Sedimentation, translational diffusion, and viscosity of lactosylated polyamidoamine dendrimers

Abstract

The hydrodynamic characteristics of six generations of lactosylated polyamidoamine dendrimers (LacPAMAM) in 0.165% NaCl have been investigated and their molecular characteristics determined. Experimental values varied over the following ranges: sedimentation velocity coefficient 0.65 < s < 6.2, translational diffusion coefficient (×10⁷ cm² s⁻¹) 19.1 > D > 4.9, which corresponds to a change in molecular weight (×l0³) in the range 2.5 < M _sd > 93 and which is in good agreements with LacPAMAM chemical structures. The intrinsic viscosity of LacPAMAMs practically did not change and the average value was (4.25 ± 0.45) cm³/g. The following scaling relationships for hydrodynamic values were thus established: s = 4.84×l0^-16 M ^0.63±0.015, D = 3.56×l0^-5 M ^{-(0.37±0.015)}, [η] = 2.59 × M ^0.05±0.05. The hydrodynamic invariant is A₀ = (2.61 ± 0.07)10^-10. In the case of the dendrimers the value of the intrinsic viscosity became insensitive to molecular weight changes. In contrast, the sedimentation velocity coefficient became more sensitive to M in comparison to that of linear molecules. The hydrodynamic values of LacPAMAM molecules were compared to the values obtained for lactosylated dendrimers based on a poly(propylene imine) core.