No abstract

Cell migration plays an important role in physiological and pathological processes where the fibrillar morphology of extracellular matrices (ECM) could regulate the migration dynamics. To mimic the morphological characteristics of fibrillar matrix structures, low-voltage continuous electrospinning was adapted to construct straight, wavy, looped and gridded fibre patterns made of polystyrene (of fibre diameter ca. 3 μm). Cells were free to explore their different shapes in response to the directly-adhered fibre, as well as to the neighbouring patterns. For all the patterns studied, analysing cellular migration dynamics of MDA-MB-231 (a highly migratory breast cancer cell line) demonstrated two interesting findings: first, although cells dynamically adjust their shapes and migration trajectories in response to different fibrillar environments, their average step speed is minimally affected by the fibre global pattern; secondly, a switch in behaviour was observed when the pattern features approach the upper limit of the cell body’s minor axis, reflecting that cells’ ability to divert from an existing fibre track is limited by the size along the cell body’s minor axis. It is therefore concluded that the upper limit of cell body’s minor axis might act as a guide for the design of microfibre patterns for different purposes of cell migration.

Imprinting “sticky” features on the surfaces of common non-sticky flexible materials, such as paper, textile, and polymeric films produces a myriad of adhesive tapes that we use in our daily lives. Recently, the rise of flexible electronics has harnessed the distinct adhesive behavior of adhesive tapes to achieve special scientific and engineering purposes. In this review, recent advances including the structures, properties, mechanisms, and functionalities of adhesive tapes and relevant flexible smart electronics are summarized. We provide a key focus on how the distinct adhesive behavior of adhesive tapes contributes to the redesign and engineering of flexible electronics via physical and/or chemical modifications. The applications of these flexible smart electronics enabled by adhesive tapes are widespread, including high-performance sensors, energy storage/conversion devices, medical and healthcare patches, etc. Finally, we discuss unmet needs and current challenges in the development of adhesive tape-enabled materials and techniques for flexible electronics. With ongoing material and technical innovations, adhesive tape-related electronic products are expected to revolutionize our lifestyle and lead us into the era of artificial intelligence.

Embryonic tissues undergoing shape change draw mechanical input from extraembryonic substrates. In avian eggs, the early blastoderm disk is under the tension of the vitelline membrane (VM). Here we report that the chicken VM characteristically downregulates tension and stiffness to facilitate stage-specific embryo morphogenesis. Experimental relaxation of the VM early in development impairs blastoderm expansion, while maintaining VM tension in later stages resists the convergence of the posterior body causing stalled elongation, failure of neural tube closure, and axis rupture. Biochemical and structural analysis shows that VM weakening is associated with the reduction of outer-layer glycoprotein fibers, which is caused by an increasing albumen pH due to CO2 release from the egg. Our results identify a previously unrecognized potential cause of body axis defects through mis-regulation of extraembryonic tissue tension.