A23187-MEDIATED CD2-SORBING VESICLES( UPTAKE BY HIGHLY STABLE, POLYMERIZED METAL)

Vesicles formed from the polymerizable phospholipid, 1,2-diacyl-sn cer o-3-(N-2(methacryloyloxy)ethyl)-phosphocholine, and the crosslinker, 1 ,2-dihydroxyethylene-bis-acrylamide, exhibit significantly enhanced st ability relative to egg phosphatidylcholine (PC) vesicles. As evidence d by absorbance measurements, methacrylate PC vesicles with a 1:75 cro sslinker-to-lipid molar ratio retain their integrity in up to 20% (v/v ) ethanol as opposed to <10% (v/v) for egg PC vesicles. These crosslin ked-polymerized vesicles also remain impermeable to Cd2+ (in the absen ce of ionophore) for up to 15 mM octyl glucoside. Furthermore, the cro sslinked-polymerized vesicles show enhanced stability under osmotic st ress. These improvements in vesicle robustness are attained without dr amatic loss in A23187-mediated Cd2+ permeability. The initial Cd2+ per meability of crosslinked-polymerized (1:75 crosslinker-to-lipid molar ratio) and egg PC vesicles, with A23187 as ionophore, measured 6.0x10( -5) and 9.8x10(-5) cm s(-1), respectively.