(215e) An Electrospray Nanocolloid Assay for Rapid Biomarker Detection

The development of fast and highly-sensitive bioassays has attracted considerable attention for a wide variety of application in molecular diagnosis. In this talk, we introduce a new nanocolloid electrospray technology that allows detection of different sized biomolecules in 5 minutes by a rapid and highly sensitive nanocolloid DC electrospray technique. DNA hybridization, antigen-antibody binding and micro-vesicles released from ovarian cancerous cells are shown to be successfully detected by this technique. This is achieved by spraying a mixture, composed of species specific probe (oligomer probe/antibody/antigen) functionalized nanocolloids with target biomolecules by DC electrospray, which allows nanocolloids and target biomolecules to concentrate at the tip of the Taylor cone of radius smaller than 1 micron. Upon exiting the cone, Rayleigh fission and evaporation endow the aggregates with much larger charge than undocked DNA/antibody and nanocolloids, hence allowing precise separation and deposition of the large aggregates in concentric bands (under atmospheric conditions), whose locations can be predicted from the discrete Laplace harmonics of the Taylor cone. This concentrated field-induced dipolar interaction, which results in the stretching of long target DNA molecules greatly enhance the rate of DNA hybridization. With multiple antibodies functionalized onto the nanocolloids behaving as a network of polyvalent linkers bind the biomarkers to multiple docking sites resulting into aggregates large enough for clear separation in Taylor harmonics. Janus colloids with asymmetric hemispheres are shown to exhibit even higher induced dipoles and to further promote hybridization and aggregation. The aggregates show different connectivity and geometry with the Janus colloid linkers.