www.afm-journal.de FULL PAPER © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1133 www.MaterialsViews.com wileyonlinelibrary.com 1. Introduction DNA–copolymers composed of either water-soluble or hydro- phobic polymer segments of various compositions are nowadays available through both organic and molecular bio- technology routes. [1] Amphiphilic DNA–polymer can self- assemble in aqueous solution into micelles of various shapes such as spherical core–shell micelles [1a,b] or vesicles, [1c] which are closed spherical copolymer shells. Sizes in the sub-microm- eter range could be achieved by this mechanism of microphase separation. [1] Of particular interest is Watson–Crick base pairing between complementary nucleotide sequences, which assemble to form a double helix through hybridization to enable further either structure manipulations such as stimulation of mor- phological transitions from spherical to rod-like micelles, [1a,b] immobilization of self-assembled struc- tures on surfaces [2] as well as chemical functionalization using a labeled comple- mentary sequence to target cell surface receptors for instance. [1a,b] Besides hybridization, nucleotide sequences might however interact spe- cifically with a target moiety. We ourselves observed a positive response of bacteria to surface-tethered nucleotide sequences and self-assembled structures thereof. [2] Although no specificity of the nucleo- tide sequences towards Escherichia Coli could be expected, the bacteria produced curli, which are organelles of adhesion expressed upon interaction with surfaces coated with nucleotide sequences. [2a] Aptamers however are synthetic single stranded nucleotide sequences that undergo remarkable molecular recogni- tion properties. [3] Binding affinities are comparable to those achieved with antibodies due to an effi- cient in vitro combinatorial strategy of selection called system- atic evolution of ligands by exponential enrichment (SELEX), a major advantage over production of antibodies. [3a] The spe- cific and complex 3D shape of aptamers, which are short single-stranded nucleotide sequences (ssDNA or RNA) ena- bles binding with high specificity to a wide variety of targets from single molecules to complex mixtures or whole organ- isms. We therefore describe herein the grafting of the aptamer against the immunoglobulin E (IgE), an allergy biomarker, to a hydrophobic polymer segment. Anti-IgE aptamers have been shown to block interactions with the IgE receptor with high affinity to inhibit IgE-mediated serotonin release from cells in tissue culture. [3a] Anti IgE-apatmers might therefore prove to be useful for blocking local inflammatory responses mediated by IgE. With future biomedical applications in mind and the pos- sibility to use methods developed in polymer science to investi- gate the system under consideration, we thus report in here the grafting of the IgE-aptamer to a poly(2-alkyl-2-oxazoline) with N-Boc protected amino acid and alkenyl side chains. This syn- thetic macromolecule is a bioinspired amphiphilic copolymer with a structural relation to polypeptides, which therefore reveals high potential for biomedical applications. [4] The emul- sification methodology to prepare both aqueous and liquid oil cores enables the facile encapsulation of various water soluble or hydrophobic active agents with efficient applicability in var- ious fields like pharmacy, food and cosmetics. [5] Of particular interest is the combination of the emulsification process with Polymer–Aptamer Hybrid Emulsion Templating Yields Bioresponsive Nanocapsules Dawid Kedracki, Plinio Maroni, Helmut Schlaad, and Corinne Vebert-Nardin * This article describes the synthesis of a DNA–polymer, being the nucleotide sequence an aptamer selected in vitro to target specifically the immuno- globulin E (IgE) protein, an allergy biomarker. Subsequent to coupling to poly(2-alkyl-2-oxazoline) with N-Boc protected amino acid side chains, the resulting amphiphilic DNA–polymer hybrid composed of the water-soluble DNA fragment grafted to the hydrophobic polymer segment can be regarded as a high molecular weight analogue of a surfactant. It is demonstrated that the copolymer–aptamer stabilizes efficiently submicrometer size oil-in-water and water-in-oil emulsions, by dynamic light scattering, microscopy, and reflectometry. Particularly interesting is that the aptamer remains functional after coupling to a polymer backbone, stabilization of the emulsion droplets, and locking of the structure subsequent to cross-linking polymerization. The resulting nanocapsules still target specifically the IgE protein. The biological- stimulus responsiveness of the structures is of high potential for future developments of carriers for sustained and targeted delivery. DOI: 10.1002/adfm.201302475 MSc D. Kedracki, Dr. P. Maroni, Prof. C. Vebert-Nardin University of Geneva Faculty of Sciences Department of Inorganic and Analytical Chemistry Quai Ernest Ansermet 30, 1211, Geneva 4, Switzerland E-mail: corinne.vebert@unige.ch Dr. H. Schlaad Max Planck Institute of Colloids and Interfaces Department of Colloid Chemistry Research Campus Golm, 14424, Potsdam, Germany Adv. Funct. Mater. 2014, 24, 1133–1139