Generation-dependent host-guest interactions: Solution states of polyglycerol dendrimers of generations 3 and 4 modulate the localization of a guest molecule

摘要

Host-guest interactions between polyglycerol dendrimers of generations 3 and 4 (PGD-G3 and G4) and 4-amino-3-hydroxynapthalene-2-sulphonic acid (AHSA) were investigated by fluorescence spectroscopy, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). PGD-G3 molecules were found to form an associated state with an average diameter of 82.7 nm in aqueous solution, in which PGD-G3 provided a much more polar microenvironment than glycerol. PGD-G3 and AHSA interacted attractively, showing a binding constant of 5.3×10~5 M~(-1) with a 2:1 stoichiometry. On the other hand, AHSA interacted with the periphery of PGD-G4, the majority of which existed as a unimer, forming a less polar microenvironment. The driving force of the interactions for PGD-G3 and -G4 were mainly enthalpically and entropically driven, respectively. The generation-dependent host-guest interactions were described in conjunction with thermodynamic parameters. Be my guest: Polyglycerol dendrimers (PGDs) of generations 3 and 4, which are believed to be biologically inert nanomaterials, were examined for interaction with a fluorescent molecule. A PGD of generation 3 formed an association state, in which the guest molecule interacted attractively through an enthalpically driven mechanism (see figure).