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Preparation workflows of fluorescent nm- and µm-sized polymer particles used as reporters in fluorescent assays, bioimaging, and sensing studies or calibration tools for fluorescence methods in the life sciences can be time-consuming and labor-intensive. Also, the outcome can be operator dependent. Here, we present simple and cost-efficient automated workflows for dye loading and surface labeling of polystyrene particles (PSP), using a commercial self-programmable pipetting robot. For developing and fine-tuning automated staining workflows, hydrophobic Nile Red (NR) was incorporated into 100 nm, 200 nm, and 1000 nm PSP by an adapted swelling procedure of premanufactured particles in the presence of hydrophobic dyes, thereby confirming its reliability and versatility. Subsequent expansion of our automation concept to the labeling of carboxylated PSP with pH-sensitive 6-aminofluorescein (6-AMF) and aminated PSP with pH-responsive fluorescein isocyanate (FITC) demonstrated its broad applicability. All automated workflows were optimized and validated by gravimetry and spectroscopic measurements with a microtiter plate (MTP) reader in absorption and fluorescence mode to ensure particle recovery and reproducible fluorescence features and determine PSP dye loading and labeling efficiencies. Comparison with the manual fabrication of NR-stained PSP using an established swelling protocol showed that our automation approach utilizing a pipetting robot considerably reduced the variability in particle recovery and dye loading efficiency. Overall, our simple, labor- and time-efficient workflows with inexpensive and broadly available commercial automation tools present attractive alternatives to manual particle loading and labeling and provide the basis for fast parameter screening, parallel processing, and decreased hands-on time.
Trace ammonia impurities in hydrogen fuel poison proton-exchange-membrane fuel cells (PEMFC), causing irreversible performance degradation. Accurate quantification of ammonia in so-called Grade D hydrogen fuel is crucial for ensuring PEMFCs long-term operational stability and performance. According to ISO 14687 grade D hydrogen fuel sets a stringent threshold value of just 100 nmol/mol for ammonia impurities. Given the potential of an ammonia-based hydrogen supply chain, reliable quantification of ammonia contamination appears even more relevant.
Hydrogen quality assessments for ammonia impurities typically employ techniques such as gas chromatography, cavity-enhanced absorption spectroscopy, or mass spectrometry. These techniques, however, require stable reference gases for calibration and long-term method validation. Typically, gravimetrically produced reference gases are used. However, ammonia poses unique challenges due to its chemical reactivity and stickiness. By applying (ultra )long-path Optical Feedback Cavity Enhanced Absorption Spectroscopy we observed that above a certain amount of ammonia, the gravimetric amount deviates from the analytically determined amount. This discrepancy most likely arises due to strong adsorption of ammonia onto the inner surface of the gas cylinder. Therefore, we investigated the lowest gravimetrically preparable amount of ammonia in hydrogen for which the analytically measured amount of the cylinder remains congruent with the gravimetric amount of substance. We further investigated the applicability of passivated cylinders for trace ammonia gas standards and compared their performance to aluminum alloy cylinders. To confirm reproducibility of our results, we conducted three independent gravimetric preparation campaigns, each employing optimizations, or changes in methodology, at different times. Finally, we investigated whether those gravimetrically prepared trace amounts of ammonia in hydrogen gas standards were long-term-stable.
Beyond gravimetrically prepared gas standards, we evaluated how a cutting-edge dynamic dilution system could reliably extend trace-ammonia calibration down to the ISO limit of 100 nmol/mol. For this purpose, we developed an advanced dynamic dilution system capable of a one-in-a-billion dilution ratio, validated for its SI traceability, reproducibility, and operational limits by applying an internal standard.
In summary, our results demonstrate that precise dynamic dilution, coupled with concentrated gravimetrically prepared ammonia gas mixture, provides a route to full SI-traceable trace-ammonia reference sample gases.
The German National Hydrogen Strategy (NWS) envisions a transition towards a hydrogen-based energy grid. However, due to the material incompatibility of existing pipeline infrastructure for amounts of hydrogen higher than 10 cmol/mol, many system components of the existing grid must be replaced with significant costs and considerable time investments. Given these constraints, the admixture of hydrogen into natural gas (NG) to create a hydrogen-enriched NG blend has been designated as a transitional technology. The NWS supports this approach on a regional and time-limited basis, but clearly states that it is not intended as a permanent solution.
Nevertheless, the conversion to a fully hydrogen-based grid is expected to take several decades. During this transitional phase, precise process analytical monitoring of hydrogen amounts in the NG blend is essential to ensure both energy efficiency via calorific value control and operational safety. These procedures require cost-effective, robust, and reliable sensor technologies capable of real-time, in situ/on-site quantification of hydrogen amounts in NG.
In response to this need, we have advanced a physical sensing approach utilizing an oscillating cantilever in collaboration with Truedyne Sensor AG. This sensor system enables quantification of hydrogen amounts, direct calorific value determination as well as display of beneficial gas properties, like density, viscosity, and thermal conductivity. Moreover, the enhanced cantilever system enables direct physical sensing and can also be operated in a quasi-binary mode.
We performed comparative evaluations against two benchmark sensor systems to validate the developed technology. One utilizes chemical sensing, and the other operates on thermal conductivity measurements for hydrogen quantification. Through standardized testing, we demonstrated that the cantilever-based sensor offers both high effectiveness and competitive performance compared to current state-of-the-art technologies for accurate hydrogen detection in natural gas and precise determination of its calorific value.
The outcome of an implant procedure largely depends on the implant's surface properties. Biomaterials are now designed to have surfaces with multifunctionality, such as favorable tissue integration and the ability to combat bacterial adhesion and colonization. Herein, we report on a simple approach to improve the antibacterial properties of zirconia nanotubes (ZrNTs) coatings by decorating with silver nanoparticles (AgNP), achieved through electrochemical anodization of a zirconium–silver alloy (Zr–Ag). The AgNPs were shown to partially consist of Ag2O, potentially enhancing the availability of Ag+ ions for antibacterial activity. The modified ZrNTs were characterized using SEM, EDS, ToF-SIMS, and XPS to determine their structural morphology and chemical composition, and were further subjected to antibacterial testing. The silver and zirconium ion release behavior was monitored via ICP-MS. ZrNTs decorated with AgNP exhibit strong antimicrobial activity (>99% bacterial killing) against both S. aureus and E. coli. Antimicrobial tests indicate that the antibacterial activity against the Gram-positive pathogen S. aureus was improved by a factor of 100 compared to unmodified ZrNTs, while unmodified ZrNTs already showed a comparable reduction of viable Gram-negative E. coli. This strategy illustrates a straightforward and effective modification that optimizes the interface between the host environment and the biomaterial surface to meet the very important criteria of biocompatibility and active antibacterial response.
Advances in Analytical Chemistry and Mass Spectrometry to Support a Sustainable and Circular Economy
(2025)
Recent advances in analytical chemistry have significantly supported efforts to realize a sustainable circular economy and circular chemistry. By enabling rapid materials analysis and characterization of materials transformation throughout their life cycle, analytical methods are playing a key role in supporting waste reduction, resource recovery, pollution monitoring, and sustainable manufacturing. In this presentation, recent developments in analytical chemistry and analytical instrumentation to support a sustainable and circular economy will be reviewed and selected contributions from our laboratories will be discussed. For example, high-resolution mass spectrometry combined with chromatography is an indispensable tool for the identification and characterization of plastics. To support the transition from linear to circular chemistry, whichs prioritizes reuse, recycling, and resource efficiency, accurate and detailed chemical information about plastic materials is essential. Here, targeted and non-targeted screening approaches help to characterize, for example, the quality and safety of recycled plastics. In addition, green analytical chemistry has emerged as a topic of interest, emphasizing the use of solvent-free and low-energy methods to minimized environmental impact during analysis. Here, ambient desorption/ionization high-resoluton mass spectrometry (ADI-MS) is considered a very attractive tool because it dos not require chromatography or large amounts of solvent, reduces sample preparation time, and produces virtually no chemical waste. Here, a solvent-free, plasma-based ADI-MS method is presented, which was carefuly developed for the direct identification and fast screening of per- and polyfluoroalkyl substances (PFAS). PFAS are a large class of thousands of synthetic chemicals that are used worldwide. However, growing environmental and human health concerns in the last two decades have led to more stringent regulatory requirements and the development of quantitative analytical methods for PFAS detection. Today, standardized and powerful methods exist, e.g., for the determination PFAS in water, sludge, compost, soil, and drinking water. While liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is often used, sample preparation, solvent consumption, and total analysis times can be challenging. Here, ADI-MS is considered interesting, because it requires only minimal sample preparation and little solvent consumption. In this work, a plasma-based pin-to-capillary flowing atmospheric-pressure afterglow source (FAPA) is used for the direct desorption/ionization of PFAS from thin-layer chromatography (TLC) plates. Selected PFAS samples were directly probed on functionalized TLC surfaces without a preceding planar chromatography step. In addition, direct analysis of PFAS mixtures and selected matrices was performed with little solvent consumption, no sample preparation and short analysis time.
Effortless Antimicrobial Shield: Spray-coated Silica Nanoparticles For Safer High-touch Surfaces
(2025)
Functional films with tailored interfacial properties play a pivotal role for the development of next generation surface coatings, particularly in healthcare-related environments. In this contribution, we present a facile spray-coating method for the creation of antimicrobial thin films on high-touch surfaces using mesoporous silica nanoparticles (MSNs) that were specifically functionalized to enable strong adhesion and sustained release of metal-based antimicrobial agents. The process is scalable and addresses key challenges in adhesion control, film homogeneity, and long-term antimicrobial function against a large range of key pathogens responsible for nosocomial infections. Three distinct types of MSNs – bearing amine (MSN-NH₂), carboxy (MSN-COOH), and thiol (MSN-SH) surface groups – were synthesized to optimize both metal ion loading and interactions with polyelectrolyte-based adhesion layers. These surface modifications not only provide chemical handles for Cu²⁺ and Ag⁺ ion coordination but also modulate nanoparticle-substrate interactions and dispersion behavior during film formation. The coating architecture consists of a two-step process: first, spray deposition of polyelectrolyte primers that anchor strongly to stainless steel substrates; second, a nanoparticle layer that bonds electrostatically and chemically to the primer, forming robust films with great surface coverage. The films were characterized to assess structural integrity, adhesion, and functional performance. Transmission electron microscopy (TEM) and N₂ sorption analysis confirmed the mesoporous structure. ATR-FTIR and zeta potential measurements validated surface functionalization and colloidal stability. Environmental SEM revealed conformal coating across the stainless-steel surfaces with uniform nanoparticle distribution. The coating's adhesion strength was maintained through mechanical wiping and simulated wear and abrasion tests, demonstrating film durability relevant in real-world use scenarios. Antimicrobial testing under semi-dry, application-relevant conditions showed excellent performance for Ag⁺-loaded MSN-SH films, inhibiting growth of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. These results highlight the synergistic role of surface chemistry, metal ion loading, and film-substrate adhesion in creating effective and wear-resistant functional coatings. Moreover, these films do not show any cytotoxic properties towards Human Dermal Fibroblasts (HDF). This study contributes new insights into the design of multifunctional films where adhesion, surface functionality, and scalable processing are co-optimized for enhanced performance and shows how combining tailored surface chemistry and wide-ranging antimicrobial activity brings together smart material design for practical and safe use.
Nano- and advanced materials have been recognized as a key enabling technology of the 21st century, due to their high potential of driving innovations in new clean energy technologies, sustainable manufacturing by substitution of critical raw materials and replacement of hazardous substances, breakthroughs in energy conversion and storage, improvement of the environmental performance of products and processes, and facilitation of circularity. Consequently, new tools that enhance the development and optimization cycle of nano- and advanced materials are crucial.
In this contribution, we present our Self-Driving Lab (SDL) for Nano and Advanced Materials [1], that integrates robotics for batched autonomous synthesis – from molecular precursors to fully purified nanomaterials – with automated characterization and data analysis, for a complete and reliable nanomaterial synthesis workflow. By fully automating the processing steps for seven different materials from five representative, completely different classes of nano- and advanced materials (metal, metal oxide, silica, metal organic framework, and core–shell particles) that follow different reaction mechanisms, we demonstrate the great versatility and flexibility of the platform. The system also exhibits high modularity and adaptability in terms of reaction scales and incorporates in-line characterization measurement of hydrodynamic diameter, zeta potential, and optical properties (absorbance, fluorescence). We discuss the excellent reproducibility of the various materials synthesized on the platform in terms of particle size and size distribution, and the adaptability and modularity that allows access to a diverse set of nanomaterial classes.
We also present several key aspects of the central backend that orchestrates the (parallelized) syntheses workflows. One key feature is the resource management or “traffic control” for scheduling and executing parallel reactions in a multi-threaded environment. Another is the interface with data analysis algorithms from in-line, at-line, and off-line measurements. Here, we will give examples of how automatic image segmentation of electron microscopy images with the help of AI [2] can be used for reducing the “data analysis bottleneck” from an off-line measurement. We will also discuss various machine learning (ML) algorithms that are currently implemented in the backend and can be used for ML-guided, closed-loop material optimization in our SDL. Lastly, we will show our recent efforts [3] in making the workflow generation on SDLs more user-friendly by using large language models to generate executable workflows automatically from synthesis procedures given in natural language and user-friendly graphical user interfaces based on node editors that also allow for knowledge graph extraction from the workflows. In this context, we are currently also working on a common description or ontology for representing the process steps and parameters of the workflows, which will greatly facilitate the semantic description and interoperability of workflows between different SDL hardware and software platforms.
These features underscore the SDL’s potential as a transformative tool for advancing and accelerating the development of nano- and advanced materials, offering solutions for a sustainable and environmentally responsible future.
Melanoma skin cancer has an increasingly higher incidence , and w hen detected in advanced stages, tumour eradication is often incomplete, contributing to poor prognosis with conventional treatments. Upconversion nanoparticles (UCNPs) have unique properties, such as excitability under near infrared (NIR) excitation light, which confers a relatively high penetration depth in tissue that allow their effective use in several biomedical applications Mesoporous silica nanoparticles (MSN) with nanovalves or derived coatings have widely been used for triggered and targeted drug delivery in the past. Anticancer drugs can be loaded into the pores of MSN, enabling controlled drug release. In this work, UCNPs were coated with a mesoporous silica shell yielding UCNP@MSN core shell nanoparticles which were equipped with thermoresponsive retro Diels Alder nanovalves and then loaded with DOX , a chemotherapeutic agent for melanoma treatmen t (UCNP@MSN DOX) Subsequent DOX release from this drug delivery system was triggered by 980 nm NIR light. Melanoma cells exposed to UCNP@MSN DOX or the NIR laser exhibited no change in ROS production , while the combination of both induced an increase in ROS production. This combination of conditions also induced changes on apoptosis and necrosis levels. These findings underscore the potential use of UCNP @MSN drug delivery systems with thermoresponsive caps as effective drug delivery platforms for melanoma therapy.
Upconversion nanoparticles (UCNPs) exhibit several remarkable optical properties, including excitation by near infrared (NIR) light, which enables deep tissue penetration, multiple distinct emission bands across a wide range of wavelengths, long luminescen ce lifetimes, and high photostability. These features make them particularly attractive for various biomedical applications. Mesoporous silica nanoparticles (MSNs), functionalized with nanovalves or specific coatings, have been explored for controlled and targeted drug delivery, where therapeutic agents are encapsulated within the nanopores, allowing spatiotemporal release 1 3 ]]. Among the promising approaches, photoactivated drug delivery systems have drawn considerable interest due to their versatility and potential. One relevant application is in the treatment of melanoma, an aggressive form of skin cancer with a rising global incidence. In advanced stages, conventional therapies often fail to achieve complete tumour eradication, resulting in poor prognose s 4 In this study, UCNPs were coated with a mesoporous silica shell to form core shell UCNP@MSN nanoparticles, which were further functionalized with thermoresponsive retro Diels Alder nanovalves and loaded with doxorubicin (DOX), a chemotherapeutic drug used in melanoma treatment. Upon exposure to 980 nm NIR light, DOX release was successfully triggered in the culture medium. Exposure to functionalized UCNPs decreased the viability of the tested melanoma cell lines, with further reductions observed when the ex posure to the nanoparticles was combined with irradiation. Subsequently, t he toxicity mechanisms were evaluated and showed that w hile individual treatments with either the functionalized UCNPs or NIR irradiation alone had no effect on reactive oxygen species (ROS) production, their combination significantly increased ROS levels in two of the three tested cell lines. This combined treatment also led to notable increases in apoptotic , necrotic or both type of cells’ percentages on all cell lines. Overall, these findings highlight the potential of these nanoparticles with thermoresponsive gating mechanisms as effective platforms for targeted drug delivery in melanoma therapy.
Upconversion nanoparticles (UCNPs) possess unique photophysical characteristics, such as excita bility by near infrared (NIR) light, which facilitates deep tissue penetration, multi color emission , long luminescence lifetimes, and an excellent photostability. These features have made UCNPs promising tools for biomedical applications . M esoporous silica nanoparticles (MSNs) functionalized with stimuli responsive nanovalves or specific coatings enable the encapsulation and controlled release of therapeutic agen ts, thereby offering spatiotemporal precision in drug delivery 1 3 ]]. Among drug delivery strategies, photoresponsive systems have attracted growing attention due to their potential for clinical applications . This is especially relevant for melanoma, an aggressive skin cancer with increasing global incidence, for which conventional therapeutic modalities remain largely insufficient in advanced stage 4 In this work, core shell UCNP@MSN nanoparticles were synthetised by coating UCNPs with a mesoporous silica layer, which was subsequently functionalized with thermoresponsive retro Diels Alder nanovalves [ and loaded with the chemotherapeutic agent doxorubicin (DOX). Controlled drug release was effectively achieved under 980 nm NIR i llumination . Treatment with functionalized nanoparticles significantly reduced the viability of melanoma cell lines, with an enhanced cytotoxicity being observed upon combined nanoparticle exposure and NIR illumination . Mechanistic analyses revealed that neither UCNPs nor NIR i llumination alone could induce the production of reactive oxygen species (ROS); however, their combination induced a marked increase in ROS levels in two of the three tested cell lines. Furthermore, this dual treatment promoted substantial apoptotic and/or necrotic responses across all cell models. These findings underscore the potential of UCNP@MSN nanoplatforms, equipped with thermoresponsive ga tes , as efficient photoactivated drug delivery systems for melanoma therapy.