Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation.

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Biophysics

Background:

• Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is crucial for analyzing biomolecules.
• Heterogeneous analyte distribution in MALDI crystals hinders quantitative analysis and data reproducibility.
• Conventional air-drying methods often lead to non-uniform analyte crystallization.

Purpose of the Study:

• To develop a method for achieving homogeneous analyte distributions in MALDI-MS.
• To improve data reproducibility in quantitative MALDI-MS experiments.
• To investigate the role of Marangoni flows in controlling analyte heterogeneity.

Main Methods:

• Inducing Marangoni flows by creating temperature gradients across drying droplets.
• Utilizing substrate temperature control during the droplet drying process.
• Analyzing hydrodynamic flows semi-empirically and employing imaging mass spectrometry.

Main Results:

• Marangoni flows significantly reduce analyte heterogeneity during droplet drying.
• Decreasing substrate temperature enhances Marangoni velocities and improves analyte distribution.
• Biomolecular ion heterogeneity was reduced by 65%-80% using a 5 °C substrate compared to ambient conditions.

Conclusions:

• Controlling substrate temperature to induce Marangoni flows is a simple and effective method to reduce analyte heterogeneity.
• This technique enhances spatial distribution uniformity, leading to improved data reproducibility in MALDI-MS.
• The findings offer a practical approach for more reliable quantitative analysis in mass spectrometry.