Understanding nonviral nucleic acid delivery with quantum dot-FRET nanosensors.

Nonviral delivery of nucleic acids is a potentially safe and viable therapeutic modality for inherited and acquired diseases. However, current systems have proven too inefficient for widespread clinical translation. The rational design of improved carriers depends on a quantitative, mechanistic understanding of the rate-limiting barriers to efficient intracellular delivery. Separation of the nucleic acid from the carrier is one of the barriers, which may be analyzed by Förster resonance energy transfer (FRET), a mechanism used to detect interactions between fluorescently labeled molecules. When applied to the molecular components of polymer or lipid-based nanocomplexes, FRET provides information on their complexation status, uptake, release and degradation. Recently, the design of FRET systems incorporating quantum dots as energy donors has led to improved signal stability, allowing prolonged measurements, as well as increased sensitivity, enabling direct detection and the potential for multiplexing. The union of quantum dots and FRET is providing new insights into the mechanisms of nonviral nucleic acid delivery through convergent characterization of delivery barriers, and has the potential to accelerate the design of improved carriers to realize the potential of nucleic acid therapeutics and gene medicine.