Covalent biofunctionalization of silicon nitride surfaces

Area of Science:

• Materials Science
• Surface Chemistry
• Biotechnology

Background:

• Silicon nitride (SixN4) is a crucial material in microelectronics and biosensing.
• Controlling surface chemistry is vital for integrating SixN4 with biological systems.

Purpose of the Study:

• To develop methods for covalently attaching organic monolayers to etched silicon nitride surfaces.
• To functionalize these surfaces for biomolecule immobilization.
• To explore photopatterning capabilities for creating functionalized areas.

Main Methods:

• Etching silicon nitride surfaces using dilute hydrofluoric acid (HF).
• Attaching 1-alkenes and 1-alkynes via covalent Si-C bonds.
• Functionalizing surfaces with terminal carboxylic acid or amino groups.
• Characterization using contact angle, XPS, IRRAS, AFM, and ToF-SIMS.

Main Results:

• Successful formation of stable organic monolayers on etched SixN4.
• Demonstrated two methods for introducing carboxylic acid groups, including a photocleavable approach.
• Confirmed the attachment of oligopeptides and proteins using EDC/NHS chemistry.
• Created amino-terminated monolayers for further functionalization.

Conclusions:

• Covalent organic monolayers can be reliably formed on etched silicon nitride.
• The developed methods enable versatile surface functionalization for biomolecule attachment.
• Photopatterning offers potential for spatially controlled surface modification.