Engineering matrix-free laser desorption ionization mass spectrometry using glancing angle deposition films

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Thin, nanoporous films are crucial for solid matrix laser desorption/ionization mass spectrometry (SMALDI-MS).
• Glancing Angle Deposition (GLAD) offers precise control over film properties like nanoporosity, thickness, and material composition.

Purpose of the Study:

• To demonstrate the fabrication of Co-GLAD and Si-GLAD films for SMALDI-MS.
• To investigate the impact of film thickness, post density, and post angle on SMALDI performance.

Main Methods:

• GLAD films were prepared using electron beam evaporation with controlled substrate rotation.
• Laser desorption/ionization (LDI) performance was evaluated using a time-of-flight MALDI mass spectrometer.

Main Results:

• Co-GLAD films achieved a limit of quantitation of 6 fmol for complex carbohydrate derivatives.
• Slanted-post Si-GLAD films exhibited up to three times higher sensitivity compared to vertical post structures.
• GLAD films demonstrated superior reproducibility and detection limits compared to conventional MALDI methods and other nanostructured materials.

Conclusions:

• GLAD technology provides a flexible platform for fabricating diverse nanoporous LDI materials.
• Fine control over structural conformation, thickness, and porosity is achievable with GLAD.
• Co-GLAD films significantly outperform previous cobalt-based materials for SMALDI-MS.