Novel cationic lipopolyplexes as gene therapy vectors

A major obstacle in the development of gene therapy is delivery of therapeutic genes to the desired cell/tissue. The objective of our study is to use a non-viral ternary system (lipopolyplexes) to encapsulate and deliver therapeutic DNA. Our lipopolyplexes comprise a glycerol-based cytofectin, a targeting peptide and plasmid DNA. Novel derivatives of the cationic lipids DOTMA and DOTAP have been synthesized and tested in a breast cancer cell line. A range of branched cationic peptides varying in number of residues, composition and linker to a targeting head group were also designed and prepared. The bio-physical studies demonstrated that all LPD complexes were positively charged, small (60-80 nm) and were shown to effectively condense DNA. Gel assays showed which peptides were able to protect DNA more effectively and gave high transfection efficiency. Further studies are underway investigating these systems in siRNA delivery

Tuning a gene delivery vector: the role of peptide sequence and peptide branching in delivering of DNA and siRNA to the cytoplasm

Tuning a gene delivery vector: the role of peptide sequence and peptide branching in delivering of DNA and siRNA to the cytoplas

A facile method to clickable sensing polymeric nanoparticles

Clickable biocompatible nanoparticles were prepared in a one-pot process by microemulsion polymerization using acrylamide, N,N′-methylene bisacrylamide and either N-(11-azido-3,6,9-trioxaundecanyl)acrylamide or N-propargylacrylamide, which were then readily modified by CuAAC reaction to afford sensing nanomaterials. © The Royal Society of Chemistry 2009

Protease responsive nanoprobes with tethered fluorogenic peptidyl 3-arylcoumarin substrates

Protease responsive nanosensors were obtained by the attachment of unique green fluorescent bifunctional 3-arylcoumarin-derived fluorogenic substrates to poly(acrylamide-co-N-(3-aminopropyl)methacrylamide) nanoparticles, in which proteolysis results in substantial signal amplification. © The Royal Society of Chemistry 2009

Protease sensing with nanoparticle based platforms

Nanoparticulate systems in various unique configurations are highly effective at detecting protease activity both in vivo and in vitro. In this article, we have summarised the conventional modern methods for monitoring protease activity, and critically appraised recent advances in protease-responsive nanosensors. © The Royal Society of Chemistry

Non-viral, coated nanoparticles as vectors for gene therapy

Successful non-viral gene therapy is driven by the molecular makeup and architecture of the gene vector. For optimal delivery, consideration must be given to payload packaging/release, vector distribution/stability, cell-specific targeting and the physical properties of the therapeutic. Our focus is the construction of 'coated' liposomes for the targeted delivery of siRNA and DNA. In this presentation, we show small nanoparticles containing DNA/siRNA can be successfully formulated and coated with polyethylene glycol and other modified polymers. We also demonstrate cell specific targeting on addition of target peptides to the liposome coat. Furthermore, we demonstrate the role of novel branched, linear and cleavable polycationic peptides in payload packaging and intracellular release within our liposomal system. The chemical synthesis, biophysical properties andin vitrotransfection efficiencies of these systems will be fully discussed in this presentation

Tailoring Nanocomplexes for the Delivery of Plasmid DNA or siRNA: The Role of Cationic Peptide Sequence and Branching

Tailoring Nanocomplexes for the Delivery of Plasmid DNA or siRNA: The Role of Cationic Peptide Sequence and Branchin

Gene Delivery Using Ternary Lipopolyplexes Incorporating Branched Cationic Peptides: The Role of Peptide Sequence and Branching

Cationic peptide sequences, whether linear, branched, or dendritic, are widely used to condense and protect DNA in both polyplex and lipopolyplex gene delivery vectors. How these peptides behave within these particles and the consequences this has on transfection efficiency remain poorly understood. We have compared, in parallel, a complete series of cationic peptides, both branched and linear, coformulated with plasmid DNA to give polyplexes, or with plasmid DNA and the cationic lipid, DOTMA, mixed with 50% of the neutral helper lipid, DOPE, to give lipopolyplexes, and correlated the transfection efficiencies of these complexes to their biophysical properties. Lipopolyplexes formulated from branched Arg-rich peptides, or linear Lys-rich peptides, show the best transfection efficiencies in an alveolar epithelial cell line, with His-rich peptides being relatively ineffective. The majority of the biophysical studies (circular dichroism, dynamic light scattering, zeta potential, small angle neutron scattering, and gel band shift assay) indicated that all of the formulations were similar in size, surface charge, and lipid bilayer structure, and longer cationic sequences, in general, gave better transfection efficiencies. Whereas lipopolyplexes formulated from branched Arg-containing peptides were more effective than those formulated from linear Arg-containing sequences, the reverse was true for Lys-containing sequences, which may be related to differences in DNA condensation between Arg-rich and Lys-rich peptides observed in the CD studies