Biofunctionalization on alkylated silicon substrate surfaces via "click" chemistry

Area of Science:

• Materials Science
• Surface Chemistry
• Biotechnology

Background:

• Silicon-based biosensors require stable, functionalized surfaces for sensitive detection.
• Existing organic monolayers on silicon have limitations, including low bioconjugation yields and nonspecific protein adsorption.
• Direct Si-C bonding offers enhanced stability compared to conventional methods.

Purpose of the Study:

• To develop a novel
• clickable
• monolayer platform on silicon substrates for improved biosensor applications.
• To overcome limitations of low yields and nonspecific protein adsorption in previous monolayer systems.
• To enable precise surface functionalization for specific biological target capture.

Main Methods:

• Photoactivated surface hydrosilylation of α,ω-alkenynes with protected alkynyl terminals (trimethylgermanyl group).
• Selective deprotection of alkynyl groups using Cu(I) in aqueous solutions.
• Combined deprotection and copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) for bioconjugation.
• Surface modification with oligo(ethylene glycol) (OEG) for protein resistance and functionalization with mannose and biotin.

Main Results:

• Achieved high yields in a combined deprotection and CuAAC reaction step.
• Developed OEG-terminated surfaces that reduced nonspecific protein adsorption by over 98%.
• Successfully created microarray formats with varied densities of mannose and biotin.
• Demonstrated specific capture of living bacteria (Escherichia coli) using mannose-functionalized surfaces.

Conclusions:

• The new monolayer platform offers a robust and versatile method for biofunctionalizing silicon substrates.
• The developed surfaces significantly enhance biosensor performance by minimizing protein fouling and enabling specific molecular interactions.
• This approach holds promise for advancing the development of next-generation silicon-based diagnostic and sensing devices.