Fluorescence imaging of electrical activity in cardiac cells using an all-solid-state system

Area of Science:

• Biophysics
• Cardiovascular Physiology
• Optical Imaging

Background:

• Optical mapping of cardiac cells is crucial for understanding arrhythmogenesis.
• Existing techniques face challenges in cost and complexity.
• Need for accessible tools to study cellular electrophysiology and calcium dynamics.

Purpose of the Study:

• To develop a compact, low-cost system for fluorescence-based optical mapping of cardiac cell networks.
• To utilize novel light-emitting diodes (LEDs) as excitation sources and custom-fabricated filters for improved measurements.
• To demonstrate the system's utility in characterizing cardiac electrophysiological properties.

Main Methods:

• Employed high-power blue and green LEDs for exciting voltage-sensitive (di-8-ANEPPS) and calcium-sensitive (Fluo-3) dyes.
• Developed simple techniques for fabricating thin, durable, auto-fluorescence-free emission filters.
• Integrated LEDs and filters with a fiber-optic system for contact fluorescence imaging.
• Utilized the system for macro-scale conduction velocity restitution measurements and single-cell epi-illumination recordings.

Main Results:

• Demonstrated the first use of high-power LEDs for cardiac optical mapping.
• Achieved stable excitation light sources with acceptable signal-to-noise ratios.
• Observed negligible cell photodamage and indicator dye photobleaching.
• Showcased the system's versatility, including high-frequency light modulation capabilities.

Conclusions:

• The developed compact system offers a low-cost, effective solution for optical mapping of cardiac cellular activity.
• LEDs and custom filters provide stable, high-quality fluorescence measurements with minimal photodamage.
• This technology facilitates advanced research into cardiac arrhythmogenesis and electrophysiology.