Figure 1. Quantification of the amount and functionality of sulfate-modified alginate.

(A) The reaction of alginate with chlorosulfonic acid yields sulfated alginate. (B) Sulfate modification of alginate was verified by ¹H NMR. (C, D) Sulfate modification was quantified at different chlorosulfonic acid concentrations and between different batches via DMMB assay. (E) DMMB staining of crosslinked hydrogels exhibited uniform staining throughout the gel. (F) Recombinant HGF was entrapped in sulfated alginate hydrogels and the amount retained after 7 days was quantified. (G) Quantification of HGF release confirms that sulfate groups are functional and retain this heparin binding GF. Data are mean ± SD (n=3–4). Groups with statistically significant differences do not share the same letters; ns denotes no significance among all groups.