Micro-Raman spectroscopy of lipid halo and dense-core amyloid plaques: aging process characterization in the Alzheimer's disease APPswePS1ΔE9 mouse model

Abstract

The deposition of amyloid plaques is considered one of the main microscopic features of Alzheimer’s disease (AD). Since plaque formation can precede extensive neurodegeneration and the main clinical manifestations of...

Unraveling Molecular Composition in Biological Samples–Systematic Evaluation of Statistical Methods for the Analysis of Hyperspectral Raman Data

“…Cell nuclei indicated by the DNA peak can also be detected as elliptical structures surrounding the plaque. The Aβ plaque indicated by the β-sheet peak at 1670 cm –1 is distinguishable from the surrounding tissue and correlates in size and shape to plaques reported in other studies . Yet, cell nuclei also exhibit an elevated intensity compared to the surrounding tissue, which could be attributed to peaks specific for cell nuclei between 1663 and 1690 cm –1 .…”

“…Peaks commonly found in biological spectra were chosen for univariate data analysis (Table S1). ,,, Each peak (±5 cm –1 ) was integrated, and results were plotted as 2D heat maps. The consistent narrow interval of ±5 cm –1 was used to ensure comparability of the maps.…”

“…Recent research has revealed few key alterations in the Aβ plaque Raman spectrum compared to the surrounding tissue; however, they are only subtle, such as an increase in the phenylalanine peak or the β-sheet peak. Moreover, these peaks are not unique features of the Aβ plaque but rather common throughout the tissue. − Thus, accurate processing of acquired raw Raman spectra is both crucial and challenging (Figure ).…”

Raman Spectroscopy Techniques for the Investigation and Diagnosis of Alzheimer's Disease

“…The main features of RS techniques described in this review, are summarized in Table 1 (Ref. [5,6,[18][19][20][21][22]24,25,27,28,[31][32][33][34][35][36][37][38][42][43][44][45][46][47][48]52,[54][55][56][57][60][61][62][63][64]).…”

“…Exploiting these peculiarities, RS demonstrated great potential for the analysis of AD biosamples, such as histologic specimens and biological fluids. Several studies have shown that Raman experiments can allow detection of amyloid plaques and neurofibrillary tangles in unlabelled samples as derived from human brain tissue of AD patients or in animal models, as well as distinguish them from the surrounding areas [18][19][20][21][22]. For example, a Raman study in mice demonstrated the ability to differentiate AD from healthy subjects with an accuracy of 85.9%, identifying distinctive disease-related biochemical alterations in retina samples [23].…”