We report a label-free infrared surface plasmon biosensor with a double-chamber flow cell for continuous monitoring of morphological changes in cell culture exposed to various stimuli. In this technique, the monolayer of cultured cells is divided into two halves by a barrier, allowing the treatment of one half while the other serves as control. We demonstrate the advantages of this setup in test experiments that track kinetics of the IEC-18 cell layer response to variations in extracellular Ca2+ concentration. The sensitivity of the presented method was found to be an order of magnitude higher compared to the single-chamber biosensor.
Cell morphology is often used as a valuable indicator of the physical condition and general status of living cells. We demonstrate a noninvasive method for morphological characterization of adherent cells. We measure infrared reflectivity spectrum at oblique angle from living cells cultured on thin Au film, and utilize the unique properties of the confined infrared waves (i.e., surface plasmon and guided modes) traveling inside the cell layer. The propagation of these waves strongly depends on cell morphology and connectivity. By tracking the resonant wavelength and attenuation of the surface plasmon and guided modes we measure the kinetics of various cellular processes such as (i) cell attachment and spreading on different substrata, (ii) modulation of the outer cell membrane with chlorpromazine, and (iii) formation of intercellular junctions associated with progressive cell polarization. Our method enables monitoring of submicron variations in cell layer morphology in real-time, and in the label-free manner.
The cell morphology is a valuable indicator of the physical condition and general status of the cell. Here we demonstrate
a methodology for noninvasive biosensing of adherent living cells. Our method is based on infrared reflection
spectroscopy of living cells cultured on thin Au film. To characterize cell morphology we utilized the unique properties
of the infrared surface plasmon (λ=1-3 μm) and infrared guided wave that travel inside the cell monolayer. We
demonstrate that our method enables monitoring of submicron variations in cell morphology in real-time and in a labelfree
manner. In addition to morphological characterization, our method allows investigation of chemical composition
and molecular structure of cells through infrared absorption spectroscopy analysis.
We fabricated a photonic bandgap material consisting of a stack of containers with steel spheres. In the absence of external magnetic field the particles are in a disordered state. Magnetic field magnetizes the particles and they self-assemble into ordered crystalline state. We study mm-wave transmission through the stack as a function of magnetic field, i.e. for different degrees of order. This system exhibits a well-defined stopband in the ordered state, while in the disordered state the stopband becomes completely smeared. We model our results using the effective-medium approximation. We relate the disappearance of the stopband in the disordered state to the fluctuations in refraction index and admittance of individual layers. These fluctuations arise from the in-plane density fluctuations. Magnetic field suppresses density fluctuations and thus controls electromagnetic wave propagation through teh stack.