Reversible Nanopatterning on Self-Assembled Monolayers on Gold

Abstract

The reversible fabrication of positive and negative nanopatterns on 1-hexadecanethiol (HDT) self-assembled monolayers (SAMs) on Au(111) was realized by bias-assisted atomic force microscopy (AFM) nanolithography using an ethanol-ink tip. The formation of positive and negative nanopatterns via the bias-assisted nanolithography depends solely on the polarity of the applied bias, and their writing speeds can reach 800 μm/s and go beyond 1000 μm/s, respectively. The composition of the positive nanopatterns is gold oxide and the nanometer-scale gold oxide can be reduced by ethanol to gold, as proved by X-ray photoelectron spectroscopy (XPS) analysis, forming the negative nanopatterns which can be refilled with HDT to recover the SAMs. The inked material of ethanol acts as a reductant which is transferred to the substrate for the local chemical reactions like that in dip-pen nanolithography (DPN). The negative nanopatterns can be used as templates, for example, for the immobilization of magnetic nanoparticles. Interestingly, we found that the nanometer-scale gold oxide was very stable on hydrophobic HDT/Au(111) in air, whereas on hydrophilic SAMs it decomposed soon and resulted in the formation of the negative nanopattern. In addition, the effect of bias on the nanolithography was investigated.

Facet, Junction and Electric Field Engineering of Bismuth‐Based Materials for Photocatalysis

“…[207,208] The composite photocatalyst exhibited a significantly enhanced photocatalytic performance due to the cooperative contribution of the efficient separation of photoinduced charges, the SPR effect, and the prolonged lifetime of charge carriers. Other reported works about Bi plasmonic properties include Bi/ BiOIO 3 , [24] Bi/BiOBr, [36] Bi/BiWO 6 , [209] Bi/Bi 2 MoO 6 , [210] Bi/BiOBr x I 1-x , [211] Bi nanowires/BiOCl nanosheets. [212] There are three types of Bi nanowires in Bi nanowires/BiOCl nanosheets, single Bi nanowire, three Bi nanowires for a triangle, and five parallel Bi nanowires.…”

Spectroscopic study of ionic liquid adsorption from solution onto gold

“…However, the O 1s region contains a peak that can be deconvoluted into two components, one at 532.4 eV, and the other at 530.8 eV. The higher binding energy component is assigned to the oxygen in the anion, 32,54 whilst the lower binding energy component is attributed to residual oxidation of the gold substrate, 55,56 whose presence on gold is almost ubiquitous after substrate cleaning. 51 This is in agreement with the substrate XPS characterisation shown in Fig.…”

Nanoscale Patterning of Multicomponent Proteins by Bias‐Assisted Atomic Force Microscopy Nanolithography

“…Subsequently, Au 2 O 3 is unstable on hydrophilic Eg3-SH SAM under ambient conditions and could be reduced to gold soon. [22] To fabricate the aptamer arrays, a series of trenches with gold exposed at the bottom surface was used as a template. After incubating the Eg3-SH SAMs with trenches in a 1.0 mm PDGF-BB aptamer solution (Figure 1 To fabricate other protein nanopatterns, arrays of trenches with the same size were created just below the PDGF-BB aptamer patterns by bias-assisted nanolithography (Figure 1 d).…”

“…Bias-assisted AFM nanolithography is one of the most promising methods to construct nanoscale arrays for its feasible nanomanipulation. Depending on the magnitude of bias, substrate materials, and environments, the application of the bias can lead to local anodic oxidation of various substrates, [18][19][20][21][22] surface group conversion of self-assembled monolayers (SAM) on silicon [23,24] and electrochemical removal of SAMs on gold. [25] Bias-assisted AFM nanolithography does not only generate patterns at the nanoscale but can also control locations precisely.…”