Application of polymer-embedded proteins to fabrication of DNA array

A plasma-polymerized film (PPF) of hexamethyldisiloxane [HMDS; (CH3)(3)SiOS i(CH3)(3)] was used to immobilize streptavidin on a glass substrate. Anothe r layer of HMDS-PPF was also applied to the protein, which was first adsorb ed to an underlayer of the same kind of film. As the result, the streptavid in was "embedded" between the two layers of HMDS, whereby biotinylated mole cules could be efficiently captured. The second layer of approximately 30 t o 45 Angstrom PPF was sufficient to allow the binding of biotinylated molec ules, whereas thicknesses of >90 Angstrom significantly hindered the strept avidin-biotin interactions. Fluorescence analysis revealed that the absence of an HMDS plasma-polymer (HMDS-PP) layer on either side of the streptavid in film resulted in a decrease in biotin binding. This immobilization techn ique was used to bind biotinylated oligonucleotides in sequence-specific DN A-DNA interactions. The hydrophobic properties of the plasma-polymerized HM DS thin film acted to minimize nonspecific DNA binding to the glass substra te. A DNA array was fabricated using this procedure and showed greatly decr eased nonspecific DNA binding compared with a poly-L-lysine coated substrat e. (C) 2000 John Wiley & Sons, Inc.