Single-cell impedance cytometry of anticancer drug-treated tumor cells exhibiting mitotic arrest state to apoptosis using low-cost silver-PDMS microelectrodes.

Chemotherapeutic drugs such as paclitaxel and vinblastine interact with microtubules and thus induce complex cell states of mitosis arrest at the G2/M phase followed by apoptosis dependent on drug exposure time and concentration. Microfluidic impedance cytometry (MIC), as a label-free and high-throughput technology for single-cell analysis, has been applied for viability assay of cancer cells post drug exposure at fixed time and dosage, yet verification of this technique for varied tumor cell states after anticancer drug treatment remains a challenge. Here we present a novel MIC device and for the first time perform impedance cytometry on carcinoma cells exhibiting progressive states of G2/M arrest followed by apoptosis related to drug concentration and exposure time, after treatments with paclitaxel and vinblastine, respectively. Our results from impedance cytometry reveal increased amplitude and negative phase shift at low frequency as well as higher opacity for HeLa cells under G2/M mitotic arrest compared to untreated cells. The cells under apoptosis, on the other hand, exhibit opposite changes in these electrical parameters. Therefore, the impedance features differentiate the HeLa cells under progressive states post anticancer drug treatment. We also demonstrate that vinblastine poses a more potent drug effect than paclitaxel especially at low concentrations. Our device is fabricated using a unique sacrificial layer-free soft lithography process as compared to the existing MIC device, which gives rise to readily aligned parallel microelectrodes made of silver-PDMS embedded in PDMS channel sidewalls with one molding step. Our results uncover the potential of the MIC device, with a fairly simple and low-cost fabrication process, for cellular state screening in anticancer drug therapy.

[Temporal and spatial characteristics and correlation of the coordinated development of economy, society and ecological environment in the Yangtze River Delta, China]. / é•¿ä¸‰è§’åŒºåŸŸç»æµŽç¤¾ä¼šä¸Žç”Ÿæ€çŽ¯å¢ƒåè°ƒå‘å±•æ—¶ç©ºç‰¹å¾åŠç›¸å ³æ€§.

The imbalance of regional development is one of the important obstacles for the implementation of regio-nal coordinated development strategy. Based on the panel data of 41 cities in the Yangtze River Delta from 2010 to 2019, the regional coordinated development index system with five subsystems was constructed, including economic development, science and education, infrastructure, people's life, and resource and environment. With the help of GeoDa and ArcGIS software, we used measurement model of regional coordinated development and method of exploratory spatial data analysis to analyze the temporal and spatial variations and internal correlation of various elements of regional coordinated development in the Yangtze River Delta. The results showed that, from the perspective of regional development, the coordination of regional development in the Yangtze River Delta had increased annually from 2010 to 2019. The level of economic development and science and education in Shanghai and Suzhou was ahead of other cities, while the development coordination of Northwest Anhui, Zhoushan and Huangshan was weaker than other cities. The order of average autocorrelation degree of each subsystem from high to low in the Yangtze River Delta from 2010 to 2019 was people's life, economic development, resource and environment, science and education, and infrastructure. Among them, the global Moran's index (Moran I) of economic development and science and education subsystem showed a downward trend, while science and education subsystem showed no significant correlation. Moran I of infrastructure subsystem was mostly at the low level with a great fluctuation in different years. People's life had obvious spatial characteristics of high-high and low-low agglomeration. The global Moran I of resources and environment showed a pattern of "V" distribution. Economic development and science and education were the two factors most closely related to regional coordinated development.

Giant pyroelectricity in nanomembranes.

Pyroelectricity describes the generation of electricity by temporal temperature change in polar materials1-3. When free-standing pyroelectric materials approach the 2D crystalline limit, how pyroelectricity behaves remained largely unknown. Here, using three model pyroelectric materials whose bonding characters along the out-of-plane direction vary from van der Waals (In2Se3), quasi-van der Waals (CsBiNb2O7) to ionic/covalent (ZnO), we experimentally show the dimensionality effect on pyroelectricity and the relation between lattice dynamics and pyroelectricity. We find that, for all three materials, when the thickness of free-standing sheets becomes small, their pyroelectric coefficients increase rapidly. We show that the material with chemical bonds along the out-of-plane direction exhibits the greatest dimensionality effect. Experimental observations evidence the possible influence of changed phonon dynamics in crystals with reduced thickness on their pyroelectricity. Our findings should stimulate fundamental study on pyroelectricity in ultra-thin materials and inspire technological development for potential pyroelectric applications in thermal imaging and energy harvesting.