Our study describes the influence of the thermal treatment on the fundamental properties of the vertical oriented iron oxide nanorods synthesized under hydrothermal condition onto a conductor substrate. X-ray diffraction and X-ray absorption near edge structure spectra were used to investigate the phase evolution from iron oxyhydroxide (β-FeOOH) to pure hematite phase. The formation of nanorods distributed along of substrate was observed by top-view SEM images and the rod growth preferentially oriented at the highly conductive (001) basal plane of hematite, perpendicular to the substrate. Light absorption capacity increases with the temperature of treatment and the electronic transitions (direct and indirect electronic transition) were estimated from this result. From the electrochemical measurement, the hematite/electrolyte interface was evaluated. These findings demonstrated that the temperature plays an important role on the hematite (structural, morphological, and catalytic) properties and that many influences must work in great harmony in order to produce a promising hematite photoanode.

As bottom up DNA nanofabrication creates increasingly complex and dynamic mechanisms, the implementation of actuators within the DNA nanotechnology toolkit has grown increasingly important. One such actuator, the I-motif, is fairly simple in that it consists solely of standard DNA sequences and does not require any modification chemistry or special purification beyond that typical for DNA oligomer synthesis. This study presents a new implementation of parallel I-motif actuators, emphasizing their future potential as drivers of complex internal motion between substructures. Here we characterize internal motion between DNA origami substructures via AFM and image analysis. Such parallel I-motif design and quantification of actuation provide a useful step toward more complex and effective molecular machines.

Here, a pH-induced nanomechanical switching of i-motif structures incorporated into DNA origami bound onto cysteamine-modified basal plane HOPG was electronically addressed, demonstrating for the first time the electrochemical read-out of the nanomechanics of DNA origami. This paves the way for construction of electrode-integrated bioelectronic nanodevices exploiting DNA origami patterns on conductive supports.