title: The role of the disulfide group in disulfide-based polymeric gene carriers.
abstract: BACKGROUND
  An essential prerequisite for successful gene therapy is the development of safe and efficient gene delivery carriers. For this purpose, cationic polymers have been widely studied as non-viral carriers, but they generally suffer from low transfection efficiency and/or high cytotoxicity. To address these problems, disulfide-based cationic polymers have been designed as intelligent gene carriers that are capable of inducing highly efficient gene transfection with low cytotoxicity.
  
  
  OBJECTIVE
  The present review discusses the effects of the disulfide linker on the gene delivery properties of cationic polymers in relation to various gene delivery barriers.
  
  
  METHODS
  The literature regarding the gene delivery barriers encountered by polymeric gene delivery is reviewed and discussed in relation to the presence of the disulfide moiety in these gene carriers.
  
  
  CONCLUSIONS
  The presence of disulfide linkages in cationic polymers can in many aspects favorably influence the gene delivery properties, such as increasing DNA binding ability, enabling de-shielding of 'stealth' (PEG) groups, fine-tuning of the buffer capacity for enhanced endosomal escape, improving carrier-unpacking and decreasing cytotoxicity. Therefore, disulfide-based cationic polymers are promising candidates for the next generation of non-viral carriers.
authors.affiliation: University of Twente, Institute for Biomedical Technology, Department of Biomedical Chemistry, AE Enschede, The Netherlands.
authors.forename: Chao
authors.initials: C
authors.lastname: Lin
authors.forename: Johan F J
authors.initials: JF
authors.lastname: Engbersen
mesh_terms: D002412:Cations; D004220:Disulfides / Q000737:chemistry; D018390:Gene Targeting / Q000379:methods; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000737:chemistry / Q000633:toxicity; D006801:Humans; D011108:Polymers / Q000737:chemistry* / Q000633:toxicity
chemical_list: D002412:Cations; D004220:Disulfides; D011108:Polymers