Search results for "Gold nanoparticles"

Nanoparticles coated by chloramphenicol in hydrogels as a useful tool to increase the antibiotic release and antibacterial activity in dermal drug de…

2023

Abstract Background Nanocarriers for antibacterial drugs became hopeful tools against the increasing resistance of bacteria to antibiotics. This work focuses on a comprehensive study of the applicability and therapeutic suitability of dermal carbopol-based hydrogels containing chloramphenicol carried by various nanoparticles (AuNPs and SiNPs). Methods The different forms of carbopol-based drugs for dermal use were obtained. Five different concentrations of chloramphenicol and two types of nanoparticles (silica and gold) in carbopol-based ointments were tested. The influence of different carbopol formulations with nanocarriers on the rheological properties as well as the release profile of a…

Resorcinol Functionalized Gold Nanoparticles for Formaldehyde Colorimetric Detection

2019

[EN] Gold nanoparticles functionalized with resorcinol moieties have been prepared and used for detecting formaldehyde both in solution and gas phases. The detection mechanism is based on the color change of the probe upon the aggregation of the nanoparticles induced by the polymerization of the resorcinol moieties in the presence of formaldehyde. A limit of detection of 0.5 ppm in solution has been determined. The probe can be deployed for the detection of formaldehyde emissions from composite wood boards.

Nanodevices by DNA based gold nanostructures

2017

In this thesis DNA based structures were utilized to create gold nanostructures for nanosensing and nanoelectronic applications. In the past, both of these fields have been dominated by the conventional lithography methods, e.g., electron beam lithography and UV-lithography, but more recently scaling down the components by these techniques has become increasingly more complex and costly. Especially in the micro- and nanoelectronics, the increase in the component density and thus computational power would require fabrication of sub-10-nm components, which is challenging for the top-down approaches. Aforementioned developments have led researchers to seek alternative methods to fabricate these…

SYNTHESIS AND CHARACTERIZATION OF NEW AMPHIPHILIC COPOLYMERS BASED ON A POLY(HYDROXYETHYL)-D,L-ASPARTAMIDE (PHEA) FOR THE COATING OF GOLD NANOPARTICL…

2012

Polyphenols Epigallocatechin Gallate and Resveratrol, and Polyphenol-Functionalized Nanoparticles Prevent Enterovirus Infection through Clustering an…

2021

To efficiently lower virus infectivity and combat virus epidemics or pandemics, it is important to discover broadly acting antivirals. Here, we investigated two naturally occurring polyphenols, Epigallocatechin gallate (EGCG) and Resveratrol (RES), and polyphenol-functionalized nanoparticles for their antiviral efficacy. Concentrations in the low micromolar range permanently inhibited the infectivity of high doses of enteroviruses (107 PFU/mL). Sucrose gradient separation of radiolabeled viruses, dynamic light scattering, transmission electron microscopic imaging and an in-house developed real-time fluorescence assay revealed that polyphenols prevented infection mainly through clustering of…

Micro/nanostructured thin films : synthesis by ALD of composites associating TiO2 inverse opals and gold nanoparticles for photocatalysis applications

2021

The aim of this work was to improve the photocatalytic properties of titanium dioxide (TiO2) thin films, a semiconductor that is widely used for photocatalysis applications, particularly for the treatment of polluted water. For this purpose, two complementary approaches were studied: increasing the surface area available for photocalatytic reactions and coupling between TiO2 and gold nanoparticles.. For the first approach, TiO2 thin films with different morphological structures were fabricated by Atomic Layer Deposition: dense and porous flat films, and inverse opals films.In order to evaluate photocatalytic activity of the different films, the degradation of methylene blue in aqueous solut…

Structure and the metal-support interaction of the Au/Mn oxide catalysts

2010

Gold catalysts with loading 1 and 10 wt % were-prepared by deposition precipitation method with urea over mesoporous manganese oxide, obtained through a surfactant-assisted procedure by using cetyltrimethylammonium bromide (CTAB), followed by treatment with sulphuric acid. For comparison, Au(10 wt %) was also deposited over commercial CeO2 and SiO2 supports. The materials were characterized by XRD and EXAFS at the Mn K and Au L-III edges and XPS. Moreover, the analyses were performed on the samples treated under 1%CO/He, at 250 degrees C for 90 min. The structural and surface results of the as prepared manganese oxide confirmed the formation of gamma-MnO2 along with some amorphous Mn3O4 upo…

Selective and sensitive colorimetric detection of the neurotransmitter serotonin based on the aggregation of bifunctionalised gold nanoparticles

2018

[EN] We report a simple, sensitive and selective method for the colorimetric detection of serotonin (5-HT) in aqueous media using bifunctionalized gold nanoparticles (AuNPs). The probe (1) consisted of AuNPs functionalised with dithiobis(succinimidylpropionate) (DSP) and N-acetyl-l-cysteine (NALC). DSP was chosen to react with the amino group of 5-HT, whereas NALC was chosen to bind the hydroxyl group in 5-HT through hydrogen bonding and electrostatic interactions. A double interaction between nanoparticles and the hydroxyl and the amino group of serotonin led to interparticle-crosslinking aggregation. This, resulted in a colour change from red to blue that can be observed by the naked eye.…

Gold nanoparticles/electrochemically expanded graphite composite: A bifunctional platform toward glucose sensing and SERS applications

2019

Abstract An integrated nanogold/expanded graphite based sensor was fabricated by a former electrochemical etching of the pencil lead electrode (PLE) and a later in-situ deposition of gold nanoparticles (AuNPs). The electrochemical pretreatment of PLE (EPLE) created a 3D graphene-like surface, enhanced the electrode surface area and facilitated the electron transfer ability within 5 min without any hazardous chemicals added. The obtained AuNPs/EPLE sensor had an excellent electrochemical response to glucose with a wide linear concentration range, from 0.05 to 38 mM and 38 to 60 mM, and a low detection limit of 5 μM (S/N = 3). Furthermore, the AuNPs/EPLE sensor was successfully employed to de…

Comparative evaluation of the impact on endothelial cells induced by different nanoparticle structures and functionalization

2015

In the research field of nanoparticles, many studies demonstrated a high impact of the shape, size and surface charge, which is determined by the functionalization, of nanoparticles on cell viability and internalization into cells. This work focused on the comparison of three different nanoparticle types to give a better insight into general rules determining the biocompatibility of gold, Janus and semiconductor (quantum dot) nanoparticles. Endothelial cells were subject of this study, since blood is the first barrier after intravenous nanoparticle application. In particular, stronger effects on the viability of endothelial cells were found for nanoparticles with an elongated shape in compa…