Light-Induced Surface Wettability of a Tethered DNA Base

Abstract

We show that the DNA base thymine and other uracil derivatives, when alkylated with a hydrocarbon chain and assembled at a gold interface, dimerize when subjected to UV irradiation. The process is robust and reversible and is accompanied by a substantial decrease in wettability as well as a marked decrease in acidity constant when the dimer is formed. There is a concerted molecular reorientation that accompanies photodimerization, with the dimer displaying a marked affinity for the gold surface. The spatial requirements for this reorganization are satisfied during dimerization by the reduction in intermolecular distance that occurs when the cyclobutane ring is formed between adjacent bases. The structural changes observed here for a tethered DNA base provide a direct route for exploring reactions, in two dimensions, that are of central interest in biology.

Functionalized gold nanoparticles: Synthesis, structure and colloid stability

“…Both UV-vis and FTIR spectra confirmed that the photodimerization of terminal thymine molecules under 280 nm light irradiation occurred on 7.0 nm gold particles in pH 12.5 water and 2.2 nm particles in a DMF/H 2 O mixture. During photodimerization, the orientation of thymine molecules on the gold surface is changed and as a consequence the gold surface becomes more hydrophobic when the dimer is present similar to those observed on flat gold surfaces [54]. It is proposed that the change in hydrophobicity is sufficient to trigger the aggregation of the 7.0 nm gold particles in high-pH water and ultimately lead to the coagulation of the suspension (see Fig.…”

“…Photocontrolled, reversible contact angle changes as a consequence of the photoreaction of thymine occurring on surfaces were observed [53,54]. Mixed monolayer capped gold nanoparticles containing thymine moieties were prepared recently for the assembly of gold particles into nanostructures via photoreaction of thymine or molecular recognition [55,56].…”

“…Thymine SAMs on quartz and gold showed larger reversible photoinduced contact angle changes when compared with spin-cast and LB films due to their optimum molecular ordering. Lake et al [54] studied further the molecular events taking place during UV exposure. Uracil and uracil derivatives were grafted onto gold through chains attached at N1 position.…”

Fast photo‐switched wettability and color of surfaces coated with polymer brushes containing spiropyran

“…This phenomenon is due to the mechanism that involves photogenerated electrons and holes as well as absorbed water 17. In addition, several kinds of organic compounds and their derivates, such as azobenzenes, spiropyrans (SPs), and cinhamates,18–24 have a photoinduced transformation between two chemical configurations. This may lead to the changes of molecular polar and surface‐free energy that result in a transition of surface wettability accordingly.…”

Stimuli‐Responsive Surfaces in Biomedical Applications

“…Scientists have long tried to reproduce these dynamic biological events and have recently made an important step in that direction by creating artificial stimuli-responsive surfaces [3][4][5][6][7]. These smart substrates present modulatory surface properties that are able to respond to external chemical/biochemical [8][9][10][11][12], thermal [13][14][15], electrical [16][17][18][19][20], and optical stimuli [21][22][23][24][25][26][27][28][29][30][31]. Due to their dynamic nature such substrates are very appealing for applications in the biomedical field [32].…”