AVS 52nd International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI2-WeM

Paper BI2-WeM8
A Method to Quantify and Evaluate the Efficiency of Nanometer-Sized Lipid Vesicle Modifications

Wednesday, November 2, 2005, 10:40 am, Room 312

Session: Biomembranes and Spectroscopy
Presenter: I. Pfeiffer, Chalmers University of Technology, Sweden
Authors: I. Pfeiffer, Chalmers University of Technology, Sweden
F. Höök, Lund University, Sweden
Correspondent: Click to Email
We recently demonstrated a DNA-hybridization-based concept for site-selective and sequence-specific sorting of lipid vesicles on DNA arrays.@footnote1@ By utilizing bivalent cholesterol-based coupling of oligonecleotides to lipid membranes, we showed that the coupling was irreversible in a broad concentration range on planar supported phospholipids bilayers (SPBs) and that exchange between differently modified vesicles in a suspension was sufficiently low to provide efficient sorting. In order to evaluate in further detail the efficiency of this and other lipid vesicle modification protocols, we present in this work a generic method that provides a simple means of quantifying the modification in terms of number of molecules per lipid vesicle. By exposing an SPB to a mixture of cholesterol-modified DNA and lipid vesicles, the amount of free DNA, i.e. DNA not anchored to the lipid vesicles, can be estimated by recording the initial rate of binding to the supported membrane. By comparing the so obtained response with a calibration curve based on the initial rate of binding from suspensions of free DNA, it was demonstrated that the efficiency of the bivalent coupling was 100% in the range of <1 to 35 oligonucleotides per vesicle - thus demonstrating a high stability and efficiency of this particular coupling. The generic value of the method for other types of modifications was demonstrated using cholera toxin binding to GM1 modified lipid vesicles, and given that a solid support can be made inert to colloidal particles, the method holds great promise to be generic for any type of modification scheme. @FootnoteText@ @footnote1@Pfeiffer, I.; Hook, F. Journal of the American Chemical Society 2004, 126, 10224-10225.