Hybrid Lithographic and DNA-Directed Assembly of a Configurable Plasmonic Metamaterial That Exhibits Electromagnetically Induced Transparency.

Metamaterials are architectures that interact with light in novel ways by virtue of symmetry manipulation, and have opened a window into studying unprecedented light-matter interactions. However, they are commonly fabricated via lithographic methods, are usually static structures, and are limited in how they can react to external stimuli. Here we show that by combining lithographic techniques with DNA-based self-assembly methods, we can construct responsive plasmonic metamaterials that exhibit the plasmonic analog of an effect known as electromagnetically induced transparency (EIT), which can dramatically change their spectra upon motion of their constituent parts. Correlative scanning electron microscopy measurements, scattering dark-field microscopy, and computational simulations are performed on single assemblies to determine the relationship between their structures and spectral responses to a variety of external stimuli. The strength of the EIT-like effect in these assemblies can be tuned by precisely controlling the positioning of the plasmonic nanoparticles in these structures. For example, changing the ionic environment or dehydrating the sample will change the conformation of the DNA linkers and therefore the distance between the nanoparticles. Dark-field spectra of individual assemblies show peak shifts of up to many tens of nanometers upon DNA perturbations. This dynamic metamaterial represents a stepping stone toward state-of-the-art plasmonic sensing platforms and next-generation dynamic metamaterials.

A Mechanogenetic Toolkit for Interrogating Cell Signaling in Space and Time.

Tools capable of imaging and perturbing mechanical signaling pathways with fine spatiotemporal resolution have been elusive, despite their importance in diverse cellular processes. The challenge in developing a mechanogenetic toolkit (i.e., selective and quantitative activation of genetically encoded mechanoreceptors) stems from the fact that many mechanically activated processes are localized in space and time yet additionally require mechanical loading to become activated. To address this challenge, we synthesized magnetoplasmonic nanoparticles that can image, localize, and mechanically load targeted proteins with high spatiotemporal resolution. We demonstrate their utility by investigating the cell-surface activation of two mechanoreceptors: Notch and E-cadherin. By measuring cellular responses to a spectrum of spatial, chemical, temporal, and mechanical inputs at the single-molecule and single-cell levels, we reveal how spatial segregation and mechanical force cooperate to direct receptor activation dynamics. This generalizable technique can be used to control and understand diverse mechanosensitive processes in cell signaling. VIDEO ABSTRACT.

Prognostic significance of nondiagnostic molecular changes in urine detected by UroVysion fluorescence in situ hybridization during surveillance for bladder cancer.

OBJECTIVES: To determine the outcomes for patients with nondiagnostic fluorescence in situ hybridization (FISH) (ie, < 4 gains of chromosomes 3, 7, or 17 in < or = 3 cells). FISH detects urothelial carcinoma and is especially beneficial in patients with negative or atypical urine cytology findings. A positive result is defined as a gain of > or = 2 chromosomes (3, 7, or 17) in 4 cells, isolated loss of 9p21 in 12 cells, or isolated gains of only 1 chromosome in > or = 10% of cells. Most FISH-positive patients will develop recurrent urothelial carcinoma within 1 year. METHODS: We compared the data from 149 patients with a nondiagnostic FISH result and > or = 30 months of follow-up with the data from patients with a negative FISH result from the same period. The time to conversion to a positive FISH result or the development of a bladder tumor was recorded. RESULTS: Patients with nondiagnostic FISH results had significantly greater rates of progression to positive FISH findings or the development of a bladder tumor than did patients with negative FISH findings. Most progression occurred within 1 year. Patients with nondiagnostic FISH results and concurrent negative cytology and cystoscopy had a very low risk of developing recurrent disease, similar to that found with truly negative FISH results. CONCLUSIONS: Nondiagnostic FISH results are related to a greater risk of progression to positive FISH results and tumor recurrence than those with negative FISH findings. However, after controlling for negative cytologic and cystoscopic status, a nondiagnostic FISH result does not appear to be an independent predictor of disease recurrence, and aggressive investigation is not warranted.