Probing nanoscale interactions on biocompatible cluster-assembled titanium oxide surfaces by atomic force microscopy.

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Investigating adhesion properties of biocompatible materials is crucial for biomedical applications.
• Nanostructured titanium oxide (ns-TiO(x)) films offer unique surface characteristics.
• Atomic Force Microscopy (AFM) tips serve as model nanoprobes for surface interactions.

Purpose of the Study:

• To investigate the adhesive properties of ns-TiO(x) films against a silicon nitride (Si3N4) AFM tip in air and water.
• To understand the molecular interaction mechanisms governing adhesion.
• To explore the potential of ns-TiO(x) for biocompatible surface applications.

Main Methods:

• Utilized nanosphere lithography and supersonic cluster beam deposition to create ns-TiO(x) films.
• Employed AFM to probe adhesion forces between ns-TiO(x) and Si3N4 tips.
• Analyzed interaction channels including van der Waals, electrostatic, and chemical bonding.

Main Results:

• Adhesion of ns-TiO(x) films to Si3N4 AFM tips was enhanced in aqueous medium compared to amorphous silica.
• Adhesion in humid air showed different behavior compared to water.
• Coordinate (dative covalent) bonding between the Si3N4 tip and Ti atoms was identified as a key interaction mechanism.

Conclusions:

• The enhanced adhesion in water is attributed to the displacement of adsorbed molecules and coordinate bonding on ns-TiO(x).
• Nanostructuring significantly increases effective surface area and porosity, enhancing these interactions.
• Findings provide insights into protein-ns-TiO(x) interactions and general metal-oxide surface behavior.