Guanidinylation: A simple way to fabricate cell penetrating peptide analogue‐modified chitosan vector for enhanced gene delivery

In view of the analogous transmembrane function to cell penetrating peptides, guanidine group was incorporated into chitosan by chemical modification to enhance the transfection performance of chitosan vectors. Guanidinylated chitosan (GCS) was shown to be well soluble in neutral aqueous solution. The interaction between GCS with plasmid DNA was characterized by agarose retardation experiment and ethidium bromide displacement assay. GCS formed more stable complexes with DNA under physiological pH than chitosan. The transfection efficiency of GCS was evaluated employing COS‐7 cell line—GCS polyplexes demonstrated higher transfection efficiency and lower cytotoxicity relative to chitosan. The optimum efficiency of GCS was achieved in the vicinity of the critical complexing ratio. The results of flow cytometry indicated that guanidinylation promoted an eightfold increase in the cell uptake. The study revealed that guanidinylated chitosan is a promising candidate as an effective nonviral vector for in vivo gene delivery. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Guanidinylated poly(allyl amine) as a gene carrier

Guanidinylated poly(allyl amine) (GA) was synthesized and used as a gene carrier. The degree of guanidinylation in GA increased linearly when the feed ratio of guanidino groups in 1H‐pyrazole‐1‐carboxamidine to amino groups in poly(allyl amine) (PA) was below 0.7, and the amino groups of poly(allyl amine) with a weight‐average molecular weight of 15,000 (PA15) were almost replaced with guanidino groups when the ratio reached 2. GA showed good plasmid condensation and protection ability. Nanoparticles with a narrow size distribution, good dispersity, and spherical shape could be assembled between GA and DNA. With an increase in the N/P ratio [where N is the amount of nitrogen in the polycation (for GA, three nitrogens per guanidino group) and P is the amount of plasmid phosphate in the DNA as moles] or the degree of guanidinylation, the ζ‐potential of GA/DNA nanoparticles increased, whereas the sizes of GA/DNA nanoparticles decreased sharply with increasing N/P ratios. Compared with polyethylenimine with a weight‐average molecular weight of 25,000 and PA15, GA essentially showed decreased cytotoxicity to HeLa, 293T, and HepG2 cell lines, and guanidinylated PA15 exhibited the lowest cytotoxicity. Guanidinylation of PA enhanced its gene transfection. This enhancement was dependent on the degree of guanidinylation and the cell lines. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009