Probing proteins on functionalized silicon surfaces using matrix-assisted laser desorption/ionization mass...

Area of Science:

• Materials Science
• Surface Chemistry
• Analytical Chemistry

Background:

• Surface modification of silicon substrates is crucial for controlling biomolecule interactions.
• Understanding non-specific protein binding is essential for sensitive and accurate mass spectrometry analysis.
• Alkyl monolayers offer tunable surface properties for biomaterial applications.

Purpose of the Study:

• To functionalize flat H-terminated Si(111) substrates with hydrophobic and hydrophilic alkyl monolayers.
• To investigate the non-specific binding of proteins from complex mixtures using modified silicon surfaces.
• To evaluate the effectiveness of these modified surfaces for direct analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS).

Main Methods:

• Surface functionalization of Si(111) with alkyl monolayers.
• Characterization using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).
• Analysis of protein adsorption from complex mixtures using MALDI-MS, including on-probe fractionation.

Main Results:

• Protein adsorption was dependent on the functional groups of the alkyl monolayers.
• The nature and pH of rinsing solutions significantly influenced protein adsorption.
• Simple silicon surface modifications proved effective for direct MALDI-MS analysis of complex protein mixtures.
• Functionalized porous silicon substrates demonstrated superior performance compared to flat silicon due to increased surface area.

Conclusions:

• Tailored silicon surface modifications with alkyl monolayers can effectively control non-specific protein binding.
• Direct analysis of complex protein mixtures by MALDI-MS is feasible using these functionalized silicon substrates.
• Porous silicon substrates offer advantages for protein analysis due to their higher surface area.