Multi-Fluorophore DNA Origami Beacon as a Biosensing Platform.

Biosensors play increasingly important roles in many fields, from clinical diagnosis to environmental monitoring, and there is a growing need for cheap and simple analytical devices. DNA nanotechnology provides methods for the creation of sophisticated biosensors, however many of the developed DNA-based sensors are limited by cumbersome and time-consuming readouts involving advanced experimental techniques. Here we describe design, construction and characterization of an optical DNA origami nano-biosensor device exploiting arrays of precisely positioned organic fluorophores. Two arrays of donor and acceptor fluorophores make up a multi-fluorophore Förster resonance energy transfer (FRET) pair that results in a high output signal for microscopic detection of single devices. Arrangement of fluorophores into arrays increases signal to noise ratio allowing detection of signal output from singular biosensors using a conventional fluorescence microscopy setup. Single device analysis enables detection of target DNA sequences in concentrations down to 100 pM in less than half an hour. We expect that the presented nano-biosensor can function as a general platform for incorporating sensor modules for a variety of targets, and that the strong signal amplification properties may allow detection in portable microscope systems to be used for biosensor applications in the field.