Considerable evidence points to cancer stem-like cells (CSCs) as responsible for promoting progression, metastasis, and drug resistance. Without damage to the cell biological properties, single-cell-derived tumor-sphere is encouraging options for CSCs identification and studies. Although several single cell-based microfluidic methods have been developed for CSCs studies, clarifying liaison between the biomechanics of cells (such as size and deformability) and stem (such as tumor-sphere formation and drug resistance) remains challenging. Herein, we present a platform of integrated microfluidics for the analysis of single-cell-derived tumor-sphere formation and drug resistance. Tumor-spheres derived from different biomechanics (size and/or deformation) single-cells could be formed efficiently using this device. To demonstrate the microfluidic-platform capability, a proof-of-concept experiment was implemented by evaluating single-cell-derived sphere formation of single glioblastoma cells with different biomechanics. Additionally, a course of chemotherapy to study these single-cell-derived spheres was determined by coculture with vincristine. The results indicate that tumor cell biomechanics is associated with single-cell-derived spheres formation; that is, smaller and/or more deformable tumor cells are more stem-like defined by the formation of single-cell-derived spheres than more prominent and/or lesser deformable tumor cells. Also, tumor-spheres derived from single small and/or more deformable tumor cell have higher drug resistance than more prominent and/or less deformable tumor cells. Our device offers a new approach for single-cell-derived sphere formation according to tumor cell different biomechanical properties. Furthermore, it offers a new method for CSC identification and downstream analysis on a single-cell level.

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We study the indentation of a free-standing lipid membrane suspended over a nanopore on a hydrophobic substrate by means of molecular dynamics simulations. We find that in the course of indentation the membrane bends at the point of contact and the fringes of the membrane glide downward intermittently along the pore edges and stop gliding when the fringes reach the edge bottoms. The bending continues afterward, and the large strain eventually induces a phase transition in the membrane, transformed from a bilayered structure to an interdigitated structure. The membrane is finally ruptured when the indentation goes deep enough. Several local physical quantities in the pore regions are calculated, which include the tilt angle of lipid molecules, the nematic order, the included angle, and the distance between neighboring lipids. The variations of these quantities reveal many detailed, not-yet-specified local structural transitions of lipid molecules under indentation. The force-indentation curve is also studied and discussed. The results make a connection between the microscopic structure and the macroscopic properties and provide deep insight into the understanding of the stability of a lipid membrane spanning over nanopore.

A particle-based display medium and a driving mechanism insensitive to the charge polarity of those particles, based on the transformation of particle chains, are developed for reflective electronic paper displays. Particle chains are formed by dipole-dipole interactions between polarized particles with an appropriate electric field applied across the tested display medium, i.e. the solution that regulates the light in the field of display technology, containing neutral polystyrene (PS) particles dispersed in water. Formation of the particle chains results in a large change in optical transmittance and reflectance of the display medium. The performance of the particle chain displays (PCD) was evaluated according to macroscopic (device), microscopic (particle) and optical (reflectance) points of view. A display medium (thickness 100 μm) containing colored PS particles (3 μm, 2.5% w/v) was polarized to display the fixed images of the directly driven electrodes and programmable images of arrayed (5 × 5) electrodes with electric fields (0.48 MV m(-1) and 0.09 MV m(-1), 500 kHz, respectively). The formation of particle chains under electric fields (0.2 MV m(-1) and 0.4 MV m(-1), 500 kHz) was observed in the microscopic images of a display medium (thickness 100 μm) with fluorescent PS particles (5 μm, 1%). Images recorded with a confocal microscope demonstrated the particle chains. The opacity, a common parameter serving to characterize a display medium, was derived by measuring the reflectance ratio of a black background to a white background of the display medium with varied thickness and particle concentration. The temporal response of a display medium (thickness 50 μm) with black PS particles (3 μm, 5%) was tested. When an electric field (0.6 MV m(-1), 500 kHz) was applied, the reflectance increased twice at the first data point in 0.7 s, attaining a contrast ratio of 2. Application of a voltage (20 s) yielded a contrast ratio of 10. The performance of a tested display medium, composed of simple PS particles and water and driven to form particle chains by polarization, is reported.