INHIBITION OF PLATELET SPREADING FROM PLASMA ONTO GLASS BY AN ADSORBED LAYER OF A NOVEL FLUORESCENT-LABELED POLY(ETHYLENE OXIDE) POLY(BUTYLENE OXIDE) BLOCK-COPOLYMER - CHARACTERISTICS OF THE EXCLUSION ZONE PROBED BY MEANS OF POLYSTYRENE BEADS AND MACROMOLECULES/

We have investigated the anti-adhesive properties of a newly synthesiz ed fluorescent triblock copolymer containing poly(ethylene oxide). Thi s adsorbs from aqueous solution onto glass that has been rendered hydr ophobic. When the polymer-treated surface was exposed to human platele t-rich plasma (PRP) or whole blood at 37 degrees C, platelet adhesion and spreading were prevented. Avid adhesion and rapid platelet spreadi ng occurred along tracks scraped in the adsorbed polymer coating, as s een by video-enhanced interference reflection microscopy. Leukocytes f rom whole blood are eventually able to adhere to the polymer-treated s urface and were seen to remove labeled polymer from their vicinity and accumulate it at the cell body. Interferometry using polystyrene sphe res showed that they do not adhere to polymer-coated glass and are una ble to approach closer than 70-95 nm. On scraped tracks, beads make mo lecular contacts with the glass. Because the fully extended solvated ( EO)(400) arms may extend up to 100 nm from the glass, this suggests th at the polymer forms a monolayer with the hydrophilic arms projecting into the water, whereas the hydrophobic (BO)(55) Segment binds the mol ecule to the hydrophobic surface. Another tribloc copolymer with short er hydrophilic arms allows particles to approach more closely. (C) 199 4 John Wiley and Sons, Inc.