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.

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.

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.

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^® 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 α-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.

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.