Search results for "SURFACE MODIFICATION"
showing 10 items of 417 documents
Colloidal stability of halloysite clay nanotubes
2019
Abstract The colloidal stability of halloysite clay nanotubes dispersion is reviewed showing the strategy and the mechanism to obtain stable systems in water and apolar solvents. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting electrostatic interactions. The adsorption of anionic surfactants onto the halloysite cavity allows generating inorganic cylindrical micelles that can be separated from the solvent. On the other hand, the functionalization of halloysite shell by positively charged surfactants drives to obtain stable water-in-oil emulsions. The interactions with ionic and nonionic polymers alters the dispersability of halloysite due to electr…
Rapid formation of plasma protein corona critically affects nanoparticle pathophysiology
2013
In biological fluids, proteins bind to the surface of nanoparticles to form a coating known as the protein corona, which can critically affect the interaction of the nanoparticles with living systems. As physiological systems are highly dynamic, it is important to obtain a time-resolved knowledge of protein-corona formation, development and biological relevancy. Here we show that label-free snapshot proteomics can be used to obtain quantitative time-resolved profiles of human plasma coronas formed on silica and polystyrene nanoparticles of various size and surface functionalization. Complex time- and nanoparticle-specific coronas, which comprise almost 300 different proteins, were found to …
Anti-oxidative effects and harmlessness of asymmetric Au@Fe3O4 Janus particles on human blood cells
2014
AbstractThe physical properties of asymmetric Janus particles are highly promising for future biomedical applications. However, only a few data is available on their biological impact on human cells. We investigated the biological impact of different Au@Fe3O4 Janus particle formulations in vitro to analyse specific uptake modalities and their potential cytotoxic effects on human cells of the blood regarding intravenous injection. We demonstrate that Au@Fe3O4 Janus particles exhibit a similar or even better biocompatibility compared to the well-studied spherical iron oxide nanoparticles. The impact of Janus particles on cells depends mainly on three factors. (1) Surface functionalization: NH…
A Promising Family of Fluorescent Water-Soluble aza-BODIPY Dyes for in Vivo Molecular Imaging.
2019
A new family of water-soluble and bioconjugatable aza-BODIPY fluorophores was designed and synthesized using a boron- functionalization strategy. These dissymmetric bis-ammonium aza-BODIPY dyes present optimal properties for a fluorescent probe; i.e., they are highly water-soluble, very stable in physiological medium; they do not aggregate in PBS, possess high quantum yield; and finally, they can be easily bioconjugated to antibodies. Preliminary in vitro and in vivo studies were performed for one of these fluorophores to image PD-L1 (Programmed Death-Ligand 1), highlighting the high potential of these new probes for future in vivo optical imaging studies.
Electronic and Functional Scope of Boronic Acid Derived Salicylidenehydrazone (BASHY) Complexes as Fluorescent Dyes
2017
[EN] A series of boronic acid derived salicylidenehydrazone (BASHY) complexes was prepared and photophysically characterized. The dye platform can be modified by (a) electronic tuning along the cyanine-type axis via modification of the donor-acceptor pair and (b) functional tuning via the boronic acid residue. On the one hand, approach (a) allows the control of photophysical parameters such as Stokes shift, emission color, and two-photon absorption (2PA) cross section. The resulting dyes show emission light-up behavior in nonpolar media and are characterized by high fluorescence quantum yields (ca. 0.5-0.7) and brightness (ca. 35000-40000 M-1 cm(-1)). Moreover, the 2PA cross sections reach …
Reactions of electron-rich heterocycles with orthocarboxylic acid derivatives.11. Reactions of carbazole and 4-methoxycarbazole with triethyl orthofo…
1988
Carbazole (1a) and 4-methoxycarbazole (1b) can be regioselectively functionalized by reaction with triethyl orthoformate. Whereas the reaction of 1a with the ortho ester furnishes the amide acetal 2, the new carbazole derivatives 4–10 are formed, depending on the reaction conditions, in the electrophilic substitution of 1b. The products of this reaction sequence provide a contribution to studies on the mechanism of the transformation of 1b to tris-carbazolylmethane 5. Compound 5 represents a new, three-bladed propeller in the triheteroarylmethane series.
Functionalization of Metal and Carbon Nanoparticles with Potential in Cancer Theranostics
2021
Cancer theranostics is a new concept of medical approach that attempts to combine in a unique nanoplatform diagnosis, monitoring and therapy so as to provide eradication of a solid tumor in a non-invasive fashion. There are many available solutions to tackle cancer using theranostic agents such as photothermal therapy (PTT) and photodynamic therapy (PDT) under the guidance of imaging techniques (e.g., magnetic resonance—MRI, photoacoustic—PA or computed tomography—CT imaging). Additionally, there are several potential theranostic nanoplatforms able to combine diagnosis and therapy at once, such as gold nanoparticles (GNPs), graphene oxide (GO), superparamagnetic iron oxide nanoparticles (SP…
Carbon Nanostructures: Covalent and Macromolecular Chemistry
2012
The aim of this introductory chapter is to bring to the attention of the readers the achievements made in the chemistry of carbon nanostructures and, mostly, in the chemistry of fullerenes, carbon nanotubes (CNTs), and the most recent graphenes. Since the discovery of fullerenes in 1985 and their further preparation in multigram amounts, the chemistry and reactivity of thesemolecular carbon allotropes have been well established. Actually, this chemical reactivity has been used as a benchmark for further studies carried out in the coming carbon nanotubes (single andmultiple wall) and graphenes. Assuming that the fundamental chemistry of fullerenes is known and basically corresponds to that o…
Functionalization of Porphyrins: Mechanistic Insights, Conformational Studies, and Structural Characterizations
2006
The condensation of 3-chloromethylbenzoyl chloride with three atropisomers of meso-5,10,15,20-tetrakis(2-aminophenyl)porphyrin (TAPP) is reported, followed by the reaction of the anion of diethyl malonate to prepare various strapped porphyrins. According to two different geometries of the straps, the resulting preorganization of the hanging ethoxycarbonyl groups is more or less adapted to the coordination of cations such as lanthanides. The conformational study, as well as the X-ray structures of three strapped porphyrins, demonstrate that among the three atropisomers investigated in this work, only two of them lead to strapped porphyrins in which an ethoxycarbonyl group is directed towards…
A Versatile and Convenient Method for the Functionalization of Porphyrins
2001
International audience; The condensation of 3-(chloromethyl)benzoyl chloride with different atropisomers of meso-(tetra-o-aminophenyl)porphyrin (TAPP), followed by the reaction of a series of nucleophilic reagents leads, among others, to precursors of biomimetic models of heme proteins such as cytochrome c oxidase (CcO). This synthesis can also be applied as an efficient two-step reaction to obtain highly functionalized porphyrin derivatives potentially useful for cation binding.