A combinatorial droplet microfluidic device integrated with mass spectrometry for enzyme screening

Area of Science:

• Biochemistry
• Analytical Chemistry
• Microfluidics

Background:

• Mass spectrometry (MS) offers high specificity but limited throughput for biochemical research.
• Microfluidics integration with MS shows potential for enhanced throughput and accelerated research.
• Nanostructure-initiator mass spectrometry (NIMS) is a matrix-free laser desorption ionization technique.

Purpose of the Study:

• To introduce Drop-NIMS, a novel platform combining microfluidics and NIMS for high-throughput screening.
• To enable rapid screening of enzymatic reactions using minimal reactant volumes.
• To identify enzymes with industrial applications in food and biofuel sectors.

Main Methods:

• Developed a passive droplet loading microfluidic device integrated with NIMS.
• Generated combinatorial libraries of enzymatic reactions by combining droplets randomly.
• Utilized MS barcodes for identifying substrate and enzyme combinations.
• Screened glycoside reactants and glycoside hydrolase enzymes in nanoliter volumes.

Main Results:

• Successfully screened enzymatic reactions with low nL volumes.
• Assigned xylanase activities to several putative glycoside hydrolases.
• Demonstrated the utility of MS barcodes for reaction identification.
• Showcased the platform's simplicity in fabrication, assembly, and operation.

Conclusions:

• Drop-NIMS is a simple, efficient platform for high-throughput enzymatic reaction screening.
• The technology accelerates the discovery of enzymes relevant to industrial applications.
• Drop-NIMS has broad potential for screening various small molecule metabolites.