MODELING IN-VIVO TRANSFER OF LONG-CIRCULATING POLYMERS (2 CLASSES OF LONG CIRCULATING POLYMERS AND FACTORS AFFECTING THEIR TRANSFER IN-VIVO)

The relationships between polymer structure and circulation in vivo are discussed on the basis of a mathematical model of polymer transfer. Significant differences in polymer distribution in liquid compartments allow to divide long-circulating polymers and particulates into two groups, large (non-extravasating) and small (extravasating) polymers. Transfer processes that members of these two groups undergo are distinctively different and can be described by different idealized models. Although polymers of both classes may consist of the same constituents, their in vivo localization in liquid compartments and capability of cooperative interactions with components of biological systems may be essentially different. Therefore, relative impact of polymer structure on biokinetics of large and small polymers may differ. Minimization of polymer clearance due to interactions with biological systems and renal filtration is important in the development of long-circulating polymers. Hydrophilic interface brushes assembled of non-reactive polymer chains proved to be effective in prolongation of circulation of both extravasating and non-extravasating polymers, although prolongation mechanisms may differ.