Inger Odnevall Wallinder

Adsorption of proteins and other biomolecules on stainless steel and other functional metallic surfaces is a key interfacial phenomenon in food processing environments, leading to progressive surface accumulation of organic residues. Their presence can impair the material performance, promote microbial adhesion, complicate cleaning procedures, and ultimately create significant hygiene challenges. In this study, UV–vis fluorescence spectroscopy was evaluated for its suitability in monitoring the adsorption of plant‐derived biomolecules on AISI 316L stainless steel surfaces, using rice protein concentrate in artificial tap water, both in the presence and absence of stearic acid and NaCl. Instrumental parameters were optimized based on multi‐Gaussian peak deconvolution using Bayesian Information Criterion evaluation. This approach enabled robust resolution of overlapping spectral features and improved sensitivity in complex matrices. Fluorescence peak shifts and intensity variations were analyzed to probe protein–alloy surface interactions, providing diagnostic indicators of protein‐induced spectral changes and proposed conformational transitions resulting from protein adsorption. The results demonstrate that fluorescence spectroscopy is a valuable technique for monitoring interfacial protein adsorption and residue accumulation on stainless steel under food‐processing conditions. Overall, the findings provide insights relevant to hygiene control strategies and the optimization of material performance in food‐processing systems.

Nickel (Ni) is utilized in a wide range of applications, including the production of austenitic stainless steel, superalloys, rechargeable batteries, catalysts, and foundry products. Historically high exposure to mixed Ni dust has been associated with various health effects, including an increased risk of respiratory cancer. Different chemical forms of Ni exhibit distinct physicochemical properties and biological effects, and the role of these properties, including nanoparticles (NPs) vs microparticles (MPs), in the cellular uptake and fate is not completely understood. This study aims to explore the uptake, intracellular fate, and cytotoxicity of eight well-characterized Ni substances in BEAS-2B cells. Characterization was conducted using scanning electron microscopy, X-ray photoelectron spectroscopy, and dynamic light scattering. Uptake in BEAS-2B cells was investigated using transmission electron microscopy, Newport Green staining in combination with super-resolution microscopy, and atomic absorption spectroscopy. The characterization showed that the Ni substances differed in primary size but were all highly agglomerated under the conditions tested, with Ni3S2 having the largest size. At 48 h and based on the same mass of added Ni, Ni3S2 was the most cytotoxic, followed by the water-soluble salt NiSO4·6H2O and Ni metal NPs with a primary size of 80 nm (Ni80), while nickel oxide (NiO) NPs were noncytotoxic under the tested conditions. Biodissolution (released Ni per mass Ni added) in cell culture medium varied substantially across substances and generally increased with time. At 48 h, Ni biodissolution followed this order: Ni3S2 (55%) > Ni80 (9%) > NiO MPs (4%) > Ni 20 nm and NiO 80 nm (3%), > NiO 20 nm (2%) > Ni MPs (0.3%). All sparingly soluble Ni substances were clearly observable in intracellular membrane-bound structures in BEAS-2B cells. A key observation from the quantitative uptake was the distinctly lower uptake of Ni ions from the water-soluble NiSO4·6H2O compared to the sparingly soluble Ni substances. There was thus no clear correlation between apparent uptake and cytotoxicity. After fractionation into cytosolic, nuclear, and particulate fractions, followed by analysis of dissolved Ni from the particles within the cells, the three substances showing the highest amount of Ni per added Ni mass (indicating both uptake and intracellular Ni ion release) in both cytosol and nucleus were Ni20 NPs, Ni MPs, and Ni3S2. Super-resolution microscopy indicated increased Newport Green fluorescence, suggestive of intracellular Ni accumulation, predominantly in cells exposed to Ni MPs and Ni3S2. However, the findings were not sufficiently robust to allow firm conclusions. These findings highlight the complex interplay between biodissolution, cellular uptake and cytotoxicity of Ni substances.

Metal additive manufacturing (AM) relies on alloy feedstock powders that may come into contact with the workers' skin during handling, yet skin-relevant data on metal release and biological reactivity remain limited. Here, we assessed the cutaneous bioactivity of the fine particle fraction of four gas-atomized Fe-based AM powders (316L stainless steel, Fe-powder A, and tooling steels B and C). Powders were sieved to ex vivo full-thickness human skin explant model, including superficial barrier disruption, IL-8/CXCL8 quantification, and histological assessment. ASW exposure induced marked shifts in the outermost surface composition across powders, indicating sweat-driven surface transformation. Biodissolution was low and medium-dependent, with Fe dominating the release in ASW, and with an overall metal release remaining limited in cell culture medium. In HaCaT cells, MCP-1/CCL2, IL-6, and IL-8/CXCL8 were quantifiable but showed no significant changes following powder exposure. Cell Painting revealed subtle, shared phenotypic signatures, primarily involving mitochondrial-associated features, without evidence of broad cellular stress. In the ex vivo skin model, AM powders did not increase IL-8/CXCL8 secretion, the particles remained localized to the skin surface without detectable penetration, and coexposure with Staphylococcus epidermidis did not enhance bacterial colonization or induce inflammation. To the best of our knowledge, this is the first study that applies a human skin explant model to evaluate dermal responses to metal AM powders. Overall, the tested AM powders showed low short-term cutaneous reactivity under skin-relevant conditions, providing human-relevant evidence to inform occupational risk assessment in AM environments.

Improving the sustainability of cosmetic products while maintaining a good performance requires a deeper understanding on the way that new eco-respectful ingredients interact with hair or skin. In the case of shampoos, the surface science is dominated by the diverse changes on the hair fiber due to both chemical and physical damages that particularly affect physicochemical properties such as hydrophobicity. A native, undamaged fiber is covered with a monolayer of lipids, mainly 18-methyleicosanoic acid (18-MEA), while a highly damaged hair surface, having completely lost the protective lipids, is hydrophilic and negatively charged. Intermediate states exist, where there is a partial loss of 18-MEA (“partially damaged hair”). Here, four model surfaces have been produced, to mimic different types of hair surfaces. Their interaction with selected surfactants and polyelectrolytes (natural and synthetic) has been studied by neutron reflectometry (NR). NR can reveal hierarchical adsorption from mixtures thanks to the scattering contrast between deuterated and hydrogenous molecules. Atomic force microscopy (AFM) measurements complement the study by adding information about the in-plane structure of adsorbed species. The presence of the methyl branch of 18-MEA is found to affect the interaction of the surface with adsorbates. For surfactant/polyelectrolyte mixtures, for example, the adsorption of polymer is enhanced. Of particular interest are the results on the partially damaged hair model, as it manifests patches of hydrophobic and hydrophilic moieties; it is possible to separately observe the different adsorption behaviors to the different sites in a single experiment.

The use of copper and its alloys in architecture, especially in arid regions, is growing, driven by visual appeal, functional advantages, and sustainability. Changes in visual and colorimetric appearances and patina formation were evaluated for architectural Cu metal, brass (CuZn15), bronze (CuSn4), and a golden alloy (CuZn5Al5). Coupons were exposed over 4 years in Dubai, United Arab Emirates, at a test site located 2 km from the seashore under unsheltered conditions, and at various surface inclinations. Comparative exposures were conducted in Brest, France, at sites of increasing distance from the seashore. Visual appearance was assessed by colorimetry and optical imaging; patina cross-sections were characterized by means of scanning electron microscopy and elemental analysis (SEM/EDS), and crystalline phase identification was conducted by means of x-ray diffraction (XRD). All Dubai surfaces developed red-yellowish, heterogeneous patinas with embedded sand and dust, reducing lightness and visual appeal. Inclination had minor effect, although some extent of spallation occurred on downward-facing CuSn4. Even the corrosion-resistant CuZn5Al5 alloy lost its golden hue due to the incorporation of sand and dust into the patina. In Brest, appearance depended on the distance from the seashore, with green-blue patinas near the sea and red-yellowish farther inland, similar to Dubai. Cleaning may restore some luster, but the desert exposure generally reduced the long-term aesthetic performance of all materials.

Porous polymer-based materials of high electrical conductivity are essential for a wide range of applications. An innovative nanocomposite of V₂O₅/rGO/polyaniline hydrogel (VG/PANi-HG) was synthesized using in situ oxidative polymerization in the presence of V₂O₅/rGO (VG) and phytic acid on a carbon fiber substrate. Subsequently, the corresponding electrode was employed as a flexible free-standing electrode and examined through a range of electrochemical methods to assess its performance in high-rate supercapacitors. The VG/PANi-HG supercapacitor demonstrated an excellent specific capacitance of 982 F g^–1 at a current density of 2.7 A g^–1. Furthermore, an asymmetric all-solid-state (ASC) device was assembled using VG/PANi-HG as a positive electrode in combination with a graphene oxide electrode as a negative electrode and a polyvinyl alcohol (PVA) hydrogel electrolyte. This flexible asymmetric device exhibited an impressive cycle life stability and a power density of 2 kW kg^–1 at an energy density of 29.44 Wh kg^–1. Our results reveal that the VG/PANi-HG electrode material is a promising candidate for future electrochemical energy storage devices.

The toxicity of micro- and nanoparticles in cell culture studies is influenced by factors like particle size, agglomeration, dissolution of the particles, and methodological factors like sonication protocols. The main aim of this study was to investigate the influence of sonication on the particle size, dissolution, cytotoxicity, and dosing accuracy of nickel (Ni) metal and Ni oxide (NiO) particle dispersions. Such investigations are important to enable studies on the cellular uptake of different Ni substances in lung cells. The effect of sonication was evaluated in ultrapure water, two types of cell media, and A549 human lung cells using the tip and water bath methods. Extended sonication significantly decreased particle size and increased particle dissolution, emphasizing the need for optimized sonication conditions tailored to the specific particle type and study design. Observed findings demonstrate that the sonication step potentially can have a large impact on the results due to changes in particle characteristics, size, and dissolution, properties which are highly dependent on the particle type, solution composition, and sonication parameters. Although only small differences were observed in the limited assessment of cytotoxicity (A549 cells) in this study, further investigation is required to determine the impact of sonication on toxicity. This study also emphasizes the need to evaluate transferred dose samples due to the evident effects of agglomeration, sedimentation, and losses during sample transfer of particle dispersions. The study clearly illustrates that the choice of sonication protocol is particularly critical for toxicity studies, which are the basis of government regulatory decisions and human exposure limits.