title: Fine-tuned PEGylation of chitosan to maintain optimal siRNA-nanoplex bioactivity.
abstract: Polyethylene glycol (PEG) is a widely used modification for drug delivery systems. It reduces undesired interaction with biological components, aggregation of complexes and serves as a hydrophilic linker of ligands for targeted drug delivery. However, PEGylation can also lead to undesired changes in physicochemical characteristics of chitosan/siRNA nanoplexes and hamper gene silencing. To address this conflicting issue, PEG-chitosan copolymers were synthesized with stepwise increasing degrees of PEG substitution (1.5% to 8.0%). Subsequently formed PEG-chitosan/siRNA nanoplexes were characterized physicochemically and biologically. The results showed that small ratios of chitosan PEGylation did not affect nanoplex stability and density. However, higher PEGylation ratios reduced nanoplex size and charge, as well as cell uptake and final siRNA knockdown efficiency. Therefore, we recommend fine-tuning of PEGylation ratios to generate PEG-chitosan/siRNA delivery systems with maximum bioactivity. The degree of PEGylation for chitosan/siRNA nanoplexes should be kept low in order to maintain optimal nanoplex efficiency.
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany.
authors.forename: Andra
authors.initials: A
authors.lastname: Guţoaia
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany.
authors.forename: Liane
authors.initials: L
authors.lastname: Schuster
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany.
authors.forename: Simona
authors.initials: S
authors.lastname: Margutti
authors.affiliation: University of Tuebingen, Institute of Pharmacy, Tuebingen, 72076 Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Laufer
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Schlosshauer
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany; Reutlingen University, Faculty of Applied Chemistry, Reutlingen, 72762 Germany.
authors.forename: Rumen
authors.initials: R
authors.lastname: Krastev
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany; University of Applied Sciences, Albstadt-Sigmaringen, Sigmaringen, 72488 Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Stoll
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, 72770 Germany.
authors.forename: Hanna
authors.initials: H
authors.lastname: Hartmann
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D048271:Chitosan / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D004337:Drug Carriers; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D053758:Nanoparticles; D010078:Oxazines / Q000737:chemistry; D010316:Particle Size; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D012342:RNA, Small Nuclear / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics; D012995:Solubility; D014966:Xanthenes / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D007202:Indicators and Reagents; D010078:Oxazines; C000601335:PEG-chitosan copolymer; D012342:RNA, Small Nuclear; D014966:Xanthenes; D049452:Green Fluorescent Proteins; C005843:resazurin; D011092:Polyethylene Glycols; D048271:Chitosan
keywords: Chitosan; Chitosan (PubChem CID: 21896651); Ethylene glycol (PubChem CID: 174); Gene silencing; N-Hydroxysuccinimide (PubChem CID: 80170); Nanoplex functionality; PEGylated chitosan; Resazurin (PubChem CID: 11077); siRNA-delivery