Specific cell targeting and efficient intracellular delivery are major hurdles for the widespread therapeutic use of nucleic acid technologies, particularly siRNA mediated gene silencing. To enable receptor-mediated cell-specific targeting, we designed a synthesis scheme that can be generically used to engineer Designed Ankyrin Repeat Protein (DARPin)-siRNA bioconjugates. Different linkers, including labile disulfide-, and more stable thiol-maleimide- and triazole- (click chemistry) tethers were employed.
View Article and Find Full Text PDFRNA interference is an essential method for studying genomic functions of single genes by loss-of-function experiments. Short interfering siRNAs are efficiently transfected into cultured cells to enable RISC-mediated mRNA cleavage and inhibition of translation in a sequence-specific manner. RNAi enables knockdown of single genes and screening for specific cellular processes or outcomes.
View Article and Find Full Text PDFTherapeutic gene silencing promises significant progress in pharmacotherapy, including considerable expansion of the druggable target space and the possibility for treating orphan diseases. Technological hurdles have complicated the efficient use of therapeutic oligonucleotides, and siRNA agents suffer particularly from insufficient pharmacokinetic properties and poor cellular uptake. Intense development and evolution of delivery systems have resulted in efficient uptake predominantly in liver tissue, in which practically all nanoparticulate and liposomal delivery systems show the highest accumulation.
View Article and Find Full Text PDFLigand conjugation is an attractive approach to rationally modify the poor pharmacokinetic behavior and cellular uptake properties of antisense oligonucleotides. Polyethylene glycol (PEG) attachment is a method to increase solubility of oligonucleotides and prevent the rapid elimination, thus increasing tissue distribution. On the other hand, the attachment of long PEG chains negatively influences the pharmacodynamic effect by reducing the hybridization efficiency.
View Article and Find Full Text PDFThe therapeutic application of siRNA suffers from poor bioavailability caused by rapid degradation and elimination. The covalent attachment of PEG is a universal concept to increase molecular size and enhance the pharmacokinetic properties of biomacromolecules. We devised a facile approach for attachment of PEG molecules with a defined molecular weight, and successful purification of the resulting conjugates.
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