The IRIS THz/Infrared beamline at BESSY II

At BESSY II a large acceptance angle, multipurpose infrared beamline is available, comprising several end stations suitable for material and life science investigations. The beamline provides highly brilliant infrared radiation over the energy range from about 20,000 down to 30 cm-1 and even lower when BESSY II is run in the so-called low-a mode

Deciphering a potential toxic synergy between persistent organic pollutants

Plastic, massively used in everyday life, inevitably accumulates in the environment, becoming a persistent pollutant due to its reduced and/ or extremely slow recyclability1. Plastic particles in the micro and nano range, known as micro (MP) and nanoplastics (NP), respectively represent a huge ecotoxicological challenge. Due to their high surface areas, they might ad/absorb other persistent pollutants with similar chemical properties, such as polycyclic aromatic hydrocarbons (PAHs), with unpredictable effects on persistence and distribution in the environment2. MPs/NPs, with or without pollutants ad/absorbed, could enter the trophic chain at the level of invertebrates, inflicting toxicological effects through all levels of the ecosystem3. Polystyrene MPs and PAHs previously found in water samples (e.g. fluoranthene, phenanthrene)4 and known to be adsorbed by MPs (Pyrene, benzo(a) pyrene)5 will be used in the study. PAH’s mixtures will be used to mimic environmental samples and single compounds will be used in order to understand the individual contribution of each compound for the observed toxic effect. This experimental approach will also allow to evaluate a potential synergy between compounds with effect on toxicity. Since PAHs and MPs have similar chemical properties, they are known to adsorb to each other. We will use PAHs adsorbed to MPs to test higher concentrations of PAHs (not soluble in aqueous solutions such as cell culture medium) and to document the intracellular distribution of adsorbed versus free PAHs. Concerning MPs only one material will be used at this stage. Polystyrene was selected because it is commercially available in spheres suitable for internalization by HepG2 cells and was previously isolated from environmental samples 4. This study could contribute to identify differences in toxicity and contribute to the elucidation of the underlying toxicity mechanisms using molecular biology protocols, light/electron microscopy and FTIR micro/spectrometry.Funding: Infrared spectroscopy measurements were carried out at the IRISbeamline at the BESSY II electron storage ring operated by the Helmholtz- Zentrum Berlin für Materialien und Energie (Proposals No 231-11744-ST/2022).N/

In situ infrared imaging of the local orientation of cellulose fibrils in plant secondary cell walls

The mechanical and chemical properties of plant cell walls greatly rely on the supramolecular assembly of cellulose fibrils. To study the local orientation of cellulose in secondary plant cell walls, diffraction limited infrared (IR) micro-spectroscopic mapping experiments were conducted at different orientation of transverse leaf section of the grass Sorghum bicolor with respect to the polarization direction of the IR radiation. Two-dimensional maps, based on polarization-sensitive absorption bands of cellulose were obtained for different polarization angles. They reveal a significant degree of anisotropy of the cellulose macromolecules as well as of other biopolymers in sclerenchyma and xylem regions of the cross section. Quantification of the signals assigned to polarization sensitive vibrational modes allowed to determine the preferential orientation of the sub-micron cellulose fibrils in single cell walls. A sample of crystalline nano-cellulose comprising both a single microcrystal as well as unordered layers of nanocrystals was used for validation of the approach. The results demonstrate that diffraction limited IR micro-spectroscopy can be used to study hierarchically structured materials with complex anisotropic behavior.Peer Reviewe

Occurence of persistent environmental pollutants in freshwater

Freshwater pollution is a huge concern. Occurence of 2 groups of persistent pollutants with similar chemical properties (polycyclic aromatic hydrocarbons and microplastics) in Alqueva’s surface water were evaluated during 2021. Samples were collected, once per season, at 3 spots related to touristic activities. Biofilm presence on plastic and natural materials was monitored and compared.Funding: Infrared spectroscopy measurements were carried out at the IRISbeamline at the BESSY II electron storage ring operated by the HelmholtzZentrum Berlin für Materialien und Energie (Proposals No 202-10133-ST/ UR, 2020 and 212-10726-ST/UR, 2021). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 730872. We thank INSA for financial support [2020DSA1756, 2020]N/

Chemical analysis of acoustically levitated drops by Raman spectroscopy

An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS), is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation. After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid–base reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension

Infrared spectroscopy across scales in length and time at BESSY II

The infrared beamline at BESSY II storage ring was upgraded recently to extend the capabilities of infrared microscopy. The endstations available at the beamline are now facilitating improved characterization of molecules and materials at different length scales and time resolutions. Here, the current outline of the beamline is reported and an overview of the endstations available is given. In particular, the first results obtained by using a new microscope for nano-spectroscopy that was implemented are presented. The capabilities of the scattering-type near-field optical microscope (s-SNOM) are demonstrated by investigating cellulose microfibrils, representing nanoscopic objects of a hierarchical structure. It is shown that the s-SNOM coupled to the beamline allows imaging to be performed with a spatial resolution of less than 30 nm and infrared spectra to be collected from an effective volume of less than 30 nm × 30 nm × 12 nm. Potential steps for further optimization of the beamline performance are discussed

C-amidation of substituted β 3oligoamides yields novel supramolecular assembly motif

N-acylated substituted β 3 oligoamides are known to form unique supramolecular nanorods based on a 3-point hydrogen bond self-assembly motif. This motif is an intermolecular extension of the hydrogen bonding network that stabilizes the 14-helix secondary structure unique to β 3 oligoamides. Acetylation of the N-terminus of the molecule provides the necessary third hydrogen bond pair of the motif. Here, the possibility of introducing the third hydrogen bond pair via amidation of the C terminus is investigated. While similar in purpose, this modification introduces a chemically distinct new self-assembly motif, also removing the bulky carboxyl group that does not fold into the 14 helix positioning instead as a side chain. Three substituted β 3 oligoamide variants with the base sequence LIA (where the letters denote β 3 residues with side chains analogous to α amino acids) were compared: N-acylated Ac-β 3[LIA] as a reference, C-amidated β 3[LIA]-CONH2, and β 3[LIA] with free unmodified N and C termini as a negative control. The three variants were dissolved in water to promote self-assembly. The self-assembly was characterised using mid- and far-infrared spectroscopy, small angle x-ray scattering (SAXS) and atomic force microscopy (AFM). IR measurements confirmed that all three samples were in a similar conformation, consistent with pseudo 14-helical secondary structures. Far-infrared spectroscopy measurements of β 3[LIA]-CONH2 showed distinct peaks consistent with highly organised skeletal modes, i.e. regular supramolecular assembly, that was largely absent from the other two oligoamides. Modelling of SAXS data is consistent with elliptical cylinder structures resulting from nanorod bundling for both β 3[LIA]-CONH2 and Ac-β 3[LIA], but not in the unmodified sample. Consistently, AFM imaging showed large nanorod bundling structures in β 3[LIA]-CONH2, varied bundling structures in Ac-β 3[LIA], and only aggregation in β 3[LIA]. Amidation showed much more organised and robust assembly compared to acetylation, providing a new, easy to synthesize self-assembly motif for helical nanorod assembly that is similar but distinct to N-acylatio

Exploring the interplay between microplastics and biofilms in freshwater

Plastic inevitably accumulates in the environment becoming a persistent. In the present work, we aim at documenting MPs occurrence in three collection spots of the biggest European artificial lake over one year period using infrared microscopy. Scanning electron microscopy was used to evaluate MPs colonization by biofilms. PE was the most abundant polymer and biofilms were identified in all plastics.CALIPSOplus: 1004; 202-10133 ST/UR; 212-10726 ST/URN/

Coordination crosslinking of helical substituted oligoamide nanorods with Cu(II)

Substituted oligoamides are short sequences of unnatural amino acids. Oligoamides made entirely of β3 amino acids yield helical monomers that, if N-acylated, assemble into nanorod structures via a supramolecular assembly motif. In this work, coordination crosslinking was used to create complex nanomaterials from oligoamides WKLWEL (KE) and WELWEL (EE) (the letters denote the analogous α-amino acids). Upon Cu(II) addition, atomic force microscopy and small angle neutron scattering revealed morphologic changes specific to KE but absent in EE. Vibration spectroscopy measurements revealed that Cu(II) can coordinate to the amine moieties of the side chains, without direct effect on the backbone amides. While coordination in excess solvent lead to regular nanostructures, fast drying of the sample yielded oligoamide templated crystallization of CuCl2. The metal coordination crosslinking of supramolecular assemblies as reported here is the first realization of a metallosupramolecular framework structure