As the use of electronics and mobile devices increases, indium and its related compounds are increasingly prevalent in consumer products. However, the effects of the ionic form of indium on the mammalian renal cells are unclear. Understanding indium toxicity in these cells is important, as it relates to kidney health. Kidneys remove heavy metals, maintain electrolyte balance, and perform other vital functions. This in vitro study examines the effects of indium chloride (InCl3) on Vero cells, focusing on cell morphology, viability, reactive oxygen species (ROS) production, and expression of key focal adhesion proteins. Cells were incubated in culture media with InCl3 concentrations ranging from 0 to 3.2 mM for 24 h. Fluorescence confocal microscopy analyses revealed that concentrations above 0.8 mM caused the cells to become more compact and display decreased actin filament lengths, suggesting cellular degeneration, which was further supported by the AlamarBlue (R) Cell Viability Reagent. Using a 2 ',7 '-dichlorofluorescin diacetate (DCFDA/H2DCFDA) assay, we show that ROS levels increase with InCl3 concentration, accompanied by significant increases in focal adhesion kinase (FAK) and paxillin at InCl3 concentrations above 0.8 mM. Interestingly, the level of alpha-actinin detected is not affected by exposure to InCl3. Our findings demonstrate that InCl3 has negative impacts on the growth and behaviour of Vero cells at concentrations exceeding 0.8 mM, underscoring the need for further investigation into the biological effects of indium-containing compounds.

Metalcone films have traditionally been deposited using chamber-based molecular layer deposition. Here, hybrid organic-inorganic polymer films consisting of zinc alkoxide repeating units in the form (-Zn-O-CH2CH2-O-) known as "zincone" are successfully deposited in open air using an atmospheric-pressure spatial molecular deposition technique (AP-SMD) with diethylzinc and ethylene glycol as the precursors. A custom-designed AP-SMD reactor head that provides better shielding of the reaction zone from ambient moisture and oxygen enables their deposition. The deposition parameters are optimized, with higher N2-curtain flow rates in the reactor head, lower metal bubbling flow rates, and effective ethylene glycol delivery resulting in a purer zincone film. Optical characterization of the zincone shows a distinct blue shift and decrease in refractive index as compared to zinc oxide. Chemical analysis indicates successful incorporation of carbon into the zincone films, and structural analysis indicates a limited high-order crystallinity in an otherwise amorphous film. The zincone films are also exposed to humidity and water-etching conditions, and distinct morphological changes are observed as compared to ZnO controls. Similarly, nanoindentation and bending studies show increased flexibility and crack resistance in the zincone films. The ability to produce metalcone films using a rapid, open-air, scalable AP-SMD technique enables their use in high-throughput, large-area applications.

Mammalian tissues and cells often orient naturally in specific patterns to function effectively. This cellular alignment is influenced by the chemical nature and topographic features of the extracellular matrix. In implants, a range of different materials have been used in vivo. Of those, tantalum and its alloys are promising materials, especially in orthopedic implant applications. Previous studies have demonstrated that nano- and micro-scale surface features, such as symmetric comb structures, can significantly affect cell behavior and alignment. However, patterning need not be restricted to symmetric geometries, and there remains a gap in knowledge regarding how cells respond to asymmetric comb structures, where the widths of the trenches and lines in the comb differ. This study aims to address this gap by examining how Vero cells (cells derived from an African green monkey) respond when applied to tantalum and tantalum/silicon oxide asymmetric comb structures having fixed trench widths of 1 μm and line widths ranging from 3 μm to 50 μm. We also look at the cell responses on inverted patterns, where the line widths were fixed at 1 μm while trench widths varied. The orientation and morphology of the adherent cells were analyzed using fluorescence confocal microscopy and scanning electron microscopy. Our results indicate that the widths of the trenches and lines are important design parameters influencing cell behavior on asymmetric comb structures. Furthermore, the ability to manipulate cell morphology using these structures decreased when parts of the tantalum lines were replaced with silicon oxide.

Tantalum metal and tantalum oxide thin films are commonly used in semiconductor devices, protective coatings, and biomedical implants. However, there is limited information on their nanotribological behavior and small-scale mechanical properties. This study characterized the chemical, mechanical, and tribological properties of as-deposited and 400 °C annealed β-Ta thin films using nanoindentation and atomic force microscope (AFM)-based nanoscale friction and wear tests. X-ray photoelectron spectroscopy (XPS) results revealed that a thermally grown Ta oxide layer forms on the surface of Ta film after being annealed at 400 °C. The nanoindentation data indicated an increase in both the hardness and elastic modulus in the heat-treated sample compared to the as-deposited Ta film (13.1 ± 1.3 GPa vs. 12.0 ± 1.4 GPa for hardness) and (213.1 ± 12.7 GPa vs. 175.2 ± 12.3 GPa for elastic modulus). Our nanotribological results show that the friction increased and wear resistance decreased on the surface of the annealed sample compared to the as-deposited Ta film. This discrepancy may be caused by the oxidation of Ta on the film surface, which induces residual compressive stresses in the film and degrades its wear resistance. Our results highlight the influence of thermal annealing and oxidation on nanotribological behavior and small-scale mechanical properties of Ta thin films.

Graphene oxide (GO)-based membranes hold significant promise for applications ranging from energy storage to protective coatings, to saline water and produced water treatment, owing to their chemical stability and unique barrier properties achieving a high selectivity for water permeation. However, unmodified GO membranes are not stable when submerged in liquid water, creating challenges with their commercial utilization in aqueous filtration and pervaporation applications. To mitigate this, we develop an approach to modify GO membranes through a combination of low temperature thermal reduction and metal cation crosslinking. We demonstrate that Zn2+-rGO and Fe3+-rGO membranes had the highest permeation flux of 8.3 +/- 1.5 l m-2 h-1 and 7.0 +/- 0.4 l m-2 h-1, for saline water separation, respectively, when thermally reduced after metal cross-linking; These membranes maintained a high flux of 7.5 +/- 0.7 l m-2 h-1, and 5.5 +/- 0.3 l m-2 h-1 for produced water separation, respectively. All the membranes had a salt rejection higher than 99%. Fe3+ crosslinked membranes presented the highest organic solute rejections for produced water of 69%. Moreover, long term pervaporation testing was done for the Zn2+-rGO membrane for 12 h, and only a minor drop of 6% in permeation flux was observed, while Zn2+-GO had a drop of 24%. Both modifiers significantly enhanced the stability with Fe3+-rGO membranes displaying the highest mechanical abrasion resistance of 95% compared to non-reduced and non-crosslinked GO. Improved stability for all samples also led to higher selectivity to water over organic contaminants and only slightly reduced water flux across the membrane.

Tissues and organs consist of cells organized in specified patterns that support their function, as exemplified by tissues such as skin, muscle, and cornea. It is, therefore, important to understand how external cues, such as engineered surfaces or chemical contaminants, can influence the organization and morphology of cells. In this work, we studied the impact of indium sulfate on human dermal fibroblast (GM5565) viability, production of reactive oxygen species (ROS), morphology, and alignment behavior on tantalum/silicon oxide parallel line/trench surface structures. The viability of cells was measured using the alamarBlue™ Cell Viability Reagent probe, while the ROS levels in cells were quantified using cell-permeant 2′,7′-dichlorodihydrofluorescein diacetate. Cell morphology and orientation on the engineered surfaces were characterized using fluorescence confocal and scanning electron microscopy. When cells were cultured in media containing indium (III) sulfate, the average cell viability decreased by as much as ~32% and the concentration of cellular ROS increased. Cell geometry became more circular and compact in the presence of indium sulfate. Even though actin microfilaments continue to preferentially adhere to tantalum-coated trenches in the presence of indium sulfate, the cells are less able to orient along the line axes of the chips. Interestingly, the indium sulfate-induced changes in cell alignment behavior are pattern dependent—a larger proportion of adherent cells on structures with line/trench widths in the range of 1 μm and 10 μm lose the ability to orient themselves, compared to those grown on structures with line widths smaller than 0.5 μm. Our results show that indium sulfate impacts the response of human fibroblasts to the surface structure to which they adhere and underscores the importance of evaluating cell behaviors on textured surfaces, especially in the presence of potential chemical contaminants.

Cell adhesion is an essential biological function for division, migration, signaling and tissue development. While it has been demonstrated that this cell function can be modified by using nanometer-scale surface topographic structures, it remains unknown how contaminants such as indium (III) ion might influence this specific cell behavior. Herein, the influence of indium chloride on human dermal fibroblast (GM5565) adhesion characteristics was investigated, given the frequent contact of contaminants with skin. The morphology of the adherent cells and their mitochondrial reticulum was characterized on cell culture dishes and nanopatterned surfaces by using fluorescence confocal microscopy and scanning electron microscopy. Results showed a significant proportion of cells lost their ability to align preferentially along the line axes of the nanopattern upon exposure to 3.2 mM indium chloride, with cells aligned within 10° of the pattern line axes reduced by as much as ~70%. Concurrent with the cell adhesion behaviors, the mitochondria in cells exposed to indium chloride exhibit a punctate staining that contrasts with the normal network of elongated tubular geometry seen in control cells. Our results demonstrate that exposure to indium chloride has detrimental effects on the behavior of human fibroblasts and adversely impacts their mitochondrial morphology. This shows the importance of evaluating the biological impacts of indium compounds.

Engineered nanomaterials are often used in tissue engineering applications to influence and manipulate the behavior of cells. Recently, a number of tungsten-silicon oxide nanocomposite devices containing equal width (symmetric) tungsten and silicon oxide parallel line comb structures were developed and used by our group. The devices induced over 90% of seeded cells (Vero) to align within ±20° of the axes of 10 µm wide tungsten lines. Furthermore, a mathematical model was successfully developed to predict this alignment behavior and forecast the minimum width of isolated tungsten lines required to induce such behavior. However, the mechanism by which the widths of the symmetrical tungsten and silicon oxide lines induce the alignment behavior is still unknown. Furthermore, the model was never tested on more complex asymmetrical structures. Herewith, experiments were conducted with mammalian cells on complex asymmetrical structures with unequal tungsten and silicon oxide line widths. Results showed that the model could be extended to more complex pattern structures. In addition, cell morphology on the patterned structures reset during cell division because of mitotic rounding, which reduced the population of cells that elongated and aligned on the tungsten lines. Ultimately, we concluded that it was impossible to achieve a 100% alignment with cells having unsynchronized cell cycles because cell rounding during mitosis took precedence over cell alignment; in other words, internal chemical cues had a stronger role in cell morphology than external cues.

The high interest in wearable technologies has inspired an increased demand for portable, flexible energy storage devices. Currently, most commercial electrochemical energy storage units, such as supercapacitors, are available only in rigid formats, failing to meet the flexibility standards that allow their integration into wearables such as smart textiles and flexible electronics. To achieve flexibility, many research studies have separately reported different flexible substrates coated with active materials for flexible supercapacitor applications. However, there is a lack of studies comparing these substrates for their impact on the electrochemical performance of a supercapacitor cell, which can provide important reference and guidance for the design of flexible supercapacitors. To combat these limitations, we have compared the electrochemical performance of flexible supercapacitor constructed by three different commonly used substrates-commercially obtained conductive polyester fabric (Cu:Ni-PET), carbon cloth, and stainless-steel wire mesh (SSWM). Particularly, the effects of substrate properties such as conductivity, morphology, wettability on the electrochemical performance of the resulting polypyrrole-graphene-polypyrrole sandwich structure electrode are investigated in-depth. It is found that the best electrochemical performance is obtained for Cu:Ni-PET based device with a high areal capacitance of 684 mF/cm(2) at the current density of 2 mA/cm(2) and capacitance retention of 94.2% after 40 00 cycles. The best electrochemical performance of Cu:Ni-PET based supercapacitors are mainly attributed to its high conductivity, good wettability, and unique surface morphology as well as excellent bendability. (C) 2020 Published by Elsevier Ltd.

Nano- and micro-scale engineered surface structures are often used to control cell morphology and mimic the extracellular matrix in tissue engineering. However, there is little understanding of how toxins produced by common bacteria might affect cell adhesion to these structures. In this study, human dermal fibroblast (GM5565) cells were incubated on patterned tungsten/silicon oxide nanocomposite in media in the presence or absence of Antimycin A. This composite consists of parallel tungsten and silicon oxide lines with identical widths in the range of 0.18 and 50 μm. The morphology of the cells and of their mitochondria was characterized by using high-resolution scanning electron microscopy and fluorescence confocal microscopy. Results show that cells preferentially align along the line axes in a pattern-dependent manner, with a maximum population of cells oriented within 10° of the line axes on the structures containing 10 μm wide lines. Cells treated with Antimycin A, however, show a smaller proportion of cells oriented in this direction as compared to cells cultured in Antimycin A-free media (34.4% vs 53.0%). The majority of mitochondria in cells growing in Antimycin A-free media are tubular in shape and are preferentially positioned on the tungsten lines, whereas these organelles exhibit a circular geometry and are less attracted to the metal lines in the presence of Antimycin A.

Nanoindentation techniques have been used to reliably characterize mechanical properties at small scales for the past 30 years [...]

By incorporating polymers both the electrical and mechanical properties of MAPbI3 perovskite films are modulated.

The primary goal of this work was to investigate the resulting morphology of a mammalian cell deposited on three-dimensional nanocomposites constructed of tantalum and silicon oxide. Vero cells were used as a model. The nanocomposite materials contained comb structures with equal-width trenches and lines. High-resolution scanning electron microscopy and fluorescence microscopy were used to image the alignment and elongation of cells. Cells were sensitive to the trench widths, and their observed behavior could be separated into three different regimes corresponding to different spreading mechanism. Cells on fine structures (trench widths of 0.21 to 0.5 μm) formed bridges across trench openings. On larger trenches (from 1 to 10 μm), cells formed a conformal layer matching the surface topographical features. When the trenches were larger than 10 μm, the majority of cells spread like those on blanket tantalum films; however, a significant proportion adhered to the trench sidewalls or bottom corner junctions. Pseudopodia extending from the bulk of the cell were readily observed in this work and a minimum effective diameter of ~50 nm was determined for stable adhesion to a tantalum surface. This sized structure is consistent with the ability of pseudopodia to accommodate ~4–6 integrin molecules.

Tantalum is one of the most important biomaterials used for surgical implant devices. However, little knowledge exists about how nanoscale-textured tantalum surfaces affect cell morphology. Mammalian (Vero) cell morphology on tantalum-coated comb structures was studied using high-resolution scanning electron microscopy and fluorescence microscopy. These structures contained parallel lines and trenches with equal widths in the range of 0.18 to 100 μm. Results showed that as much as 77% of adherent cell nuclei oriented within 10° of the line axes when deposited on comb structures with widths smaller than 10 μm. However, less than 20% of cells exhibited the same alignment performance on blanket tantalum films or structures with line widths larger than 50 μm. Two types of line-width-dependent cell morphology were observed. When line widths were smaller than 0.5 μm, nanometer-scale pseudopodia bridged across trench gaps without contacting the bottom surfaces. In contrast, pseudopodia structures covered the entire trench sidewalls and the trench bottom surfaces of comb structures with line-widths larger than 0.5 μm. Furthermore, results showed that when a single cell simultaneously adhered to multiple surface structures, the portion of the cell contacting each surface reflected the type of morphology observed for cells individually contacting the surfaces.

Tsui joined Advanced Micro Devices (AMD

Advanced engineered surfaces can be used to direct cell behavior. These behaviors are typically characterized using either optical, atomic force, confocal, or electron microscopy; however, most microscopic techniques are generally restricted to observing what’s happening on the “top” side or even the interior of the cell. Our group has focused on engineered surfaces typically reserved for microelectronics as potential surfaces to control cell behavior. These devices allow the exploration of novel substrates including titanium, tungsten, and tantalum intermixed with silicon oxide. Furthermore, these devices allow the exploration of the intricate patterning of surface materials and surface geometries i.e., trenches. Here we present two important advancements in our research: (1) the ability to split a fixed cell through the nucleus using an inexpensive three-point bend micro-cleaving technique and image 3D nanometer scale cellular components using high-resolution scanning electron microscopy; and (2) the observation of nanometer projections from the underbelly of a cell as it sits on top of patterned trenches on our devices. This application of a 3-point cleaving technique to visualize the underbelly of the cell is allowing a new understanding of how cells descend into surface cavities and is providing a new insight on cell migration mechanisms.

Bacteria have evolved as intelligent microorganisms that can colonize and form highly structured and cooperative multicellular communities with sophisticated singular and collective behaviors. The initial stages of colony formation and intercellular communication are particularly important to understand and depend highly on the spatial organization of cells. Controlling the distribution and growth of bacterial cells at the nanoscale is, therefore, of great interest in understanding the mechanisms of cell-cell communication at the initial stages of colony formation. Staphyloccocus aureus, a ubiquitous human pathogen, is of specific clinical importance due to the rise of antibiotic resistant strains of this species, which can cause life-threatening infections. Although several methods have attempted to pattern bacterial cells onto solid surfaces at single cell resolution, no study has truly controlled the 3D architectures of growing colonies. Herein, we present a simple, low-cost method to pattern S. aureus bacterial colonies and control the architecture of their growth. Using the wetting properties of micropatterened poly(dimethyl siloxane) platforms, with help from the physiological activities of the S. aureus cells, we fabricated connected networks of bacterial microcolonies of various sizes. Unlike conventional heterogeneous growth of biofilms on surfaces, the patterned S. aureus microcolonies in this work grow radially from nanostrings of a few bacterial cells, to form micrometer-thick rods when provided with a nutrient rich environment. This simple, efficient, and low-cost method can be used as a platform for studies of cell-cell communication phenomena, such as quorum sensing, horizontal gene transfer, and metabolic cross-feeding especially during initial stages of colony formation.

Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

The effects of specimen size and strain rate on the plastic deformation response of sub-mu m-sized nanocrystalline Cu pillars were examined through a series of micro-compression experiments, with particular emphasis on the stochastic nature of the measured responses. A large number of micropillars two different diameters, both with an average grain size of 6 nm, were prepared by employing the single batch process of e-beam lithography and electroplating and tested. By recourse to statistical analysis, it was recognized the yield strength and flow stress increase with pillar size and strain rate. Further, the rate sensitivity in smaller pillars was more pronounced, implying synergetic interactions between the deformed volume and the strain rate imposed. The coupling influence of size and rate on yield was analyzed by estimating the parameters in a statistical distribution having Weibull-like formula, revealing that the enhanced role of free surface in smaller pillar may make it easy to trigger yielding. The size dependence of rate-sensitive plastic flow was also statistically examined in detail and discussed in terms of strain-rate sensitivity, activation volume, and the combined roles of free surfaces and grain boundaries. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.