Study of the interactions of PAMAM G3-NH2 and G3-OH dendrimers with 5‐fluorouracil in aqueous solutions

The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, 1H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate spontaneous (ΔG<0ΔG<0) bonding of 5‐fluorouracil by both cationic PAMAM G3-NH2 dendrimer and hydroxyl PAMAM G3-OH dendrimer in aqueous solutions. PAMAM G3-NH2 dendrimer bonds about n=n= 25 ± 8 drug molecules. Some of them n1=n1= 5 ± 1 are bonded by terminal amine groups with equilibrium constant K1=K1= 3890 ± 930, while the remaining ones n2=n2= 24 ±3 are bonded by amide groups with equilibrium constant K2=K2= 110 ± 30. Hydroxyl PAMAM G3-OH dendrimer bonds n=n=6.0 ± 1.6 molecules of 5-fluorouracil through tertiary amine groups with equilibrium constant K=K= 65 ± 10. The parameters of bonding 5-fluorouracil by PAMAM G3-NH2 and G3-OH dendrimer were compared with those of bonding this drug by the macromolecules of PAMAM of generations G4-NH2, G5-NH2 and G5-OH.

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