Quantum-dots-FRET nanosensors for detecting unamplified nucleic acids by single molecule detection

Quantitative and sensitive detection of minute copies of nucleic acid sequences is critical in diagnosing disease and in understanding biomolecular processes. An inorganic-organic hybrid fluorescence resonance energy transfer (FRET) nanosensor based on quantum dots (QDs) was developed to overcome the limitations of conventional FRET-based probes. Functionalized QDs served as FRET donors and as nanoassemblies that can couple to multiple targets hybridized as a sandwich between a capture probe and a reporter probe. Target sequences are detected directly in solution by single molecule detection (SMD) without prior separation or amplification. This system is sensitive enough to detect approximately 50 or fewer copies and to discriminate point mutations. QD-FRET and SMD are platform technologies that will find many applications for detecting biomarkers or studying various biomolecules in a highly sensitive and quantitative manner.