Droplet Microfluidic Device for Chemoenzymatic Sensing

Area of Science:

• Analytical Chemistry
• Biotechnology
• Environmental Science

Background:

• Enzymatic probes offer rapid detection of water pollutants.
• Pollutant presence often decreases the catalytic light-emitting activity of these probes.
• Continuous monitoring systems are crucial for early-warning water pollution detection.

Purpose of the Study:

• To develop a microfluidic system for continuous chemoenzymatic biosensing.
• To utilize droplet microfluidics for enhanced reagent mixing and detection.
• To establish a basis for early-warning online water pollution monitoring systems.

Main Methods:

• A microfluidic chip was designed to generate water-in-oil emulsion droplets (0.1 μL) at a frequency of 12 drops/min.
• The system incorporated bacterial bioluminescent enzymes (luciferase and NAD(P)H:FMN-oxidoreductase) and necessary substrates.
• Bioluminescent signals from individual droplets were measured using a photomultiplier tube (signal-to-noise ratio up to 3000/1).

Main Results:

• The system successfully generated and manipulated emulsion droplets for chemoenzymatic reactions.
• The bioluminescent signal intensity correlated with copper sulfate concentration, with a detection limit of 5 μM.
• Bioluminescent enzymatic reactions were effectively performed in droplet reactors within dispersed streams.

Conclusions:

• Droplet microfluidics enables efficient chemoenzymatic sensing for water quality monitoring.
• The developed system demonstrates potential for real-time, online water pollution detection.
• This technology can form the foundation for advanced early-warning water pollution systems.