High-efficiency, two-dimensional separations of protein digests on microfluidic devices.

Area of Science:

• Analytical Chemistry
• Microfluidics
• Biochemistry

Background:

• Two-dimensional separations are crucial for complex biological sample analysis.
• Microfluidic devices offer miniaturization and enhanced separation efficiency.
• Existing methods face challenges in speed and resolution for peptide analysis.

Purpose of the Study:

• To develop and validate a high-efficiency, two-dimensional microfluidic separation system for tryptic digests.
• To optimize micellar electrokinetic chromatography (MEKC) and capillary electrophoresis (CE) for peptide analysis.
• To demonstrate the system's capability in peptide identification and protein digest differentiation.

Main Methods:

• Utilized glass microfluidic devices with a serpentine first-dimension channel for MEKC and a second-dimension channel for CE.
• Asymmetric tapering of serpentine channel turns to minimize band broadening.
• High electric field strengths (200 V/cm for MEKC, 2400 V/cm for CE) for rapid separations.
• Analysis of model compounds (rhodamine B) and biological samples (bovine serum albumin, ovalbumin, hemoglobin tryptic digests).

Main Results:

• Achieved high plate numbers (230,000 in MEKC, 40,000 in CE) with low plate heights (0.9 µm and 0.3 µm).
• Obtained a peak capacity of 4200 in under 15 minutes for bovine serum albumin tryptic digest.
• Successfully identified a peptide from ovalbumin digest and distinguished between human and bovine hemoglobin digests.

Conclusions:

• The developed 2D microfluidic system provides high-efficiency and rapid peptide separations.
• This technology enables sensitive peptide identification and differentiation of complex protein mixtures.
• Microfluidic platforms hold significant promise for advancing proteomic analyses.