Fabrication of Arrays
Drug-lipid interactions have been measured in a label-free manner using synthetic lipids in the form of liposomes. In this assay, natural cell membranes from Spodoptera frigiperda Sf9 insect cells (Invitrogen) were immobilized on gold-coated SPRi chips. The core of this approach is the incorporation of biotinylated PEG-phospholipids into the membrane (using double sonication) to generate biotin-tagged, small membrane vesicles.
Membrane fractions of Sf9 insect cells were sonicated with polymeric micelles composed of biotin-PEG-DSPE (Avanti Polar Lipids). After washing and centrifugation, the supernatant containing the biotinylated cell membranes (biMEM) was diluted and spotted on streptavidin-coated SPRi sensors where they were immobilized via the biotin-containing anchors.
An image of a typical biMEM array on a SpotReady16™ chip before exposure to analyte is shown in Figure 1A. biMEM capture on the chip surface is specific, and probe density of tethered membranes increases as the concentration of spotted biMEM increases (Figure 1B).