A novel bio-sensing method was designed using DNA-mediated fusion of phospholipid and polyethylene glycol (PEG)-stabilized oil-in-water (O/W) emulsions. This method was inspired by the N-ethyl-maleimide-sensitive-factor attachment protein (SNARE) in cells, which induces fusion between cell organelles and membranes. These bio-sensing droplets have cholesterol-anchored oligonucleotides incorporated in the shell, and the fusion of the droplets is driven by hybridization of these complimentary oligonucleotide strands in a zipper-like fashion. The droplet fusion was studied and optimized as a function of interfacial chemistry such as phospholipid chain-length (C18 and C22), PEG molecular weight and concentration, and orientation of oligonucleotides (zippering or tethering mechanism). Based on these studies, a thrombin sensor was designed using competitive binding of thrombin aptamer strands. One of the oligonucleotide strands was designed to partially hybridize to thrombin aptamer sequence, so that the thrombin aptamer had affinity for both thrombin and the oligonucleotide strands on the droplets. The droplet fusion increased as a function of thrombin in accordance with a simple binding model, with sensitivity down to 100 nM. Future efforts will focus on optimization of this sensing mechanism and new detection schemes for in-solution biochemical assays.

Specific DNA-mediated fusion of oil-in-water emulsions to detect biological markers

248th National Meeting (2014)

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