Ulrich Lächelt

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Although our understanding of RNAi and our knowledge on designing and synthesizing active and safe siRNAs significantly increased during the past decade, targeted delivery remains the major limitation in the development of siRNA therapeutics. On one hand, practical considerations dictate robust chemistry reproducibly providing precise carrier molecules. On(More)
In the forthcoming era of cancer gene therapy, efforts will be devoted to the development of new efficient and non-toxic gene delivery vectors. In this regard, the use of Fmoc/Boc-protected oligo(ethane amino)acids as building blocks for solid-phase-supported assembly represents a novel promising approach towards fully controlled syntheses of effective gene(More)
Intracellularly-acting therapeutic proteins are considered promising alternatives for the treatment of various diseases. Major limitations of their application are low efficiency of intracellular delivery and possible reduction of protein activity during derivatization. Herein, we report pH-sensitive covalent modification of proteins with a histidine-rich(More)
UNLABELLED The cationizable nature of 'proton-sponge' transfection agents facilitates pDNA delivery in several steps. Protonated amines account for electrostatic DNA binding and cellular uptake, buffering amines mediate polyplex escape from acidifying intracellular vesicles. As demonstrated with a sequence-defined library of oligo(ethanamino)amides(More)
For active cell targeting, viruses frequently capitalize on dual-receptor binding. With the intention to mimic this natural process, a dual peptide-based approach for targeting cancer cells was evaluated. For this purpose, sequence-defined pDNA binding oligo (ethane amino) amides containing a PEG chain with a peptidic targeting ligand at its distal end were(More)
Gene silencing mediated by small interfering RNA (siRNA) is a novel approach in the development of new cancer therapeutics. Polycations used for nucleic acid delivery still remain heterogeneous compounds, despite continuous progress in polymer synthetic technologies. Here we report the development of a structural defined folic acid polyethylene glycol (PEG)(More)
Overexpression of the hepatocyte growth factor receptor/c-Met proto oncogene on the surface of a variety of tumor cells gives an opportunity to specifically target cancerous tissues. Herein, we report the first use of c-Met as receptor for non-viral tumor-targeted gene delivery. Sequence-defined oligomers comprising the c-Met binding peptide ligand cMBP2(More)
The antifolate drug methotrexate (MTX) can serve as a dual-functional ligand in antitumoral drug delivery, inducing both a folate receptor mediated cellular uptake and an intracellular cytotoxic action. Bioactivity of MTX however changes by conjugation; the activity can be affected by the hampered intracellular conversion to more potent poly-γ-glutamyl(More)
Native chemical ligation (NCL) was established for the conversion of sequence-defined oligomers of different topologies into targeted and PEG shielded pDNA and siRNA carriers. From an existing library of non-targeted oligoethanamino amides, six oligomers containing N-terminal cysteines were selected as cationic cores, to which monodisperse polyethylene(More)