Author(s): Lu, T; Anvari, B | Abstract: Ovarian cancer is the deadliest gynecological cancer in women. It is a highly metastatic disease with pelvis, regional lymph nodes, and peritoneal cavity as major sites for tumor deposits. Mechanical properties of ovarian cancer cells can play a major role in metastasis as the cells detach from the ovaries and undergo deformation during the metastatic process. Herein, we have characterized the viscoelastic properties of the plasma membrane of normal epithelial (IOSE364) and cancerous (SKOV3) ovarian cells by optical tweezers and quantitative phase imaging. Using optical tweezers, we obtained time-resolved force profiles associated with membrane tethers pulled from the cells. We used quantitative phase imaging to measure the diameter of membrane tethers, and subsequently, estimated the membrane bending modulus and membrane tension in the tether. Our results indicate that the force (190 ± 76npN) (mean ± standard deviation) required to separate the membrane of SKOV3 cells from the cytoskeleton was significantly lower (p = 0.0004) than the force (350 ± 81npN) for IOSE364 cells. The mean stiffness (2.8 ± 0.8npN/μm) of membrane tethers pulled from SKOV3 cells was significantly lower (p = 0.032) than the value for IOSE 364 cells (3.7 ± 0.8npN/μm). Mean value of the force relaxation characteristic time associated with diffusive flow of lipids was also significantly lower (p = 0.018) for SKOV3 membranes (12.9 ± 6.9ns) as compared to the value for IOSE 364 membranes (20.4 ± 6.2ns). Similarly, the mean value of the membrane bending modulus for SKOV3 cells [(0.51 ± 0.23) × 10–18nJ] was significantly lower (p = 0.007) than the value for IOSE364 cells [(1.29 ± 0.32) × 10–18nJ]. Overall, our results suggest that the membranes of SKOV3 cells are less resistant to mechanical deformation. Increased membrane susceptibility to mechanical deformation may be a facilitating factor in the metastatic behavior of cancerous ovarian cells. Characterization of membrane biomechanics may provide a useful diagnostic biomarker for assessment of the metastatic potential of ovarian cancer, and a target for development of therapeutics.

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Characterization of the Viscoelastic Properties of Ovarian Cancer Cells Membranes by Optical Tweezers and Quantitative Phase Imaging

In this paper, we review spatial light interference microscopy (SLIM), a common-path, phase-shifting interferometer, built onto a phase-contrast microscope, with white-light illumination. As one of the most sensitive quantitative phase imaging (QPI) methods, SLIM allows for speckle-free phase reconstruction with sub-nanometer path-length stability. We first review image formation in QPI, scattering, holography, and microcopy. Then, we outline SLIM imaging from theory to instrumentation. Zernike phase-contrast microscopy, phase retrieval in SLIM, and halo removal algorithms are discussed. Next, we discuss the requirements for operation, with a focus on software developed in-house for SLIM that high-throughput acquisition, whole slide scanning, mosaic tile registration, and imaging with a color camera. Lastly, we review the applications of SLIM in basic science and clinical studies. SLIM can study cell dynamics, cell growth and proliferation, cell migration, and mass transport, etc. In clinical settings, SLIM can assist with cancer studies, reproductive technology, and blood testing, etc. Finally, we review an emerging trend, where SLIM imaging in conjunction with artificial intelligence (AI) brings computational specificity and, in turn, offers new solutions to outstanding challenges in cell biology and pathology.

Spatial light interference microscopy (SLIM): principle and applications to biomedicine

Particles fabricated from red blood cells (RBCs) can serve as vehicles for delivery of various biomedical cargos. Flipping of phosphatidylserine (PS) from the inner to the outer membrane leaflet normally occurs during the fabrication of such particles. PS externalization is a signal for phagocytic removal of the particles from circulation. Herein, we demonstrate that membrane cholesterol enrichment can mitigate the outward display of PS on microparticles engineered from RBCs. Our in-vitro results show that the phagocytic uptake of cholesterol-enriched particles by murine macrophages takes place at a lowered rate, resulting in reduced uptake as compared to RBC-derived particles without cholesterol enrichment. When administered via tail-vein injection into healthy mice, the percent of injected dose (ID) per gram of extracted blood for cholesterol-enriched particles was ∼1.5 and 1.8 times higher than the particles without cholesterol enrichment at 4 and 24 h, respectively. At 24 h, ∼43% ID/g of the particles without cholesterol enrichment was eliminated or metabolized while ∼94% ID/g of the cholesterol-enriched particles were still retained in the body. These results indicate that membrane cholesterol enrichment is an effective method to reduce PS externalization on the surface of RBC-derived particles and increase their longevity in circulation.

Membrane Cholesterol Enrichment of Red Blood Cell-Derived Microparticles Results in Prolonged Circulation.

The invention relates to a zoom optical-tweezer light-sheet microscopy imaging device and method and belongs to the technical field of optical microscopy imaging and optical manipulation. The device comprises a light-sheet illumination module, a light-sheet detection module, an optical-tweezer focusing module and an optical-tweezer axial focusing module. In a conventional optical-tweezer microscope system, an axial focusing device formed by a polarizing beam splitter, a quarter-wave plate, low-aperture objective lenses, tube lenses and a plane mirror is added, thereby realizing axial movementof an optical tweezer focal plane in an optical tweezer light-sheet microscope, realizing axial movement of a grabbed suspension sample and finishing light-sheet three-dimensional tomographic scanningimaging.

Optical-tweezer light-sheet microscopy imaging device and method

The invention discloses a confocal microimaging device of zooming optical tweezers and a confocal microimaging method of the zooming optical tweezers, and belongs to the technical field of optical microimaging and optical operation. The confocal microimaging device is technically featured by being composed of a confocal lighting module, a confocal scanning module, a confocal detecting module, an optical tweezers focusing module and an optical tweezers axial zooming module. The regular optical tweezers microscopy system is added with an axial zooming device consisting of a polarizing beam splitter, a quarter-wave plate, a low aperture objective lens, a pipe lens and a plane reflective lens; thus the axial movement of the optical tweezers focal face in the co-path optical tweezers confocal microscopy is realized, thereby grabbing a suspending sample and achieving the axial movement, and completing the confocal three-dimensional chromatography scanning imaging. The confocal microimaging device has the advantages of being simple in assembly, quick in zooming and axial chromatography speed, and low in observing cost.

Confocal microimaging device and method of zooming optical tweezers

Various embodiments disclosed relate to a system. According to various embodiments the present disclosure provides a system. The system includes a movable sample stage configured to receive a sample. The movable sample stage includes a first major surface and a second major surface opposite the first major surface. A portion of the first major surface and the second major surface can be transparent. An excitation light source is aligned with and is in optical communication with the first major surface of the sample stage. A microscope objective is disposed on the second major surface and is substantially aligned with the excitation light source. A laser source is in optical communication with the sample stage. A dichroic mirror is aligned with the microscope objective and is configured to direct light emitted from the laser in a first direction towards the microscope objective.

Mohammad Sarshar

Papers

Combined optical micromanipulation and interferometric topography