Conductive AFM Patterning on Oligo(ethylene glycol)-Terminated Alkyl Monolayers on Silicon Substrates: Proposed Mechanism and Fabrication of Avidin Patterns

• Published in: Langmuir Vol. 27; no. 11; pp. 6987 - 6994
• Main Authors: Qin, Guoting, Gu, Jianhua, Liu, Kai, Xiao, Zhongdang, Yam, Chi Ming, Cai, Chengzhi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 07.06.2011
• Subjects: Alkanes - chemistry; Avidin - chemistry; Biological Interfaces: Biocolloids, Biomolecular and Biomimetic Materials; Biotinylation; Chemistry; Colloidal state and disperse state; Dendrimers - chemistry; Electric Conductivity; Exact sciences and technology; General and physical chemistry; Gold - chemistry; Metal Nanoparticles - chemistry; Microscopy, Atomic Force; Microtechnology - methods; Nanotechnology - methods; Oxidation-Reduction; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Polyethylene Glycols - chemistry; Printing; Silicon - chemistry; Surface physical chemistry; Surface Properties; Binding; Monolayer; Atomic force microscopy; Patterning; Film; Nanoparticle; Ethylene; Immobilization; Biotin; Nanostructure; Microelectronics; Aldehyde; Density; Avidin; Mechanism; Protein; Substrate; Carboxylic acid; Alkyl; Oxidation; Silicon; Glycol; Interface
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la1047358

Micro- and nanopatterns of biomolecules on inert, ultrathin platforms on nonoxidized silicon are ideal interfaces between silicon-based microelectronics and biological systems. We report here the local oxidation nanolithography with conductive atomic force microscopy (cAFM) on highly protein-resistant, oligo(ethylene glycol) (OEG)-terminated alkyl monolayers on nonoxidized silicon substrates. We propose a mechanism for this process, suggesting that it is possible to oxidize only the top ethylene glycol units to generate carboxylic acid and aldehyde groups on the film surface. We show that avidin molecules can be attached selectively to the oxidized pattern and the density can be varied by altering the bias voltage during cAFM patterning. Biotinylated molecules and nanoparticles are selectively immobilized on the resultant avidin patterns. Since one of the most established methods for immobilization of biomolecules is based on avidin–biotin binding and a wide variety of biotinylated biomolecules are available, this approach represents a versatile means for prototyping any nanostructures presenting these biomolecules on silicon substrates.