Synthesis of polyamidoamine dendrimers modified by cyclodextrin and their molecular inclusion interaction with levofloxacin lactate

The polyamidoamine (PAMAM) dendrimers having different generations (G2 and G4) modified by β-cyclodextrin (β-CD) , PAMAM (G2 , G4) -β-CD , were synthesized using substitution reaction from mono-6iodine-β- cyclodextrin and PAMAM dendrimers, and the molecular structures were characterized by H-NMR and IR. The molecular interaction between various dendrimers and levofloxacin lactate (LFL) was determined by fluorimetry in buffer solution (pH =7. 4) at 251. It was found that the PAMAM (G2,G4) -β-CD possesses higher sensitizing ability than that of the corresponding parent dendrimers and natural β-CD, and it increases concomitantly with the increases of generation and content of β-CB, suggesting that the PAMAM (G2 , G4) -βCD possesses strong inclusion ability with LFL. The possible interaction mechanism between PAMAM-CD and LFL was proposed by ¹H-NMR analysis and theoretical calculation. The results showed that the LFL molecule was placed in the amino end of dendrimer molecule and between the sides of cyclodextrin cavities to form supramolecular complexes. Furthermore,the results indicate that the main driving force of the system could be attributed to the electrostatic interaction as well as hydrogen bonding between the LFL and PAMAM-CD, and fully reflects the synergistic effect of intermolecular forces.