Gianpiero Adami

Human skin penetration of cobalt nanoparticles through intact and damaged skin

Cobalt nanoparticles (CoNPs) are produced for several industrial and biomedical applications but there is a lack of data on human cutaneous absorption. Cobalt is also a skin sensitizer that can cause allergic contact dermatitis. Co applied as NPs, due to their small size and high surface, can penetrate into the skin in higher amount that bulk material. The aim of this study was to evaluate the absorption of Co applied as NPs in both intact and damaged skin. Experiments were performed using Franz cells and 1.0 mg cm(-2) of CoNPs was applied as donor phase for 24h. Mean Co content of 8.5 ± 1.2 ng cm(-2) and 1.87 ± 0.86 μg cm(-2) were found in the receiving solutions of Franz cells when the CoNPs suspension was applied on intact skin and on damaged skin, respectively. Twenty-four hours Co flux permeation was 76 ± 49 ng cm(-2)h(-1) in damaged skin with a lag time of 2.8 ± 2.1h. This study suggests that Co applied as NPs is able to penetrate the human skin in an in vitro diffusion cell system.

Nanoparticle dermal absorption and toxicity: a review of the literature

IntroductionNanotechnologies are among the fastest growing areas of scientific research and have important applications in a wide variety of fields. The data suggest that in the future workers and consumers exposed to nanoparticles will significantly increase.Dermal absorption and toxicity of nanoparticlesAt now there are gaps in understanding about the human and environmental risk that manufactured nanoparticles pose for occupational exposed people and for consumers. There is a need for assessing the health and environmental impacts, the nanoparticles life cycle, the human exposure routes, the behavior of nanoparticles in the body, and the risk for workers. Possible routes of entry into the body include inhalation, absorption through the skin or digestive tract, injection, and absorption or implantation for drugs delivery systems. In particular, dermal absorption and skin penetration of nanoparticles needs a better evaluation because few and contradictory data are present in the literature, mainly on titanium dioxide.ConclusionsThere are limited data on carbon-based nanoparticles and very few data on other metal nanoparticles increasingly used in industry. The article reviews the literature on the percutaneous absorption of nanoparticles and their effect on skin.

CuOx−TiO2 Photocatalysts for H2 Production from Ethanol and Glycerol Solutions†

Hydrogen production by photocatalytic reforming of aqueous solutions of ethanol and glycerol was studied with the use of impregnated and embedded CuO(x)/TiO(2) photocatalysts. Embedded CuO(x)@TiO(2) was prepared by a water-in-oil microemulsion method, which consists in the formation of Cu nanoparticles in the microemulsion followed by controlled hydrolysis and condensation of tetraisopropyl orthotitanate with the aim of covering the protected metal particles with a surrounding layer of porous titanium oxyhydroxide. Mild calcination leads to the complete removal of the organic residues, the crystallization of TiO(2), and an unavoidable oxidation of copper. Two reference samples were prepared by classical wet impregnation of preformed TiO(2) with different ratios of anatase, rutile, and brookite polymorphs. The two supports were prepared by sol-gel (TiO(2)-SG) and microemulsion (TiO(2)-ME) methods. Superior performances have been observed for the embedded system, which shows higher hydrogen production rates with respect to the impregnated systems using either ethanol or glycerol as sacrificial molecules. Deep structural characterization of the materials has been performed by coupling high resolution transmission electron microscopy (HRTEM), high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), X-ray absorption fine structure (XAFS), and electron paramagnetic resonance (EPR) techniques. Correlation between copper oxidation state and its dispersion and reactivity has been attempted. Finally, the stability of the CuO(x)/TiO(2) catalysts was also studied with respect to carbonaceous deposits and copper leaching.

Nanostructured Cu/TiO2 Photocatalysts for H2 Production from Ethanol and Glycerol Aqueous Solutions.

The sustainable development of the human society requires an increasing use of renewable raw materials and energy sources. In this context, photocatalysis represents a promising and necessary way to produce solar fuels and chemicals. The photocatalytic hydrogen production of renewable oxygenated compounds from aqueous solutions could represent an important alternative 6] to the more complex water splitting, or to conventional thermal reforming processes. Noble and base metals, including Pt, Au, Pd, Ni, Cu, and Ag, have been reported to be very efficient at increasing the production of H2 in TiO2 photocatalysis. [11] Increasing attention has been devoted to Cu2O and CuO as photocatalysts. [12, 13] Both copper oxides are abundant natural p-type semiconductors and are attractive owing to their virtual non-toxicity. Their bandgaps (2.1 eV for Cu2O and 1.2 eV for CuO) are suitable for photosplitting water to produce hydrogen by using visible light. However, these materials have been shown to be unstable in electrolytic solutions owing to their facile photooxidation. Siripala et al. prepared a Cu2O/TiO2 heterojunction by electrodeposition of copper oxide; the device was shown to perform photoelectrolysis of water, the TiO2 layer providing protection against photocorrosion. Herein, a cheap and active photocatalysts based on Cu nanoparticles dispersed on TiO2 supports, which are capable of operating under solar radiation, are investigated for the production of hydrogen from ethanol and glycerol. Second generation ethanol and sugars, extracted from lignocellulosic parts of vegetables, and glycerol, produced as a by-product of bio-diesel, are attractive and largely available sacrificial agents. 16] Two different TiO2 supports were prepared, the former from titanium isopropoxide (TiO2-SG) [17] by a sol–gel method, the latter from titanyl sulphate (TiO2-PS) by precipitation, [18] followed in both cases by calcination at 450 8C for 6 h. TiO2-SG (surface area 69 mg ) was composed of a mixture of polymorphs (Figure S1 in the Supporting Information). The analysis of its XRD pattern, following the work of Zhang et al. , evidenced the presence of anatase (64 wt %), rutile (8 wt %) and brookite (28 wt %). Mean crystallite sizes of 11, 32, and 11 nm were calculated for anatase, rutile, and brookite, respectively. TiO2-PS possessed a slightly higher surface area (104 m 2 g ). Its powder XRD pattern showed the presence of a pure anatase phase (Figure S1 in the Supporting Information), with a mean crystallite size of 8 nm. The photodeposition of Cu on the surface of both TiO2 supports was performed by using UV/Vis irradiation (2 h) in the presence of copper nitrate and CH3OH as a hole scavenger (Figure S2). XRD analysis of the Cu/TiO2 nanocomposites did not allow the identification of Cu-related phases probably because of their low amount and/or high dispersion. Therefore, the Cu phases photodeposited on TiO2 supports were characterized by using X-ray absorption near-edge structure (XANES) or extended X-ray absorption fine structure (EXAFS) spectroscopy. Immediately after photodeposition, XANES spectra at the Cu K edge was in good agreement with that of Cu foil used as reference standard (Figure 1), thus indicating that copper is deposited in the form of zero-valent copper. The results of the analysis of the EXAFS spectra are summarized in Table 1.

Nanoparticles skin absorption: New aspects for a safety profile evaluation

Nanoparticles (NPs) skin absorption is a wide issue, which needs to be better understood. The attempt of this review is to summarize the scientific evidence concerning open questions, i.e.: the role of NPs intrinsic characteristics (size, shape, charge, surface properties), the penetration of NPs through the intact or impaired skin barrier, the penetration pathways which should be considered and the role of NPs interaction in physiological media. The outcomes suggest that one main difference should be made between metal and non-metal NPs. Both kinds have a secondary NPs size which is given after interaction in physiological media, and allows a size-dependent skin penetration: NPs⩽4nm can penetrate and permeate intact skin, NPs size between 4 and 20nm can potentially permeate intact and damaged skin, NPs size between 21 and 45nm can penetrate and permeate only damaged skin, NPs size>45nm cannot penetrate nor permeate the skin. Other aspects play an important role, mostly for metal NPs, i.e., dissolution in physiological media, which can cause local and systemic effects, the sensitizing or toxic potential and the tendency to create aggregates. This paper suggests a decision tree to evaluate the potential risk for consumers and workers exposed to NPs.

Levels of cadmium and zinc in hepatopancreas of reared Mytilus galloprovincialis from the Gulf of Trieste (Italy).

Cadmium and zinc concentrations were determined in hepatopancreatic tissues of Mytilus galloprovincialis, reared in three non-contaminated hatcheries of the Gulf of Trieste (Northern Adriatic Sea). Mussels were collected in 13 sampling exits with monthly frequency for verifying possible seasonal variations. Freeze dried hepatopancreatic tissues were dissolved by nitric acid procedure using a microwave system; analysis of Zn and Cd followed by AAS technique. Metal concentrations were below the critical values for mollusc soft tissues, but xenobiotic cadmium had values requiring monitoring attention. Cadmium and zinc showed moderate variations along the months, with a slight winter maximum followed by a summer pre-spawning minimum, matching the seasonal trends of temperature/salinity. The estuarine site appears to have the best quality of the examined area in terms of metal contents. The results can constitute a guideline for the water quality in the Northern Adriatic Sea, and permit comparisons with the quality of other areas of the Mediterranean Sea.

Using chemical and physical parameters to define the quality of karstic freshwaters (Timavo River, North-eastern Italy): a chemometric approach

Abstract The Timavo River, rising in Monte Nevoso (Slovenia), sinks into a limestone fissure and proceeds subterraneously toward the Adriatic Sea, feeding many springs and ponds in the Karst region near Trieste (Italy). In order to characterize and discriminate the freshwaters of this complex hydrological system, 84 samples were taken in 14 selected sites during the autumnal flood. Six chemical-physical parameters were determined: temperature, pH and conductivity in situ ; chloride, nitrate and sulphate contents in the laboratory, by high-performance ion-exchange chromatography (HPIEC). Univariate analysis of dispersion and centrality estimates of the populations of the experimental data allow us to discriminate a group of typically-karstic springs situated near S.Giovanni di Duino, as well as a group—to the north—of “mixed waters” that receive run-off from the northern Isonzo and Vipacco river-beds, and also seem affected by seasonal conditions. The multivariate cluster analysis (CA) confirms the discriminating ability of the considered parameters, and allow us to observe occasional intrusions of waters belonging to a group within a different group. The principal component analysis (PCA) supports the results of CA and permits us to assert the existence of a common watershed for the examined karstic freshwaters, which are characterized by 2 PCs: the ionic solutes are associated with the first component, whereas temperature and pH are associated with the second one. Factor scores show seasonal and meteorological effects on the chemical composition of the freshwaters.

Silver nanoparticles exert a long-lasting antiproliferative effect on human keratinocyte HaCaT cell line.

For their antibacterial activity, silver nanoparticles (Ag NPs) are largely used in various commercially available products designed to come in direct contact with the skin. In this study we investigated the effects of Ag NPs on skin using the human-derived keratinocyte HaCaT cell line model. Ag NPs caused a concentration- and time-dependent decrease of cell viability, with IC(50) values of 6.8 ± 1.3 μM (MTT assay) and 12 ± 1.2 μM (SRB assay) after 7 days of contact. A 24h treatment, followed by a 6 day recovery period in Ag NPs-free medium, reduced cell viability with almost the same potency (IC(50)s of 15.3 ± 4.6 and 35 ± 20 μM, MTT and SRB assays, respectively). Under these conditions, no evidence of induction of necrotic events (propidium iodide assay) was found. Apocynin, NADPH-oxidase inhibitor, or N(G)-monomethyl-L-argynine, nitric oxide synthase inhibitor, did not prevent NPs-induced reduction of cell viability. TEM analysis of cells exposed to NPs for 24h revealed alteration of nuclear morphology but only a marginal presence of individual NPs inside the cells. These results demonstrate that on HaCaT keratinocytes a relatively short time of contact with Ag NPs causes a long-lasting inhibition of cell growth, not associated with consistent Ag NPs internalization.

Human skin penetration of gold nanoparticles through intact and damaged skin.

Abstract Gold nanoparticles (AuNPs) are produced for many applications but there is a lack of available data on their skin absorption. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. A physiological solution was used as receiving phase and 0.5 mL (1st exp) and 1.5 mL (2nd exp) of a solution containing 100 mgL-1 of AuNPs (15 and 45 μg cm-2, respectively) was applied as donor phase to the outer surface of the skin for 24 h. Skin absorption was dose dependent. Mean gold content of 214.0 ± 43.7 ng cm-2 and 187.7 ± 50.2 ng cm-2 were found in the receiving solutions of cells where the AuNPs solution was applied in higher concentration on intact skin (8 Franz cells) and on damaged skin (8 Franz cells), respectively. Twenty-four hours gold flux permeation was 7.8 ± 2.0 ng cm-2 h-1 and 7.1 ± 2.5 ng cm-2 h-1 in intact and damaged skin, respectively, with a lag time less than 1 hour. Transmission Electron Microscope analysis on skin samples and chemical analysis using Inductively Coupled Plasma-Mass Spectrometry demonstrated the presence of AuNPs into epidermis and dermis. This study showed that AuNPs are able to penetrate the human skin in an in vitro diffusion cell system.

In vitro absorption of metal powders through intact and damaged human skin.

The bioavailability of metals, which are known as important contact allergens, is decisive for the development and the maintenance of contact dermatitis. The aim of this study was to evaluate the percutaneous penetration of metal powders of cobalt (Co), nickel (Ni) and chromium (Cr) and the effect of skin lesions on skin absorption. In vitro permeation experiments were performed using the Franz diffusion cells with intact and damaged human skin. Physiological solution was used as receiving phase and metal powders (Co, Ni and Cr) dispersed in synthetic sweat at pH 4.5 were applied as donor phase to the outer surface of the skin for 24h. The amount of each metal permeating the skin was analysed by electro-thermal atomic absorption spectroscopy (ETAAS). Donor solution analysis demonstrated that metals were present as ions. Measurements of metals skin content were also exploited. Median Co and Ni concentrations found in the receiving phase were significantly higher when Co and Ni powders were applied on the abraded skin than after application on the intact skin (3566 and 2631ngcm(-2) vs. 8.4 and 31ngcm(-2), respectively). No significant difference was found in Cr permeation through intact and damaged skin. The measurement of metals skin content showed that Co, Ni and Cr concentrations were significantly higher in the damaged skin than in the intact skin. Co and Ni ions concentrations increased significantly when the donor solutions were applied on the damaged skin, while Cr ions concentrations did not increase. This study demonstrated that Co and Ni powders can permeate through damaged skin more easily than Cr powder, which has probably a stronger skin proteins binding capacity. Therefore, our results suggest that is necessary to prevent skin contamination when using toxic substances because a small injury to the skin barrier can significantly increase skin absorption.