A robust post-insertion method for the preparation of targeted siRNA LNPs

L E Swart, C A Koekman, C W Seinen, H Issa, M Rasouli, R M Schiffelers, O Heidenreich

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Targeted delivery of nucleic acids is gaining momentum due to improved efficacy, selectivity, increased circulation time and enhanced tissue retention in target cells. Using nucleic acid-based therapies previously undruggable targets have proven now to be amenable for treatment. Currently, several methods for preparing targeted or labelled delivery vehicles for nucleic acids are based on liposomal formulations. Lipid nanoparticles (LNPs) are structurally different from liposomes and these methods should therefore be evaluated before being translated to siRNA LNPs preparation protocols. Here, we describe a robust and facile method for the preparation of targeted or fluorescently labelled siRNA LNPs. Using a copper free strain-promoted azide-alkyne cycloaddition (SPAAC) we demonstrate that post-insertion of ligand-lipid conjugates into preformed LNPs is superior to direct-surface modification because it preserves the physicochemical parameters of the LNPs. We found that the time point of solvent removal by dialysis is critical and affects the hydrodynamic diameter of the LNPs; post-insertion after dialysis shows the smallest increase in hydrodynamic diameter and polydispersity index (PDI). The post-insertion of ligand-lipid conjugates also proceeded with rapid kinetics and high efficacy over a wide temperature range. Using this optimised protocol, we generated siRNA LNPs containing both targeting and fluorescent tracking ligands allowing us to monitor siRNA LNP uptake kinetics in dependence of the targeting ligand. In aggregate, we describe a robust approach for the generation of targeted and labelled siRNA LNPs that allows their controlled and facile decoration with ligand combinations.

Original languageEnglish
Article number121741
Pages (from-to)1-11
JournalInternational Journal of Pharmaceutics
Volume620
Early online date11 Apr 2022
DOIs
Publication statusPublished - 25 May 2022

Keywords

  • Click chemistry
  • copper free strain-promoted azide alkyne cycloaddition (SPAAC)
  • Ligand post-insertion
  • siRNA lipid nanoparticles (LNPs)
  • Targeted delivery

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