Figure 1.

Schematic diagrams of albumin inhibition of the clinical LS Survanta and two distinct mechanisms of polymer-enhanced Survanta adsorption. (A) Albumin-inhibited diffusion of Survanta to the interface. The negative charges on albumin and Survanta create an electrostatic barrier that prevents Survanta from reaching the interface (Eq. 1). (B) Polycationic chitosan binds to the negative charges on albumin and Survanta, and reduces the magnitude of the electrostatic barrier toward Survanta diffusion to the interface, which allows Survanta to replace the interfacial film of albumin. (C) PEG is physically excluded from approaching the interface, albumin, or Survanta aggregates within the radius of gyration of PEG (dotted regions). When these excluded volumes overlap, PEG cannot enter the gap between the Survanta aggregates and the interface (or between aggregates), which leads to an osmotic pressure that pushes the aggregates toward the interface or each other. This is equivalent to increasing the volume available to PEG, which is an entropically favorable process (Eq. 2).