Acoustically shaped DNA-programmable materials

Abstract

Recent advances in DNA nanotechnology allow for the assembly of nanocomponents with nanoscale precision, leading to the emergence of DNA-based material fabrication approaches. Yet, transferring these nano- and micron-scale structural arrangements to the macroscale morphologies remains a challenge, which limits the development of materials and devices based on DNA nanotechnology. Here, we demonstrate a materials fabrication approach that combines DNA-programmable assembly with actively driven processes controlled by acoustic fields. This combination provides a prescribed nanoscale order, as dictated by equilibrium assembly through DNA-encoded interactions, and field-shaped macroscale morphology, as regulated by out-of-equilibrium materials formation through specific acoustic stimulation. Using optical and electron microscopy imaging and x-ray scattering, we further revealed the nucleation processes, domain fusion, and crystal growth under different acoustically stimulated conditions. The developed approach provides a pathway for the fabrication of complexly shaped macroscale morphologies for DNA-programmable nanomaterials by controlling spatiotemporal characteristics of the acoustic fields.

Fig. 1. Controlling DNA-assembled materials on a macroscale using acoustic waves.

a Schematic representation of the acoustic field use for directing the formation of DNA-based assemblies. DNA strands are designed to fold into octahedral frames, which assemble into simple cubic lattices. SSAW (red dashed line), either after, or during lattice formation, direct the assembly toward nodes where minimal acoustic pressure is applied within a capillary, where elongated organizations from DNA crystals are formed at the millimetric scale. Red arrows represent pressure produced by the SSAW. b Acoustic device. Two IDTs connected to a function generator produce a SSAW in the active region between the electrodes (highlighted in orange). A capillary of 1 mm inner width and 50 µm height with the sample sealed inside is placed in the active region. c Brightfield microscopy image of DNA crystals dispersed in a glass capillary. Capillary with DNA crystallites without field. Inset is a magnification of the same sample. d The same capillary shown in (c), after applying an acoustic field, crystals form chains in the nodes within the capillary. Inset is a magnification of the same sample.

Fig. 2. Fusing crystallites into macroscale materials.

a Thermal profile for reannealing preformed crystals. Active acoustic waves pulsing is represented by a dashed blue line; inactive acoustic field (no pulsing waves) is represented by a solid red line. b–e Brightfield microscopy images of crystals subjected to the thermal reanneal protocol and acoustic waves at the different stages of the protocol, corresponding to the numerical notation in (a). f, g SEM images showing that the crystal reanneal protocol induces fusing of the crystals to form elongated macroscale morphology of crystals. h Crystals filled with AuNP aligned using acoustic waves. The red hue is the result of AuNP loaded into the lattice.

Fig. 3. Crystal size formed with acoustic waves.

Crystal size formed with varied τ. The colors of the plotted sample correspond to the frame of the brightfield microscopy image frame. All samples (other than No Wave) were subjected to 50 ms wave pulses with varied periods (τ = period/pulse, as shown in the inset). Box-plot overlayed shows the median, Q1, Q3 and 1.5 Interquartile range whiskers. n is the number of crystals measured for each sample.

Fig. 4. Acoustic waves affect nucleation and growth.

a Histogram of crystal size distribution with no acoustic waves (blue) and with τ = 20 (red) for a fast temperature decrease rate of 0.03 °C/min (some of the data is shown in Fig. 3 with different representation). The nucleation and growth theory fit (blue line), and the infusion model (red line) account for the effect of the acoustic waves. b Crystal size distribution vs. τ, showing both discrete experimental data points (as shown in Fig. 3) and continuous model-calculated behavior. c, d Slow thermal anneal (temperature decrease rate of 0.01 °C/min) of crystals with no waves applied (c) and with τ = 20. e Fast thermal anneal (0.03 °C/min) with τ = 20, followed by a thermal reanneal to fuse crystals together, results in elongated macroscale structures at the millimetric scale. The width of the capillary (left wall to right wall) is 1 mm. f Measured SAXS structure factor (S(q)) of the crystals assembled under acoustic field and untreated crystals corresponds to modeled S(q) of simple cubic crystal structure.