Single-molecule photoreaction quantitation through intraparticle-surface energy transfer (i-SET) spectroscopy

Area of Science:

• Nanotechnology
• Spectroscopy
• Single-molecule analysis

Background:

• Quantifying nanoparticle-molecule interactions at the single-molecule level is challenging due to weak emission and environmental perturbations.
• Existing methods struggle with sensitivity and accuracy in detecting individual molecular events.

Purpose of the Study:

• To develop a novel sensing strategy for sensitive single-molecule detection using nanoparticle probes.
• To enable quantitative analysis of nanoparticle-molecule interactions with enhanced sensitivity.

Main Methods:

• Rational design of an intraparticle-surface energy transfer (i-SET) process utilizing Tb³⁺-activator-rich core-shell upconversion nanoparticles.
• Implementation of enhanced non-radiative energy transfer for improved spectral response.
• Quantitative analysis of spectral changes in single fluorophores tethered to nanoparticles via i-SET spectroscopy.

Main Results:

• Achieved significantly faster non-radiative energy transfer rates (over an order of magnitude) compared to conventional methods.
• Demonstrated quantitative spectral analysis of one to four fluorophores on a single nanoparticle.
• Showcased unprecedented sensitivity in detecting single-molecule interactions.

Conclusions:

• The developed i-SET process provides a powerful new tool for single-molecule sensing.
• Enables detailed studies of photoreaction kinetics and individual molecular behaviors with high sensitivity.
• Opens opportunities for advancing fields requiring precise molecular-level understanding.