Hydrodynamic properties of carbohydrate-coated dendrimers

Abstract

The hydrodynamic properties of poly(propylene imine) dendrimers, modified with outer-surface b-thiolactosyl residues (''lactodendrimers'') of generation number 1-5, have been investigated by velocity sedimentation, translational diffusion, and viscosity measurements in 0.165% NaCl aqueous solution. It has been demonstrated that apparent molecular weights (from the Svedberg equation) M sD of synthetic lactodendrimers, determined by sedimentation and diffusion experiments, are consistent with complete functionalization of initial poly-(propylene imine) dendrimers with sugar residues. The values of M sD range from 1900 to 45000 Da for generation numbers 1-5. Corresponding hydrodynamic (''equivalent Stokes'') radii range from ϳ10 to ϳ37 Å . Scaling relations of the conformation-dependent sedimentation coefficient, translational diffusion coefficient and intrinsic viscosity with molecular weight have been considered in detail and are all indicative of a spherical molecule with an inhomogeneous distribution of density (Mark-Houwink-Kuhn-Sakurada a, b and , coefficients of ϳ0.24, ϳ0.69 and ϳ0.31, respectively). ᭧

Molecular simulation of host–guest inclusion compounds: an approach to the lactodendrimers case

“…5 shows a sketch of the equilibrated simulation cell. Although no salts were included in the system, the values of the corresponding radius of gyration R gWATER obtained from these virtual experiments for the ®rst two generations are in very good agreement with the values obtained experimentally by Pavlov et al (1999) (see Table 2). This seems to con®rm the validity of the force ®eld selection and the reliability of the applied simulation conditions.…”

“…Since, however, their full application potentials (particularly in materials science and engineering) will not be realized before the understanding of their physical properties is considerably more advanced, in this work we report the ®rst results obtained from an investigation of the structural details of the ®rst two generations of LDs. In order to verify the validity of the data obtained on isolated structures, we report also the comparison of the information gained on the same structures in an aqueous environment with the available experimental data (Pavlov et al, 1999). Finally, we show and discuss the results obtained from an investigation of the interaction between LDs and four molecules of pharmaceutical interest.…”

“…Even more recently, the synthesis of a series of carbohydrate-coated poly(propylene imine) dendrimers (hereafter referred to as lactodendrimers, LDs) has been reported in the literature (Ashton et al, 1997), and subjected to an extensive hydrodynamic investigation (Pavlov et al, 1999). Since, however, their full application potentials (particularly in materials science and engineering) will not be realized before the understanding of their physical properties is considerably more advanced, in this work we report the ®rst results obtained from an investigation of the structural details of the ®rst two generations of LDs.…”

Hydrodynamic Behavior of Dendrigraft Polylysines in Water and Dimethylformamide

“…In the latter case, the scaling exponents are very sensitive to thermodynamic quality of the solvent [24]. Compared to other dendritic structures, such as PAMAM in methanol [1,25], carbohydrate coated PAMAM [26] and DAB modified by lactose-end groups [27] in aqueous buffers, similar exponents from 0.25 to 0.37 were obtained. Indeed, diffusion scaling indexes for dendrimers and dendrimer-like structures are in the vicinity of 1/3.…”

Molecular characteristics of poly(propylene imine) dendrimers as studied with translational diffusion and viscometry

“…In several works the hydrodynamic properties of dendrimer molecules were measured by different techniques [9,16,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. It is reported that the intrinsic viscosity of dendrimer molecules is small and has a very low dependency on the molecular weight or that this dependency has a small maximum depending on the number of generations.…”