title: Synthesis and evaluation of tetramethylguanidinium-polyethylenimine polymers as efficient gene delivery vectors.
abstract: Previously, we demonstrated that 6-(N,N,N',N'-tetramethylguanidinium chloride)-hexanoyl-polyethylenimine (THP) polymers exhibited significantly enhanced transfection efficiency and cell viability. Here, in the present study, we have synthesized a series of N,N,N',N'-tetramethylguanidinium-polyethylenimine (TP1-TP5) polymers via a single-step reaction involving peripheral primary amines of bPEI and varying amounts of 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU). These polymers were found to interact efficiently with negatively charged pDNA and formed stable complexes in the size range of ~240-450 nm. Acid-base titration profiles revealed improved buffering capacity of TP polymers as compared to bPEI. Transfection and cytotoxicity assays performed with TP/pDNA complexes on HEK293, CHO, and HeLa cells showed significantly higher transfection efficiency and cell viability with one of the complexes, TP2/pDNA complex, exhibited the highest transfection efficiency (~1.4-2.3-fold) outcompeting native bPEI and the commercially available transfection reagent, Lipofectamine 2000. Compared to previously reported THP polymers, the transfection efficiency of TP/pDNA complexes was found to be lower, as examined by flow cytometry. These results highlight the importance of the hydrophobic C-6 linker in THP polymers in forming compact nanostructures with pDNA, which might lead to efficient uptake and internalization of the complexes; however, the projected TP polymers offer an advantage of their rapid and economical one-step synthesis.
authors.affiliation: Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Delhi University Campus, Mall Road, Delhi 110 007, India.
authors.forename: Manohar
authors.initials: M
authors.lastname: Mahato
authors.affiliation: Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Delhi University Campus, Mall Road, Delhi 110 007, India.
authors.forename: Santosh
authors.initials: S
authors.lastname: Yadav
authors.affiliation: Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Delhi University Campus, Mall Road, Delhi 110 007, India.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Delhi University Campus, Mall Road, Delhi 110 007, India.
authors.forename: Ashwani Kumar
authors.initials: AK
authors.lastname: Sharma
mesh_terms: D000818:Animals; D002021:Buffers; D002460:Cell Line; D002470:Cell Survival; D055598:Chemical Phenomena; D004247:DNA / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D018014:Gene Transfer Techniques; D019791:Guanidine / Q000138:chemical synthesis* / Q000737:chemistry*; D006146:Guanidines / Q000138:chemical synthesis* / Q000737:chemistry*; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D010957:Plasmids / Q000378:metabolism; D011094:Polyethyleneimine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry*; D055672:Static Electricity; D014162:Transfection
chemical_list: D002021:Buffers; D006146:Guanidines; D011094:Polyethyleneimine; D004247:DNA; D003850:Deoxyribonuclease I; D019791:Guanidine