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Haemoglobin (HGB) and its various isoforms are powerful markers for diagnostic and treatment control. For the first time a species-specific isotope dilution mass spectrometry (IDMS) method for the quantification of the whole protein without peptide digestion was developed in this study. The required species-specific HGB spike material was prepared by substituting the entire protohaem containing natFe for the same group enriched with 57Fe. The spike material was characterised regarding isotopic enrichment and structural modification compared to natural HGB. Two different separation methods using a MonoQ® ion exchange chromatography column and a size exclusion column (SEC), respectively, have been developed for the separation of HGB from the matrix and their results for the quantification using IDMS were compared. For this, a high-performance liquid chromatography (HPLC) system was linked to an inductively coupled plasma mass spectrometer (ICP-MS) and HGB was quantified via its iron content. The IRMM/IFCC-467 and JCCRM 912-2 reference materials were used as control samples and for comparison of both separation techniques (MonoQ® and SEC). The HGB values obtained for both methods were found to be identical within the expanded uncertainty. [ABSTRACT FROM AUTHOR]

Relaxor PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 single crystals are studied at room temperature using resonance Raman scattering. It is shown that the phonon modes associated with O localized BO6 vibrations in ferroic clusters strongly resonate in the vicinity of the maximum of the optical dielectric response function at 3.71 eV. Resonance Raman spectroscopy can be used to estimate the fraction and the average size of polar nanoclusters in the relaxor state. [ABSTRACT FROM AUTHOR]

Raman spectroscopy was applied to study nano-scale structure and related phonon anomalies in relaxor-ferroelectric materials of type PbB′0.5B″0.5O3. By comparing the polarized spectra of single crystals, measured at temperature higher than the maximum of the dielectric permittivity, Tm, and by performing normal mode calculations the observed Raman peaks were assigned to definite atomic vibrations. Further, the temperature evolution of the phonon anomalies was investigated on the basis of calculated modes of representative structural units at various atomic positions. It is shown that within a few nm doubling of the unit cell should exist, independently of the degree of B-site ordering. The Raman activity of the silent F2u mode reveals the existence of dynamical off-centred structural fluctuations. The structural perturbation consists of a non-coplanarity of the Pb and O atoms in the planes perpendicular to the cubic body diagonal and non-centre-symmetrical deformations of the BO6 octahedra. On cooling, different structural changes are preferential: for B″=Nb the temperature decrease amplifies the deformation of the individual BO3–Pb species; for B″=Ta the temperature decrease favours the non-coplanarity of Pb and O atoms and enhances the correlation between the stereoactive electron lone pairs of Pb atoms. Besides, within nano-scale spatial regions, PbSc0.5Ta0.5O3 undergoes an additional phase transition near 180 K that involves a reduction of the rotational symmetry. The comparison between the temperature dependence of the inelastic light scattering in stoichiometric and Nb-doped PbSc0.5Ta0.5O3 shows that the presence of Nb even in small concentrations affects the Pb–O sublattice and changes the direction of the local structural transformations. [Copyright &y& Elsevier]

Relaxor PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 single crystals are studied at room temperature using resonance Raman scattering. It is shown that the phonon modes associated with O localized BO6 vibrations in ferroic clusters strongly resonate in the vicinity of the maximum of the optical dielectric response function at 3.71 eV. Resonance Raman spectroscopy can be used to estimate the fraction and the average size of polar nanoclusters in the relaxor state. [ABSTRACT FROM AUTHOR]

DNA origami is a flexible platform for the precise organization of nano-objects, enabling numerous applications from biomedicine to nano-photonics. Its huge potential stems from its high flexibility that allows customized structures to meet specific requirements. The ability to generate diverse final structures from a common base by folding significantly enhances design variety and is regularly occurring in liquid. This study describes a novel approach that combines top-down lithography with bottom-up DNA origami techniques to control folding of the DNA origami with the adsorption on pre-patterned surfaces. Using this approach, tunable plasmonic dimer nano-arrays are fabricated on a silicon surface. This involves employing electron beam lithography to create adsorption sites on the surface and utilizing self-organized adsorption of DNA origami functionalized with two gold nanoparticles (AuNPs). The desired folding of the DNA origami helices can be controlled by the size and shape of the adsorption sites. This approach can for example be used to tune the center-to-center distance of the AuNPs dimers on the origami template. To demonstrate this technique's efficiency, the Raman signal of dye molecules (carboxy tetramethylrhodamine, TAMRA) coated on the AuNPs surface are investigated. These findings highlight the potential of tunable DNA origami-based plasmonic nanostructures for many applications., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

This study explores important parameters for achieving a high-level positional control of DNA-nanoparticle hybrid structures by drop-casting onto a pre-structured silicon surface, in which the active adsorption sites were defined using electron beam lithography. By confining the adsorption sites to the scale of the DNA origami, we create multi-dimensional patterns and study the effect of diffusion and hybrid nanostructure concentration in the liquid on site occupation. We also propose a physical diffusion model that highlights the importance of surface diffusion in facilitating the adsorption of hybrid nanostructure onto active sites, particularly for two and one-dimensional adsorption sites. Our study shows prominent results of the hybrid nanostructure's selective adsorption, indicating high adsorption efficiency and precise control over the position, as well as the spatial orientation. We anticipate similar results in related systems, both in terms of different surfaces and similar DNA structures. Overall, our findings offer promising prospects for the development of large-scale nanoarrays on micrometer-scale surfaces with nanometer precision and orientation control., (Creative Commons Attribution license.)

In confocal Raman microscopy, depth profiling is a key application that enables analysis of the structural and chemical composition and size of three-dimensional (3D) transparent objects. However, the precise interpretation of a probed sample's Raman depth profile measurement can be significantly affected by both its size and surrounding objects. This study provides a more comprehensive understanding of the observed optical effects at the interface between polymer spheres and different substrates. Ray- and wave-optical simulations support our results. We derive a correction factor that, depending on the instrumental configuration, allows us to determine the nominal dimensions of the scanned objects more accurately from Raman depth profiles. Our studies support the need for careful consideration when employing depth profiling in confocal Raman microscopy for nondestructive, quantitative tomography of 3D objects.

The growth parameters for epitaxial growth of graphene on silicon carbide (SiC) have been the focus of research over the past few years. However, besides the standard growth parameters, the influence of the substrate pretreatment and properties of the underlying SiC wafer are critical parameters for optimizing the quality of monolayer graphene on SiC. In this systematic study, we show how the surface properties and the pretreatment determine the quality of monolayer graphene using polymer-assisted sublimation growth (PASG) on SiC. Using the spin-on deposition technique of PASG, several polymer concentrations have been investigated to understand the influence of the polymer content on the final monolayer coverage using wafers of different miscut angles and different polytypes. Confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), Raman spectroscopy, and scanning electron microscopy (SEM) were used to characterize these films. The results show that, even for SiC substrates with high miscut angles, high-quality graphene is obtained when an appropriate polymer concentration is applied. This is in excellent agreement with the model understanding that an insufficient carbon supply from SiC step edge decomposition can be compensated by additionally providing carbon from a polymer source. The described methods make the PASG spin-on deposition technique more convenient for commercial use., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The reconstruction of the three-dimensional (3D) morphology of polymeric microsphere layers based on confocal Raman microscopy was studied. Refraction of the Raman laser beam at the curved surface of the spheres broadens the focus volume inside the sphere. Compared to planar layers, the focus gets trapped inside the spheres such that the measured depth profiles are shifted and broadened. Additionally, the Raman signal of the underlying substrate is already observed for nominal focus positions above the microsphere layer. The results are successfully modeled with ray-optical simulations that allow for a clear understanding of the relevant mechanisms that lead to the generation of the Raman signals in the complex three-dimensional structures.

Background: As in other countries, there is concern and some fragmentary evidence that GPs' central role in the Swiss healthcare system as the primary provider of care might be changing or even be in decline. Our study gives a systematic account of GPs' involvement in accident care from 2008 to 2016 and identifies changes in GPs' involvement in this typical field of primary care: how frequently GPs were involved along the care pathway, to what extent they figured as initial care provider, and what their role in the care pathway was., Methods: Using a claims dataset from the largest Swiss accident insurer with two million accident cases, we constructed individual care pathways, i.e., when and from which providers patients received care. We calculated probabilities for the involvement of various care provider groups, for initial care provision, and for the role of GPs in patients' care pathways, adjusted for injury and patient characteristics using multinomial regression., Results: In 2014, GPs were involved in 70% of all accident cases requiring outpatient care but no inpatient stay, and provided initial care in 56%. While involvement stayed at about the same level for accidents occurring from 2008 to 2014, the share of accidents where GPs provided initial care decreased by 4 percentage points. The share of cases where GPs acted as sole care provider decreased by 7 percentage points down to 44%. At the same time, accident cases involving care from an ED at any point in time increased from 38 to 46% and the share receiving initial care from an ED from 30 to 35 percentage points - apparently substituting for the declining involvement of GPs in initial care. GPs' involvement in accident care is higher in rural compared to urban regions, among elderly compared to younger patients, and among Swiss compared to non-Swiss citizens., Conclusions: GPs play a key role in accident care with considerable variation depending on region and patient profile. From 2008 to 2014, there is a remarkable decline in GPs' provision of initial care after an accident. This is a strong indication that the GPs' role in the Swiss healthcare system is changing.

We report a bottom-up synthesis of iron oxide and gold nanoparticles, which are functionalized and combined to form a nanohybrid serving as an immune sensor, which selectively binds to tau protein, a biomarker for diagnosis of Alzheimer's disease. Detection of the target analyte is achieved by surface-enhanced Raman scattering originating from the diagnostic part of the nanohybrid that was prepared from Au nanoparticles functionalized with 5,5'-dithiobis-(2-nitrobenzoic acid) as a Raman reporter and monoclonal anti-tau antibody. The magnetic part consists of Fe x O y nanoparticles functionalized with polyclonal anti-tau antibody and is capable to separate tau protein from a complex matrix such as cerebrospinal fluid. We further identified and validated a set of analytical tools that allow monitoring the success of both nanoparticle preparation and each functionalization step performed during the assembly of the two binding sites by an immune reaction. By applying UV/Vis spectroscopy, dynamic light scattering, zeta potential measurements, X-ray diffraction, small-angle X-ray scattering, and transmission electron microscopy, we demonstrate a proof-of-concept for a controlled and step-by-step traceable synthesis of a tau protein-specific immune sensor., (© 2019 The Authors. Journal of Biophotonics published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nucleic acids, proteins, and polysaccharides are the most important classes of biopolymers. The inherent properties of biomacromolecules are contrary to those of well-defined small molecules consequently raising a number of specific challenges which become particularly apparent if biomacromolecules are treated as objects in quantitative analysis. At the same time, their specific functional ability of molecular recognition and self-organization (e.g., enzymes, antibodies, DNA) enables us to make biomacromolecules serving as molecular tools in biochemistry and molecular biology, or as precisely controllable dimensional platforms for nanometrological applications. Given the complexity of biomacromolecules, quantitative analysis is not limited to the measurement of their concentration but also involves the determination of numerous descriptors related to structure, interaction, activity, and function. Among the biomacromolecules, glycans set examples that quantitative characterization is not necessarily directed to the measurement of amount-of-substance concentration but instead involves the determination of relative proportions (molar ratios) of structural features for comparison with theoretical models. This article addresses current activities to combine optical techniques such as Raman spectroscopy with isotope dilution approaches to realize reference measurement procedures for the quantification of protein biomarkers as an alternative to mass spectrometry-based techniques. Furthermore, it is explored how established ID-MS protocols are being modified to make them applicable for quantifying virus proteins to measure the HIV viral load in blood samples. As an example from the class of carbohydrates, the challenges in accurate determination of substitution patterns are outlined and discussed. Finally, it is presented that biomacromolecules can also serve as tools in quantitative measurements of dimensions with an example of DNA origami to generate defined dimensional standards to be used for calibration in super-resolution fluorescence microscopy. Graphical abstract Quantitative analysis of biomacromolecules is accompanied with special challenges different from low molecular weight compounds. In addition, they are not only objects but also tools applicable for quantitative measurements.

The total haemoglobin (Hb) concentration in blood is one of the most frequently measured analytes in clinical medicine because of its significance for evaluating the health state of a human. The spectrophotometric cyanmethaemoglobin (HiCN) method is the internationally accepted conventional reference method to determine this biomarker. It is frequently used in clinical routine diagnostics but is not traceable to the International System of Units and thus does not meet highest metrological demands. A further critical issue is the toxicity of the necessary potassium cyanide. Different methods to solve these problems are reported here. They all were validated against the HiCN method in an interlaboratory comparison by measuring the total Hb concentration present in the certified reference material JCCRM 912-2M. Methods considered were the spectrophotometric alkaline haematin detergent (AHD) method as well as several isotope dilution (ID)-based approaches. The latter include inductively coupled plasma mass spectrometry (ICP-MS), species-specific (SS) ICP-MS, organic MS and Raman spectrometry. Graphical abstract ᅟ.

The direct growth of single-layer graphene patterns via electron irradiation of aromatic self-assembled monolayers and subsequent annealing is demonstrated. In this way, a reduction in the number of necessary manufacturing steps is achieved. The formed micro- and nanostructures can be arbitrarily shaped and eventually implemented in a manifold of applications., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)