Search results for " Nanoparticle"
showing 10 items of 936 documents
Physico-chemical characterization of Pd nanoparticles synthesized in w/o microemulsions
1998
Abstract The long time stability of surfactant-coated Pd nanoparticles in w/o microemulsions has been investigated. It has been proven that in suitable conditions, the use of the functionalized surfactant Pd(AOT)2 allows to obtain very stable nanosized Pd particles and to finely control their average size.
Breaking the Nd3+-sensitized upconversion nanoparticles myth about the need of onion-layered structures
2018
Up to now, most strategies to build efficient 800 nm-light responsive upconversion nanoparticles (UCNPs) have included onion-layered structures, in which Nd3+ is confined within the inorganic crystal structure of at least one layer. We report here an easy room-temperature modular preparation of core-shell UCNPs consisting of NaYF4:Yb,Er(Tm)/NaYF4 (UCCS) with Nd3+ anchored at the organic capping by using cucurbituril[7] (CB[7]) as an adhesive. Strikingly, excitation at 800 nm effectively triggers the upconversion emission of UCCS@CB[7]@Nd nanohybrids.
Synergism at the Nanoscale
2016
Photoactive nanoparticles are smart systems that exhibit unique optical properties. In general, their intrinsic properties are size dependent. The degree and type of response to size are both related to their composition. Nanoparticles usually require to be capped with organic ligands in order to be dispersible in an aqueous or organic media, thus leading to nanoparticle colloidal dispersions and enhancing the processability of the material. The organic ligand also plays a key role in their preparation. In addition, the high surface-to-volume ratio of the nanoparticles combined with the affinity of the ligands for the nanoparticle surface can be used to place a large number of functional mo…
Ultralow-intensity near-infrared light induces drug delivery by upconverting nanoparticles
2014
Mesoporous silica coated upconverting nanoparticles are loaded with the anticancer drug doxorubicin and grafted with ruthenium complexes as photoactive molecular valves. Drug release was triggered by 974 nm light with 0.35 W cm(-2). Such low light intensity minimized overheating problems and prevented photodamage to biological samples.
SERS activity of photoreduced silver chloride crystals
2019
Metal nanoparticles are widely acclaimed as plasmonic substrates for surface -enhanced Raman spectroscopy (SERS) due to their unique particle plasmon resonances at visible and near infrared regions. Silver nanoparticles are typically employed in SERS when the targeted Raman signature zone of analytes lies at ultra-violet and/or blue to green spectral regimes. Even though silver has strong plasmonic properties, silver-based substrates are often affected by the atmospheric oxidation and show degradation in their SERS performance. One way to overcome this limitation is to use silver chloride crystals as oxidation resistant intermediate and photoreduce them to 'fresh' silver just before SERS an…
Donor–Acceptor Interfaces by Engineered Nanoparticles Assemblies for Enhanced Efficiency in Plastic Planar Heterojunction Solar Cells
2016
Precisely positioning functionalized gold nanoparticles assemblies at planar donor-acceptor interfaces results in 14-fold enhancement of power conversion efficiency in P3HT/PCBM organic solar cells on plastic (ITO/PET) substrates. This result has been achieved by employing naphthalenethiol-capped gold nanoparticles (NT-Au-NPs) produced by laser ablation in liquid and size varied in the 10-30 nm range. Upon surface functionalization with the aromatic thiol, these particles self-assemble in submicrometer aggregates, which give increased light scattering. When these aggregates are deposited in the planar heterojunction between the donor and the acceptor systems, the localized scattering leads …
Oxide-based nanomaterials for fuel cell catalysis:the interplay between supported single Pt atoms and particles
2017
The concept of single atom catalysis offers maximum noble metal efficiency for the development of low-cost catalytic materials. Among possible applications are catalytic materials for proton exchange membrane fuel cells. In the present review, recent efforts towards the fabrication of single atom catalysts on nanostructured ceria and their reactivity are discussed in the prospect of their employment as anode catalysts. The remarkable performance and the durability of the ceria-based anode catalysts with ultra-low Pt loading result from the interplay between two states associated with supported atomically dispersed Pt and sub-nanometer Pt particles. The occurrence of these two states is a co…
Photothermal Ablation of Cancer Cells Using Folate-Coated Gold/ Graphene Oxide Composite
2017
Objective: A new tumor targeted polymer-coated gold/graphene hybrid has been developed for achieving simultaneously thermoablation and chemoterapy of folate receptor-positive cancer cells. Methods: The gold/graphene hybrid was prepared by depositing gold nanospheres onto graphene oxide and coating it with an inulin-folate conjugate. Paclitaxel was loaded by sonication. The hybrid was characterized by UV-Vis spectroscopy, DSC analysis and SEM microscopy. The cytotoxicity, thermoablation and anticancer activity were evaluated in vitro on MCF-7 and 16 HBE. Results: In vitro tests showed that the paclitaxel-loaded hybrid improved the effectiveness of the drug especially after photothermal treat…
Near-infrared photochemistry assisted by upconverting nanoparticles
2019
Abstract Upconverting nanoparticles (UCNPs) combine unique optical and imaging properties with high chemical and biological stability. The capability of UCNPs to emit visible light upon near-infrared light excitation, in an anti-Stokes fashion, is extremely attractive for the design of light-responsive nanomaterials whose action can be controlled spatially and temporally. In this chapter, we analyze the most promising approaches developed so far to functionalize the surface of UCNPs with photoactivatable organic and inorganic molecular systems. In particular, we emphasize the key advances in the design of upconverting nanosystems that exploit bioactive transition metal complexes.
Multiband light emission and nanoscale chemical analyses of carbonized fumed silica
2018
Fumed silica with a specific area of 295 m2/g was carbonized by successive phenyltrimethoxysilane treatments followed by annealing in inert atmosphere up to 650 °C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated by steady state and time-resolved photoluminescence spectroscopies. The local chemistry was also studied by infrared transmission spectroscopy. Strong ultraviolet and visible photoluminescence was observed in the samples after the chemical treatments/modifications and thermal annealing. It has been shown that ultraviolet photoluminescence in chemically modified fumed silica is associated with phenyl groups, while near ultraviolet and visible em…