Investigation of the binding behavior of PAMAMs-NH2 dendrimers with ofloxacin via NMR studies

Ofloxacin is one of the most potent antibiotics. But its low solubility in water has limited its use in site targeted delivery and topical applications. This study investigates the PAMAM-NH2 (amine-terminated polyamidoamine dendrimers) delivery of ofloxacin in water based on host-guest chemistry and reveals the interaction mechanism of PAMAM-NH2 with ofloxacin by utilizing NMR techniques including 1D chemical shift titration, 2D 1H–13C HSQC titration, NOESY technique, STDD method, and 2D DOSY analysis. Ofloxacin interacts with surface amine groups of PAMAM-NH2 via ionic interactions, and ofloxacin is also encapsulated into the PAMAM interior cave through hydrophobic interactions. An overall mechanism was proposed for the PAMAM-NH2 adsorption of ofloxacin, and then the binding affinity was determined. The experimental data demonstrate the potential of the PAMAM-NH2 for the drug molecules delivery.