Long-Range Energy Transfer between Dye-Loaded Nanoparticles: Observation and Amplified Detection of Nucleic Acids

Area of Science:

• Nanomaterials Science
• Biophysics
• Optical Materials

Background:

• Förster resonance energy transfer (FRET) is crucial for optical applications but limited by a short operating range (≈5 nm).
• Existing FRET applications in light-harvesting, photovoltaics, and biosensing face limitations due to the Förster radius constraint.

Purpose of the Study:

• To overcome the Förster radius limitation in FRET.
• To investigate FRET efficiency between fluorescent organic nanoparticles (NPs) at extended distances.
• To develop a novel, highly sensitive biosensor based on long-distance FRET.

Main Methods:

• Fabrication of donor and acceptor fluorescent organic NPs using charged hydrophobic polymers, cationic dyes, and hydrophobic counterions.
• Surface functionalization of NPs with DNA to precisely control inter-particle distances.
• Characterization of FRET efficiency as a function of NP surface-to-surface distance.
• Development of a DNA nanoprobe for cancer marker detection using long-distance FRET.

Main Results:

• Observed FRET efficiency significantly exceeding predictions of the canonical Förster law for NP-NP distances of 15 and 20 nm (efficiencies of 0.70 and 0.45, respectively).
• Demonstrated a power-four decay of FRET efficiency with increasing NP-NP surface-to-surface distance.
• Developed a DNA nanoprobe detecting the cancer marker survivin, achieving a color switch for over 5000 dyes upon single-molecular recognition.
• Achieved an ultra-low limit of detection of 18 attomoles for the cancer marker.

Conclusions:

• The study successfully breaks the conventional Förster distance limit for FRET using engineered nanoparticles.
• The developed long-distance FRET mechanism enables amplified optical signaling for highly sensitive biosensing.
• This approach paves the way for advanced optical nanomaterials and amplified FRET-based diagnostic tools.