16-mercaptohexadecanoic-acid and n-octadecyl-mercaptan

Experiments that utilize structures generated by dip-pen nanolithography (DPN) as positive resists for fabricating nanohole arrays and lithographic masters are described. The technique takes advantage of the difference in desorption potentials for patterned structures made from 16-mercaptohexadecanoic acid (MHA) and 1-octadecanethiol (ODT), respectively. In this approach, patterns of MHA on gold are generated by DPN, and surrounding areas are passivated by ODT. Electrochemistry is used to selectively remove the MHA nanofeatures made by DPN. The exposed gold can be used as an electrode to plate silver from solution, generating raised features and structures that can be transferred to PDMS to make a lithographic master, or alternatively, they can be etched to make arrays of nanoholes.

Topics: Electric Conductivity; Electrochemistry; Gold; Materials Testing; Nanostructures; Nanotechnology; Palmitic Acids; Particle Size; Silver; Sulfhydryl Compounds; Surface Properties

Four TAT peptide fragments were used to functionalize GaAs surfaces by adsorption from solution. In addition, two well-studied alkylthiols, mercaptohexadecanoic acid (MHA) and 1-octadecanethiol (ODT) were utilized as references to understand the structure of the TAT peptide monolayer on GaAs. The different sequences of TAT peptides were employed in recognition experiments where a synthetic RNA sequence was tested to verify the specific interaction with the TAT peptide. The modified GaAs surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS). AFM studies were used to compare the surface roughness before and after functionalization. XPS allowed us to characterize the chemical composition of the GaAs surface and conclude that the monolayers composed of different sequences of peptides have similar surface chemistries. Finally, FT-IRRAS experiments enabled us to deduce that the TAT peptide monolayers have a fairly ordered and densely packed alkyl chain structure. The recognition experiments showed preferred interaction of the RNA sequence toward peptides with high arginine content.

Topics: Arginine; Arsenicals; Gallium; Gene Products, tat; Microscopy, Atomic Force; Palmitic Acids; Peptide Fragments; RNA; Spectroscopy, Fourier Transform Infrared; Sulfhydryl Compounds; Surface Properties; X-Rays

We describe a new combinatorial method for studying the exchange between solution adsorbates and nanoscale features within libraries generated via dip-pen nanolithography. Four different compounds, 1-octadecanethiol, 16-mercaptohexadecanoic acid, ferrocene (11-mercaptoundecyl), and ferrocene (11-mercapto-1-oxoundecyl), are studied on amorphous and single-crystal gold substrates. This series of adsorbates allows us to compare the exchange properties of patterns of nanoscale features as a function of composition, feature size, and type of underlying substrate. Moreover, these properties can be compared and contrasted with bulk SAM properties. The novel strategy provides not only a method for initiating site-specific exchange processes but also a way of extracting kinetic information about the rate of such processes in situ.

Topics: Combinatorial Chemistry Techniques; Ferrous Compounds; Gold; Metallocenes; Nanotechnology; Palmitic Acids; Sulfhydryl Compounds