Scattering correction for samples with cylindrical domains measured with polarized infrared spectroscopy

Scattering artifacts are one of the most common effects distorting transmission spectra in Fourier-Transform Infrared spectroscopy. Their increased impact, strongly diminishing the quantitative and qualitative power of IR spectroscopy, is especially observed for structures with a size comparable to the radiation wavelength. To tackle this problem, a wide range of preprocessing techniques based on the Extended Multiplicative Scattering Correction method was developed, using physical properties to remove scattering presence in the spectra. However, until recently those algorithms were mostly focused on spherically shaped samples, for example, cells. Here, an algorithm for samples with cylindrical domains is described, with additional implementation of a linearly polarized light case, which is crucial for the growing field of polarized IR imaging and spectroscopy. An open-source code with GPU based implementation is provided, with a calculation time of several seconds per spectrum. Optimizations done to improve the throughput of this algorithm allow the application of this method into the standard preprocessing pipeline of small datasets

Gradient chitosan hydrogels modified with graphene derivatives and hydroxyapatite : physiochemical properties and initial cytocompatibility evaluation

In this study, we investigated preparation of gradient chitosan-matrix hydrogels through a novel freezing–gelling–thawing method. The influence of three types of graphene family materials (GFM), i.e., graphene oxide (GO), reduced graphene oxide (rGO), and poly(ethylene glycol) grafted graphene oxide (GO-PEG), as well as hydroxyapatite (HAp) on the physicochemical and biological properties of the composite hydrogels was examined in view of their potential applicability as tissue engineering scaffolds. The substrates and the hydrogel samples were thoroughly characterized by X-ray photoelectron spectroscopy, X-ray diffractometry, infrared spectroscopy, digital and scanning electron microscopy, rheological and mechanical analysis, in vitro chemical stability and bioactivity assays, as well as initial cytocompatibility evaluation with human umbilical cord Wharton’s jelly mesenchymal stem cells (hUC-MSCs). We followed the green-chemistry approach and avoided toxic cross-linking agents, using instead specific interactions of our polymer matrix with tannic acid, non-toxic physical cross-linker, and graphene derivatives. It was shown that the most promising are the gradient hydrogels modified with GO-PEG and HAp

SOLARIS National Synchrotron Radiation Centre in Krakow, Poland

The SOLARIS synchrotron located in Krakow, Poland, is a third-generation light source operating at medium electron energy. The first synchrotron light was observed in 2015, and the consequent development of infrastructure lead to the first users’ experiments at soft X-ray energies in 2018. Presently, SOLARIS expands its operation towards hard X-rays with continuous developments of the beamlines and concurrent infrastructure. In the following, we will summarize the SOLARIS synchrotron design, and describe the beamlines and research infrastructure together with the main performance parameters, upgrade, and development plans

Spatially resolved macromolecular orientation in biological tissues using FT-IR imaging

Fourier-transform infrared spectroscopy (FT-IR) in combination with machine learning and chemometrics is an intensively developed, powerful tool for investigation of tissue biochemical composition with simultaneous microscopic visualization. This nondestructive, information rich and label-free technique has been successfully applied in cancer diagnostics. During the development of a disease or inflammatory processes, not only the chemical composition of tissues changes, but also their spatial organization. FT-IR imaging with linear polarization can provide new and useful information about chemically-specific orientation of macromolecules. Here, we present results of spatial macromolecular orientation in human, pancreatic tissue using four-polarization FT-IR method. Despite the much more complex chemical structure of tissue compared to artificial materials such as fibrillar polymers, the obtained orientations of biomolecules in tissue agreed with theoretical prediction

Scattering correction for samples with cylindrical domains measured with polarized infrared spectroscopy

Scattering artifacts are one of the most common effects distorting transmission spectra in Fourier-Transform Infrared spectroscopy. Their increased impact, strongly diminishing the quantitative and qualitative power of IR spectroscopy, is especially observed for structures with a size comparable to the radiation wavelength. To tackle this problem, a range of preprocessing techniques based on the Extended Multiplicative Scattering Correction method was developed, using physical properties to remove scattering presence in the spectra. However, until recently those algorithms were mostly focused on spherically shaped samples, for example, cells. Here, an algorithm for samples with cylindrical domains is described, with additional implementation of a linearly polarized light case, which is crucial for the growing field of polarized IR imaging and spectroscopy. The approach is tested on a polymer fiber and on human tissue collagen fiber. An open-source code with GPU based implementation is provided, with a calculation time of several seconds per spectrum. Optimizations done to improve the throughput of this algorithm allow the application of this method into the standard preprocessing pipeline of small datasets

Super-resolved 3D mapping of molecular orientation with vibrational techniques

When a sample has an anisotropic structure, it is possible to obtain different information, when changing polarization of incident light. Using polarized light of a single vibrational band to determine the in-plane orientation and internal ordering of a sample is a typical practice in materials science. Acquiring mapping data at four different polarizations with a stationary sample than just at two polarizations offers much more insight into the sample structure with proper mathematical treatment. A concurrent analysis of two vibrational bands with perpendicular transition moment orientations allows the understanding of the orientational ordering in three dimensions. We show here, to the best of our knowledge, the first application of concurrent analysis to IR spectromicroscopy data and obtain orientation angles of a model spherulite polycaprolactone sample. Moreover, we show that this method can be easily applied to high resolution, diffraction limited FT-IR and Raman imaging and even to sub-diffraction limit O-PTIR imaging. Due to the non-tomographic experimental approach, no image distortion is visible and nanometer scale orientation domains can be observed. 3D bond orientation maps will enable in-depth characterization of sample structure in a quantitative manner enabling more precise control of their physicochemical properties and function

Polylactide/Hydroxyapatite Nonwovens Incorporated into Chitosan/Graphene Materials Hydrogels to Form Novel Hierarchical Scaffolds

In this study, hierarchical, cylindrical scaffolds based on polylactide (PLA) microfibers incorporated into chitosan (CS) hydrogel were prepared for potential use in bone tissue engineering. PLA nonwovens modified with hydroxyapatite particles (HAp) were obtained using the electrospinning method. Then, three-dimensional scaffolds were created by rolling up the nonwovens and immersing them in CS-based solutions with graphene oxide (GO) or reduced graphene oxide (rGO) dispersed in the polymer matrix. Hydrogels were cross-linked using a novel freezing-thawing-gelling method. A broad spectrum of research methods was applied in order to thoroughly characterize both the nanofillers and the composite systems: scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, attenuated total reflection Fourier transform infrared spectroscopy, rheological and mechanical testing, as well as the assessment of chemical stability, bioactivity and cytocompatibility

Super-resolved 3D mapping of molecular orientation using vibrational techniques

[Image: see text] When a sample has an anisotropic structure, it is possible to obtain additional information controlling the polarization of incident light. With their straightforward instrumentation approaches, infrared (IR) and Raman spectroscopies are widely popular in this area. Single-band-based determination of molecular in-plane orientation, typically used in materials science, is here extended by the concurrent use of two vibration bands, revealing the orientational ordering in three dimension. The concurrent analysis was applied to IR spectromicroscopic data to obtain orientation angles of a model polycaprolactone spherulite sample. The applicability of this method spans from high-resolution, diffraction-limited Fourier transform infrared (FT-IR) and Raman imaging to super-resolved optical photothermal infrared (O-PTIR) imaging. Due to the nontomographic experimental approach, no image distortion is visible and nanometer scale orientation domains can be observed. Three-dimensional (3D) bond orientation maps enable in-depth characterization and consequently precise control of the sample’s physicochemical properties and functions