Molecular Photonic Logic Gates that use Fluorescent (Förster) Resonance Energy Transfer: The Future of Biocomputing

J.C. Claussen, S. Buckhout-White, W. Russ Algar, M.G. Ancona, N. Hildebrandt, I.L. Medintz
Naval Research Laboratory, US

Keywords: quantum dots, logic, biocomputing, FRET

Summary:

Molecular logic devices (MLDs) hold tremendous promise for a wide variety of applications including sensing,1 medical diagnostics, and nanorobotics. MLDs typically utilize chemical/biochemical inputs that are transduced to electrochemical or photonic output signals. Such nonhomogeneous standard Input/Output (I/O) signals greatly limit circuit complexity as logic gate concatenation is rendered nearly impossible. However, we demonstrate how all-photonic MLDs that utilize Fluorescent (Förster) Resonance Energy Transfer (FRET) can create complex logic circuits by varying both the temporal and spatial dynamics of FRET. By conjugating both long lifetime luminescent terbium(III) complexes (Tb) and fluorescent dyes (A647) to a single QD, we can create multiple FRET lanes that change temporally as the QD acts as both an acceptor and donor at distinct time intervals. In this work we fabricate unique three luminophore systems (Tb-QD-A647) with distinct valences of Tb and A647 to create multi-step FRET cascades that are capable of performing both Boolean and arthimetic logic operations. Such sophisticated logic operations open the door to a wide range of applications including multiplexed in vivo biodetection and biosensing for disease diagnostics and treatment.