A Nanoengineering Approach to Regulate the Lateral Heterogeneity of Self-Assembled Monolayers

Abstract

Using a scanning probe lithography method known as nanografting in conjunction with knowledge of self-assembly chemistry, regulation of the heterogeneity of self-assembled monolayers (SAMs) is demonstrated. While nanografting in single-component thiols produces areas of SAMs with designed geometry and size, nanofabrication in mixed thiol solution yields segregated domains. The reaction mechanism in nanografting differs significantly from self-assembly in mix-and-grow methods, as proven in systematic studies reported in this article and a companion paper of theoretical calculations of the nanografting process. Knowledge of the reaction pathways enables development of methods for shifting the interplay between the kinetics and thermodynamics in SAM formation, and thus the heterogeneity of mixed SAMs. By varying fabrication parameters, such as shaving speed, and reaction conditions, such as concentration and ratio of the components, the lateral heterogeneity can be adjusted ranging from near molecular mixing to segregated domains of several to tens of nanometers.

A Nanoengineering Approach for Investigation and Regulation of Protein Immobilization

“…25 In this investigation, we extended the regulatory capability to binary SAMs with protein adhesive groups, such as aldehydes. Figure 5A is a 500 nm × 500 nm AFM topographic image revealing two nanografted rectangular patterns, at 180 nm × 120 nm and 220 nm × 205 nm, labeled as pattern 4 and 5, within the mixed SAM of C 6 and C 10 CHO.…”

“…22 By regulating the composition of protein binding components and surface reaction conditions, this method was proven to be effective in changing surface domain structures and therefore impacted protein adhesion. 2, 25 To attain a higher degree of control of protein-surface interactions, instead of relying on the trade-off of thermal dynamics and kinetics of surface reactions in the mixing-and-growth, AFM based nanolithography techniques, such as nanografting, 25–27 were used in this investigation. AFM lithography is best known for the production of nanostructures of ligands, DNA and proteins on surfaces.…”

Engineered Nanostructures of Antigen Provide an Effective Means for Regulating Mast Cell Activation

“…17 The phase segregation behavior is characteristic of binary SAMs. 34–37 Typical domain size of DNP in the mixed SAMs is 9.6 ± 5.8 nm, with the center-to-center separation ranging from 10.7 to 32.5 nm and the edge-to-edge separation from 5.6 to 23.6 nm. The DNP domains were 0.3 ± 0.1 nm above the surrounding C18 matrix.…”

Achieving Precision and Reproducibility for Writing Patterns of n‐alkanethiol Self‐assembled Monolayers with Automated Nanografting

“…Designed 2-D arrays of patterns of SAMs with tunable dimensions can be applied with AFM measurements of surface properties such as friction and elasticity (Price et al ., 2005). Well-defined nanostructures provide precise reproducible dimensions for multiple measurements, and enable tunable material compositions for studies of size-dependent properties (Yu et al ., 2006). Advancement of viable nanotechnologies will require a thorough understanding of properties at the molecular scale, and AFM-based lithographies such as nanografting furnish a practical toolkit for nanoscale research.…”