Holographic Plasmonic Nanotweezers for Dynamic Trapping and Manipulation

We demonstrate dynamic trapping and manipulation of nanoparticles with plasmonic holograms. By tailoring the illumination pattern of an incident light beam with a computer-controlled spatial light modulator, constructive and destructive interference of plasmon waves create a focused hotspot that can be moved across a surface. Specifically, a computer-generated hologram illuminating the perimeter of a silver Bull’s Eye nanostructure generates surface plasmons that propagate toward the center. Shifting the phase of the plasmon waves as a function of space gives complete control over the location of the focus. We show that 200 nm diameter nanoparticles trapped in this focus can be moved in arbitrary patterns. This allows, for example, circular motion with linearly polarized light. These results show the versatility of holographically generated surface plasmon waves for advanced trapping and manipulation of nanoparticles

Holographic Plasmonic Nanotweezers for Dynamic Trapping and Manipulation

We demonstrate dynamic trapping and manipulation of nanoparticles with plasmonic holograms. By tailoring the illumination pattern of an incident light beam with a computer-controlled spatial light modulator, constructive and destructive interference of plasmon waves create a focused hotspot that can be moved across a surface. Specifically, a computer-generated hologram illuminating the perimeter of a silver Bull’s Eye nanostructure generates surface plasmons that propagate toward the center. Shifting the phase of the plasmon waves as a function of space gives complete control over the location of the focus. We show that 200 nm diameter nanoparticles trapped in this focus can be moved in arbitrary patterns. This allows, for example, circular motion with linearly polarized light. These results show the versatility of holographically generated surface plasmon waves for advanced trapping and manipulation of nanoparticles

Host population diversity as a driver of viral infection cycle in wild populations of green sulfur bacteria with long standing virus-host interactions.

Temperate phages are viruses of bacteria that can establish two types of infection: a lysogenic infection in which the virus replicates with the host cell without producing virions, and a lytic infection where the host cell is eventually destroyed, and new virions are released. While both lytic and lysogenic infections are routinely observed in the environment, the ecological and evolutionary processes regulating these viral dynamics are still not well understood, especially for uncultivated virus-host pairs. Here, we characterized the long-term dynamics of uncultivated viruses infecting green sulfur bacteria (GSB) in a model freshwater lake (Trout Bog Lake, TBL). As no GSB virus has been formally described yet, we first used two complementary approaches to identify new GSB viruses from TBL; one in vitro based on flow cytometry cell sorting, the other in silico based on CRISPR spacer sequences. We then took advantage of existing TBL metagenomes covering the 2005-2018 period to examine the interactions between GSB and their viruses across years and seasons. From our data, GSB populations in TBL were constantly associated with at least 2-8 viruses each, including both lytic and temperate phages. The dominant GSB population in particular was consistently associated with two prophages with a nearly 100% infection rate for >10 years. We illustrate with a theoretical model that such an interaction can be stable given a low, but persistent, level of prophage induction in low-diversity host populations. Overall, our data suggest that lytic and lysogenic viruses can readily co-infect the same host population, and that host strain-level diversity might be an important factor controlling virus-host dynamics including lytic/lysogeny switch