101 small 2011, 7, No. 1, 101–111 © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com 1. Introduction DNA is widely used for the assembly of nanostructured materials due to its remarkable molecular recognition proper- ties and structural features. By exploiting the conformational properties and base-pairing interactions of oligonucleotides, a number of 2D and 3D DNA architectures have been con- structed, resulting in nanopatterned materials with tailored structural and dynamic properties. [1,2] In most cases, the Thin Multilayer Films and Microcapsules Containing DNA Quadruplex Motifs Francesca Cavalieri, Sher Leen Ng, Claudia Mazzuca, Zhongfan Jia, Volga Bulmus, Thomas P. Davis, and Frank Caruso* Watson–Crick base pairing is the fundamental driving force for specific recognition and assembly. Thus, the bottom-up assembly of Watson–Crick base-paired double-stranded DNA has been a powerful approach for the fabrication of assem- blies in the field of structural DNA nanotechnology. [3] The use of oligonucleotide-polymer conjugates, a combination of oligonucleotides and synthetic polymers, confers additional structural and functional features to DNA nanoassemblies. We recently reported the assembly of DNA-grafted poly( N- isopropylacrylamide) (PNIPAM) into multilayered thin films and microcapsules, and showed that the physical and chem- ical properties of these microcapsules (e.g., permeability) is significantly altered when compared with microcapsules made solely of DNA. [4] The assembly of the multilayer films in our previous work was driven by complementary oligonu- cleotide hybridization. In addition to DNA duplex assembly, DNA triple- stranded and four-stranded structures can also be formed. [5,6] The potential of non-Watson–Crick base-paired building blocks to yield DNA superstructures has not yet been fully exploited, and advances in this area are likely to progress the assembly of stable and multifunctional DNA nanosized objects that require complex building blocks. Single-stranded guanosine-rich oligodeoxynucleotides have a propensity to adopt intermolecular or intramolecular quadruplex struc- tures that are stabilized by a basic structural motif, also known as the Hoogsteen hydrogen-bonded G-quartets. The DOI: 10.1002/smll.201001246 S. L. Ng, Prof. F. Caruso Centre for Nanoscience and Nanotechnology Department of Chemical and Biomolecular Engineering The University of Melbourne Parkville, Victoria 3010, Australia E-mail: fcaruso@unimelb.edu.au Dr. F. Cavalieri, Dr. C. Mazzuca Dipartimento di Scienze e Tecnologie Chimiche Università di Roma Tor Vergata 00173 Rome, Italy Z. Jia, Dr. V. Bulmus, Prof. T. P. Davis Centre for Advanced Macromolecular Design School of Chemical Engineering The University of New South Wales Sydney, NSW 2052, Australia The assembly of multifunctional nanostructures bearing G-quadruplex motifs broadens the prospects of using G-quadruplexes as therapeutic carriers. Herein, we report the synthesis and characterization of an oligodeoxyguanosine, G15-mer polymer conjugate. We demonstrate that G15-mer oligonucleotides grafted to a polymer chain preserve the ability to self-assemble into ordered structures. The G-quadruplex-polymer conjugates were assembled onto a surface via hybridization with 30-mer cytosine strands, C30-mer, using a layer-by-layer approach to form microcapsules. A mechanism for the sequential assembly of the multilayer films and microcapsules is presented. We further investigate the photophysical behavior of porphyrin TMPyP4 bound to multilayer-coated particles. This study shows that the multilayer films bear residual and functional quadruplex moieties that can be used to effectively bind therapeutic agents. Drug Delivery