Search results for "NANOMATERIALS"
showing 10 items of 291 documents
Nanomaterials for use in immunosensing of carcinoembryonic antigen (CEA): Recent advances
2017
Abstract This review (with 86 refs.) covers the state of the art in electrochemical and optical immunoassay of carcinoembryonic antigen (CEA). The purpose of the review is to provide useful insights in terms of (a) choice of materials, (b) methods/techniques preferably applied, (c) immunological procedures, (d) immobilization procedures, and (d) other practical aspects. Following an introduction into the field, we give a short account on the principle and general types of immunoassay, and then treat immunoassay for CEA. The first section covers nanomaterial based electrochemical immunoassay, with subsections on using of nanoparticles, hyperbranched polymers, graphene and their derivatives f…
Combustion Formation of Novel Nanomaterials: Synthesis and Cathodoluminescence of Silicon Carbide Nanowires
2009
This paper presents the combustion synthesis and characterization of one-dimensional silicon carbide nanostructures (nanowires of 3C-SiC polytype with zincblend structure) by means of cathodoluminescence technique. Cathodoluminescence spectra of nano-SiC samples and, as a reference, of a commercially available SiC micropowder are compared. It is shown that the emission band at 1.97 eV which is slightly evidenced in the spectrum of the commercial SiC under 10 keV electron beam irradiation becomes the prevailing band in CL of the purified silicon carbide nanowires.
Effectiveness of a new nanostructured consolidant on the biocalcarenite from Agrigento Temples Valley.
2013
A study of the effectiveness of a crack-free consolidant nanomaterial and a nanostructured consolidant with hydrophobic properties, developed in University of Cadiz was carried out for a biocalcareous stone from Agrigento (Italy). The products were obtained by a silica oligomer in presence of a surfactant and, in the hydrophobic product,with the addition of PDMS. The purposes of the research were increasing hydrophobicity and consolidation of the stone. The tests effectuated demonstrated the desired characteristics improved.
Steric stabilization of modified nanoclays triggered by temperature.
2015
Halloysite clay nanotubes were modified through the adsorption of poly(N-isopropylacrylamide)-amine terminated (PNIPA-NH2) onto the external surface by exploiting electrostatic interactions at pH=6. In spite the amount of attached polymer is rather low (1 wt%), the properties of the nanotubes are deeply modified. The apparent specific volume and isentropic compressibilities of the hybrid nanomaterial dispersed in water evidenced the transferring of the termosensitive property from the polymer to halloysite. The hydrodynamic radius as well as the ζ-potential of the nanohybrid are consistent with the attachment of a positively charged polymer onto the negative surface of the nanotube. The col…
Sedimentation of halloysite nanotubes from different deposits in aqueous media at variable ionic strengths
2019
Abstract Halloysite clay is a natural nanomaterial that is attracting a growing interest in colloidal science. The halloysite aqueous dispersion stability is a key aspect for the configuration of a purification protocol as well as to establish the durability of a formulation. A physico-chemical study demonstrated the role of ionic strength and nanotube characteristic sizes on the sedimentation behavior. We highlighted the importance of the electrostatic repulsions exercised between the particles in the settling process. A protocol for image analysis has been proposed to provide robust information from time resolved optical images on the suspensions. In conclusion, we managed to correlate mi…
Chemical modification of halloysite nanotubes for controlled loading and release.
2020
Clay minerals have been used for medical purposes from ancient times. Among them, the halloysite nanotube, an aluminosilicate of the kaolin group, is an emerging nanomaterial which possesses peculiar chemical characteristics. By means of suitable modifications, such as supramolecular functionalization or covalent modifications, it is possible to obtain novel nanomaterials with tunable properties for several applications. In this context the covalent grafting of suitable organic moieties on the external surface or in the halloysite lumen has been exploited to improve the loading and release of several biologically active molecules. The resulting hybrid nanomaterials have been applied as drug…
Effect of Reaction Parameters on Composition and Morphology of Titanate Nanomaterials
2009
International audience; In the present article, we report the synthesis of titanate nanotubes and nanoribbons with controlled morphology, structure, and chemical composition depending on the main parameters of the synthesis. Hydrothermal processing time, grain size of the precursor, type of agitation, and acid treatment were investigated, and the principal controversies mentioned in the literature such as nanotube crystallographic structure, their chemical composition, and acid treatment impact are discussed. These controversies may be due to the heterogeneities present in all the samples and are rarely considered in the literature. These nanostructures were characterized by Raman spectrosc…
Carbon nanotubes as high-pressure cylinders and nanoextruders.
2006
Closed-shell carbon nanostructures, such as carbon onions, have been shown to act as self-contracting high-pressure cells under electron irradiation. We report that controlled irradiation of multiwalled carbon nanotubes can cause large pressure buildup within the nanotube cores that can plastically deform, extrude, and break solid materials that are encapsulated inside the core. We further showed by atomistic simulations that the internal pressure inside nanotubes can reach values higher than 40 gigapascals. Nanotubes can thus be used as robust nanoscale jigs for extruding and deforming hard nanomaterials and for modifying their properties, as well as templates for the study of individual n…
General Approach to the Description of Fundamental Properties of Disordered Nanosized Media
2017
Physics of non-regular nanosystems is a branch of physics dealing with nanoagents – nanoparticles when non-regular nanosized morphological characteristics predetermine the nature and essence of physical phenomenon (nanophenomenon). In particular, multiple technological interfaces of nanoparticles with morphologically regular systems imply a creation of micro- or mesostructures with essential nanodimensional effects (e.g. in various schemes of functionalization of nanocarbon systems, viz. carbon nanotubes (CNTs), graphene nanoribbons (GNRs), graphene nanoflakes (GNFs), carbon-based nanoaerogels and nanofoams, etc.). However, classes of nanomaterials, in addition to nanocarbon systems, can be…
Selenium and tellurium nanomaterials
2018
Abstract Over the last 40 years, the rapid and exponential growth of nanotechnology led to the development of various synthesis methodologies to generate nanomaterials different in size, shape and composition to be applied in various fields. In particular, nanostructures composed of Selenium (Se) or Tellurium (Te) have attracted increasing interest, due to their intermediate nature between metallic and non-metallic elements, being defined as metalloids. Indeed, this key shared feature of Se and Te allows us the use of their compounds in a variety of applications fields, such as for manufacturing photocells, photographic exposure meters, piezoelectric devices, and thermoelectric materials, t…