in Wiley Online Library (wileyonlinelibrary.com)Sepharose FF was modified with diethylaminoethyl-dextran (DEAE-dextran, DexD) and/or DEAE (D) to fabricate three types of ion exchangers FF-DexD (grafting-ligand resin), FF-D (surface-ligand resin), and FF-D-DexD (mixed-ligand resin), for protein adsorption equilibria and kinetics study. It was found that both adsorption capacity and uptake rate (effective diffusivity, D e ) were significantly enhanced by grafting DEAE-dextran. Notably, the D e values on FF-DexD and FF-D-DexD (D e /D 0 > 1.4) were six times greater than those on FF-D (D e /D 0 < 0.3). More importantly, the increase of surface-ligand density greatly enhanced uptake kinetics on FF-D-DexD. The results indicate that the surface ligands assisted the transport of bound proteins on polymer chains in the mixed-ligand resins. That is, surface ligands worked as "transfer stations" between two neighboring chains, resulting in enhanced transport of bound proteins on chains. The research thus disclosed the unique role of surface ligands in facilitating protein uptake kinetics onto polymergrafted ion-exchangers.The static adsorption equilibrium experiments of BSA on the resins were carried out in 20 mmol/L Tris-HCl (pH 8.0) as described earlier. 24 The adsorption density of protein (q) was calculated by mass balance with the free protein concentration in equilibrium (c), and the Langmuir model was used to describe the adsorption isotherms,The black lines represent agarose matrix, the blue curves represent dextran chains, the green lines represent the spacers, the red circles represent ion-exchange groups, and the pink and purple circles represent bound proteins. The dashed blue curves and faded circles represent the grafted polymer chains with adsorbed proteins after swing, and the dashed black boxes highlight the sites for the "relay"/delivery of proteins. The quantities of the dextran chains, spacers and the ion-exchange groups in this figure do not represent their real densities in the resins. In (a) it shows that the upper protein (pink) on the chain is delivered while the lower one (purple) is not. In (b) it shows that chain delivery occurs for the lower protein (purple), which was mediated by the surface DEAE ligands. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]