6.5 Synthese und Streuverfahren nanostrukturierter Materialien
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Challenges in nanoplastic analysis: Reference materials, complex matrices, and limits of detection
(2026)
The growing concern over nanoplastic particles (< 1 µm) in food and the environment has intensified the need for robust analytical approaches to detect, quantify, and characterize these particles. But the lack is high of standardized and well-characterized reference materials that reflect environmentally relevant nanoplastics according to:
• Size distribution
• Low abundance
• Chemical diversity
• Surface properties
• Behavior in complex matrices.
This poster shows different methods like FFF and AF4-MALS and their results when measuring a nanoPP reference materials candidate.
The lack of nanoplastic (NPs) reference materials capable of mimicking real-world scenarios is currently hampering the development of validated extraction techniques from complex matrices, the development of analytical approaches for robust identification and quantification, and the ability to use environmentally relevant test materials in (eco)toxicity testing and hazard assessment.
Here, we present a strategy towards the development of a potential NP reference material based on nano-sized polyproplyene particles (nanoPP) developed within the EURAMET-funded PlasticTrace project (https://plastictrace.eu/). The strategy includes the preparation, the physicochemical characterization and the stability assessment of nanoPP in suspension both in its pristine state, but also when spiked into complex matrices like mineral water and milk.
NanoPP was produced reproducibly in a top-down approach by crushing in acetone with an UltraTurrax, filtering and change of solvent to MilliQ water. The prepared nanoPP material was subjected to a comprehensive physicochemical characterization including e.g., DLS, PTA and AF4-MALS for particle size distribution assessment, PTA and SEM for particle number concentration determination, SEM and AFM for shape analysis and pyrolysis GC-MS for chemical identification. Performed studies showed that the prepared nanoPP material is irregularly shaped and highly polydisperse with a particle size of around 180 nm (e.g., Dh,z-ave from DLS) and a particle size distribution from around 15 nm up to 135 nm (radius of gyration Rg from AF4-MALS).
Storage stability studies using DLS, PTA and AF4-MALS revealed nanoPP in aqueous suspension to be stable for at least 22 months with respect to particle size distribution and number concentration rendering it a promising NP candidate reference material. However, conducted spiking experiments in mineral water and milk showed a time-dependent agglomeration of nanoPP that needs further investigation.
Supramolecular systems exhibit collective functions that emerge from the hierarchical assembly of individual molecular building blocks. Metal−organic polyhedra (MOPs) are a class of functional supramolecular architectures with well-defined molecular geometry and an intrinsic cavity. In recent years, considerable progress has been made in assembling MOPs into extended networks to create porous solids. However, most reported MOP assemblies are limited to three-dimensional networks, which, owing to their high-dimensional connectivity, hinder effective stress dissipation and render them brittle under mechanical stress.
Here, we report the one-dimensional (1D) self-assembly of MOPs into supramolecular polymeric aerogels that combine permanent microporosity with exceptional mechanical flexibility. The reaction between amino acid-functionalized naphthalenediimide (NDI) linkers and copper salts led to the synthesis of octahedral copper-based MOPs, followed by their spontaneous self-assembly to form supramolecular gels. The corresponding aerogels converted from the gels possessed uniform 1D fibrillar networks (14.8 ± 2.2 nm in width) with intrinsic microporosity derived from individual MOP cavities. The aerogel endured 87% compressive strain without fracture, demonstrating distinct ductility. Furthermore, these fibrils in the supramolecular gels were converted to crystals after 2 weeks. Single-crystal X-ray diffraction revealed that MOPs are arranged via face-to-face interaction between octahedral MOPs to form a 1D helical chain structure. An analysis of the self-assembly process using Hansen solubility parameters unveiled that solvent conditions with high polarity and low dispersion interaction drive the formation of anisotropic assemblies. This work provides a new strategy for tailoring the mechanical properties of supramolecular materials through dimensional control of their assemblies.
Recycling existing materials and products as far as possible is an integral part of the circular economy. Plastic-based packaging, including containers for food and beverages but also for storing and transporting chemicals and dangerous goods, are presently made to a wide range from fossil resources. However, even for these “contact sensitive” products, there is still the aim of sustainability using recycled materials. For packings for the transport of dangerous goods, safety characteristics of the containments made from the “virgin” materials including polyethylene (PE) are well known and tested within the frame of their design type approval. Much less, however, is known about their counterparts made from recycled materials. Apart from material weaking, incorporation of residues into recycled plastics can cause contamination of the goods inside the packaging.
To fill this gap, we have evaluated high-density PE (HDPE) canisters made from post-consumer waste towards release of plastic additives and contaminants such as residues from former contents. Using a comprehensive untargeted high-resolution mass spectrometry (HRMS) approach as well as thermal extraction-desorption gas chromatography-mass spectrometry (TED-GC/MS), we detected up to 870 distinct components depending on the type of stored chemical and storage duration. Most of the components were unique to or released in significantly higher amounts from recycled HDPE compared to conventional HDPE. 129 of the components could be identified and analyzed for functional use. The analysis revealed “cosmetics”, “fragrance” and “flavoring” as major associations next to known and expected uses in the field of “plastics”, indicating significant introduction of foreign contaminants into the product. We present details on the compound classes involved and discuss consequences for political targets on increasing recycling rates in this product segment.
Engineered particles are essential for sustainable innovation and modern industrial applications, but their reliable, number‑based characterisation remains a major challenge. Regulatory frameworks in healthcare, personal care (EU 745/2017, 749/2017, 1223/2009), and environmental monitoring—such as the EU Drinking Water Directive 21840/2020—demand robust particle measurements across complex matrices. Yet standardised methods currently exist only for simple particle systems, leaving significant gaps for technologically relevant materials and for micro‑ and nanoplastics as emerging pollutants. These challenges are amplified by the lack of well‑defined input parameters, particularly density and refractive index, which are critical for many analytical and modelling approaches.
This talk highlights BAM’s work on developing nanoplastics reference materials to support validated, traceable, and harmonised measurement methods. I will outline strategies for producing stable, well‑characterised polymeric nanoparticles, establishing accurate material parameters, and integrating these reference materials into interlaboratory and standardisation activities. These efforts provide the metrological foundation urgently needed for regulatory testing, environmental monitoring, and industry innovation.
Polymer electrolyte fuel cells are paramount for future emission-free mobility. One of the vital challenges for prospering commercialization of PEFCs is water management in the cells. A microporous layer (MPL) is typically positioned between the gas Diffusion layer (GDL) and the catalyst layer (CL) to boost the cell performance and facilitate water management. In this study, three different MPLs were investigated, namely, carbon black-based MPLs with different PTFE binder contents (20 wt % PTFE as a base case and 40 wt % PTFE), as well as perforated MPLs with micron-sized pores coated on the same GDL- Substrate (Freudenberg H14). The water content in the membrane, catalyst layers (CL), and MPLs was explored using operando scanning small- and wide-angle X-ray scattering (S/WAXS). At Tcell = 80 °C, relative humidity = 100%, pabs = 3 bar, the MPL with larger pores exhibits slightly higher performance than the base case, while a considerably lower cathode CL and MPL saturation levels were observed for the MPL. In contrast, the MPL with higher amounts of PTFE binder shows lower performance than the base case, with considerably higher cathode CL and MPL saturation levels. 3D representations of how the pores could be filled in the cathode CLs were obtained from operando SAXS profiles using representative structure modeling for the different materials and operating conditions.
Direct Interactions of Micro- and Nanoplastics with Proteins – A Key to Mechanistic Understanding?
(2026)
Micro-/Nanoplastics (MNP) have gained widespread scientific and public attention within the last two decades. While knowledge about measuring techniques, occurrence and exposure was improved substantially, questions on toxicological impact of MNP remained unclear. A major reason for that are the continued remaining knowledge gaps with regard to mechanistical understanding of MNP effects. Our work aimed at investigating MNP properties, protein interactions, and cellular effects in combination. Therefore, we characterized MNP-protein- adsorption, changes in protein structure, cellular uptake and cellular modes of action. In a first study, we studied the molecular interactions of β-lactoglobulin, a serum and storage protein, with different MNP materials1. We identified structural changes, depending on physicochemical MNP properties, using FTIR- and fluorescence spectroscopy. Furthermore, we investigated cellular uptake of MNP individually and as a complex with β-lactoglobulin and studied the effects on cell growth and viability, using colorimetric MTT testing, flow cytometry, and cell impedance measurements. MNP material properties, especially hydrophobicity, had an impact on protein folding and consequently also on cellular interactions. In a second study, we applied α-amylase, an extracellular digestive protein with enzymatic activity. Here, in addition, we investigated the influence of MNP binding on enzyme activity, using a colorimetric starch degradation assay. We observed for the most MNP, that adsorption processes resulted in a decrease of enzyme activity. Furthermore, we used Alexa633 staining to visualize MNP uptake with and without the presence of α-amylase. Taken together, this work aims to close data gaps regarding mechanistical effects of MNP on cells by investigating direct MNP-protein-interactions. Mechanistic knowledge is crucial for understanding toxicological effects of MNP, and therefore, also for the risk assessment of possible hazards on human health.
Metal-organic frameworks (MOFs), particularly the zeolitic imidazolate framework (ZIF) family, are attractive precursors for advanced energy-storage materials. Upon pyrolysis, ZIFs can be transformed into electrically conductive carbon materials while preserving their original particle morphology, which is crucial for achieving high-performance sodium-ion battery anodes. Despite these advantages, large-scale implementation remains challenging due to the need for synthesis routes that balance performance, cost, and sustainability. The present study addresses these challenges by developing environmentally benign and economically feasible strategies for the scalable production of ZIF-8-derived carbon anodes suitable for industrial applications.
The role of microplastics as vectors for horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs) is increasingly recognized. This study investigated whether bio-based microplastics, often promoted as environmentally friendly alternatives, exhibit similar or enhanced HGT potential compared to conventional plastics. We examined the HGT rates of the trimethoprim resistance gene (dfrA1) and tetracycline resistance gene (tetA), carried on a broad-host-range plasmid, among Escherichia coli (donor) and Vibrio parahaemolyticus, Pseudomonas sp., or a natural lake microbial community (recipients). Four bio-based polymer types—polylactic acid (PLA) granules, commercial PLA, high-density polyethylene (HDPE) granules, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)- were compared with two conventional microplastics, polyethylene terephthalate (PET) and bottle-derived HDPE. The bio-based microplastics exhibited significantly higher HGT frequencies, with a 21–48-fold increase compared to control chitosan in single-strain experiments and a 13-fold increase within the lake microbial community. 16S rRNA amplicon sequencing revealed distinct bacterial community compositions colonizing different microplastic types in the lake water. The transconjugant communities, indicative of successful HGT events, were strongly influenced by microplastic type. While Nannocystis was generally dominant, the PLA (granule) microplastic exhibited a unique profile dominated by Candidatus Megaira and Niveispirillum. Additionally, Flavobacterium and Fluviicola were uniquely detected as transconjugants on HDPE (granule). These findings demonstrate that bioplastics have a significant influence on the selective enrichment of specific transconjugant genera, suggesting a prominent role of microplastics, particularly bio-based plastics, in shaping ARG dissemination within complex microbial ecosystems. We recommend a comprehensive risk assessment of bio-based plastics, particularly their potential to enhance the spread of ARGs, before their widespread implementation in consumer products.
The synthesis of composite membranes based on PVA, PPy, and sulfonated–hydrolyzed TMPS was investigated for application in proton–exchange membrane fuel cells. FT–IR confirmed the hydrolysis of TMPS through the appearance of Si–OH vibrations, disappearance of Si–O–CH3 bands, reduced CH3 stretching intensity (2840 cm− 1), and successful sulfonation of the phenyl ring (1030 cm− 1). XPS verified the introduction of sulfonic acid groups by identifying S2p peaks between 166–170 eV. Scanning electron microscopy (SEM) showed an incorporation of PPy and that the membrane morphology altered by silanol leading to an increased surface roughness and inducing phase separation in comparison to pure PVA. The PVA–PPy–Si membrane which did not undergo phase separation demonstrated improved mechanical stability (maximum stress 5.91 MPa), reduced methanol uptake (22%, lower than Nafion’s 30%), and enhanced thermal resistance compared to PVA–PPy and PVA–Si. It also exhibited a high ion–exchange capacity (1.5mmol g− 1, exceeding Nafion® at 0.9mmol g− 1 ) and a proton conductivity of 0.036 S/cm, twice that of Nafion 117. These combined properties identify the PVA–PPy–Si composite as a promising high–performance polyelectrolyte membrane for fuel cell applications.