DNA-mediated regioselective encoding of colloids for programmable self-assembly.

How far we can push chemical self-assembly is one of the most important scientific questions of the century. Colloidal self-assembly is a bottom-up technique for the rational design of functional materials with desirable collective properties. Due to the programmability of DNA base pairing, surface modification of colloidal particles with DNA has become fundamental for programmable material self-assembly. However, there remains an ever-lasting demand for surface regioselective encoding to realize assemblies that require specific, directional, and orthogonal interactions. Recent advances in surface chemistry have enabled regioselective control over the formation of DNA bonds on the particle surface. In particular, the structural DNA nanotechnology provides a simple yet powerful design strategy with unique regioselective addressability, bringing the complexity of colloidal self-assembly to an unprecedented level. In this review, we summarize the state-of-art advances in DNA-mediated regioselective surface encoding of colloids, with a focus on how the regioselective encoding is introduced and how the regioselective DNA recognition plays a crucial role in the self-assembly of colloidal structures. This review highlights the advantages of DNA-based regioselective modification in improving the complexity of colloidal assembly, and outlines the challenges and opportunities for the construction of more complex architectures with tailored functionalities.

Meta-DNA Strand Displacement for Sub-Micron-Scale Autonomous Reconfiguration.

Dynamic molecular interactions in chemical reaction networks lead to complex behaviors in living systems. Whereas recent advances in programming DNA molecular reactions have reached a high level of complexity at molecular and nanometer scales, achieving programmable autonomous behavior at submicron or even larger scales remains challenging. Here, we present a mechanism of meta-DNA strand displacement reactions (M-SDRs) that is mediated solely by meta-toehold (M-toehold) using versatile submicron building blocks of meta-DNA (M-DNA). M-SDR emulates the toehold binding and branch migration processes of conventional strand displacement. Importantly, the kinetics of M-SDR can be modulated over a range of five orders of magnitude reaching a maximum rate of about 1.62 × 105 M-1 s-1. Further, we demonstrate the use of M-SDR to program autonomous reconfiguration in information transmission and logical computation systems. We envision that M-SDR serves as a versatile mechanism for emulating autonomous behavior approaching the cellular level.

A Ratiometric Dual Color Luciferase Reporter for Fast Characterization of Transcriptional Regulatory Elements in Plants.

Plant synthetic biology requires precise characterization of genetic elements to construct complex genetic circuits that can improve plant traits or confer them with new characteristics. Transcriptional reporter assays are essential to quantify the effect of gene expression regulator elements. Additionally, transcriptional reporter systems are a key tool in understanding control of gene expression in biology. In this work, we construct and characterize a dual color luciferase ratiometric reporter system that possesses several advantages over currently used reporters. It is ratiometric, thus reducing variability and increasing consistency between experiments; it is fast, as both reporters can be measured at the same time in a single reaction, and it is less expensive to perform than current dual luciferase reporter assays. We have validated our system quantifying the transcriptional capability of a panel of promoters and terminators commonly used in synthetic biology with a broad range of expression magnitudes, and in a biologically relevant system, nitrate response.