Breast cancer has been one of the most common malignant tumors threatening female health with high incidence. Cell mechanics is becoming an important issue and could serves as a potential indicator for early cancer diagnosis. In this study, atomic force microscopy (AFM) was applied to characterize and compare the surface nanostructure and viscoelasticity of different breast cell lines. Our results show that breast cancerous cells MCF-7 exhibit more disorganized filamentous cytoskeleton structure with increased membrane roughness compared to benign breast cells MCF-10A (P < 0.05). The viscoelastic properties, including elasticity and viscosity, are significantly different between the two cell lines. MCF-7 displays reduced elasticity and viscosity, indicating that breast cancer cells are softer and more fluid than benign counterpart. Our findings provide new insights into the biophysical changes of cells during tumor transformation and suggest it could be used for early cancer detection at single cell level. SCANNING 38:558-563, 2016. © 2016 Wiley Periodicals, Inc.

Optical microscopy allows us to observe the biological structures and processes within living cells. However, the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di®raction. Structured illumination microscopy (SIM), a type of new emerging super-resolution microscopy, doubles the spatial resolution by illuminating the specimen with a patterned light, and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy. In addition, SIM is easier to combine with the other imaging techniques to improve their imaging resolution, leading to the developments of diverse types of SIM. SIM has great potential to meet the various requirements of living cells imaging. Here, we review the recent developments of SIM and its combination with other imaging techniques.

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Far-¯eld°uorescence microscopy has made great progress in the spatial resolution, limited by light di®raction, since the super-resolution imaging technology appeared. And stimulated emission depletion (STED) microscopy and structured illumination microscopy (SIM) can be grouped into one class of the super-resolution imaging technology, which use pattern illumination strategy to circumvent the di®raction limit. We simulated the images of the beads of SIM imaging, the intensity distribution of STED excitation light and depletion light in order to observe e®ects of the polarized light on imaging quality. Compared to¯xed linear polarization, circularly polarized light is more suitable for SIM on reconstructed image. And right-handed circular polarization (CP) light is more appropriate for both the excitation and depletion light in STED system. Therefore the right-handed CP light would be the best candidate when the SIM and STED are combined into one microscope. Good understanding of the polarization will provide a reference for the patterned illumination experiment to achieve better resolution and better image quality.

Low-level lasers have been used to relieve pain in clinical for many years. But the mechanism is not fully clear. In animal models, nitric oxide (NO) has been reported involving in the transmission and modulation of nociceptive signals.So the objective of this study was to establish whether low-level laser with different fluence could stimulate the production of nitric oxide synthese (NOS), which produces NO in cultured primary dorsal root ganglion neurons (DRG neurons). The primary DRG neurons were isolated from healthy Sprague Dawley rats (8-12 weeks of age) and spread on 35 mm culture dishes specially used for confocal microscopy. 24 hours after spreading, cells were irradiated with 658 nm laser for two consecutive days at the energy density of 20, 40, 60 and 80 mJ· cm -2 respectively. Control groups were not exposed to the laser, but were kept under the same conditions as the irradiated ones. The synthesis of NOS after laser irradiation was detected by immunofluorescence assay, and the changes of NOS were evaluated using confocal microscopy and Image J software. The results showed that all the laser fluence could promote the production of NOS in DRG neurons, especially the 60 mJ· cm -2 . These results demonstrated that low-level laser irradiation could modify protein synthesis in a dose-or fluence-dependent manner, and indicated that low-level laser irradiation might achieve the analgesic effect through modulation of NO production.