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The article presents a pulse radiolysis study of the mechanisms of the redox reactions of different radicals with hydrolyzed Bi(III) ions. The results show that such reactions usually slow down in the presence of a polymer.

Abstract: Rare earth doped zirconium oxides are of interest as active materials in high-performance luminescent devices. Transparent ZrO2:Eu3+ mesoporous thin films with different doping ion concentrations were prepared by Evaporation Induced Self Assembly (EISA). The films exhibited high specific area and periodicity through connected networks of nanometer scaled pores. Thermal treatments at 600°C allowed the conversion of amorphous films into semi-crystalline ones. A detailed analysis of the structural and optical characterizations revealed that the Eu3+ ions sit inside the ZrO2 tetragonal crystallites as well as in the enriched zirconia amorphous phase of the walls nanoarchitecture. The introduction of silver nanoparticles in the porous network allowed to a strong modulation of the photoluminescence emission intensity. [Copyright &y& Elsevier]

Semitransparent organic photovoltaics (ST-OPVs) offer promising prospects for application in building-integrated photovoltaic systems and greenhouses, but further improvement of their performance faces a delicate trade-off between the two competing indexes of power conversion efficiency (PCE) and average visible transmittance (AVT). Herein, the authors take advantage of coupling plasmonics with the optical design of ST-OPVs to enhance near-infrared absorption and hence simultaneously improve efficiency and visible transparency to the maximum extent. By integrating core-bishell PdCu@Au@SiO 2 nanotripods that act as optically isotropic Lambertian sources with near-infrared-customized localized surface plasmon resonance in an optimal ternary PM6:BTP-eC9:L8-BO-based ST-OPV, it is shown that their interplay with a multilayer optical coupling layer, consisting of ZnS(130 nm)/Na 3 AlF 6 (60 nm)/WO 3 (100 nm)/LaF 3 (50 nm) identified from high-throughput optical screening, leads to a record-high PCE of 16.14% (certified as 15.90%) along with an excellent AVT of 33.02%. The strong enhancement of the light utilization efficiency by ≈50% as compared to the counterpart device without optical engineering provides an encouraging and universal pathway for promoting breakthroughs in ST-OPVs from meticulous optical design., (© 2024 Wiley‐VCH GmbH.)

The nanostructures of natural species offer beautiful visual appearances with saturated and iridescent colors, and the question arises whether we can reproduce or even create unique appearances with man-made metasurfaces. However, harnessing the specular and diffuse light scattered by disordered metasurfaces to create attractive and prescribed visual effects is currently inaccessible. Here, we present an interpretive, intuitive, and accurate modal-based tool that unveils the main physical mechanisms and features defining the appearance of colloidal disordered monolayers of resonant meta-atoms deposited on a reflective substrate. The model shows that the combination of plasmonic and Fabry-Perot resonances offers uncommon iridescent visual appearances, differing from those classically observed with natural nanostructures or thin-film interferences. We highlight an unusual visual effect exhibiting only two distinct colors and theoretically investigate its origin. The approach can be useful in the design of visual appearance with easy-to-make and universal building blocks having a large resilience to fabrication imperfections and potential for innovative coatings and fine-art applications.

To address the impact of cadmium sulfide nanoparticles (CdS NPs) in freshwater ecosystems, aquatic oligochaete Tubifex tubifex were exposed through the sediment to a low dose (0.52 mg of 8 nm in size of CdS NPs/kg) for 20 days using microcosms. Cadmium (Cd) was released from the CdS NPs-contaminated sediment to the water column, and during this period the average concentrations of Cd in the filtered water fraction were 0.026 ± 0.006 µg/L in presence of oligochaetes. Similar experiments with microparticular CdS and cadmium chloride (CdCl2) were simultaneously performed for comparative purposes. CdS NPs exposure triggered various effects on Tubifex worms compared to control, microsized and ionic reference, including modification of genome composition as assessed using RAPD-PCR genotoxicity tests. Bioaccumulation levels showed that CdS NPs were less bioavailable than CdCl2 to oligochaetes and reached 0.08 ± 0.01 µg Cd/g for CdS NPs exposure versus 0.76 ± 0.3 µg Cd/g for CdCl2 exposure (fresh weight). CdS NPs altered worm's behavior by decreasing significantly the bioturbation activity as assessed after the exposure period using conservative fluorescent particulate tracers. This study demonstrated the high potential harm of the CdS nanoparticular form despite its lower bioavailability for Tubifex worms.

Increasing use of metallic nanomaterials is likely to result in release of these particles into aquatic environments; nevertheless it is unclear whether these materials present a hazard to aquatic organisms. The impact of contaminated sediment containing 14-nm gold nanoparticles (AuNPs) was investigated in the zebrafish Danio rerio exposed for 20 days to two concentrations, 16 and 55 µg/g dry weight. AuNPs were released from the sediment to the water column, and during this period the mean concentrations of AuNP in the filtered water fraction were 0.25 ± 0.05 and 0.8 ± 0.1 µg/L, respectively. A similar experiment with ionic gold contamination was simultaneously performed to obtain a positive control. AuNP exposure triggered various effects in fish tissues including modifications of genome composition, shown using a random amplified polymorphic DNA-PCR genotoxicity test. Expression of genes involved in oxidative stress, mitochondrial metabolism, detoxification and DNA repair were also modulated in response to AuNP contamination. Gold altered neurotransmission, since brain acetylcholine esterase activity increased for both tested doses of AuNP but not for ionic gold. Gold accumulation in fish tissues demonstrated the lower bioavailability of AuNP compared to ionic Au, and underlined the higher toxic potential of the nanoparticle form.

Silica particles with a controlled number of entropic patches, i.e. dimples, are synthesized through the growth of the silica core of binary multipods that have been produced by a seeded-growth emulsion polymerization reaction. Transmission electron microscopy studies indicate that the silica surface conforms to the shape of the polystyrene (PS) nodules of the multipods while growing, allowing good control of the final shape of the dimpled silica particles. The PS nodules are also used as protecting masks to regioselectively graft amino groups, as revealed by the adsorption of gold markers. After dissolution of the PS nodules, some polymer chains remain grafted onto the silica surface, forming organic bumps. These residues are also selectively functionalized, leading to silica particles with both entropic and enthalpic patches.

To address the impact of cadmium sulphide nanoparticles (CdSNPs) of two different sizes (8 and 50 nm), Danio rerio zebrafish were dietary exposed to very low doses: 100 or 40 ng CdSNPs/day/g body weight for 36 or 60 days, respectively. The results obtained using RAPD-PCR genotoxicity test showed genomic alteration since the number of hybridisation sites of the RAPD probes was significantly modified after CdSNPs exposure. In addition, selected stress response genes were either repressed or upregulated in tissues of CdSNPs-exposed fish. Mitochondrial dysfunction was also caused by the presence of CdSNPs in food. Cadmium accumulation in fish tissues (brain and muscles) could only be observed after 60 days of exposure. CdSNPs toxicity was dependent on their size and concentration.

Herein, we report a new drug-delivery system (DDS) that is comprised of a near-infrared (NIR)-light-sensitive gold-nanorod (GNR) core and a phase-changing poly(ε-caprolactone)-b-poly(ethylene glycol) polymer corona (GNR@PCL-b-PEG). The underlying mechanism of the drug-loading and triggered-release behaviors involves the entrapment of drug payloads among the PCL crystallites and a heat-induced phase change, respectively. A low premature release of the pre-loaded doxorubicin was observed in PBS buffer (pH 7.4) at 37 °C (<10% of the entire payload after 48 h). However, release could be activated within 30 min by conventional heating at 50 °C, above the Tm of the crystalline PCL domain (43.5 °C), with about 60% release over the subsequent 42 h at 37 °C. The NIR-induced heating of an aqueous suspension of GNR@PCL-b-PEG under NIR irradiation (802 nm) was investigated in terms of the irradiation period, power, and concentration-dependent heating behavior, as well as the NIR-induced shape-transformation of the GNR cores. Remotely NIR-triggered release was also explored upon NIR irradiation for 30 min and about 70% release was achieved in the following 42 h at 37 °C, with a mild warming (<4 °C) of the surroundings. The cytotoxicity of GNR@PCL-b-PEG against the mouse fibroblastic-like L929 cell-line was assessed by MTS assay and good compatibility was confirmed with a cell viability of over 90% after incubation for 72 h. The cellular uptake of GNR@PCL-b-PEG by melanoma MEL-5 cells was also confirmed, with an averaged uptake of 1250(±110) particles cell(-1) after incubation for 12 h (50 μg mL(-1)). This GNR@PCL-b-PEG DDS is aimed at addressing the different requirements for therapeutic treatments and is envisaged to provide new insights into DDS targeting for remotely triggered release by NIR activation., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The impact of a daily ration of food containing gold nanoparticles (AuNPs) of two sizes (12 and 50 nm) was investigated in the zebrafish Danio rerio at very low doses (from 36-106 ng gold/fish/day). AuNP exposure resulted in various dysfunctions at the sub cellular scale, and AuNP concentration in food, AuNP size and exposure duration modulated the observed adverse effects. Indeed, we showed alteration of genome composition using a RAPD-PCR genotoxicity test as the number of hybridization sites of the RAPD probes was significantly modified after AuNP exposure. Moreover, the expression of genes involved in DNA repair, detoxification processes, apoptosis, mitochondrial metabolism and oxidative stress was also modulated in response to AuNP contamination. Mitochondrial dysfunctions appeared in brain and muscle for both tested doses (40 and 100 ng gold/fish/day), but gold accumulation in fish tissues could only be observed in the case of the highest exposure dose.

Surface-enhanced Raman spectroscopy (SERS) is now a well-established technique for the detection, under appropriate conditions, of single molecules (SM) adsorbed on metallic nanostructures. However, because of the large variations of the SERS enhancement factor on the surface, only molecules located at the positions of highest enhancement, so-called hot-spots, can be detected at the single-molecule level. As a result, in all SM-SERS studies so far only a small fraction, typically less than 1%, of molecules are actually observed. This complicates the analysis of such experiments and means that trace detection via SERS can in principle still be vastly improved. Here we propose a simple scheme, based on selective adsorption of the target analyte at the SERS hot-spots only, that allows in principle detection of every single target molecule in solution. We moreover provide a general experimental methodology, based on the comparison between average and maximum (single molecule) SERS enhancement factors, to verify the efficiency of our approach. The concepts and tools introduced in this work can readily be applied to other SERS systems aiming for detection of every single target molecule.

Periodic mesoporous Eu(3+) doped titania materials were obtained through the EISA (Evaporation Induced Self Assembly) process. Eu(3+) ions, entrapped within the semi-crystalline walls of the highly porous framework, appear to be advantageous during the probing of surface photochemical reactions. Its emission intensity is very sensitive to the presence of physisorbed molecules, in gas or liquid phase, that reside within the pores. In particular, strong fluctuations in intensity of the (5)D(0)→(7)F(2) transition were observed under UV light exposure on the time scale of tens of seconds. The emission modulation dynamics show a strong correlation with the crystallinity of the titania matrix. Correlation of the emission with the photocatalytic activity of the semiconductor for photodegradation of an organic molecule is observed. A model is proposed to describe the involved mechanisms., (This journal is © the Owner Societies 2011)

Herein, Eu(III)-doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied. The rare-earth-doped titania thin films-synthesized via evaporation-induced self-assembly (EISA)-are characterized by using environmental ellipsoporosimetry, electronic microscopy (i.e. high-resolution scanning electron microscopy, HR-SEM, and transmission electron microscopy, HR-TEM), X-ray diffraction, and luminescence spectroscopy. Structural characterizations show that high europium-ion loadings can be incorporated into the titanium-dioxide walls without destroying the mesoporous arrangement. The luminescence properties of Eu(III) are investigated by using steady-state and time-resolved spectroscopy via excitation of the Eu(III) ions through the titania host. Using Eu(III) luminescence as a probe, the europium-ion sites can be addressed with at least two different environments within the mesoporous framework, namely, a nanocrystalline environment and a glasslike one. Emission fluctuations ((5)D(0)-->(7)F(2)) are observed upon continuous UV excitation in the host matrix. These fluctuations are attributed to charge trapping and appear to be strongly dependent on the amount of europium and the level of crystallinity.