Oligo-guanidyl targeted bioconjugates forming rod shaped polyplexes as a new nanoplatform for oligonucleotide delivery

Alessio Malfanti, Anna Scomparin, Sabina Pozzi, Hadas Gibori, Adva Krivitsky, Rachel Blau, Ronit Satchi-Fainaro, Francesca Mastrotto, Paolo Caliceti, Stefano Salmaso

Research output: Contribution to journalArticlepeer-review


Novel bioconjugates (Agm6-M-PEG-FA) for active oligonucleotide (ON) delivery have been developed by conjugating a cationic oligo-guanidyl star-like shaped “head” (Agm6-M) to a polymeric “tail” (PEG) terminating with folic acid (FA) as targeting agent or methoxy group (Agm6-M-PEG-FA and Agm6-M-PEG-OCH3, respectively). Gel electrophoresis showed that the bioconjugates completely associated with ONs at 3 nitrogen/phosphate (N/P) ratio. Studies performed with folate receptor (FR)-overexpressing HeLa cells, showed that optimal cell up-take was obtained with the 75:25 w/w Agm6-M-PEG-OCH3:Agm6-M-PEG-FA mixture. Dynamic light scattering and transmission electron microscopy showed that the polyplexes had size <80 nm with narrow polydispersity and rod-shaped morphology. The polyplexes were stable for several hours in plasma while ON was released in the presence of heparin concentration 16-times higher than the physiological one. The polyplexes displayed negligible cytotoxicity, hemolysis and low pro-inflammatory TNF-α release. Studies performed with FR-overexpressing HeLa and MDA-MB-231 cells using siRac1 revealed that the folated polyplexes caused significantly higher gene silencing (86.1 ± 9.6%) and inhibition of cell migration (40%) than the non-folated polyplexes obtained with Agm6-M-PEG-OCH3 only. Although cytofluorimetric analyses showed similar cell uptake for both folated and non-folated polyplexes, confocal, TEM and competition studies showed that the folated polyplexes were taken-up by lysosome escaping caveolin-mediated pathway with final polyplex localization within cytosol, while non-folated polyplexes were preferentially taken-up via clathrin-mediated pathway to localize in the lysosomes. Finally, preliminary in vivo studies carried out in mice revealed that the folated polyplexes dispose in the tumor mass.

Original languageEnglish
Pages (from-to)58-73
Number of pages16
JournalJournal of Controlled Release
StatePublished - 28 Sep 2019


  • Active targeting
  • Endocytotic pathways
  • Folate receptor
  • Oligonucleotide delivery
  • Polycationic polymers
  • Polyplexes
  • Supramolecular carriers
  • siRNA


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