User-friendly point-of-care detection of influenza A (H1N1) virus using light guide in three-dimensional photonic crystal.

This paper proposes a user-friendly and highly sensitive detection method for influenza A (H1N1) virus using the cooperation of quantum dot (Qdot)-aptamer beacons and light guide in a three-dimensional (3D) photonic crystal (PC). For easy use, we present a fluorescent probe-based 'OFF-ON' detection protocol. First, a mixture composed of Qdot-aptamer beacons and dark quencher-labeled guard DNA (G-DNA) was prepared. It initially quenched the fluorescent signals to significantly low intensity, i.e., 'OFF' state. Then, the influenza A (H1N1) virus preferentially bound to the aptamer and G-DNA was released, so that the fluorescent signal was restored and biosensor turned to 'ON' state. The restored fluorescence signal changed quantitatively according to the concentration of the target influenza A (H1N1) virus. Owing to the light guide of the 3D nanoporous PC structure, we achieved high sensitivity with ultra-low limit of detection (LOD) of 138 pg mL-1 and high selectivity over other species of influenza A virus and biomolecules. Additionally, with the benefit of enhanced output fluorescent signals, the target virus could be easily detected with a low-cost and portable home-made setup (total cost of only 20 US dollars) and a built-in camera in a smartphone.