Affinity Two-Phase Partitioning in Acoustically Levitated Drops

Sabina Santesson, Irene Barinaga-Rementeria Ramírez, Peter Viberg, Bengt Jergil, Staffan Nilsson

    Research output: Contribution to journalArticlepeer-review


    Miniaturized (<1 μL) biospecific affinity two-phase partitioning in an acoustically levitated drop is described. Miniaturization commonly gives unfavorable surface/volume ratios, but in the levitation approach adsorption problems are minimized since the only surrounding wall is the liquid/air interface of the drop. Biotinylated liposomes were partitioned in aqueous poly(ethylene glycol)/dextran two-phase drops with NeutrAvidin-dextran as the affinity ligand. A two-phase drop was trapped and manipulated in a node of a standing ultrasonic wave. Alternatively, a two-phase system was formed by levitation and evaporation of a polymer one-phase drop. Phase mixing was achieved by adjusting the ultrasonic field and phase separation by readjusting the field. NeutrAvidin-dextran brought about the redistribution of biolinylated liposomes from the poly(ethylene glycol)-rich phase into the dextranrich phase. Thus, an entire affinity two-phase separation procedure, including mixing of the phases and incubation to allow affinity interactions to develop under constant volume, followed by phase separation under controlled evaporation, can be performed in a single levitated drop. This miniaturized technique would allow the separation of biologically active membranes or organelles from individual cells for analysis.
    Original languageEnglish
    Pages (from-to)303-308
    Number of pages5
    JournalAnalytical Chemistry
    Issue number2
    Publication statusPublished - 12 Jan 2004


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