Search results for " Nanoparticle"

Lysosomal degradation of the carboxydextran shell of coated superparamagnetic iron oxide nanoparticles and the fate of professional phagocytes

2010

Contrast agents based on dextran-coated superparamagnetic iron oxide nanoparticles (SPIO) are internalized by professional phagocytes such as hepatic Kupffer cells, yet their role in phagocyte biology remains largely unknown. Here we investigated the effects of the SPIO ferucarbotran on murine Kupffer cells and human macrophages. Intravenous injection of ferucarbotran into mice led to rapid accumulation of the particles in phagocytes and to long-lasting increased iron deposition in liver and kidneys. Macrophages incorporate ferucarbotran in lysosomal vesicles containing α-glucosidase, which is capable of degrading the carboxydextran shell of the ferucarbotran particles. Intravenous injectio…

Initial Biological Assessment of Upconversion Nanohybrids

2021

Nanoparticles for medical use should be non-cytotoxic and free of bacterial contamination. Upconversion nanoparticles (UCNPs) coated with cucurbit[7]uril (CB[7]) made by combining UCNPs free of oleic acid, here termed bare UCNPs (UCn), and CB[7], i.e., UC@CB[7] nanohybrids, could be used as photoactive inorganic-organic hybrid scaffolds for biological applications. UCNPs, in general, are not considered to be highly toxic materials, but the release of fluorides and lanthanides upon their dissolution may cause cytotoxicity. To identify potential adverse effects of the nanoparticles, dehydrogenase activity of endothelial cells, exposed to various concentrations of the UCNPs, was determined. Da…

Single Unlabeled Protein Detection on Individual Plasmonic Nanoparticles

2012

The ultimate detection limit in analytic chemistry and biology is the single molecule. Commonly, fluorescent dye labels or enzymatic amplification are employed. This requires additional labeling of the analyte, which modifies the species under investigation and therefore influences biological processes. Here, we utilize single gold nanoparticles to detect single unlabeled proteins with extremely high temporal resolution. This allows for monitoring the dynamic evolution of a single protein binding event on a millisecond time scale. The technique even resolves equilibrium coverage fluctuations, opening a window into Brownian dynamics of unlabeled macromolecules. Therefore, our method enables …

PROTEOMIC IDENTIFICATION OF NOVEL MARKERS IN BREAST AND COLON CANCER

Background: Discovery of new biomarker represent the greatest promise for the detection and management of cancer. Although progress in cancer biology has been rapid during the past few years, the complete understanding of molecular basis for cancer initiation, progression and efficacious treatments is still lacking. In this context, the application of proteomic strategies is now holding a focal position. The main reason is that proteins are the functional players that drive cancer phenotypes. Among cancers, breast and colon represent the most frequent forms. The evolution of these type of cancer are not easily predictable since there are several types that behave differently among patients.…

Quality control of gold nanoparticles as pharmaceutical ingredients

2019

Abstract Nanoparticles are being developed for a wide range of medical applications such as, controlled release, drug delivery systems or imagery, theranostics, implants…. For the moment, there is no legal definition of nanoparticles or nanomaterials for therapeutic use. The specific case of gold nanoparticles is not an exception: their current definition as nanoparticle material does not correspond to classic pharmaceutical ingredients as described in Pharmacopoeias. In this study, more than 30 different batches of citrate stabilized gold nanoparticles (AuNP) were synthesized and analyzed thanks to both classical approaches (UV–Vis spectrophotometry, dynamic light scattering coupled or not…

Nonlinear dynamics of semiflexible magnetic filaments in an ac magnetic field

2006

Flexible spontaneously magnetized filaments exist in the living world (magnetotactic bacteria) and arise in magnetic colloids with large magnetodipolar interaction parameter. We demonstrate that these filaments possess variety of novel nonlinear phenomena in an ac magnetic field: orientation of the filament in the direction perpendicular to the field and the development of the oscillating U-like shapes, which presumably can lead to the formation of rings of magnetic filaments. It is found that these phenomena are determined by the development of the localized boundary modes of the filament deformation. We have illustrated by qualitative estimates that the phenomena found may be useful for i…

The use of quantum dots in organic chemistry

2009

Abstract We discuss the main mechanisms of interaction between quantum dots (QDs) of different types and organic molecules within the framework of the use of photo-physical properties of colloidal semiconductor nanoparticles for sensing organic and biochemical compounds. We reviewed the recent literature in the field to provide a picture of the state of the art of our knowledge and perspectives on this challenging field. Bearing in mind analysis in organic chemistry based on luminescence and electrochemical changes, we discuss surface interaction based on the use of QDs capped with thiol, cystein, citrate, surfactant, purine and nitroxides, and we explain ligand-analyte, bioconjugate-analyt…

Spectral Measurement of Photon Emission from Individual Gold Nanoparticles Using Scanning Tunneling Microscopy

2016

The light emission spectra of individual Au nanoparticles induced by a scanning tunneling microscope (STM) have been investigated. Two-dimensional ensembles of tunnel-coupled Au particles were prepared by thermal evaporation onto a native oxide silicon wafer in ultrahigh vacuum (10 – 9 mbar). Our STM measurements show a single peak at photon energy 1.6 eV in the tunneling mode and two peaks at 2.2 eV (connected with the Mie plasmon) and 1.45 eV (a new peak which was not discussed in literature before) in the field emission mode.

Inorganic/organic hybrid nanoparticles synthesized in a two-step radiation-driven process

2022

In this work, we have synthesized inorganic-organic hybrid nanoparticles via radiation synthesis of inorganic nanoparticles (Ag and CeO2) in aqueous dispersions containing radiation-synthesized poly(N-vinyl pyrrolidone) (PVP) nanogels (NG). The experiments show that there are strong interactions between the inorganic precursors (Ag+ and Ce3+) and the nanogel prior to irradiation. The two hybrid systems (Ag/NG and CeO2/NG) were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD confirms the formation of crystalline Ag and CeO2. TEM reveals that the inorganic nanoparticles are evenly distributed in/on the nanogel. Both XRD and TEM show that size of the…

Gamma rays induced synthesis of graphene oxide/gold nanoparticle composites: structural and photothermal study

2022

Gamma irradiation provides an alternative pathway to conventional gold nanoparticle synthesis because it is simple, fast, and economical. Here, we employed gamma irradiation at low doses (1–20 kGy) to obtain gold nanoparticles (Au NPs) anchored onto graphene oxide (GO) sheets. GO was selected as a suitable platform for the nucleation and growth of Au NPs because of its large surface area and good dispersibility in water due to the presence of polar oxygen-containing functional groups in its structure. Gamma irradiation at all the applied doses led to the reduction of chloroauric acid and the formation of evenly distributed Au NPs at the GO surface, simultaneously causing the reduction of GO…