Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy

Area of Science:

• Materials Science
• Surface Chemistry
• Spectroscopy

Background:

• Infrared reflection absorption spectroscopy (IRRAS) is a powerful surface-sensitive technique.
• Silicon oxide surfaces are widely used in biomedical applications.
• Developing new methods to characterize surface modifications is crucial for advanced material development.

Purpose of the Study:

• To present a novel titanium-silicon oxide film structure.
• To enable polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) on silicon oxide surfaces.
• To demonstrate the utility of this structure for investigating protein-resistant self-assembled monolayers (SAMs).

Main Methods:

• Fabrication of a ~6 nm silicon oxide film on a ~200 nm titanium film.
• Characterization using electron microscopy (TEM, STEM), electron energy loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), and X-ray reflectometry (XRR).
• Application of PM-IRRAS to study a silane-anchored, biotin-terminated poly(ethylene glycol) (PEG) SAM.

Main Results:

• The titanium-silicon oxide film structure was successfully fabricated and characterized.
• Poly(ethylene glycol) (PEG)-associated infrared bands were observed using PM-IRRAS.
• The SAM demonstrated selective protein adsorption, binding streptavidin while repelling bovine serum albumin.

Conclusions:

• The developed titanium-silicon oxide film structure is effective for PM-IRRAS analysis of surface modifications.
• This technique allows for the investigation of the protein resistance of self-assembled monolayers.
• The results confirm the selective protein-repellent properties of the investigated PEG-based SAM.