Direct-write 3D printing of plasmonic nanohelicoids by circularly polarized light.

Chiral plasmonic surfaces with 3D "forests" from nanohelicoids should provide strong optical rotation due to alignment of helical axis with propagation vector of photons. However, such three-dimensional nanostructures also demand multi-step nanofabrication, which is incompatible with many substrates. Large-scale photonic patterns on polymeric and flexible substrates remain unattainable. Here, we demonstrate the substrate-tolerant direct-write printing and patterning of silver nanohelicoids with out-of-plane 3D orientation using circularly polarized light. Centimeter-scale chiral plasmonic surfaces can be produced within minutes using inexpensive medium-power lasers. The growth of nanohelicoids is driven by the symmetry-broken site-selective deposition and self-assembly of the silver nanoparticles (NPs). The ellipticity and wavelength of the incident photons control the local handedness and size of the printed nanohelicoids, which enables on-the-fly modulation of nanohelicoid chirality during direct writing and simple pathways to complex multifunctional metasurfaces. Processing simplicity, high polarization rotation, and fine spatial resolution of the light-driven printing of stand-up helicoids provide a rapid pathway to chiral plasmonic surfaces, accelerating the development of chiral photonics for health and information technologies.

Single-Particle Photoluminescence Measures a Heterogeneous Distribution of Differential Circular Absorbance of Gold Nanoparticle Aggregates near Constricted Thioflavin T Molecules.

The chirality of biomacromolecules is critical for their function, but the optical signal of this chirality is small in the visible range. Plasmonic nanoparticles are antennas that can couple to this chiral signal. Here, we examine the molecular-scale mechanism behind the induced circular dichroism of gold nanorods (AuNRs) in solution with insulin fibrils and the fibril-intercalating dye thioflavin T (ThT) with polarization-resolved single-molecule fluorescence and single-particle photoluminescence (PL) imaging. We compared the PL upon excitation by left- and right-handed circularly polarized light to calculate the differential absorbance of AuNRs near insulin fibrils with and without ThT. Overall, our results indicate that AuNRs do not act as chiral absorbers near constricted ThT molecules. Instead, we hypothesize that fibrils promote AuNR aggregation, and this templating is mediated by subtle changes in the solution conditions; under the right conditions, only a few chiral aggregates with significantly higher circular dichroism signal contribute to a large net circular dichroism.

BR-Bodies Provide Selectively Permeable Condensates that Stimulate mRNA Decay and Prevent Release of Decay Intermediates.

Biomolecular condensates play a key role in organizing RNAs and proteins into membraneless organelles. Bacterial RNP-bodies (BR-bodies) are a biomolecular condensate containing the RNA degradosome mRNA decay machinery, but the biochemical function of such organization remains poorly defined. Here, we define the RNA substrates of BR-bodies through enrichment of the bodies followed by RNA sequencing (RNA-seq). We find that long, poorly translated mRNAs, small RNAs, and antisense RNAs are the main substrates, while rRNA, tRNA, and other conserved non-coding RNAs (ncRNAs) are excluded from these bodies. BR-bodies stimulate the mRNA decay rate of enriched mRNAs, helping to reshape the cellular mRNA pool. We also observe that BR-body formation promotes complete mRNA decay, avoiding the buildup of toxic endo-cleaved mRNA decay intermediates. The combined selective permeability of BR-bodies for both enzymes and substrates together with the stimulation of the sub-steps of mRNA decay provide an effective organization strategy for bacterial mRNA decay.