Simultaneous Visualization of Wet Cells and Nanostructured Biomaterials in SEM using Ionic Liquids.

This work presents a successful methodology to image mammalian cells adhered to nanostructured titanium by using scanning electron microscopy (SEM) operating in low-vacuum mode following ionic liquid treatment. Human osteoblast-like Saos-2 cells were treated with a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and subsequently imaged on titanium by SEM. Titanium substrates were modified to create laser-induced periodic surface structures (LIPSS) for visualization at the submicron scale. By using a combination of fluorescence-based cell metabolism along with light microscopy and SEM image analysis, the shape and location of irradiated cells were confirmed to be unchanged after multiple irradiation sessions; the viability of minimally irradiated cells was also unaltered. The wet imaging conditions combined with a rapid facile protocol using ionic liquid allows this technique to fulfill a niche in examining cellular behavior on biomaterials with submicron surface features. The demonstrated method to track observed cell adhesion to submicron surface features by SEM has great implications for understanding cell migration on nanostructured surfaces as well as the exploration of simpler SEM preparation methods for cellular imaging.

Righting the handedness' dichotomy: schemes of Sagnac interferometer containing chiral elements for suppression of dependence on circular birefringence and circular dichroism.

We present two configurations (one with and another without a half-wave plate) of a Sagnac interferometer (SI) containing chiral optical elements where either the Sagnac loop mirror's (SLM) reflectance is circular birefringence (CB) independent or polarization dependence/circular dichroism (CD) is canceled in both reflection and transmission. These schemes allow use of chiral components as feedback elements/filters in SLM of a laser and in switches/modulators and sensors requiring compensation of chiral media CD, as well as allowing calibration of CD measurements. We also compare/show the differences between SI containing devices with either CB or linear birefringence (LB).

Removing left-right asymmetry in a Sagnac interferometer applied to cancel its reflectance dependence on birefringence.

We present a left-right symmetry restoring method, which removes the detrimental birefringence in the single-mode fiber Sagnac interferometer, achieved with the aid of a half waveplate oriented at a specific angle. We show theoretically and demonstrate experimentally that adding a π-shift between clockwise and counterclockwise propagating, horizontally (in fiber loop plane) polarized field components, the Sagnac loop mirror's reflection becomes independent on birefringence of an element placed in the loop.