title: Affinity-based Protein Surface Pattern Formation by Ligand Self-Selection from Mixed Protein Solutions.
abstract: Photolithographically prepared surface patterns of two affinity ligands (biotin and chloroalkane) specific for two proteins (streptavidin and HaloTag®, respectively) are used to spontaneously form high-fidelity surface patterns of the two proteins from their mixed solution. High affinity protein-surface self-selection onto patterned ligands on surfaces exhibiting low non-specific adsorption rapidly yields the patterned protein surfaces. Fluorescence images after protein immobilization show high specificity of the target proteins to their respective surface patterned ligands. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging further supports the chemical specificity of streptavidin and HaloTag® for their surface patterned ligands from mixed protein solutions. However, ToF-SIMS did detect some non-specific adsorption of bovine serum albumin, a masking protein present in excess in the adsorbing solutions, on the patterned surfaces. Protein amino acid composition, surface coverage, density and orientation are important parameters that determine the relative ToF-SIMS fragmentation pattern yields. ToF-SIMS amino acid-derived ion fragment yields summed to produce surface images can reliably determine which patterned surface regions contain bound proteins, but do not readily discriminate between different co-planar protein regions. Principal component analysis (PCA) of these ToF-SIMS data, however, improves discrimination of ions specific to each protein, facilitating surface pattern discrimination and contrast.
authors.affiliation: Departments of Pharmaceutics and Pharmaceutical Chemistry, and Bioengineering, University of Utah, Salt Lake City, UT 84112-5820 (USA).
authors.forename: David W
authors.initials: DW
authors.lastname: Grainger
authors.forename: David G
authors.initials: DG
authors.lastname: Castner
authors.forename: Manish
authors.initials: M
authors.lastname: Dubey
authors.forename: Kazunori
authors.initials: K
authors.lastname: Emoto
authors.forename: Hironobu
authors.initials: H
authors.lastname: Takahashi
keywords: ToF-SIMS; patterned proteins; photolithography; poly(ethylene glycol); protein imaging