Fig. 3. Synthesis and characterization of HA–DP. (A) Schematic of chemical reaction to generate HA–DP. The dopamine was conjugated with the carboxyl group of HA using DMTMM, MES buffer (pH 5.5). (B) The conjugation of dopamine group to HA was confirmed using ¹H-NMR. The protons of the aromatic ring of DP showed peaks at 7.4–7.2 ppm and those of N-acetyl groups of HA showed 2.0 ppm of the spectrum of ¹H-NMR confirming an appropriate conjugation of DP to HA. ¹H-NMR spectra analysis confirms 42% of degree of substitution. (C) Representative photo taken after TBO staining and washing as described in characterization method, a control tissue culture plastic was used to show difference in purple blue stain due to staining. (D) The difference between amount of bound HA on the surface between two coating method. The left column of the graph represents the coating with HA–DP and right one represents coating with free HA solution. We found no presence of HA from free solution-based coating compared to HA–DP based coating.