Fig. 2. ATP/polymer ligand–receptor interactions: (a) 31P NMR titration of ATP (40 mM) with PEO-b-PHM at variable concentration ratios (D2O). The inset shows the H-bonding interaction sites between ATP's triphosphate region and the copolymer's GA species. (b) UV-vis absorption changes of ATP (0.1 mM) upon addition of PEO-b-PHM (0–10% content). The inset gives the absorption variation (261 nm) as a function of copolymer content. (c–e) ITC results show the three ligand–receptor interactions: ATP/PEO-b-PHM (c), ATP/C1 (C1 is a copolymer counterpart without the GA spacer) (d), and ATP/C2 (C2 is another copolymer counterpart without the CD pendant) (e). 60 μM ATP solution was injected into 1.0 μM copolymer solution at 293 K (all the experiments were in Tris–HCl buffer, pH = 7.20).
