ATR-IR and EPR spectroscopy for following the membrane restoration of isolated cortical synaptosomes in aluminium-induced Alzheimer's disease - Like rat model.

Synaptosomal membrane peroxidation and alteration in its biophysical properties are associated with Aluminium (Al) toxicity that may lead to cognitive dysfunction and Alzheimer's disease (AD) like pathogenesis. Here we investigated the therapeutic potential of Lepedium sativum (LS) as a natural anti-inflammatory, antioxidant and as acetyl cholinesterase inhibitor in treating Al induced AD-like in rat model. We utilized ATR-IR spectroscopy to follow the restoration in the damaged membrane structure of isolated rat cortical synaptosomes and its biophysical properties, electron paramagnetic resonance (EPR) spin trapping to follow NADPH oxidase activity (NOX), and EPR spin labelling in response to LS treatment after Al intoxication. We measured the concentration of Ca2+ ions in rat cortical tissue by inductively coupled plasma (ICP), the brain atrophy/curing and hydrocephalus by magnetic resonance imaging (MRI) besides light microscope histopathology. Our results revealed significant increase in synaptosomal membrane rgidification, order, lipid packing, reactive oxygen species (ROS) production and Ca2+ ion concentration as a result of Al intoxication. The dramatic increase in Ca2+ ion concentration detected in AD group associated with the increase in synaptic membrane polarity and EPR-detected order S-parameter suggest that release of synaptic vesicles into synaptic cleft might be hindered. LS treatment reversed these changes in synaptic membranes, and rescued an observed deficit in the exploratory behaviour of AD group. Our results also strongly suggest that the synaptosomal membrane phospholipids that underwent free radical attacks mediated by AlCl3, due to greater NOX activity, was prevented in the LS group. The results of ATR-IR and EPR spectroscopic techniques recommend LS as a promising therapeutic agent against synaptic membrane alterations opening a new window for AD drug developers.

Synchrotron Fourier transform infrared microspectroscopy (sFTIRM) analysis of Al-induced Alzheimer's disease in rat brain cortical tissue.

Aluminium (Al) is reported to promote beta amyloid (Aß) aggregation, free radical production and disturb acetylcholine metabolism leading to cognitive dysfunction that are strongly associated with Alzheimer's disease (AD). Here we utilized synchrotron Fourier transform infrared microspectroscopy (sFTIRM) to analyse the fine structure of proteins and lipids in the rat cortical brain tissues in response to AlCl3 toxicity and Lepidium sativum (LS) treatment after 42 and 65 days. For statistical analysis, we used principal component analysis (PCA). Our results showed profusion of gauche rotomers form in membrane lipid acyl chains that increases the membrane fluidity and disorder only in AD group indicated by the detected sνCH2 band shift to higher frequency. All half bands width (HBW) values of the decomposed amide I band showed marked decrease in AD group compared to the other tested groups, together with an increase in the amounts of ß-sheets (1641 cm-1) protein and random coil structure (1654 cm-1). These were indicated by a drastic increase in the percentage areas ratios of (1638 cm-1/1654 cm-1) and (1641 cm-1/1654 cm-1) that may be attributed to a stronger the hydrogen bonds that stabilize the protein conformational structure and/or the increase of the ß-strand length due to misfolded Aß formation in response to Al toxicity through transit phase/phases dominated by random coil structure. In curative group, LS treatment reversed these changes and restored the protein and lipid integrities. To conclude, sFTIRM is a powerful tool that shed light on the biomolecular structure of AD-like cortical brain tissue and considered the therapeutic potential of LS as a promising natural AD treatment.

ATR-IR and EPR spectroscopy for detecting the alterations in cortical synaptosomes induced by aluminium stress.

Aluminium (Al) is reported to promote free radical production, decrease the antioxidant enzyme status and disturb the enzyme activity involved in acetylcholine metabolism leading to cognitive dysfunction that are strongly associated with Alzheimer's disease (AD) pathogenesis. This work aimed at investigating the effect of Al-toxicity on synaptosomal membrane biophysical properties and lipid peroxidation during 65 days. We utilized ATR-IR spectroscopy to study the changes in membrane biochemical structure and biophysical properties of isolated rat cortical synaptosomes, and EPR spin trapping and labeling to follow NADPH oxidase activity and changes of membrane order parameter, respectively. The results showed increase in membrane fluidity and disorder in early 21d of AlCl3 treatment, while after 42d the membrane rigidity, packing, and order increased. The late (65d) an increase in the amount of unsaturated fatty acids, the accumulation of lipid peroxide end products, and ROS production were detected in rat cortex synaptosomes mediated by Al toxicity and oxidative stress (OS). A dramatic increase was also detected in Ca2+ level, synaptic membrane polarity, and EPR-detected order S-parameter. These outcomes strongly suggest that the synaptosomal membrane phospholipids underwent free radical attacks mediated by AlCl3 due to greater NOX activity, and the release of synaptic vesicles into synaptic cleft might be hindered. The adopted spectroscopic techniques have shed light on the biomolecular structure and membrane biophysical changes of isolated cortical synaptosomes for the first time, allowing researchers to move closer to a complete understanding of pathological tissues.

Biocompatibility enhancement of graphene oxide-silver nanocomposite by functionalisation with polyvinylpyrrolidone.

Several materials such as silver are used to enhance graphene oxide (GO) sheets antimicrobial activity. However, these toxic materials decrease its biocompatibility and hinder its usage in many biological applications. Therefore, there is an urgent need to develop nanocomposites that can preserve both the antimicrobial activity and biocompatibility simultaneously. This work highlights the importance of functionalisation of GO sheets using Polyvinylpyrrolidone (PVP) and decorating them with silver nanoparticles (AgNPs) in order to enhance their antimicrobial activity and biocompatibility at the same time. The structural and morphological characterisations were performed by UV-Visible, Fourier transform infrared (FTIR), and Raman spectroscopic techniques, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM). The antimicrobial activities of the prepared samples against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were studied. The cytotoxicity of prepared materials was tested against BJ1 normal skin fibroblasts. The results indicated that the decoration with AgNPs showed a significant increase in the antimicrobial activity of GO and FGO sheets, and functionalisation of GO sheets and GO-Ag nanocomposite with PVP improved the cell viability about 40 and 35%, respectively.

Preparation and evaluation of warfarin-ß-cyclodextrin loaded chitosan nanoparticles for transdermal delivery.

The main objective of the present work was to prepare warfarin-ß-cyclodextrin (WAF-ß-CD) loaded chitosan (CS) nanoparticles for transdermal delivery. CS is a hydrophilic carrier therefore, to overcome the hydrophobic nature of WAF and allow its incorporation into CS nanoparticles, WAF was first complexed with ß-cyclodextrin (ß-CD). CS nanoparticles were prepared by ionotropic pre-gelation using tripolyphosphate (TPP). Morphology, size and structure characterization of nanoparticles were carried out using SEM, TEM and FTIR, respectively. Nanoparticles prepared with 3:1 CS:TPP weight ratio and 2mg/ml final CS concentration were found optimum. They possessed spherical particles (35±12nm diameter) with narrow size distribution (PDI=0.364) and 94% entrapment efficiency. The in vitro release as well as the ex vivo permeation profiles of WAF-ß-CD from the selected nanoparticle formulation were studied at different time intervals up to 8h. In vitro release of WAF-ß-CD from CS nanoparticles followed a Higuchi release profile whereas its ex vivo permeation (at pH 7.4) followed a zero order permeation profile. Results suggested that the developed WAF-ß-CD loaded CS carrier could offer a controlled and constant delivery of WAF transdermally.

Use of FT-Raman Spectroscopy to Determine the Degree of Polymerization of Dental Composite Resin Cured with a New Light Source.

OBJECTIVES: To use the FT-Raman spectroscopy for evaluation the degree of polymerization of dental composite as a result of photo curing with a new light source in comparison to the conventional halogen light. MATERIALS AND METHODS: In this study a new light source, based on a metal-halide lamp (TOPSPOT G12) was developed at NRC-Egypt for curing dental composites. Two groups of 108 composite samples each were cured using both the new light source and a conventional halogen source, as a control source. Different samples' sizes (2x2, 3x3 and 6x3 mm(2)) were cured for different periods of time (2, 4, 8, 12, 20, and 40 seconds). The spectroscopic data were analyzed statistically by ANOVA and Duncan's multiple range test (P< .05). RESULTS: The results showed that the samples cured by the new metal-halide source produced higher polymerization rates than those cured by the halogen source. The polymerization rate was directly proportional to the exposure time and inversely proportional to the sample size, irrespective to the light source used. The results also showed that 12 seconds of metal-halide light curing produced polymerization rate comparable to or even higher than that produced by 40 seconds halogen light curing. CONCLUSIONS: The new light source produced a satisfactory degree of polymerization in a remarkable shorter curing time and it can be recommended for clinical use.