Search results for "nanoparticle"

Orthogonal functionalisation of upconverting NaYF4 nanocrystals.

2013

A simple and straightforward method for the orthogonal functionalisation of upconverting NaYF4 nanocrystals (UCNCs)-doped withYb(3+) and Er(3+)-based on N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide (EDC/NHS) selective reactions between two dyes and two different reactive groups present at the periphery of the upconverting nanocrystals is reported. Organic-soluble UCNCs of 10 and 50 nm in size are encapsulated efficiently in a 1:1 mixture of two commercial 3000 Da poly(ethylene glycol) derivatives with two different reactive groups (amino and carboxylic groups). The water-dispersible UCNCs are non-cytotoxic, stable in the physiological environment, and present free ami…

Solid lipid nanoparticles from amphiphilic calixpyrroles

2016

Abstract Hypothesis Macrocyclic amphiphiles form interesting self-assembling structures, including solid lipid nanoparticles, which have potential applications in drug encapsulation. Aryl-extended calixpyrroles, which act as anion binding hosts, are expected to form solid lipid nanoparticles, even though the alkyl chains have unusual perpendicular geometry with respect to the hydrophilic head group. The preparation conditions and the alkyl chain length should affect the size and stability of the particles. Experiments Solid lipid nanoparticles of two aryl-extended calixpyrroles with resorcinol walls and either meso-dodecyl or meso-methyl alkyl chains were compared. Ethanolic solutions of th…

Metallic core nano-devices as drug delivery systems

2014

Colorimetric gas detection by the varying thickness of a thin film of ultrasmall PTSA-coated TiO

2016

Colorimetric gas sensing is demonstrated by thin films based on ultrasmall TiO2 nanoparticles (NPs) on Si substrates. The NPs are bound into the film by p-toluenesulfonic acid (PTSA) and the film is made to absorb volatile organic compounds (VOCs). Since the color of the sensing element depends on the interference of reflected light from the surface of the film and from the film/silicon substrate interface, colorimetric detection is possible by the varying thickness of the NP-based film. Indeed, VOC absorption causes significant swelling of the film. Thus, the optical path length is increased, interference wavelengths are shifted and the refractive index of the film is decreased. This cause…

Reduced graphene oxide/silver nanoparticles/β-cyclodextrin nanosponges composites with improved photocatalytic activity

2023

Significant activity improvement was achieved by associating graphene oxide-silver composite photocatalysts with cyclodextrin-based nanosponge materials, due to the synergistic effect provided by the supramolecular host abilities of the nanosponge. Three photocatalysts were prepared, fully characterized (FT-IR, ss-NMR, Raman, XRD, SEM, EDX, AFM, ICP, TGA, potentiometric titration), and tested for the oxidative photodegradation of some dyes and phenols, chosen as model organic pollutants. Compared to the unsupported photocatalyst, the nanosponge-based materials showed enhanced performances (being able to carry out the degradation even of dyes which do not react in the presence of the unsuppo…

PROPERTIES AND APPLICATIONS OF POLYAMINOCYCLODEXTRIN DERIVATIVES

Nel presente lavoro sono state prese in esame le potenziali applicazioni delle poliamminociclodestrine. In particolare, diversi derivati poliamminociclodestrinici (amCD) sono stati ottenuti utilizzando un approccio sintetico diretto, tramite reazione di sostituzione nucleofila tra la heptakis-(6-deossi)-(6-bromo)-βCD (BrβCD) e poliammine lineari. Una volta effettuata l’opportuna caratterizzazione NMR, ESI-MS e potenziometrica, sono state investigate diverse possibili utilizzazioni di tali materiali. Anzitutto, sono state valutate le capacità di dare complessi di inclusione host-guest con diversi derivati organici sia delle amCD libere che di materiali costituiti da nanospugne a base di amCD…

Green synthesis and characterizations of silver and gold nanoparticles using leaf extract of Rosa rugosa

2010

Abstract Metal nanostructures have unusual physicochemical properties and biological activities compared to their bulk parent materials. Thus in recent years a number of physical, chemical and biological techniques were applied for the development of metal nanoparticles (NP). Here we have synthesized silver and gold nanoparticles (AgNPs and AuNPs) by using leaves extracts of Rosa rugosa . Surface plasmon resonance spectra for silver and gold are obtained at 451 and 578 nm with brown yellow and pink-red color, respectively. AgNPs and AuNPs vary in size according to different leaves extract and metal concentration used for the synthesis. Different instrumental techniques were applied to chara…

Local structure of nanosized tungstates revealed by evolutionary algorithm

2015

Nanostructured tungstates, such as CoWO4 and CuWO4, are very promising catalytic materials, particularly for photocatalytic oxidation of water. The high catalytic activity of tungstate nanoparticles partially is a result of their extremely small sizes, and, consequently, high surface-to-volume ratio. Therefore their properties depend strongly on the atomic structure, which differ significantly from that of the bulk material. X-ray absorption spectroscopy is a powerful technique to address the challenging problem of the local structure determination in nanomaterials. In order to fully exploit the structural information contained in X-ray absorption spectra, in this study we employ a novel ev…

Selenium Nanoparticles Synthesized via a Facile Hydrothermal Method

2012

Crystalline selenium nanostructures were synthesized from the reaction of a GeSe3 glass with water at 85°C for 144 hours. The hydrolysis of the Ge-Se bonds releases Se fragments in the solution where they form a colloidal suspension of amorphous nanospheres. The later evolve toward a more stable hexagonal phase (trigonal) leading to the anisotropic growth of one-dimensional monocrystalline structures. Filaments, bars and tubes of monocrystalline trigonal selenium were obtained with diameters ranging from 10 nm to 1 µm and aspect ratio up to 180. This simple process in aqueous solution opens new perspectives for the synthesis of 1D nanoparticles of trigonal selenium at large scale.

One-step growth of isolated CdO nanoparticles on r-sapphire substrates by using the spray pyrolysis methodology

2014

In spite of the remarkable properties of CdO, there are only a few reports on CdO nanostructures, especially on isolated NPs. In this paper, we analyze the growth of isolated CdO nanoparticles (NPs) on 0.5° miscut r-sapphire substrates by using the spray pyrolysis methodology in its classical configuration. A systematic study has been performed to optimize the growth parameters such as precursor concentration, growth time, spray rate and growth temperature to obtain CdO NPs (size: 6–10 nm to 35–100 nm depending on the growth conditions). The study shows the control over the size and density of the CdO nanoparticles that can be achieved by adjusting the growth parameters. The CdO nanoparticl…