The gas|liquid interface eclipses the liquid|liquid interface for glucose oxidase rate acceleration in microdroplets

Area of Science:

• Chemistry
• Biochemistry
• Physical Chemistry

Background:

• Microdroplets exhibit unique chemical properties, accelerating reactions.
• Previous studies explored reactions accelerated by microdroplets but lacked direct interface comparisons.

Purpose of the Study:

• To compare reaction acceleration at liquid-liquid and gas-liquid interfaces within microdroplets.
• To investigate the role of interfaces in enzyme catalysis within confined environments.

Main Methods:

• Utilized stochastic electrochemistry to monitor single femtoliter droplet collisions on an ultramicroelectrode.
• Developed a method to quantify reaction rates in femtoliter liquid aerosol droplets, emphasizing the gas-liquid interface.
• Confined glucose oxidase within microdroplets to study glucose turnover by hexacyanoferrate (III).

Main Results:

• Demonstrated that the gas-liquid interface accelerates enzyme turnover by over an order of magnitude compared to the liquid-liquid interface.
• Showcased the ability of microdroplets to drive significant reaction rate enhancements.
• Provided the first direct comparison of reaction acceleration at distinct interfaces in microdroplets.

Conclusions:

• The gas-liquid interface plays a critical role in accelerating enzyme turnover within microdroplets.
• Microdroplet confinement, particularly at the gas-liquid interface, can drive "curious chemistry" and enhance reaction rates.
• This study highlights the importance of interface phenomena in microdroplet-based chemical reactions.