High-Throughput Characterization of Individual Microdroplets Unveils Ultrasound-Enhanced Radical Production

Area of Science:

• Environmental Chemistry
• Mechanochemistry
• Biological Oxidative Processes

Background:

• Reactive oxygen species (ROS) are crucial in various scientific fields.
• Quantifying ROS in microenvironments is challenging due to limitations in current methods.
• Existing techniques lack droplet-level resolution and high throughput, hindering mechanistic studies.

Purpose of the Study:

• To develop a high-throughput strategy for characterizing and quantifying H2O2 production in individual microdroplets.
• To investigate the influence of droplet size and ultrasound on ROS generation.
• To provide a framework for understanding ROS dynamics in microenvironments.

Main Methods:

• Utilized horseradish peroxidase (HRP)-catalyzed fluorogenic reactions for H2O2 detection.
• Implemented a ratiometric signal measurement using Rhodamine 6G (R6G) as an internal control.
• Analyzed hundreds of thousands of individual droplets simultaneously for high-throughput characterization.

Main Results:

• Confirmed that smaller droplets produce more ROS per unit volume, aligning with interfacial chemistry theories.
• Discovered that ROS generation is enhanced in larger airborne droplets (>5 μm) when treated with ultrasound.
• Demonstrated the platform's capability for rapid and parallel characterization of a large number of microdroplets.

Conclusions:

• The developed high-throughput platform enables precise quantification and characterization of ROS in microdroplets.
• The findings offer new insights into ROS generation mechanisms influenced by droplet size and external factors like ultrasound.
• This approach facilitates the controlled generation of ROS and deepens the mechanistic understanding of ROS dynamics.