Reductively Cleavable Nanocaplets for siRNA Delivery by Template-Assisted Oxidative Polymerization.

ABSTRACT

A series of water-soluble telechelic dithiol monomers bearing multiple guanidinium ion (Gu(+)) units in their main chains were synthesized for packaging siRNA by template-assisted oxidative polymerization at their thiol termini. In the presence of siRNA, oxidative polymerization of (TEG)Gu4 affords a uniform-sized (7 ± 2 nm) nanocaplet containing siRNA (P(TEG)Gu4⊃siRNA; P(TEG)Gu4 = polymerized (TEG)Gu4). When this small conjugate is incubated with live cells, cellular uptake occurs, and the nanocaplet undergoes depolymerization in the reductive cytosolic environment to liberate the packaged siRNA. Consequently, gene expression in the live cells is suppressed.