Cyclodextrin-based gene delivery systems

Cyclodextrin (CD) history has been largely dominated by their unique ability to form inclusion complexes with guests fitting in their hydrophobic cavity. Chemical funcionalization was soon recognized as a powerful mean for improving CD applications in a wide range of fields, including drug delivery, sensing or enzyme mimicking. However, 100 years after their discovery, CDs are still perceived as novel nanoobjects of undeveloped potential. This critical review provides an overview of different strategies to promote interactions between CD conjugates and genetic material by fully exploiting the inside-outside/upper-lower face anisotropy of the CD nanometric platform. Covalent modification, self-assembling and supramolecular ligation can be put forward with the ultimate goal to build artificial viruses for programmed and efficient gene therapy (222 references).

Lipopolythiourea/DNA interaction: a biophysical study

Lipopolythioureas (LPT) are original non cationic systems representing an alternative to cationic lipids. Their high transfection efficiency prompted us to investigate further their biophysical properties, and in particular how thiourea lipids interact with DNA. The interaction of lipopolythiourea with DNA was investigated by fluorescence correlation microscopy (FCS). Influence of the lipid length and nature of the thiourea head on the thiourea/DNA interaction were studied. FCS revealed a strong interaction between lipopolythiourea and DNA, occurring at 1 equivalent of a thiourea lipid by a DNA phosphate group, and leading to a condensed plasmid state. From previous in vitro experiments, we could conclude that the lipid leading to the more condensed state of DNA was also the more efficient to transfect cells.

[Amphiphilic cyclodextrins and their applications. Preparation of nanoparticles based on amphiphilic cyclodextrins for biomedical applications]

Solubilization of hydrophobic drugs at the molecular level as inclusion complexes inside cyclodextrins (CDs) offers a good alternative for improving their stability, solubility and bioavailability, and for preventing against their possible toxicity or controlling secondary effects. Therefore CDs are widely used as solubilizing excipients. However since dissociation takes place too readily upon dilution, inclusion complexes inside simple water-soluble CD appears ineffective for drug delivery applications. Chemical modifications of CDs allow them to self-organize as larger assemblies useful for resolving this lability issue. Depending on the position, the number and the nature of these groups, amphiphilic CDs can form assemblies such as vesicles, solid-lipid nanoparticles, nanospheres, liquid crystals, or micellar systems. This review deals with the synthesis of amphiphilic cyclodextrins leading to supramolecular assemblies and the physical properties of these assemblies. From the first sulfonated amphiphilic cyclodextrins isolated in our laboratory in 2003, to the latest ones being regioselectively functionalized by two or four fluoroalkyl chains, through the persubstituted fluorinated cyclodextrines, all these amphiphilic cyclodextrins have shown good abilities for encapsulation. Complexation of bioactive molecules (acyclovir) by these modified alpha-cyclodextrin derivatives, the encapsulation efficiency and release profile were measured as an assessment of the properties of such nanoparticles regarding drug delivery applications.

Poly-6-cationic amphiphilic cyclodextrins designed for gene delivery

A new series of amphiphilic cyclodextrins containing cationic groups at the 6-positions and alkyl or biolabile ester groups at the 2-positions has been synthesised. Selective 2-O-allylation followed by photochemical addition of lipophilic thiols made it possible to control lipophilicity in these mesomolecules and allow solubility and self-assembly in water. The cationic groups are cysteamine-derived, while the alkyl and ester groups are C(1)-C(16) and benzyl ester groups. This is a new general synthetic route to a potentially wide range of polycationic cyclodextrins capable of acting as gene delivery vectors by condensing DNA and forming liquid crystalline complexes with oligonucleotides.

Carrier PNA for shRNA delivery into cells

A peptide nucleic acid (PNA)-cell-penetrating peptide (CPP) conjugate (carrier PNA) was used as 'bridge-builder' to connect a CPP with an shRNA. The carrier PNA successfully formed a hybrid with an shRNA bearing complementary dangling bases and the shRNA was introduced into cells by the carrier PNA, and RNAi was induced by the shRNA.

Supramolecular approaches to biological therapy

Supramolecular chemistry is a useful methodology for construction of nano- or micro-sized objects and can significantly contribute to nanotechnology through so-called bottom-up processing. In addition, supramolecular self-assembled structures can mimic some aspects of biological systems. Bio-related functions such as molecular sensing, controlled release, signaling and materials separations have been realized. Supramolecular chemistry is a multidisciplinary field that includes subjects such as molecular design and nanosized materials. In this article recent examples of supramolecular chemistry in the context of biological therapy are introduced and classified into five categories: small supramolecular systems; designer polymers; self-assembled structures; predesigned assemblies; and nanomaterials. Finally, hierarchic organization of supramolecular structures for advanced functions is introduced to illustrate future directions of investigation. We hope that scientists studying therapeutic applications receive inspiration from this review to exploit the opportunities offered by supramolecular chemistry in their respective research areas.

Preorganized macromolecular gene delivery systems: amphiphilic beta-cyclodextrin "click clusters"

Gene delivery systems based on the beta-cyclodextrin scaffold have been synthesized by combining the copper(I)-catalyzed azide-alkyne coupling ("click chemistry") and an efficient acylation method of the secondary hydroxyls; molecular flexibility, charge density and hydrophobic-hydrophilic balance are critical parameters that can be fine-tuned by the click approach.