Characterization of biomolecule immobilization by scanning force microscopy using a wet‐masking technique

Abstract

Summary:The assemblage of molecular layers was investigated using scanning force microscopy (SFM). A wet-masking technique was used for the preparation of monolayer steps by partial masking of the substrate with an elastomeric mask during incubation in the modification buffers. The subsequent adsorption of biotin, streptavidin, and biotinylated beads onto a gold substrate was investigated by SFM visualization of the created steps. The molecular layers were characterized based on measurements of step height and surface roughness. The simultaneous visualization of the surface before and after modification minimizes artifacts introduced by changes in tip shape or imaging parameters.

Fabrication and characterization of DNA-functionalized GaN nanowires

“…After deposition of the ssDNA, samples were rinsed in a 300 mM KCl solution, 1 Technologies and Devices International, Inc., Silver Spring, MD 20904. rinsed with deionized water and dried in a nitrogen stream. Patterning of the organic layers was accomplished by masking functionalized samples with a silicone elastomer [21] and exposing them to microwave O 2 plasma (700 W, 2 scfh O 2 flow at 1 Torr for 180 s).…”

“…The thickness of the deposited organic layers was estimated by removing them in an oxygen plasma. Fully functionalized GaN films were partially covered with a silicone mask [21] and then exposed to an O 2 RF plasma for 180 s. A fluorescence image and an AFM topographic profile averaged over the interfacial region between masked and exposed areas are shown in figures 6(a) and (b), respectively. A strong fluorescence contrast was observed at this interface, indicating that the fluorescent species exposed to the O 2 plasma were removed while those under the silicone mask were protected.…”