Blood compatibility of surfaces with superlow protein adsorption

In this work, five self-assembled monolayers (SAMs) and three polymeric brushes with very low fibrinogen adsorption were prepared. The five SAMs are oligo(ethylene glycol) (OEG), phosphorylcholine (PC), oligo(phosphorylcholine) (OPC), and two mixed positively and negatively charged SAMs of SO3−/N+(CH3)3 (SA/TMA) and COO−/N+(CH3)3 (CA/TMA). Three polymer brushes were prepared on gold surfaces via surface-initiated atom transfer radical polymerization (ATRP) using three monomers, sulfobetaine methacrylate (SBMA), carboxybetaine methacrylate (CBMA), and oligo(ethylene glycol) methyl ether methacrylate (OEGMA). Surface plasmon resonance (SPR) measurements show that although all of these surfaces are “nonfouling” to fibrinogen adsorption from buffer solution, their protein adsorption from undiluted human blood plasma varies widely. Polymer brushes exhibit much lower protein adsorption from plasma than any of the five SAMs tested. However, platelet adhesion measurements on plasma-preadsorbed surfaces show that all of these surfaces have very low platelet adhesion. Clotting time measurements using recalcified platelet poor plasma (PPP) incubation with the eight types of surfaces show that they do not shorten clotting times. Linear polymers of polySBMA and polyCBMA with similar molecular weights were also synthesized and characterized. In the presence of polyCBMA linear polymers, the clotting time of PPP was prolonged and increased with the concentration of the polymer, while no anticoagulant activity was observed for the polySBMA or PEG polymers. The unique anticoagulant activity of polyCBMA, as well as its high plasma protein adsorption resistance, makes polyCBMA a candidate for blood-contacting applications.