title: Synthesis of guanidinium-modified hyaluronic Acid hydrogel.
abstract: In this report, a new guanidinylating reagent is presented, which was developed without any protection/deprotection strategy and was successfully employed for linking to hyaluronan in aqueous solution. The dually functionalised HA biopolymer bearing guanidinium and hydrazide groups was synthesised to form hydrogel in less than a minute when mixed with aldehyde-modified HA. This hydrogel exhibited higher storage modulus with enhanced stability in PBS when compared to the non-guanidine-containing gel. The gel shift assay showed that this biopolymer formed a stable complex with DNA as well as efficient gene transfection to cells that express HA-receptor CD44. The toxicity studies of this polymer with fibroblast cells revealed that the cells were almost 80% viable after 4 d of incubation at high HA concentration (2.5 × 10(-3)  M).
authors: Department of Material Chemistry, Uppsala University, Box 538, S-75121, Uppsala, Sweden. oommen.varghese@mkem.uu.se.
authors: Oommen P
authors: OP
authors: Varghese
authors: Marta
authors: M
authors: Kisiel
authors: Elena
authors: E
authors: Martínez-Sanz
authors: Dmitri A
authors: DA
authors: Ossipov
authors: Jöns
authors: J
authors: Hilborn