Organic & Biomolecular Chemistry Dynamic Article Links Cite this: Org. Biomol. Chem., 2012, 10, 5570 www.rsc.org/obc PAPER Polycationic amphiphilic cyclodextrins as gene vectors: effect of the macrocyclic ring size on the DNA complexing and delivery properties† Céline Bienvenu,‡ a Álvaro Martínez,‡ b José Luis Jiménez Blanco, b Christophe Di Giorgio, a Pierre Vierling,* a Carmen Ortiz Mellet,* b Jacques Defaye c and José M. García Fernández* d Received 24th April 2012, Accepted 31st May 2012 DOI: 10.1039/c2ob25786f A collection of homologous monodisperse facial amphiphiles consisting of an α-, β- or γ-cyclodextrin (α, β or γCD) platform exposing a multivalent display of cationic groups at the primary rim and bearing hexanoyl chains at the secondary hydroxyls have been prepared to assess the influence of the cyclooligosaccharide core size in their ability to complex, compact and protect pDNA and in the efficiency of the resulting nanocondensates (CDplexes) to deliver DNA into cells and promote transfection in the presence of serum. All the polycationic amphiphilic CDs (paCDs) were able to self- assemble in the presence of the plasmid and produce transfectious nanoparticles at nitrogen/phosphorous ratios ≥5. CDplexes obtained from βCD derivatives generally exhibited higher transfection capabilities, which can be ascribed to their ability to form inclusion complexes with cholesterol, thereby enhancing biological membrane permeability. The presence of thiourea moieties as well as increasing the number of primary amino groups then favour cooperative complexation of the polyphosphate chain, enhancing the stability of the complex and improving transfection. In the α and γCD series, however, only the presence of tertiary amino groups in the cationic clusters translates into a significant improvement of the transfection efficiency, probably by activating endosome escape by the proton sponge mechanism. This set of results illustrates the potential of this strategy for the rational design and optimisation of nonviral gene vectors. Introduction Nucleic acids (DNA, siRNA, microRNA, oligonucleotides,…) are a promising source of therapeutics for the treatment of acquired and genetic diseases including various types of cancer, cardiovascular, monogenic and infectious diseases. Due to their poor cellular uptake and rapid degradation in biological media, successful applications critically depend on the development of efficient purpose-conceived carriers that protect and deliver them into their target cells. Because of their natural ability to infect cells, modified viruses have been long considered as the vehicles of choice. However, viral-based vectors display major inherent restrictions, among which a limited DNA carrying capacity, expensive cost and safety concerns such as immunogenic response, toxicity or oncogenicity. 1 During the last three decades, non-viral gene delivery systems have gathered momen- tum. 2 Most of these non-viral nucleic acid vectors fall within the category of cationic lipids or polymers, featuring functional groups that electrostatically neutralize nucleic acids and coopera- tively promote compaction into colloidal nanoparticles termed lipoplexes and polyplexes, respectively, with increased metabolic stability and membrane permeability. Unfortunately, low efficiency and poor selectivity compared to their viral counter- parts limit their application range. 3 Progress in this field requires a better understanding of the mechanisms involved in cell and systemic traffic of vector : pDNA complexes. Despite their undisputable investigational utility, manipulation of the functional features of many of the first generation non-viral vectors is not an easy task. The intrinsic polydispersity of these materials and their random conformation- al properties make it difficult to undertake a systematic investi- gation of the influence of structural modifications on the transfecting properties. Moreover, their generally flexible † Electronic supplementary information (ESI) available: NMR spectra of all new compounds. See DOI: 10.1039/c2ob25786f ‡ These authors equally contributed to this work. a Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis – CNRS, 28, Avenue de Valrose, F-06100 Nice, France. E-mail: Pierre.Vierling@unice.fr; Fax: +33 492076151; Tel: +33 492076143 b Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Apartado 553, E-41071 Sevilla, Spain. E-mail: mellet@us.es; Fax: +34 954624960; Tel: +34 954559806 c Dépt. de Pharmacochimie Moléculaire, Institut de Chimie Moléculaire de Grenoble (CNRS – Univ. de Grenoble, UMR 5063, FR 2607), Bât. E André Rassat, BP 53, F-38041 Grenoble, France d Instituto de Investigaciones Químicas (IIQ), CSIC–Universidad de Sevilla, Américo Vespucio 49, Isla de la Cartuja, E-41092 Sevilla, Spain. E-mail: jogarcia@iiq.csic.es; Fax: +34 954460565; Tel: +34 954489553 5570 | Org. Biomol. Chem., 2012, 10, 5570–5581 This journal is © The Royal Society of Chemistry 2012 Downloaded by Centro de Investigaciones Científicas Isla de la Cartuja on 03 July 2012 Published on 01 June 2012 on http://pubs.rsc.org | doi:10.1039/C2OB25786F View Online / Journal Homepage / Table of Contents for this issue