One-Dimensional Surface-Imprinted Polymeric Nanotubes for Specific Biorecognition by Initiated Chemical Vapor Deposition (iCVD) Gozde Ozaydin Ince,* ,† Efe Armagan, † Hakan Erdogan, ‡ Fatih Buyukserin, § Lokman Uzun, ⊥ and Gokhan Demirel* ,‡ † Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Turkey ‡ Bio-inspired Materials Research Laboratory (BIMREL), Department of Chemistry, Gazi University, 06500 Ankara, Turkey § Department of Biomedical Engineering, TOBB University of Economics and Technology, 06560 Ankara, Turkey ⊥ Department of Chemistry, Hacettepe University, 06800 Ankara, Turkey * S Supporting Information ABSTRACT: Molecular imprinting is a powerful, generic, and cost-effective technique; however, challenges still remain related to the fabrication and development of these systems involving nonhomogeneous binding sites, insufficient template removing, incompatibility with aqueous media, low rebinding capacity, and slow mass transfer. The vapor-phase deposition of polymers is a unique technique because of the conformal nature of coating and offers new possibilities in a number of applications including sensors, microfluidics, coating, and bioaffinity platforms. Herein, we demonstrated a simple but versatile concept to generate one-dimensional surface- imprinted polymeric nanotubes within anodic aluminum oxide (AAO) membranes based on initiated chemical vapor deposition (iCVD) technique for biorecognition of immunoglobulin G (IgG). It is reported that the fabricated surface-imprinted nanotubes showed high binding capacity and significant specific recognition ability toward target molecules compared with the nonimprinted forms. Given its simplicity and universality, the iCVD method can offer new possibilities in the field of molecular imprinting. KEYWORDS: molecular imprinting, anodic aluminum oxide (AAO), initiated chemical vapor deposition (iCVD), biorecognition, polymeric nanotube, immunoglobulin G (IgG) ■ INTRODUCTION Molecular imprinting (MI) is an emerging and promising technology for the specific molecular recognition. In molecular imprinting, polymer matrices with specific binding sites for a target molecule are prepared using monomers with functional groups. The monomers are arranged around a template, which is the target molecule to be detected, and form covalent or noncovalent bonds with the template. Polymerization of the monomers with a cross-linker leads to a polymer network keeping the functional groups in position. The template is then removed, leaving behind a cavity with highly specific receptor sites for rebinding of target molecules. 1,2 Recently, molecularly imprinted materials, especially polymers, have received growing attention because of their chemical and mechanical stabilities, low costs, high selectivities toward target molecules, and ease of fabrications for possible applications in catalysis, drug release, sensors, and separations. 3-5 So far, different approaches have been reported for the fabrication of molecularly imprinted materials involving nanosphere lithography, 6 cryogelation, 7 sol-gel synthesis, 8 template-based approaches, 9 living polymer- ization, 10 and block copolymer self-assembly. 11 In spite of the advances in the field of MI, there are still challenges related to the template size, conformational flexibility, heterogeneous binding sites, poor site accessibility, template leakage, incompatibility with aqueous media, low rebinding capacity, and slow mass transfer. 3,4 Therefore, development of new materials and fabrication techniques are still crucial to solving these problems. The vapor-phase deposition of polymers is a solvent-free, environmentally friendly, and material-independent method and offers unique advantages compared to solvent-based polymerization techniques. 12-14 By applying this method, for example, nonplanar substrate geometries can be conformally coated, and unwanted impurities, degradation of the underlying layer, and changes in the mechanical/chemical properties associated with the use of solvents can be precisely eliminated. 13,15 Initiated chemical vapor deposition (iCVD) is a special class of vapor-phase polymerization techniques that is based on free radical polymerization. 15,16 In a typical iCVD process, monomer and initiator vapors are delivered into a Received: May 10, 2013 Accepted: June 27, 2013 Letter www.acsami.org © XXXX American Chemical Society A dx.doi.org/10.1021/am401769r | ACS Appl. Mater. Interfaces XXXX, XXX, XXX-XXX