Electrospray interfacing of polymer microfluidics to MALDI-MS

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a key technique in proteomics.
• Traditional sample preparation for MALDI-MS can be labor-intensive and affect reproducibility.
• Microfluidic devices offer precise control over sample handling and processing.

Purpose of the Study:

• To develop and validate an off-line coupling method between polymer microfluidics and MALDI-MS using electrospray deposition.
• To improve spatial control, homogeneity, and spectral reproducibility of peptide and protein deposition for MALDI-MS.
• To demonstrate the potential for high-throughput multiplexed proteomic analyses and integrated sample preparation.

Main Methods:

• Utilized polycarbonate microfluidic chips with integrated hydrophobic membrane electrospray tips.
• Deposited peptides and proteins onto a stainless steel target for subsequent MALDI-MS analysis.
• Integrated on-chip proteolytic digestion by immobilizing trypsin within the electrospray membrane.

Main Results:

• Achieved excellent spatial control and homogeneity of deposited peptide spots.
• Demonstrated significantly improved MALDI-MS spectral reproducibility compared to traditional methods.
• Reported a detection limit of 3.5 femtomoles (fmol) for angiotensin.
• Successfully performed simultaneous deposition of multiple peptides from parallel sample streams with no cross-talk.
• Successfully achieved in-line proteolytic digestion during the electrospray process.

Conclusions:

• Microchip electrospray deposition provides an effective interface for microfluidic platforms in proteomic analyses.
• The developed method enhances throughput, reproducibility, and sample preparation efficiency for MALDI-MS.
• This technology holds promise for advancing high-throughput multiplexed proteomic studies.