependent of the first contact of the biomaterial surface. Through this control, the interpretation of cellular biocompatibility and potential application of CNT films as biomaterial will be possible [5]. Here, we presented a comparative study of cellular adhesion using Materials Science and Engineering C 48 (2015) 365–371 ⁎ Corresponding author. E-mail addresses: aolobo@pq.cnpq.br, lobo.aol@gmail.com (A.O. Lobo), marcus@cemib.unicamp.br (M.A.F. Corat). http://dx.doi.org/10.1016/j.msec.2014.11.062 0928-4931/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec