title: Cellular uptake of substrate-initiated cell-penetrating poly(disulfide)s.
abstract: Substrate-initiated, self-inactivating, cell-penetrating poly(disulfide)s (siCPDs) are introduced as general transporters for the covalent delivery of unmodified substrates of free choice. With ring-opening disulfide-exchange polymerization, we show that guanidinium-rich siCPDs grow on fluorescent substrates within minutes under the mildest conditions. The most active siCPD transporters reach the cytosol of HeLa cells within 5 min and depolymerize in less than 1 min to release the native substrate. Depolymerized right after use, the best siCPDs are nontoxic under conditions where cell-penetrating peptides (CPPs) are cytotoxic. Intracellular localization (cytosol, nucleoli, endosomes) is independent of the substrate and can be varied on demand, through choice of polymer composition. Insensitivity to endocytosis inhibitors and classical structural variations (hydrophobicity, aromaticity, branching, boronic acids) suggest that the best siCPDs act differently. Supported by experimental evidence, a unique combination of the counterion-mediated translocation of CPPs with the underexplored, thiol-mediated covalent translocation is considered to account for this decisive difference.
authors.affiliation: School of Chemistry and Biochemistry, National Centre of Competence in Research (NCCR) Chemical Biology, University of Geneva , Geneva 1211, Switzerland.
authors.forename: Giulio
authors.initials: G
authors.lastname: Gasparini
authors.forename: Eun-Kyoung
authors.initials: EK
authors.lastname: Bang
authors.forename: Guillaume
authors.initials: G
authors.lastname: Molinard
authors.forename: David V
authors.initials: DV
authors.lastname: Tulumello
authors.forename: Sandra
authors.initials: S
authors.lastname: Ward
authors.forename: Shana O
authors.initials: SO
authors.lastname: Kelley
authors.forename: Aurelien
authors.initials: A
authors.lastname: Roux
authors.forename: Naomi
authors.initials: N
authors.lastname: Sakai
authors.forename: Stefan
authors.initials: S
authors.lastname: Matile
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D057846:Cell-Penetrating Peptides / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D004220:Disulfides / Q000737:chemistry*; D004705:Endocytosis; D006367:HeLa Cells; D006801:Humans; D058105:Polymerization; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D057846:Cell-Penetrating Peptides; D004220:Disulfides; D013438:Sulfhydryl Compounds