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Livshits P.,Bar - Ilan University | Inberg A.,Tel Aviv University | Shacham-Diamand Y.,Tel Aviv University | Malka D.,Bar - Ilan University | And 2 more authors.
Applied Surface Science | Year: 2012

In this work, the kinetics of 15 and 25 nm gold nanoparticle (AuNP) precipitation on silanized SiO 2/Si surfaces were studied. The NP coverage as well as distribution on the substrates was explored. It was found that at the beginning of the process, the 25 nm AuNPs precipitate faster than their 15 nm counterparts. However, early saturation and low final surface coverage by these NPs were observed. The 15 nm AuNPs, exhibited higher (∼40%) surface coverage and precipitation saturation only after longer treatment times. This makes small NPs a promising candidate for catalyzing the deposition of ultra-thin metallic films on insulating substrates. In addition, it has been demonstrated for the first time that NPs, independently of their size, precipitate with a certain regularity and order. Using high-resolution scanning electron microscopy (HRSEM) it was observed that NPs are organized in pairs, and in each pair they are located at 50-60 nm from each other and under certain angle. © 2012 Elsevier B.V. All rights reserved. Source

Eshed M.,Bar Ilan Institute of Nanotechnology and Advanced Materials | Lellouche J.,Bar Ilan Institute of Nanotechnology and Advanced Materials | Lellouche J.,Bar - Ilan University | Matalon S.,Tel Aviv University | And 2 more authors.
Langmuir | Year: 2012

Antibiotic resistance has prompted the search for new agents that can inhibit bacterial growth. We recently reported on the antibiofilm activities of nanosized ZnO and CuO nanoparticles (NPs) synthesized by using sonochemical irradiation. In this study, we examined the antibacterial activity of ZnO and CuO NPs in a powder form and also examined the antibiofilm behavior of teeth surfaces that were coated with ZnO and CuO NPs using sonochemistry. Free ZnO and CuO NPs inhibited biofilm formation of Streptococcus mutans. Furthermore, by using the sonochemical procedure, we were able to coat teeth surfaces that inhibited bacterial colonization. © 2012 American Chemical Society. Source

Saphier S.,Israel Institute for Biological Research | Haft A.,Bar Ilan Institute of Nanotechnology and Advanced Materials | Margel S.,Bar Ilan Institute of Nanotechnology and Advanced Materials
Journal of Medicinal Chemistry | Year: 2012

We compared the rate of colonic bacterial reduction of disulfide and nitro bonds to that of an azo counterpart. The disulfide and nitro reduction rates are comparable to that of azo having a similar molecular structure. We further explored QSAR of bacterial reduction of different nitro compounds giving a Hammett correlation with ρ = 0.553, R2 = 0.97. We conclude that disulfide and nitro compounds have an unexploited potential for use in prodrugs and drug delivery systems targeted to the colon. © 2012 American Chemical Society. Source

Glat M.,Bar - Ilan University | Skaat H.,Bar Ilan Institute of Nanotechnology and Advanced Materials | Menkes-Caspi N.,Bar - Ilan University | Margel S.,Bar Ilan Institute of Nanotechnology and Advanced Materials | And 2 more authors.
Journal of Nanobiotechnology | Year: 2013

Background: Tau dysfunction is believed to be the primary cause of neurodegenerative disorders referred to as tauopathies, including Alzheimer's disease, Pick's disease, frontotemporal dementia and Parkinsonism. The role of microglial cells in the pathogenesis of tauopathies is still unclear. The activation of microglial cells has been correlated with neuroprotective effects through the release of neurotrophic factors and through clearance of cell debris and phagocytosis of cells with intracellular inclusions. In contrast, microglial activation has also been linked with chronic neuroinflammation contributing to the development of neurodegenerative diseases such as tauopathies. Microglial activation has been recently reported to precede tangle formation and the attenuation of tau pathology occurs after immunosuppression of transgenic mice.Methods: Here we report the specific inhibition of microglial cells in rTg4510 tau-mutant mice by using fibrin γ377-395 peptide conjugated to iron oxide (γ-Fe2O3) nanoparticles of 21 ± 3.5 nm diameter.Results: Stabilization of the peptide by its covalent conjugation to the γ-Fe2O3 nanoparticles significantly decreased the number of the microglial cells compared to the same concentration of the free peptide. The specific microglial inhibition induces different effects on tau pathology in an age dependent manner. The reduction of activation of microglial cells at an early age increases the number of neurons with hyperphosphorylated tau in transgenic mice. In contrast, reduction of activation of microglial cells reduced the severity of the tau pathology in older mice. The number of neurons with hyperphosphorylated tau and the number of neurons with tangles are reduced than those in animals not receiving the fibrin γ377-395 peptide-nanoparticle conjugate.Conclusions: These results demonstrate a differential effect of microglial activity on tau pathology using the fibrin γ377-395 peptide-nanoparticle conjugate, depending on age and/or stage of the neuropathological accumulation and aggregation. © 2013 Glat et al.; licensee BioMed Central Ltd. Source

Levy I.,Bar Ilan Institute of Nanotechnology and Advanced Materials | Sher I.,Tel Aviv University | Corem-Salkmon E.,Bar Ilan Institute of Nanotechnology and Advanced Materials | Ziv-Polat O.,Bar Ilan Institute of Nanotechnology and Advanced Materials | And 7 more authors.
Journal of Nanobiotechnology | Year: 2015

Background: Iron oxide (IO) nanoparticles (NPs) of sizes less than 50 nm are considered to be non-toxic, biodegradable and superparamagnetic. We have previously described the generation of IO NPs coated with Human Serum Albumin (HSA). HSA coating onto the IO NPs enables conjugation of the IO/HSA NPs to various biomolecules including proteins. Here we describe the preparation and characterization of narrow size distribution core-shell NIR fluorescent IO/HSA magnetic NPs conjugated covalently to Fibroblast Growth Factor 2 (FGF2) for biomedical applications. We examined the biological activity of the conjugated FGF2 on human bone marrow mesenchymal stem cells (hBM-MSCs). These multipotent cells can differentiate into bone, cartilage, hepatic, endothelial and neuronal cells and are being studied in clinical trials for treatment of various diseases. FGF2 enhances the proliferation of hBM-MSCs and promotes their differentiation toward neuronal, adipogenic and osteogenic lineages in vitro. Results: The NPs were characterized by transmission electron microscopy, dynamic light scattering, ultraviolet-visible spectroscopy and fluorescence spectroscopy. Covalent conjugation of the FGF2 to the IO/HSA NPs significantly stabilized this growth factor against various enzymes and inhibitors existing in serum and in tissue cultures. IO/HSA NPs conjugated to FGF2 were internalized into hBM-MSCs via endocytosis as confirmed by flow cytometry analysis and Prussian Blue staining. Conjugated FGF2 enhanced the proliferation and clonal expansion capacity of hBM-MSCs, as well as their adipogenic and osteogenic differentiation to a higher extent compared with the free growth factor. Free and conjugated FGF2 promoted the expression of neuronal marker Microtubule-Associated Protein 2 (MAP2) to a similar extent, but conjugated FGF2 was more effective than free FGF2 in promoting the expression of astrocyte marker Glial Fibrillary Acidic Protein (GFAP) in these cells. Conclusions: These results indicate that stabilization of FGF2 by conjugating the IO/HSA NPs can enhance the biological efficacy of FGF2 and its ability to promote hBM-MSC cell proliferation and trilineage differentiation. This new system may benefit future therapeutic use of hBM-MSCs. © 2015 Levy et al.; licensee BioMed Central. Source

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