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1. Effects of cold atmospheric plasma treatment on the morphological and optical properties of plasmonic silver nanoparticles

   https://doi.org/https://doi.org/10.1088/1361-6528/ab9788  

   Sonawane, Apurva; Mujawar, Mubarak A; Bhansali, Shekhar (June 2020, Nanotechnology)

   The use of plasma processes in nanomaterial synthesis is limited by a lack of understanding of the effects of plasma treatment on the morphology and other properties. Here, we studied the effects of atmospheric plasma treatment on the morphology and optical properties of Ag nanoparticles. The Ag nanoparticles were deposited on substrates by injecting an aerosol into flowing argon gas and then treated with a low-temperature atmospheric plasma jet. After plasma treatment, the mean Ag nanoparticle diameter reduced to an average of 5 nm, which was accompanied by a blue shift of ~70 nm in the peak of the surface plasmon resonance; these results are similar to those obtained by thermal treatment at elevated temperatures. The reduction in nanoparticle size is explained by the redox reaction that occurs on the nanoparticle surface, which is evident from the presence of AgO and Ag2O Raman peaks in the treated sample. The surface charge changed as a result of plasma treatment, as indicated by a large change in the zeta potential from +25.1 ± 4 mV for the untreated sample to −25.9 ± 6 mV after 15 min of plasma treatment. Surface-enhanced Raman spectroscopy of the plasma-treated films was carried out with the fluorescent dye Rhodamine 6 G, which showed a ~120-fold enhancement in the signal intensity relative to the untreated substrates. We, therefore, conclude that cold-plasma treatment modified the surface morphology of the Ag nanoparticles, thereby enhancing their optical properties. This technique could be applied to a wide range of nanoparticle systems used in biosensing applications. 

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2. Single-Cell Receptor Quantification of an In Vitro Coculture Angiogenesis Model Reveals VEGFR, NRP1, Tie2, and PDGFR Regulation and Endothelial Heterogeneity

   https://doi.org/10.3390/pr7060356  

   Chen, Si; Imoukhuede, P. I. (June 2019, Processes)

   Angiogenesis, the formation of new blood vessels from pre-existing ones, is essential for both normal development and numerous pathologies. Systems biology has offered a unique approach to study angiogenesis by profiling tyrosine kinase receptors (RTKs) that regulate angiogenic processes and computationally modeling RTK signaling pathways. Historically, this systems biology approach has been applied on ex vivo angiogenesis assays, however, these assays are difficult to quantify and limited in their potential of temporal analysis. In this study, we adopted a simple two-dimensional angiogenesis assay comprised of human umbilical vein endothelial cells (HUVECs) and human dermal fibroblasts (HDFs) and examined temporal dynamics of a panel of six RTKs and cell heterogeneity up to 17 days. We observed ~2700 VEGFR1 (vascular endothelial growth factor receptor 1) per cell on 24-h-old cocultured HDF plasma membranes, which do not express VEGFR when cultured alone. We observed 4000–8100 VEGFR2 per cell on cocultured HUVEC plasma membranes throughout endothelial tube formation. We showed steady increase of platelet-derived growth factor receptors (PDGFRs) on cocultured HDF plasma membranes, and more interestingly, 1900–2900 PDGFRβ per plasma membrane were found on HUVECs within the first six hours of coculturing. These quantitative findings will offer us insights into molecular regulation during angiogenesis and help assess in vitro tube formation models and their physiological relevance. 

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3. Ultra-robust Superhydrophobic/superoleophilic Stainless Mesh Coated by PTFE/SiO2 for Oil/water Separation

   https://doi.org/10.1557/adv.2018.604  

   Chen, Chaolang; Weng, Ding; Mahmood, Awais; Wang, Jiadao (January 2019, MRS Advances)

   Abstract In this study, a superhydrophobic and superoleophilic stainless mesh coated with polytetrafluoroethylene/silicon dioxide (PTFE/SiO 2 ) was fabricated through electrostatic self-assembly method followed by sintering treatment. The PTFE was utilized to construct low-surface-energy surface and the SiO 2 nanoparticles were added to enhance its surface roughness. The as-prepared stainless mesh exhibited desirable superhydrophobicity and superoleophilicity with a water contact angle of 152° and oil contact angle of 0°. The coated stainless mesh could separate a variety of oil/water mixtures with high efficiency and it also exhibited good recyclability. Moreover, the corrosion-resistance of stainless mesh was greatly improved by coating it with PTFE. The thermogravimetric analysis (TGA) measurements showed that the coated mesh could withstand high temperature of up to 430°C, indicating excellent thermal-resistance. It is believed that this ultra-robust stainless mesh would have significant potential applications in industry. 

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4. Effect of oxygen and fluorine plasma surface treatment of silicon‐incorporated diamond‐like carbon coatings on cellular responses of mouse fibroblasts

   https://doi.org/10.1111/ijac.14107  

   Riley, Parand R.; Yang, Kai‐Hung; Liu, Yizhong; Skoog, Shelby A.; Narayan, Jagdish; Narayan, Roger J. (June 2022, International Journal of Applied Ceramic Technology)

   Abstract The surface chemistry of silicon‐incorporated diamond‐like carbon (Si‐DLC) was tailored utilizing oxygen and fluorine plasma treatments. Successful anchoring of oxygen and fluorine functional groups to the surface of Si‐DLC was verified using X‐ray photoelectron spectroscopy. The impact of surface modification of Si‐DLC on hydrophobicity was correlated with the viability of L929 mouse fibroblasts. The confocal microscopy and viability results indicated that oxygen‐treated Si‐DLC showed increased cell viability compared to untreated Si‐DLC and fluorine‐treated Si‐DLC samples 5 days after seeding. The increased cell viability was correlated with the conversion of the hydrophobic surface of Si‐DLC into a hydrophilic surface by oxygen plasma treatment. 

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5. Electromagnetic fields alter the motility of metastatic breast cancer cells

   https://doi.org/10.1038/s42003-019-0550-z  

   Garg, Ayush Arpit; Jones, Travis H.; Moss, Sarah M.; Mishra, Sanjay; Kaul, Kirti; Ahirwar, Dinesh K.; Ferree, Jessica; Kumar, Prabhat; Subramaniam, Deepa; Ganju, Ramesh K.; et al (August 2019, Communications Biology)

   Abstract Interactions between cells and their environment influence key physiologic processes such as their propensity to migrate. However, directed migration controlled by extrinsically applied electrical signals is poorly understood. Using a novel microfluidic platform, we found that metastatic breast cancer cells sense and respond to the net direction of weak (∼100 µV cm⁻¹), asymmetric, non-contact induced Electric Fields (iEFs). iEFs inhibited EGFR (Epidermal Growth Factor Receptor) activation, prevented formation of actin-rich filopodia, and hindered the motility of EGF-treated breast cancer cells. The directional effects of iEFs were nullified by inhibition of Akt phosphorylation. Moreover, iEFs in combination with Akt inhibitor reduced EGF-promoted motility below the level of untreated controls. These results represent a step towards isolating the coupling mechanism between cell motility and iEFs, provide valuable insights into how iEFs target multiple diverging cancer cell signaling mechanisms, and demonstrate that electrical signals are a fundamental regulator of cancer cell migration. 

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