Showing papers by "Joanna Schmit published in 2008"
TL;DR: It is demonstrated that LCI provides a rapid, quantitative reconstruction of the cell body with no labeling, which is an advantage over traditional microscopy and flow cytometry, which require cell surface tagging and/or destructive cell fixation for labeling.
Abstract: Cancer and many other diseases are characterized by changes in cell morphology, motion, and mechanical rigidity. However, in live cell cytology, stimulus-induced morphologic changes typically take 10−30 min to detect. Here, we employ live-cell interferometry (LCI) to visualize the rapid response of a whole cell to mechanical stimulation, on a time scale of seconds, and we detect cytoskeletal remodeling behavior within 200 s. This behavior involved small, rapid changes in cell content and miniscule changes in shape; it would be difficult to detect with conventional or phase contrast microscopy alone and is beyond the dynamic capability of AFM. We demonstrate that LCI provides a rapid, quantitative reconstruction of the cell body with no labeling. This is an advantage over traditional microscopy and flow cytometry, which require cell surface tagging and/or destructive cell fixation for labeling
68 citations
TL;DR: Interferometric optical profilers deliver non-contact, fast, full-field measurements with vertical resolution down to a fraction of a nanometer as discussed by the authors, allowing for the analysis of not only static but also dynamic objects, like cantilevers and other microelectromechanical system devices, moving or vibrating at up to 1 MHz frequencies.
Abstract: Interferometric optical profilers deliver non-contact, fast, full-field measurements with vertical resolution down to a fraction of a nanometer. Over the last decade advancements to these instruments have allowed for the analysis of not only static but also dynamic objects, like cantilevers and other microelectromechanical system devices, moving or vibrating at up to 1 MHz frequencies. Special objectives and illumination allow for imaging and testing of objects enclosed in environmental or protective chambers or immersed in liquids—including biological samples. Advanced analysis of the interference signal allows for the measurement not just of the surface profile but also transparent coatings.
56 citations
TL;DR: The results indicate that mechanical imaging interferometry is a sensitive and scalable technology for measuring the nanomechanical properties of large arrays of live cells in fluid.
Abstract: The dynamic nanomechanical properties of a large number of cells (up to hundreds), measured in parallel with high throughput, are reported. Using NIH 3T3 and HEK 293T fibroblasts and actin depolymerizing drugs, we use a novel nanotechnology to quantify the local viscoelastic properties with applied forces of 20 pN–20 nN, a spatial resolution of <20 nm, and a mechanical dynamic range of several Pa up to ~200 kPa. Our approach utilizes imaging interferometry in combination with reflective, magnetic probes attached to cells. These results indicate that mechanical imaging interferometry is a sensitive and scalable technology for measuring the nanomechanical properties of large arrays of live cells in fluid.
44 citations
Patent•
01 Jul 2008
TL;DR: In this paper, the Mirau interferometer is replaced with two achromatic λ/4 retarders, and the upper surface of the second retarder is coated with a 50 percent reflecting film, so that it also functions as a beamsplitter.
Abstract: The conventional two plates with beamsplitter of the Mirau interferometer are replaced with two achromatic λ/4 retarders. The upper surface of the second retarder is coated with a 50 percent reflecting film, so that it also functions as a beamsplitter. The objective is illuminated with a linearly polarized beam. As a result of this arrangement, the test and reference beam emerging from the Mirau interferometer are orthogonally polarized beams suitable for achromatic phase shifting, thereby facilitating the use of the Mirau interferometer for monochromatic to broadband phase-shifting interference microscopy. Alternatively, it can be used for equalization of beams intensity by placing a rotatable polarizer at the exit of the objective.
11 citations
TL;DR: A simple variable change mechanism is presented that overcomes the coupling that occurs between the planar and depth coordinates and allows for a seamless integration with the standard least-square phase-stepping procedure.
Abstract: While phase shifting interferometry (PSI) has clearly established itself as a powerful tool for surface profiling, two main
experimental drawbacks still exist, namely phase-shift errors and non-sinusoidal interferometric signals. These problems
cause a fringe print-through pattern in measured phase having a frequency typically double the original fringe frequency.
The main tool used to compensate for non-linear phase-shift errors is the least-square phase-stepping method, which is
capable of accurately determining the phase separation between consecutive frames as well as phase distribution for each
frame. Our work here extends the capabilities of this algorithm so as to account for the effects of a wide bandwidth light
source and a higher numerical aperture, which make the interference signal deviate from the ideal sinusoidal signal. We
present a simple variable change mechanism that overcomes the coupling that occurs between the planar and depth
coordinates and allows for a seamless integration with the standard least-square procedure.
4 citations
17 Mar 2008
TL;DR: In this paper, the authors demonstrate the mechanical probing of tens of cells simultaneously while an interferometric optical profiler measures both the force of the probes and the response of the cells with nanometer accuracy over a wide field.
Abstract: We demonstrate the mechanical probing of tens of cells simultaneously while an interferometric optical profiler measures both the force of the probes and the response of the cells with nanometer accuracy over a wide field.