The aim of this work was to study the effect of oxidative stress on the structural changes of the secondary peptide structure of amyloid beta 1–42 (Aβ 1–42), in the dentate gyrus of hippocampus of rats exposed to low doses of ozone. The animals were exposed to ozone-free air (control group) and 0.25 ppm ozone during 7, 15, 30, 60, and 90 days, respectively. The samples were studied by: (1) Raman spectroscopy to detect the global conformational changes in peptides with α-helix and β-sheet secondary structure, following the deconvolution profile of the amide I band; and (2) immunohistochemistry against Aβ 1–42. The results of the deconvolutions of the amide I band indicate that, ozone exposure causes a progressively decrease in the abundance percentage of α-helix secondary structure. Furthermore, the β-sheet secondary structure increases its abundance percentage. After 60 days of ozone exposure, the β-sheet band is identified in a similar wavenumber of the Aβ 1–42 peptide standard. Immunohistochemistry assays show an increase of Aβ 1–42 immunoreactivity, coinciding with the conformational changes observed in the Raman spectroscopy of Aβ 1–42 at 60 and 90 days. In conclusion, oxidative stress produces changes in the folding process of amyloid beta peptide structure in the dentate gyrus, leading to its conformational change in a final β-sheet structure. This is associated to an increase in Aβ 1–42 expression, similar to the one that happens in the brain of Alzheimer’s Disease (AD) patients.
Platelets of both healthy and hypertensive subjects were analyzed by Raman and Fourier transform infrared by attenuated total reflectance (FTIR‐ATR) spectroscopies. We compared the average relative intensities of the main Raman peaks, the areas of convoluted bands in the amide I region, and the second derivative of the FTIR‐ATR spectra. Key differences were found in the bands reflecting lipid content and protein structure. The Raman spectra exhibited statistically significant changes in the intensity of bands associated with CC stretching vibrations in the carbon chains of lipids (960 cm−1) and the amide I band (centered at 1,658 cm−1). The amide I deconvolution showed changes in the area percentages of the bands corresponding to different protein secondary structures, suggesting biochemical and protein conformational differences between healthy versus arterial hypertension platelets, which might be related to the platelet activation stage. An analysis by using the second derivative of the FTIR‐ATR spectra, followed by deconvolution of amide regions support this observation, revealing differences in the amide II and amide I bands. Moreover, modifications observed in the phosphate‐associated bands are possibly related to the phospholipids' behavior and the phosphorylation of proteins. Our results suggest interesting differences between the spectra of healthy versus hypertensive platelets, which may be mainly associated with biochemical changes at the cellular membrane level.
Chronic inflammatory diseases, such as cancer, diabetes mellitus, stroke, ischemic heart diseases, neurodegenerative conditions, and COVID-19 have had a high number of deaths worldwide in recent years. The accurate detection of the biomarkers for chronic inflammatory diseases can significantly improve diagnosis, as well as therapy and clinical care in patients. Graphene derivative materials (GDMs), such as pristine graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO), have shown tremendous benefits for biosensing and in the development of novel biosensor devices. GDMs exhibit excellent chemical, electrical and mechanical properties, good biocompatibility, and the facility of surface modification for biomolecular recognition, opening new opportunities for simple, accurate, and sensitive detection of biomarkers. This review shows the recent advances, properties, and potentialities of GDMs for developing robust biosensors. We show the main electrochemical and optical-sensing methods based on GDMs, as well as their design and manufacture in order to integrate them into robust, wearable, remote, and smart biosensors devices. We also describe the current application of such methods and technologies for the biosensing of chronic disease biomarkers. We also describe the current application of such methods and technologies for the biosensing of chronic disease biomarkers with improved sensitivity, reaching limits of detection from the nano to atto range concentration.
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