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Abstract The rational design of molecular electronics remains a grand challenge of materials science. DNA nanotechnology has offered unmatched control over molecular geometry, but direct electronic functionalization is a challenge. Here a generalized method is presented for tuning the local band structure of DNA using transmetalation in metal‐mediated base pairs (mmDNA). A method is developed for time‐resolved X‐ray diffraction using self‐assembling DNA crystals to establish the exchange of Ag⁺ and Hg²⁺ in T:T base pairs driven by pH exchange. Transmetalation is tracked over six reaction phases as crystal pH is changed from pH 8.0 to 11.0, and vice versa. A detailed computational analysis of the electronic configuration and transmission in the ensuing crystal structures is then performed. This findings reveal a high conductance contrast in the lowest unoccupied molecular orbitals (LUMO) as a result of metalation. The ability to exchange single transition metal ions as a result of environmental stimuli heralds a means of modulating the conductance of DNA‐based molecular electronics. In this way, both theoretical and experimental basis are established by which mmDNA can be leveraged to build rewritable memory devices and nanoelectronics. 

Abstract The addition of surface acoustic wave (SAW) technologies to microfluidics has greatly advanced lab-on-a-chip applications due to their unique and powerful attributes, including high-precision manipulation, versatility, integrability, biocompatibility, contactless nature, and rapid actuation. However, the development of SAW microfluidic devices is limited by complex and time-consuming micro/nanofabrication techniques and access to cleanroom facilities for multistep photolithography and vacuum-based processing. To simplify the fabrication of SAW microfluidic devices with customizable dimensions and functions, we utilized the additive manufacturing technique of aerosol jet printing. We successfully fabricated customized SAW microfluidic devices of varying materials, including silver nanowires, graphene, and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). To characterize and compare the acoustic actuation performance of these aerosol jet printed SAW microfluidic devices with their cleanroom-fabricated counterparts, the wave displacements and resonant frequencies of the different fabricated devices were directly measured through scanning laser Doppler vibrometry. Finally, to exhibit the capability of the aerosol jet printed devices for lab-on-a-chip applications, we successfully conducted acoustic streaming and particle concentration experiments. Overall, we demonstrated a novel solution-based, direct-write, single-step, cleanroom-free additive manufacturing technique to rapidly develop SAW microfluidic devices that shows viability for applications in the fields of biology, chemistry, engineering, and medicine. 

Tertiary chirality describes the handedness of supramolecular assemblies and relies not only on the primary and secondary structures of the building blocks but also on topological driving forces that have been sparsely characterized. Helical biopolymers, especially DNA, have been extensively investigated as they possess intrinsic chirality that determines the optical, mechanical, and physical properties of the ensuing material. Here, we employ the DNA tensegrity triangle as a model system to locate the tipping points in chirality inversion at the tertiary level by X-ray diffraction. We engineer tensegrity triangle crystals with incremental rotational steps between immobile junctions from 3 to 28 base pairs (bp). We construct a mathematical model that accurately predicts and explains the molecular configurations in both this work and previous studies. Our design framework is extendable to other supramolecular assemblies of helical biopolymers and can be used in the design of chiral nanomaterials, optically active molecules, and mesoporous frameworks, all of which are of interest to physical, biological, and chemical nanoscience.