Surface hydroxyl groups direct cellular response on amorphous and anatase TiO2 nanodots

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Cell Biology

Background:

• Titanium dioxide (TiO2) exists in amorphous and crystalline (anatase) forms, exhibiting different surface properties.
• The biomolecular interactions at the TiO2 surface are critical for understanding cellular responses, particularly osteoblast adhesion and mineralization.
• Surface chemistry, specifically the presence of hydroxyl groups, is hypothesized to play a key role in these interactions.

Purpose of the Study:

• To investigate the biomolecular differences between amorphous and anatase TiO2.
• To elucidate how these differences explain varying osteoblast responses on these surfaces.
• To identify key surface factors influencing protein adsorption and conformation.

Main Methods:

• Comparative analysis of amorphous and anatase TiO2 nanodots.
• Investigation of surface hydroxyl group density (TiOHT).
• Study of bovine serum albumin (BSA) and fibronectin adsorption.
• Assessment of protein conformation and its impact on osteoblast behavior.

Main Results:

• The density of surface hydroxyl groups (TiOHT) was identified as the primary differentiating factor between amorphous and anatase TiO2.
• Amorphous TiO2 nanodots adsorbed BSA as a monolayer, whereas anatase TiO2 nanodots adsorbed BSA as a multilayer.
• Differences in TiOHT groups on amorphous TiO2 attracted more -NH3+ groups on BSA, altering protein conformation compared to anatase TiO2.
• Fibronectin adsorbed on anatase TiO2 retained a more active conformation, promoting osteoblast adhesion and mineralization.

Conclusions:

• Surface hydroxyl group density is a critical determinant of protein adsorption behavior on amorphous versus anatase TiO2.
• The distinct protein adsorption patterns and conformations on different TiO2 surfaces significantly influence osteoblast response.
• Understanding these biomolecular interactions is essential for designing TiO2-based biomaterials for bone regeneration.