Development of imaging, sensing, and characterization of cells at Research Center for Applied Sciences (RCAS) of Academia Sinica in Taiwan is progressing rapidly. The research on advanced lattice light sheet microscopy for temporal visualization of cells in three dimensions at sub-cellular resolution shows novel imaging results. Label-free observation on filopodial dynamics provides a convenient assay on cancer cell motility. The newly-developed software enables us to track the movement of two types of particles through different channels and reconstruct the co-localized tracks. Surface plasmon resonance (SPR) for detecting urinary microRNA for diagnosis of acute kidney injury demonstrates excellent sensitivity. A fully automated and integrated portable reader was constructed as a home-based surveillance system for post-operation hepatocellular carcinoma. New microfluidic cell culture devices for fast and accurate characterizations prove various diagnosis capabilities.
The membrane roughness of Neuro-2a neroblastoma cells is measured by using noninterferometric wide-field optical profilometry. The cells are treated with the fibril and oligomer conformers of amyloid-beta (Aβ ) 42, which is a peptide of 42 amino acids related to the development of Alzheimer’s disease. We find that both the Aβ42 fibrils and Aβ42 oligomers reduced the cell membrane roughness, but the effect of Aβ42 oligomers was faster and stronger than that of the fibrils. We also apply direct-current electric field (dcEF) stimulations on the cells. A dcEF of 300 mV/mm can increase the membrane roughness under the treatment of Aβ42 . These results suggest that Aβ42 can decrease the membrane compliance of live neuroblastoma cells, and dcEFs may counteract this effect.
We used a liquid-crystal spatial light modulator to project 473 nm light patterns surrounding a region of adherent cells and achieved an arbitrarily micropatterned cell culture. For a group of ∼ 60 cells, the cell boundaries fit the pattern of light within 15% deviation of the side length. We also demonstrated a wound-healing experiment with a definite starting temporal point by using this technique. While observing mitochondrial structures in the illuminated cells, we found that the 473 nm light damaged the integrity of mitochondria and thus prohibited cell proliferation in the illuminated region.
An optical-field-ionization soft x-ray laser with prepulse-controlled nanoplasma expansion in a cluster gas jet was demonstrated. Pd-like xenon lasing at 41.8-nm with 95 nJ pulse energy and 5-mrad divergence was achieved, indicating near-saturation amplification. In addition, by using deflectometry of a longitudinal probe pulse to resolve the spatiotemporal distribution of the preformed plasma, we characterize and control the plasma density distribution near the target surface for the development of solid-target x-ray lasers. We show that the use of prepulses in an ignitor-heater scheme can increase the scale length of the preformed plasma and how the effect varies with target
materials.
Giant unilamellar lipsomes (diameter $GTR 10 (mu) m) are important for cell-membrane research and controlled drug delivery. Mechanical properties of unilamellar lipsomes in different physiological conditions are crucial for their applications. For example, liquid-gel phase transition of the bilayer membrane under different temperatures determines the stability and activity of liposomes. Bending rigidity is the most closely related mechanical property to phase transition. Owing to the flexible nature of bilayer membranes, accurate measurements of the bending rigidity of membranes are difficult. Here we report an all-optical technique to directly measure the bending modulus of unilamellar lipsomes. We use differential confocal microscopy, a far-field optical profilmetry with 2-nm depth resolution to monitor the thermal fluctuations and the deformation of unilamellar lipsomes. From the amplitude changes of thermal fluctuations along with temperature we can directly determine the phase-transition temperature of the membrane structure. We then employ optical force to induce sub-micrometer deformation of the unilamellar lipsomes. From the deformation we can obtain their bending rigidity with simple calculation. We find the bending modulus decreases from 8-11 pico-erg to 0.5 to 0.9 pico-erg as the liposomes are heated across the phase-transition temperature. All measurements are done without contacting the samples and the shapes of the liposomes remain the same after the experiments.
A newly developed multi-functional microscope named Morphinscope and which possesses versatile metrology functions such as that of a confocal microscope, a photon tunneling microscope, a laser based phase-shifting interferometry microscope, and an ellipsometer is presented. This microscope can switch between its various measurement functions by simply rotating its turret, which makes it a low-cost choice for surface analysis. This instrument satisfies the design goal of providing the user with a versatile instrument that can undertake various metrology functions with only one instrument. This design point circumvents a major limitation facing today's surface analyses, i.e., once after a defect is identified, the effort in locating the same defect again with a different instrument is a difficult if not impossible task. As a phase shifting interferometer has in inherent drawback in reconstructing the phase map of a non-homogeneous surface, an ellipsometer can come to the rescue by measuring the complex index of refraction of the surface. More specifically, the Fresnel equation can be used to calculate the phase change of inhomogeneous surfaces due to reflection in order to retrieve the measured complex index of refraction. Combining this understanding, this Morphinscope has the possibility of retrieving the surface profile of a non-homogeneous media.
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