Concentric Förster resonance energy transfer imaging

Area of Science:

• Biotechnology
• Nanotechnology
• Analytical Chemistry

Background:

• Concentric Förster resonance energy transfer (cFRET) probes utilize semiconductor quantum dots (QDs) for multiplexed biological sensing.
• Robust ratiometric detection is achieved through a network of FRET pathways within a single vector.
• Developing and validating cFRET imaging methodology is crucial for expanding probe utility.

Purpose of the Study:

• To present and validate a novel cFRET imaging methodology.
• To enable quantitative measurement of proteolytic activity using cFRET probes.
• To demonstrate the spatiotemporal resolution of the developed imaging technique.

Main Methods:

• A protease-sensitive cFRET configuration was designed using a green-emitting QD, Alexa Fluor 555 (A555), and Alexa Fluor 647 (A647).
• Photoluminescence (PL) images were acquired using three filter-based emission channels to measure A555/QD and A647/QD PL ratios.
• Quantitative progress curves for proteolytic activity were calculated from PL ratios using calibration samples.

Main Results:

• The imaging methodology accurately reproduced quantitative results obtained with a monochromator-based fluorescence plate reader.
• Spatiotemporal resolution was demonstrated by tracking protease diffusion in a capillary.
• The method allows for precise measurement of proteolytic activity in specific regions of interest.

Conclusions:

• The developed cFRET imaging methodology provides a robust platform for quantitative biological sensing.
• This technique offers high spatiotemporal resolution for tracking enzymatic activity.
• The methodology is expected to facilitate future cellular sensing and advanced imaging assays using cFRET probes.