DNA bricks build nanotube transistors: Semiconducting carbon nanotubes (CNTs) are an attractive platform for field-effect transistors (FETs) because they potentially can outperform silicon as dimensions shrink. Challenges to achieving superior performance include creating highly aligned and dense arrays of nanotubes as well as removing coatings that increase contact resistance. Sun et al. aligned CNTs by wrapping them with single-stranded DNA handles and binding them into DNA origami bricks that formed an array of channels with precise intertube pitches as small as 10.4 nanometers. Zhao et al. then constructed single and multichannel FETs by attaching the arrays to a polymer-templated silicon wafer. After adding metal contacts across the CNTs to fix them to the substrate, they washed away all of the DNA and then deposited electrodes and gate dielectrics. The FETs showed high on-state performance and fast on-off switching. Science , this issue p. 874 , p. 878

By integrating ATP aptamer into the linker DNA, a novel DNA hydrogel was designed, with mechanical properties that could be tuned into three phases. Based on the unique interaction between ATP and its aptamer, the mechanical strength of the hydrogel increased from 204 Pa to 380 Pa after adding ATP. Furthermore, with the addition of the complementary sequence to the ATP aptamer, the mechanical strength could be increased to 570 Pa.