title: Fine-tuning of proton sponges by precise diaminoethanes and histidines in pDNA polyplexes.
abstract: The cationizable nature of 'proton-sponge' transfection agents facilitates pDNA delivery in several steps. Protonated amines account for electrostatic DNA binding and cellular uptake, buffering amines mediate polyplex escape from acidifying intracellular vesicles. As demonstrated with a sequence-defined library of oligo(ethanamino)amides containing selected oligoethanamino acids and histidines, the total protonation capacity as well as the cationization pH profile within the endolysosomal range have critical impact on gene transfer. Building blocks with even numbered amine groups (Gtt, Sph) exhibited higher total endolysosomal buffer capacity than odd number (Stp) analogs. Within the endolysosomal range, Gtt has the highest buffer capacity around pH5, whereas Stp has its maximum around pH7. Histidines increased the total buffer capacity, resulted in a more continuous cationization pH profile and greatly improved transgene expression in vitro and in vivo. Using receptor targeted and polyethylene glycol shielded polyplexes, better endosomal escape and >100-fold enhanced transfection was detected.
  
  
  BACKGROUND
  Proton-sponge transfection agents for pDNA delivery are characterized in this study, demonstrating over 100-fold enhanced transection and better endosomal escape by using receptor targeted and polyethylene glycol shielded polyplexes.
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Lächelt
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Kos
authors.affiliation: Department of Chemistry, Physical Chemistry, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Frauke M
authors.initials: FM
authors.lastname: Mickler
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Herrmann
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Eveline E
authors.initials: EE
authors.lastname: Salcher
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rödl
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Naresh
authors.initials: N
authors.lastname: Badgujar
authors.affiliation: Department of Chemistry, Physical Chemistry, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany; Center for Nanoscience, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bräuchle
authors.affiliation: Pharmaceutical Biotechnology, Center for System-based Drug Research, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany; Center for Nanoscience, Ludwig-Maximilians-University Munich, Butenandtstrasse 5-13, Munich, Germany. Electronic address: Ernst.Wagner@cup.uni-muenchen.de.
authors.forename: Ernst
authors.initials: E
authors.lastname: Wagner
mesh_terms: D000588:Amines / Q000737:chemistry*; D000818:Animals; D011992:Endosomes / Q000737:chemistry / Q000187:drug effects; D006639:Histidine / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D011522:Protons; D014162:Transfection / Q000379:methods*
chemical_list: D000588:Amines; D011522:Protons; D011092:Polyethylene Glycols; D006639:Histidine; D011094:Polyethyleneimine
keywords: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; Endosomal escape; FolA; Gene transfer; Gtt; MTT; N/P; NA; PEG; Polymer; Proton sponge; Sph; Stp; TfR; Transfection; folic acid; glutaroyl-triethylene tetramine; nitrogen to phosphate ratio; nucleic acid; polyethylene glycol; succinoyl pentaethylene hexamine; succinoyl tetraethylene pentamine; transferrin receptor