Fabrication of DNA nanotubes with an array of exterior magnetic nanoparticles Adele Rafati a , Ali Zarrabi a, ⁎ ,1 , Pooria Gill b, ⁎ ,1 a Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, Iran b Nanomedicine Group, Immunogenetics Research Center, Mazandaran University of Medical Science, Sari, Iran abstract article info Article history: Received 14 December 2016 Received in revised form 26 April 2017 Accepted 7 May 2017 Available online 10 May 2017 Described here a methodology for arraying of magnetic nanoparticles (MNPs) on the surface of DNA nanotubes (DNTs). Positioning of magnetic nanoparticles at exterior surface of DNTs were shaped after self-assembling of oligonucleotide staples within an M13mp18 DNA scaffold via an origami process. The staples were partially labeled with biotin to be arrayed at the surface of DNTs. Gel retardation assay of the DNTs carrying magnetic nanoparticles indicated a reversely behavioral electrophoretic movement in comparison to the nanotubes have been demonstrated previously. Also, high resolution transmission electron microscopy confirmed positioning magnetic nanoparticles at the exterior surface of DNTs, correctly. Ultrastructural characteristics of these DNA nanotubes using atomic force microscopy demon- strated topographic heights on their surfaces formed through positioning of magnetic nanoparticles outside the tubules. This nanoarchitecture would be potential for multiple arraying of nanoparticles that those be useful as functionalized chimeric nanocarriers for developing novel nanodrugs and nanobiosensors. © 2017 Published by Elsevier B.V. Keywords: DNA nanotubes Magnetic nanoparticles Biotin AFM TEM Hybrid nanomaterials 1. Introduction Fabrications of hybrid nanomaterials have been considered by scientists due to their applications from as diverse as gene or drug delivery to bioelectronics [1–4]. Particularly, the incorporations of metallic and magnetic nanoparticles in hybrid or chimeric nanomaterials have expanded potentials of these nanomaterials for employing in nanotherapeutics and nanodiagnostics [5–8]. This will change physical properties of the nanocomplexes; however, the incorporation of a metallic nanoparticle within an organic matrix such as a biomaterial could be possible using the recent methodologies in nanobiotechnology [9,10]. Progress on any aspects of these challenges can greatly expand the range of applications of theses nanoarchitectures in many areas of science and technology [11–12]. Structural DNA nanotechnology [13] has recently opened a new window for the fabrication of nano-devices [14] and the massively parallel construction of arti ficial chimeric nanostructures with complex geometries or patterns by DNA self-assembly phenomena [14–18]. When functional groups and materials are incorporated in and out of self-assembled DNA nanoarray, they can serve as excellent platform for the assembly of other species such as metal nanoparticles [19–21] antibodies, [19,22,23] and proteins [24,25]. The DNA nanotubes showed greatly promising application that a range from fabrication of nano-electronic devices to biological analyses and studies has been provided in playing role of the assay platform or array because of their specifications such as their high aspect ratio and a long narrow central channel generated by DNA self-assembly that it can be readily functionalized inside the central channel or at the position facing out of their tubular sidewalls [26–28]. To achieve the surface patterning or positioning, the functionality could come from covalently attached functional groups or molecules (e.g. Thiol, amino, and carboxylic groups or biotin) that those chemically linked to their specific targeted molecules species, such as nanoparticles or proteins [29,30]. Hence, DNA nanotubes play nanocarrier roles for functional hybrid materials and also possess the functional agent properties [31]. Such functionalized DNA nanotubes can serve as excellent platforms for the assembly or capturing of other target molecules with nanometer precision in nanobiosensors designs. The precise positioning of encapsulated nanomaterials and biomolecules along the nanotube length, whether at interior or exterior surface, has the potential to create chimeric nanotube architectures that those transport materials as a cargo to target point not as a common car- rier. Hence, we describe a methodology for fabrication of DNA nanotubes as hybrid nanocarriers for MNPs at their exterior surfaces (Fig. 1) with a high aspect ratio could be used for trapping or carrying biomolecules. Materials Science and Engineering C 79 (2017) 216–220 ⁎ Corresponding authors. E-mail addresses: a.zarrabi@ast.ui.ac.ir (A. Zarrabi), pooriagill@yahoo.com, p.gill@mazums.ac.ir (P. Gill). 1 The authors contributed equally. http://dx.doi.org/10.1016/j.msec.2017.05.044 0928-4931/© 2017 Published by Elsevier B.V. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec