Reduced protein adsorption on the surface of a chemically grafted phospholipid monolayer

We have modified the surface of hydrophilic silicon oxide by chemically anc horing an organic monolayer bearing terminal phosphorylcholine (PC) groups and subsequently characterized the structure of the PC layers and their eff ectiveness in inhibiting the deposition of a range of model proteins. The P C compound was synthesized through coupling of S-aminopropyl trimethoxysila ne with acryloyloxyethylphosphorylcholine in 2-propanol. The presence of th e labile hydrogen on the secondary amine group of the monomer allowed a sub sequent coupling of two monomers with a bridging spacer such as a diisocyan ate to form a dimer. The PC dimer was coated onto a silicon substrate via d ip coating, and the chemical grafting with the substrate was strengthened b y annealing the coated layers at 150 degreesC under vacuum. Neutron reflect ion measurements showed that upon the formation of a well-packed monolayer, the small PC molecular coatings were as effective as the PC polymer coatin gs in reducing protein adsorption in vitro.