In skeletal muscle the activation of phosphorylase b is catalyzed by phosphorylase kinase. Both enzymes occur in vivo as part of a multienzyme complex. The two enzymes have been imaged by atomic force microscopy and the results compared to those previously found by scanning tunneling microscopy. Scanning tunneling microscopy and atomic force microscopy have been used to view complexes between the activating enzyme phosphorylase kinase and its substrate phosphorylase b. Changes in the size and shape of phosphorylase kinase were observed when it bound phosphorylase b.
Cell signaling often causes changes in cellular mechanical properties. Knowledge of such changes can ultimately lead to insight into the complex network of cell signaling. In the current study, we employed a combination of atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D) to characterize the mechanical behavior of A431 cells in response to epidermal growth factor receptor (EGFR) signaling. From AFM, which probes the upper portion of an individual cell in a monolayer of cells, we observed increases in energy dissipation, Young’s modulus, and hysteresivity. Increases in hysteresivity imply a shift toward a more fluid-like mechanical ordering state in the bodies of the cells. From QCM-D, which probes the basal area of the monolayer of cells collectively, we observed decreases in energy dissipation factor. This result suggests a shift toward a more solid-like state in the basal areas of the cells. The comparative analysis of these results indicates a regionally specific mechanical behavior of the cell in response to EGFR signaling and suggests a correlation between the time-dependent mechanical responses and the dynamic process of EGFR signaling. This study also demonstrates that a combination of AFM and QCM-D is able to provide a more complete and refined mechanical profile of the cells during cell signaling.
All‐inorganic perovskites have attracted increasing worldwide interest due to its significantly improved stability in atmospheric environment compared to organic–inorganic hybrid perovskites, which renders it infinitely applicable in many fields such as electronics, optoelectronics, and energy storage. However, all‐inorganic perovskites have to confront the challenges from fabrication before their wide utilization in the aforementioned applications. Liquid‐phase synthesis holds the advantage of mass production and easy modulation of composition but with the deficiencies of relatively low crystallinity and disordered products. Interestingly, gas‐phase growth has complementary characteristics compared to the liquid‐phase method. In this work, it is proposed that a novel temperature difference triggers growth strategy to integrate the merits of the liquid‐ and gas‐phase methods, and the feasibility of this strategy via a simple lab‐use hot plate is demonstrated. High quality all‐inorganic perovskites, cesium lead halide (CsPbX3) nanowire arrays, can be epitaxially grown as in a gas‐phase method, but at the same time, the composition of products can be easily modulated by predesigning the recipe of precursors as in the liquid‐phase method on a large scale. Notably, the as‐fabricated CsPbX3 perovskite nanowire arrays demonstrate excellent stability and good optoelectronic properties in air. It is believed that this novel strategy can strikingly prompt the development of perovskites fabrication and applications in future.
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