Our new paper on the oPTIR signal was published in Analytical Chemistry. Very proud of the TOC graphic. https://pubs.acs.org/doi/10.1021/acs.analchem.5c03194
Raw data and code on Zenodo: https://doi.org/10.5281/zenodo.15190267
#science #academie #optir #infrared #TUwien
Not Just Better Resolution: A Detailed Study of the Signal Distribution in Mid-Infrared Optical Photothermal Imaging
The spatial resolution of an imaging system is generally evaluated by analysis of the point spread function (PSF), that is, the system response to a point source in the object plane. The PSF, albeit a fundamental concept in light microscopy, has been sparsely studied in optical photothermal infrared (O-PTIR) imaging. Although there is only a minor difference between the photothermal and optical intensity distributions in the radial direction, the axial photothermal signal is markedly different from the imaging response of conventional light microscopes. Previous studies of particles beyond the visible diffraction limit have shown that the O-PTIR signal has two lobes and strongly varies with the offset between the foci of the pump and the probe laser. We will therefore present theoretical and experimental data to investigate the radial and axial intensity distributions of a commercial Raman microscope and a custom O-PTIR transmission instrument, with particular emphasis on the axial PSF of the O-PTIR system. Our data suggest that the two-lobed signal shape is also present in objects on the order of the probe beam wavelength.
Lipid mediated formation of antiparallel aggregates in cerebral amyloid angiopathy.
Acta Neuropathol 150, 3 (2025).
https://doi.org/10.1007/s00401-025-02911-5
#optir #infrared #lipids #openaccess
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Lipid mediated formation of antiparallel aggregates in cerebral amyloid angiopathy - Acta Neuropathologica
Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder marked by amyloid-β (Aβ) deposition in blood vessel walls, leading to hemorrhage and recurring stroke. Despite significant overlap with Alzheimer’s disease (AD) through shared Aβ pathology, the specific structural characteristics of Aβ aggregates in CAA and their variations between stages of disease severity are yet to be fully understood. Traditional approaches relying on brain-derived fibrils can potentially overlook the polymorphic heterogeneity and chemical associations within vascular amyloids. This study utilizes sub-diffraction, label-free optical photothermal infrared (O-PTIR) spectroscopic imaging to directly probe the chemical structure and heterogeneity of vascular amyloid aggregates within human brain tissues across different CAA stages. Our results demonstrate a clear increase in β-sheet content within vascular Aβ deposits corresponding to disease progression. Crucially, we identify a significant presence of antiparallel β-sheet structures, particularly prevalent in moderate/severe CAA. The abundance of antiparallel structures correlates strongly with co-localized lipids, implicating a lipid-mediated aggregation mechanism. We substantiate the ex-vivo observations using nanoscale AFM-IR spectroscopy and demonstrate that Aβ40 aggregated in-vitro with brain-derived lipids adopts antiparallel structural distributions mirroring those found in CAA vascular lesions. This work provides critical insights into the structural distributions of Aβ aggregates in CAA, highlighting the presence of polymorphs typically associated with transient intermediates, which may lead to alternate mechanisms for neurotoxicity.
Looking for #advice for trying to correct #ATR #FTATR #spectrum using #R / #rstudio .
I need to make my #spectra comparable to #OPTIR but I can’t figure out the #coding for #ATRcorrection 😭.
Note: I don’t need to do #baselinecorrection as such, more about #weighting :)
#R #spectroscopy #Bruker #FTIR
An optical photothermal infrared investigation of lymph nodal metastases of oral squamous cell carcinoma.
Scientific Reports volume 14, Article number: 16050 (2024)
https://doi.org/10.1038/s41598-024-66977-z#infrared #optir #openaccessSingle-cell mapping of lipid metabolites using an infrared probe in human-derived model systems.
Nature Communications volume 15, Article number: 350 (2024)
https://doi.org/10.1038/s41467-023-44675-0#infrared #optir #openaccessLabel-Free High-Resolution Photothermal Optical Infrared Spectroscopy for Spatiotemporal Chemical Analysis in Fresh, Hydrated Living Tissues and Embryos.
J. Am. Chem. Soc. 2023
https://doi.org/10.1021/jacs.3c08854#optir #openaccessExploration of utility of combined optical photothermal infrared and Raman imaging for investigating the chemical composition of microcalcifications in breast cancer.
Anal. Methods, 2023 Advance Article
https://doi.org/10.1039/D2AY01197B#optir #ramaneffect #breastcancer #cancer #OpenAccess
Georg Ramer
CLIRSPEC
Laura Scoble