Thermochemical and spectroscopic studies on the supramolecular complex of PAMAM-NH₂ G4 dendrimer and 5-fluorouracil in aqueous solution.

The equilibrium of the formation of polyamidoamine dendrimer (PAMAM-NH(2) G4) and an oncological drug, 5-fluorouracil (FU) in water at room temperature has been examined. Using calorimetric titration, the number of active sites in the dendrimer combining the drug molecules and the equilibrium constant of the dendrimer-drug complex were estimated. The addition of the drug to the dendrimer active sites is an exothermic process. This process is accompanied by a beneficial change in entropy. The number of drug molecules combined by the polymer was confirmed by means of (1)H NMR spectroscopy. (1)HNMR measurements show that the dendrimer macromolecule binds the drug molecules with superficial protonated or unprotonated amine groups.