Toxicity of surface-modified copper oxide nanoparticles in a mouse macrophage cell line: Interplay of particles, surface...Published: 01 April 2018 by Elsevier BV in Chemosphere
Coatings made of proteins adsorbed on TiO2 nanoparticles: a new flame retardant approach for cotton fabricsPublished: 15 March 2018 by Springer Nature in Cellulose
A novel durable intumescent flame retardant coating, based on metal oxide nanoparticles (NPs) and biomacromolecules, was designed and applied on cotton fabrics. Specifically, different TiO2 NPs/proteins systems were deposited by dip-pad-dry-cure process and the morphology of the resulting coating were assessed by SEM analysis. Enhancement of durability (i.e. resistance to washing treatments) was verified by release tests carried out in static and dynamic conditions. Flammability and cone calorimetry tests were performed for evaluating the fire behavior of the treated fabrics. More specifically, in horizontal flame spread tests, the different nanoparticle/protein based coatings provided an increase of the total burning time and a decrease of the burning rate. Furthermore, the residues at the end of the test were significantly higher with respect to untreated cotton fabric. In particular, casein-based systems seemed to be more effective as compared to the whey proteins counterparts. Cone calorimetry tests showed better fire performances for the coatings based on TiO2/caseins with respect to TiO2/whey proteins, which did not seem to be so effective in protecting the underlying fabric from the heat flux. Therefore, due to their high char-forming character, casein-based coatings may represent an effective and durable fire-resistant finishing alternative to standard flame retardant treatments for cotton.
Highlights•We investigated two encapsulation techniques as safer by molecular design approach.•Silica coated TiO2 and Ag nanophases were produced and characterized.•Nanomatrices and core–shell nanocapsules structures were identified.•The feasibility of a cost-effective colloidal approach was demonstrated. AbstractDesigning safer materials is one of the main challenges in the world of nanotechnology because of the potential risks arising from nanomaterial production, use and disposal. In this work, two nanoencapsulation techniques are investigated and proposed as a “safer by (molecular) design” strategy for controlling and harmonizing the biological reactivity of silver and TiO2 nanoparticles. SiO2 coatings were applied to silver and TiO2 nanoparticles and the feasibility of two different encapsulation techniques, a colloidal approach and chemical synthesis nucleation, were compared. Nanomatrices and core–shell nanocapsules were obtained and thoroughly characterized in terms of their wet physicochemical features (particle size distribution and ζζ-potential measurements) and TEM morphology. The colloidal and morphological identification of the samples produced served as a basis for assessing their biological reactivity (reported in subsequent publications). Graphical abstract
Silver nanoparticles as a medical device in healthcare settings: a five-step approach for candidate screening of coating...Published: 31 January 2018 by The Royal Society in Royal Society Open Science
Silver nanoparticle-based antimicrobials can promote a long lasting bactericidal effect without detrimental toxic side effects. However, there is not a clear and complete protocol to define and relate the properties of the particles (size, shape, surface charge, ionic content) with their specific activity. In this paper, we propose an effective multi-step approach for the identification of a ‘purpose-specific active applicability window’ to maximize the antimicrobial activity of medical devices containing silver nanoparticles (Ag NPs) (such as surface coaters), minimizing any consequent risk for human health (safety by design strategy). The antimicrobial activity and the cellular toxicity of four types of Ag NPs, differing in their coating composition and concentration have been quantified. Through the implementation of flow-field flow fractionation, Ag NPs have been characterized in terms of metal release, size and shape. The particles are fractionated in the process while being left unmodified, allowing for the identification of biological particle-specific contribution. Toxicity and inflammatory response in vitro have been assessed on human skin models, while antimicrobial activity has been monitored with both non-pathogenic and pathogenic Escherichia coli. The main benefit associated with such approach is the comprehensive assessment of the maximal effectiveness of candidate nanomaterials, while simultaneously indexing their properties against their safety.
Environmental Impacts by Fragments Released from Nanoenabled Products: A Multiassay, Multimaterial Exploration by the SU...Published: 27 January 2018 by American Chemical Society (ACS) in Environmental Science & Technology
Nanoenabled products (NEPs) have numerous outdoor uses in construction, transportation or consumer scenarios, and there is evidence that their fragments are released in the environment at low rates. We hypothesized that the lower surface availability of NEPs fragment reduced their environmental effects with respect to pristine nanomaterials. This hypothesis was explored by testing fragments generated by intentional micronisation (“the SUN approach”; Nowack et al. Meeting the Needs for Released Nanomaterials Required for Further Testing: The SUN Approach. Environmental Science & Technology, 2016 (50), 2747). The NEPs were composed of four matrices (epoxy, polyolefin, polyoxymethylene, and cement) with up to 5% content of three nanomaterials (carbon nanotubes, iron oxide, and organic pigment). Regardless of the type of nanomaterial or matrix used, it was observed that nanomaterials were only partially exposed at the NEP fragment surface, indicating that mostly the intrinsic and extrinsic properties of the matrix drove the NEP fragment toxicity. Ecotoxicity in multiple assays was done covering relevant media from terrestrial to aquatic, including sewage treatment plant (biological activity), soil worms (Enchytraeus crypticus), and fish (zebrafish embryo and larvae and trout cell lines). We designed the studies to explore the possible modulation of ecotoxicity by nanomaterial additives in plastics/polymer/cement, finding none. The results support NEPs grouping by the matrix material regarding ecotoxicological effect during the use phase. Furthermore, control results on nanomaterial-free polymer fragments representing microplastic had no significant adverse effects up to the highest concentration tested.
Silica modification of titania nanoparticles enhances photocatalytic production of reactive oxygen species without incre...Published: 01 January 2018 by Royal Society of Chemistry (RSC) in RSC Advances
Titania (TiO2) nanoparticles were surface modified using silica and citrate to implement a ‘safe-by-design’ approach for managing potential toxicity of titania nanoparticles by controlling surface redox reactivity.
Lipopolysaccharide Adsorbed to the Bio-Corona of TiO2 Nanoparticles Powerfully Activates Selected Pro-inflammatory Trans...Published: 03 August 2017 by Frontiers Media SA in Frontiers in Immunology
It is known that the adsorption of bioactive molecules provides engineered nanoparticles (NPs) with novel biological activities. However, the biological effects of the adsorbed molecules may also be modified by the interaction with NP. Bacterial lipopolysaccharide (LPS), a powerful pro-inflammatory compound, is a common environmental contaminant and is present in several body compartments such as the gut. We recently observed that the co-incubation of LPS with TiO2 NPs markedly potentiates its pro-inflammatory effects on murine macrophages, suggesting that, when included in a NP bio-corona, LPS activity is enhanced. To distinguish the effects of adsorbed LPS from those of the free endotoxin, a pellet fraction, denominated P25/LPS, was isolated by centrifugation from a mixture of P25 TiO2 NP (128 µg/ml) and LPS (10 ng/ml) in the presence of fetal bovine serum. Western blot analysis of the pellet eluate indicated that the P25/LPS fraction contained, besides proteins, also LPS, pointing to the presence of LPS-doped NP. The effects of adsorbed or free LPS were then compared in Raw264.7 murine macrophages. RT-PCR was used to evaluate the induction of cytokine genes, whereas active, phosphorylated isoforms of proteins involved in signaling pathways were assessed with western blot. At a nominal LPS concentration of 40 pg/ml, P25/LPS induced the expression of both NF-κB and IRF3-dependent cytokines at levels comparable with those observed with free LPS (10 ng/ml), although with different time courses. Moreover, compared to free LPS, P25/LPS caused a more sustained phosphorylation of p38 MAPK and a more prolonged induction of STAT1-dependent genes. Cytochalasin B partially inhibited the induction of Tnfa by P25/LPS, but not by free LPS, and suppressed the induction of IRF3-dependent genes by either P25/LPS or free LPS. These data suggest that, when included in the bio-corona of TiO2 NP, LPS exhibits enhanced and time-shifted pro-inflammatory effects. Thus, in assessing the hazard of NP in real life, the enhanced effects of adsorbed bioactive molecules should be taken into account.
The relationships between the physicochemical properties of engineered nanomaterials (ENMs) and their adverse health and environmental effects are still unclear. The relationships between the physicochemical properties of engineered nanomaterials (ENMs) and their adverse health and environmental effects are still unclear. In order to understand key nano-bio/eco interactions and to convert this knowledge into “Safety by Design” (S by D) strategies, it is essential to study the colloidal properties of ENMs in nano(eco)toxicology-relevant media. In the frame of such a S by D approach, this paper investigates the dispersion stability of copper oxide NPs surface-modified by means of four stabilizing agents, namely, [polyethylenimine (PEI), sodium ascorbate (ASC), sodium citrate (CIT), and polyvinylpyrrolidone (PVP)], which were used to achieve positive (PEI), negative (ASC, CIT), and neutral (PVP) surface charging of the NPs. The effects of these four stabilizers on the CuO NPs' physicochemical properties were investigated in different biological and environmental media by combining dynamic and electrophoretic light scattering (DLS and ELS), centrifugal separation analysis (CSA) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The results showed improved dispersion stability for CuO-CIT, CuO-ASC, and CuO-PEI in both Milli-Q and phosphate buffered saline (PBS) as compared to pristine CuO and CuO-PVP. The increased ionic strength of artificial fresh (AFW) and marine (AMW) waters strongly destabilized all the CuO NP suspensions, except for CuO-PEI dispersed in AFW. The presence of proteins and amino acids in the test media had a strong influence on the colloidal stability of all the dispersions. Characterization of colloidal properties and ion release rates in (eco)toxicological testing media will help to correlate some of these properties with (eco)toxicological responses, thus enabling prediction of the behavior of NPs in real environments.
While control banding has been identified as a suitable framework for the evaluation and the determination of potential human health risks associated with exposure to nanomaterials (NMs), the approach currently lacks any implementation that enjoys widespread support. Large inconsistencies in characterisation data, toxicological measurements and exposure scenarios make it difficult to map and compare the risk associated with NMs based on physicochemical data, concentration and exposure route. Here we demonstrate the use of Bayesian networks as a reliable tool for NM risk estimation. This tool is tractable, accessible and scalable. Most importantly, it captures a broad span of data types, from complete, high quality data sets through to data sets with missing data and/or values with a relatively high spread of probability distribution. The tool is able to learn iteratively in order to further refine forecasts as the quality of data available improves. We demonstrate how this risk measurement approach works on NMs with varying degrees of risk potential, namely, carbon nanotubes, silver and titanium dioxide. The results afford even non-experts an accurate picture of the occupational risk probabilities associated with these NMs and, in doing so, demonstrated how NM risk can be evaluated into a tractable, quantitative risk comparator. Keywords Risk assessment Control banding Bayesian
This work deals with the development of a green and versatile synthesis of stable mono- and bi-metallic colloids by means of microwave heating and exploiting ecofriendly reagents: water as the solvent, glucose as a mild and non-toxic reducer and polyvinylpirrolidone (PVP) as the chelating agent. Particle size-control, total reaction yield and long-term stability of colloids were achieved with this method of preparation. All of the materials were tested as effective catalysts in the reduction of p-nitrophenol in the presence of NaBH4 as the probe reaction. A synergistic positive effect of the bimetallic phase was assessed for Au/Cu and Pd/Au alloy nanoparticles, the latter showing the highest catalytic performance. Moreover, monoand bi-metallic colloids were used to prepare TiO2- and CeO2-supported catalysts for the liquid phase oxidation of 5-hydroxymethylfufural (HMF) to 2,5-furandicarboxylic acid (FDCA). The use of Au/Cu and Au/Pd bimetallic catalysts led to an increase in FDCA selectivity. Finally, preformed Pd/Cu nanoparticles were incorporated into the structure of MCM-41-silica. The resulting Pd/Cu MCM-41 catalysts were tested in the hydrodechlorination of CF3OCFClCF2Cl to CF3OCF=CF2. The effect of Cu on the hydrogenating properties of Pd was demonstrated.
Organ burden and pulmonary toxicity of nano-sized copper (II) oxide particles after short-term inhalation exposurePublished: 02 May 2016 by Informa UK Limited in Nanotoxicology
Increased use of nanomaterials has raised concerns about the potential for undesirable human health and environmental effects. Releases into the air may occur and, therefore, the inhalation route is of specific interest. Here we tested copper oxide nanoparticles (CuO NPs) after repeated inhalation as hazard data for this material and exposure route is currently lacking for risk assessment.
A panel of in vitro tests to evaluate genotoxic and morphological neoplastic transformation potential on Balb/3T3 cells ...Published: 07 April 2016 by Oxford University Press (OUP) in Mutagenesis
The FP7 Sanowork project was aimed to minimise occupational hazard and exposure to engineered nanomaterials (ENM) through the surface modification in order to prevent possible health effects. In this frame, a number of nanoparticles (NP) have been selected, among which zirconium (ZrO2) and titanium (TiO2) dioxide. In this study, we tested ZrO2 NP and TiO2 NP either in their pristine (uncoated) form, or modified with citrate and/or silica on their surface. As benchmark material, Aeroxide® P25 was used. We assessed cytotoxicity, genotoxicity and induction of morphological neoplastic transformation of NP by using a panel of in vitro assays in an established mammalian cell line of murine origin (Balb/3T3). Cell viability was evaluated by means of colony-forming efficiency assay (CFE). Genotoxicity was investigated by cytokinesis-block micronucleus cytome assay (CBMN cyt) and comet assay, and by the use of the restriction enzymes EndoIII and Fpg, oxidatively damaged DNA was detected; finally, the morphological neoplastic transformation of NP was assayed in vitro by cell transformation assay (CTA). Our results show that the surface remediation has not been effective in modifying cyto- and genotoxic properties of the nanomaterials tested; indeed, in the case of remediation of zirconia and titania with citrate, there is a tendency to emphasise the toxic effects. The use of a panel of assays, such as those we have employed, allowing the evaluation of multiple endpoints, including cell transformation, seems particularly advisable especially in the case of long-term exposure effects in the same cell type.
Titanium dioxide (TiO2) nanofibres are a novel fibrous nanomaterial with increasing applications in a variety of fields. While the biological effects of TiO2 nanoparticles have been extensively studied, the toxicological characterization of TiO2 nanofibres is far from being complete. In this study, we evaluated the toxicity of commercially available anatase TiO2 nanofibres using TiO2 nanoparticles (NP) and crocidolite asbestos as non-fibrous or fibrous benchmark materials. The evaluated endpoints were cell viability, haemolysis, macrophage activation, trans-epithelial electrical resistance (an indicator of the epithelial barrier competence), ROS production and oxidative stress as well as the morphology of exposed cells. The results showed that TiO2 nanofibres caused a cell-specific, dose-dependent decrease of cell viability, with larger effects on alveolar epithelial cells than on macrophages. The observed effects were comparable to those of crocidolite, while TiO2 NP did not decrease cell viability. TiO2 nanofibres were also found endowed with a marked haemolytic activity, at levels significantly higher than those observed with TiO2 nanoparticles or crocidolite. Moreover, TiO2 nanofibres and crocidolite, but not TiO2 nanoparticles, caused a significant decrease of the trans-epithelial electrical resistance of airway cell monolayers. SEM images demonstrated that the interaction with nanofibres and crocidolite caused cell shape perturbation with the longest fibres incompletely or not phagocytosed. The expression of several pro-inflammatory markers, such as NO production and the induction of Nos2 and Ptgs2, was significantly increased by TiO2 nanofibres, as well as by TiO2 nanoparticles and crocidolite. This study indicates that TiO2 nanofibres had significant toxic effects and, for most endpoints with the exception of pro-inflammatory changes, are more bio-active than TiO2 nanoparticles, showing the relevance of shape in determining the toxicity of nanomaterials. Given that several toxic effects of TiO2 nanofibres appear comparable to those observed with crocidolite, the possibility that they exert length dependent toxicity in vivo seems worthy of further investigation.
Silica matrix encapsulation as a strategy to control ROS production while preserving photoreactivity in nano-TiO 2Published: 01 January 2016 by Royal Society of Chemistry (RSC) in Environmental Science: Nano
Silica matrix encapsulation can control potential health risk associated with ROS production, but improves as well the photocatalytic properties of nano TiO 2 . In this work, the application of a silica coating on TiO 2 nanoparticles (NPs) represented a material design strategy for the purpose of controlling the reactive oxygen species (ROS) production, identified as one of the potentially hazardous effects for this class of materials. The study focused on characterizing redox reactivity as a source of potential adverse cellular oxidative stress and desirable photocatalytic reactivity. The SiO 2 -modified TiO 2 systems were produced using a colloidal heterocoagulation method expected to give rise to “matrix encapsulation” and the formation of a mixed structure. To assess the effect of SiO 2 surface engineering on TiO 2 NP redox reactivity, ROS production was measured by electron paramagnetic resonance (EPR) and photocatalytic tests based on NO x /NO abatement analysis were carried out. The obtained reduction in ROS production associated with an improved photoactivity in the SiO 2 -modified samples, in comparison with the TiO 2 pristine ones, encouraged the promotion of silica coating as “safer by molecular design” strategy.
Evaluation of existing control measures in reducing health and safety risks of engineered nanomaterialsPublished: 01 January 2016 by Royal Society of Chemistry (RSC) in Environmental Science: Nano
While the risk management of engineered nanomaterials (ENMS) receives significant attention, there is still a limited understanding of how to select optimal risk management measures for reducing the risks of ENMs. While the risk management of engineered nanomaterials (ENMs) receives significant attention, there is still a limited understanding of how to select optimal risk management measures (RMMs) for controlling and mitigating the risks associated with exposure to ENMs. Clearly, there exists a need to expand current risk management practices to ensure safe production, handling and use of ENMs. Moreover, the performance of the existing RMMs should be re-evaluated for ENMs since control options that are proven to be effective for preventing or limiting risks associated with traditional particles might give unsatisfactory results in the case of nano-scale particles. This paper has brought together the evidence on the adequacy of traditional controls to minimize potential health and environmental risks resulting from exposure to ENMs. The aim here is to advance our understanding of the risk management approaches relevant for ENMs, and ultimately to support the selection of the most suitable RMMs when handling ENMs. To that end, evaluative evidence collected from the review of relevant literature and survey of nanotechnology institutions are combined and summarised to understand the level of protection offered by each control measure, as well as the relative costs of their implementation. The findings suggest that most relevant risk control options are based on isolating people from hazard through engineering measures ( e.g. ventilation and chemical fume hoods) or personal protective equipment (PPE), rather than eliminating hazard at source ( e.g. substitution). Although control measures related to the modification of ENMs have high efficiency in the occupational risk control hierarchy, they are not widely employed since there is currently a high degree of uncertainty regarding the impact of manipulating nano-characteristics on the performance of final product. Lastly, despite its low cost, PPE is the least effective category in the occupational risk control hierarchy and should not be used on its own when significant risk reduction is required. Clearly, further quantitative data is needed to fully assess the feasibility and cost-effectiveness of risk control options to prevent risks from exposure to ENMs. When there is little information on the efficiency of control measures specific to ENMs, the default efficiencies can be used for initial assessment purposes although it should not be considered exhaustive.
Self-cleaning applications using TiO₂ coatings on various supporting media have been attracting increasing interest in recent years. This work discusses the issue of self-cleaning textile production on an industrial scale. A method for producing self-cleaning textiles starting from a commercial colloidal nanosuspension (nanosol) of TiO₂ is described. Three different treatments were developed for purifying and neutralizing the commercial TiO₂ nanosol: washing by ultrafiltration; purifying with an anion exchange resin; and neutralizing in an aqueous solution of ammonium bicarbonate. The different purified TiO₂ nanosols were characterized in terms of particle size distribution (using dynamic light scattering), electrical conductivity, and ζ potential (using electrophoretic light scattering). The TiO₂-coated textiles’ functional properties were judged on their photodegradation of rhodamine B (RhB), used as a stain model. The photocatalytic performance of the differently treated TiO₂-coated textiles was compared, revealing the advantages of purification with an anion exchange resin. The study demonstrated the feasibility of applying commercial TiO₂ nanosol directly on textile surfaces, overcoming problems of existing methods that limit the industrial scalability of the process.
Impact and effectiveness of risk mitigation strategies on the insurability of nanomaterial production: evidences from in...Published: 24 March 2015 by Wiley in Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology
Workers involved in producing nanomaterials or using nanomaterials in manufacturing plants are likely to have earlier and higher exposure to manufactured/engineered nanomaterials (ENM) than the general population. This is because both the volume handled and the probability of the effluence of ‘free’ nanoparticles from the handled volume are much higher during a production process than at any other stage in the lifecycle of nanomaterials and nanotechnology‐enabled products. Risk assessment (RA) techniques using control banding (CB) as a framework for risk transfer represents a robust theory but further progress on implementing the model is required so that risk can be transferred to insurance companies. Following a review of RA in general and hazard measurement in particular, we subject a Structural Alert Scheme methodology to three industrial case studies using ZrO2, TiO2, and multi‐walled carbon nanotubes (MWCNT). The materials are tested in a pristine state and in a remediated (coated) state, and the respective emission and hazard rates are tested alongside the material performance as originally designed. To our knowledge, this is the first such implementation of a CB RA in conjunction with an ENM performance test and offers both manufacturers and underwriters an insight into future applications.
Titanium dioxide nanoparticles enhance macrophage activation by LPS through a TLR4-dependent intracellular pathwayPublished: 01 January 2015 by Royal Society of Chemistry (RSC) in Toxicology Research
TiO 2 nanoparticles enhance LPS-dependent NO production and cytokine secretion through a mechanism that involves TLR4-mediated p38-signalling and requires phagocytosis. Although causing moderate cytotoxicity and inflammatory effects, TiO 2 nanoparticles (NPs) are considered relatively safe materials. However, it is known that TiO 2 NPs bind bioactive environmental contaminants, such as bacterial lipopolysaccharide (LPS, endotoxin), and it is possible that this interaction leads to increased biological activity. In this report we have investigated the pro-inflammatory responses of Raw264.7 murine macrophages exposed to two preparations of TiO 2 NPs, co-administered with LPS. The simultaneous exposure to NPs and LPS produced marked increases in Nos2 mRNA, Nos2 protein and medium nitrite concentration (an indicator of NO production) well beyond the levels observed with LPS or TiO 2 NP alone. TiO 2 NPs also synergized LPS effects on Ptgs2 expression and cytokine secretion. The cytoskeletal drug cytochalasin B lowered the amount of NPs internalized by the cells and suppressed the synergy between TiO 2 NPs and LPS in NO production and cytokine secretion. Pre-treatment with the TLR4 inhibitors polymyxin B and CLI-095 eliminated the synergy that was also partially hampered by the inhibition of p38 MAPK, but not of ERK1/2. Moreover, p38 phosphorylation was synergistically enhanced by the combined treatment at 6 h of incubation. It is concluded that TiO 2 NPs enhance macrophage activation by LPS via a TLR4-dependent mechanism that involves p38 and is mainly triggered from an intracellular site. These findings suggest that the simultaneous exposure to LPS and TiO 2 NPs may exacerbate the inflammatory response in vivo .
Our understanding of the environmental and health risks from nanotechnologies is still limited, which may result in stagnation of nanoinnovation. This emphasizes the need for an integrative assessment and adaptive management of the long-term risks from manufactured nanomaterials (MN) along the entire supply chains of nano-enabled products towards developing more sustainable nanotechnologies. Sustainable nanotechnology is being touted as a holistic and pragmatic concept that can guide incremental nanotechnology development amidst significant data gaps and uncertainty. The new European SUN (Sustainable Nanotechnologies) project is based on the hypothesis that the current knowledge on environmental and health risks from MN, whilst limited, can nevertheless guide more sustainable nanomanufacturing. SUN applies an integrated approach that estimates risks along the complete lifecycles of nano-enabled products. It aims to give clear answers to questions from regulatory authorities, and open new possibilities for innovators to design greener nanotechnologies. This will be achieved through development and application of new methods and tools for prediction of long-term exposure, effects and risks for humans and ecosystems (services), practices for risk prevention and management and tools to streamline effective decision making about safer products and processes. In order to achieve this, SUN will combine Risk Assessment and Lifecycle Assessment to develop a user-friendly software-based Decision Support System (DSS) for practical use by industries and regulators. The industrial partners in SUN will validate the DSS against real case studies in terms of risk/benefit and insurance costs. This validation will culminate in guidelines for safe nanoscale product and process design.
Highlights•Direct ceramization of textile substrates with commercial derived TiO2 nanosols.•Five nanosols, differing for starting pH and relative aggregates size.•Correlations between physico-chemical nano-macro scale properties and performances.•Industrially scalable application.•Inputs for the control of material performance by design experiments. AbstractThe present study shows the results of direct ceramization of textile substrates with commercial derived TiO2 nanosols. A deep investigation on relationship between TiO2 based nanosols and nanocoatings properties and their performances in term of hydrophilicity and photocatalytic efficiency was performed. Five nanosols, differing for starting pH and relative agglomerates size were analyzed. The hydrophilic behavior and the catalytic performance of TiO2 coatings supported on different substrates (fabric, glass and ceramic) were assessed and related to physicochemical characterization results. The described correlations between TiO2 nanoscale properties (nanostructure or surface chemistry), macroscale properties (hydrophilicity), as well as functional properties (photocatalytic activity), represents a first attempt to provide sound criteria for the control of material performance by design experiments. The pH dependent aggregation state, is correlated to an increase of surface acidity as the shift of i.e.p. towards acid pH reveals. Such increase of acidity justifies an increase of hydrophilicity, consequent to stronger interaction with water molecules, that occurs when a higher amount of Ti−O− sites are available. As well, the photocatalytic performances and the hydrophilic behavior, resulted in a good agreement: the higher the hydrophilicity, the better the self-cleaning activity, so providing useful indications for the scale-up exploitation of such application. Graphical abstract
Nanostructured particles with a magnetic core and a photocatalytic shell are very interesting systems for their properties to be magnetically separable (and so reusable) in photocatalytic water depuration implant. Here, a robust, low time-consuming, easily scale up method to produce Fe3O4/SiO2/TiO2 hierarchical nanostructures starting from commercial precursors (i.e. Fe3O4, SiO2) by employing a colloidal approach (i.e. heterocoagulation) coupled with the spray–drying technique is presented. In particular, a self-assembled layer-by-layer methodology based on the coagulation of dissimilar colloidal particles was applied. First, a passive layer of silica (SiO2, amorphous) was created on magnetite in order to avoid detrimental phenomena arising from the direct contact between magnetite and titania, then the deposition of titania onto silica-coated-magnetite was promoted. TiO2, SiO2 and Fe3O4 nanosols were characterized in terms of zeta potential, optimized and a self-assembled layer-by-layer approach was followed in order to promote the heterocoagulation of silica onto magnetite surface and of titania onto silica coated magnetite. Once optimized the colloidal route, the mixture was then spray-dried to obtain a granulated powder with nano-scale reactivity, easier to handle and re-disperse in comparison to starting nanopowders with the same surface properties. The nanostructured particles have been characterized by different techniques such as SEM, TEM, XDR and their magnetic properties have been investigated. Moreover, preliminary photocatalytic texts have been performed. Graphical Highlights► TiO2/SiO2/Fe3O4 nanostructured particles. ► Magnetic – UV light photocatalyst. ► Colloidal approach coupled with spray–drying. ► Cost-effective industrially scalable approach.
Ink-jet printing is becoming a leading technology for traditional ceramics, due to its capacity of reproducing highly resolved and customized images on tile surfaces. Nano-sized inks, produced by the polyol synthesis route, proved to fulfil the printing requirements, tailoring their chemico-physical properties (e.g. viscosity, surface tension) on industrial ink-jet devices, so representing a major breakthrough in the quadrichromy process.
Ceramic pigments with Cr-doped sphene structure (CaSn1-xCrxSiO5, CaTi1-xCrxSiO5) were synthesized by both spray drying an aqueous solution of precursor salts plus further calcining the resulting powders and conventional ceramic method. The thermal evolution of products was studied by X-Ray Powder Diffraction (XRPD). The powder morphology and chemical composition were analyzed by SEM-EDX. The color efficiency of pigments was evaluated by colorimetric analysis (CIELab system). Results showed that the spray drying process decreased the maximum firing temperature and increased the color efficiency of Cr-doped sphene pigments therefore enhancing a higher reactivity of powders compared with the solid state process.