Engineered Nanomaterials (ENMs) have several uses in various industrial fields and are embedded in a myriad of consumer products. However, there is continued concern over the potential adverse health effects and environmental impacts of ENMs due to their unique physico-chemical characteristics. Currently, there are no specific international regulations for various ENMs. There are also no Occupational Exposure Limits (OEL) regulated by the European Union (EU) for nanomaterials in the form of nano-objects, their aggregates or agglomerates (NOAA). For ENMs the question of which metric to be used (i.e., mass, surface area, number concentrations) to determine the exposure is still not resolved. The aim of this work is to assess the worker exposure by inhalation in an industrial spray coating process by using all three metrics mentioned above. Two target ENMs (N-doped TiO2, TiO2N and AgNPs capped with a quaternized hydroxyethyl-cellulose, AgHEC) generated for industrial-scale spraying processes were considered. Results showed that the averaged particle number concentration (10-100 nm) was below 2.7 10(4) cm(-3) for both materials. The Lung Deposited Surface Area (LDSA) was in the range between 73 and 98 mu m(2)cm(-3) and the particle mass concentration (obtained by means of ICP-EOS off-line analysis) resulted below 70 mu g m(-3) and 0.4 mu g m(-3) for TiO2 and Ag, respectively. Although, the airborne particles concentration compared well with the NIOSH Recommended Exposure Level (REL) limits the contribution to the background, according to EN 17058 (Annex E) was significant (particularly in the particle number and PM1 mass concentrations). We successfully evaluated the worker exposure by means of the different airborne particles' metrics (number, surface and mass concentrations). We concluded that worker exposure assessment involving ENMs is a complex procedure with requires both real time and off-line measurements and a deep investigation of the background.

Aquivion PFSA resin, a perfluorinated ion-exchange polymer, has been used as a heterogeneous strong acid catalyst for a range of reactions; however, the activity of this material is limited due to the extremely low surface area of the polymer. In this paper we described the one-step synthesis of Aquivion® PFSA-based hybrid materials using heterocoagulation and spray-freeze-drying of sols containing the precursor of the active phases. The intimated encapsulation of different nano-oxides, such as TiO and SiO in the superacid resin matrix was easily obtained using this technique and compared with similar catalysts prepared by the impregnation conventional route. The approach led to the preparation of porous micro-granules characterised by a high homogeneity in the phase distribution and high surface area. The prepared materials were active and selective for the gas phase dehydration of ethanol to ethylene in mild conditions. The increase of the porosity improved the activity of the composites, compared to the pure Aquivion® PFSA, and allowed to reduce the amount of the superacid resin. Moreover, the type of encapsulated oxide, TiO or SiO, modified the improved performance of the catalysts, having TiO the higher efficiency for ethanol conversion and selectivity in ethylene at very low temperature.

In recent years, multifunctional inorganic organic hybrid materials have been widely investigated in order to determine their potential synergetic, antagonist, or independent effects in terms of reactivity. The aim of this study was to design and characterize a new hybrid material by coupling well-known photocatalytic TiO2 nanoparticles with sodium surfactin (SS), a biosurfactant showing high binding affinity for metal cations as well as the ability to interact with and disrupt microorganisms' cell membranes. We used both chemical and colloidal synthesis methodologies and investigated how different TiO2:SS weight ratios affected colloidal, physicochemical, and functional properties. We discovered a clear breaking point between TiO2 and SS single-component trends and identified different ranges of applicability by considering different functional properties such as photocatalytic, heavy metal sorption capacity, and antibacterial properties. At low SS contents, the photocatalytic properties of TiO2 are preserved (conversion of organic dye = 99% after 40 min), and the hybrid system can be used in advanced oxidation processes, taking advantage of the additional antimicrobial SS properties. At high SS contents, the TiO2 photoactivity is inhibited, and the hybrid can be usefully exploited as a UV blocker in cosmetics, avoiding undesired oxidative effects (UV adsorption in the range between 300-400 nm). Around the breaking point (TiO2:SS 1:1), the hybrid material preserves the high surface area of TiO2 (specific surface area around 180 m2/g) and demonstrates NOx depletion of up to 100% in 80 min, together with improved adhesion of hybrid antibacterial coating. The last design demonstrated the best results for the concurrent removal of inorganic, organic, and biological pollutants in water/soil remediation applications.

Magnetic nanoparticles (MNPs) present outstanding properties making them suitable as therapeutic agents for hyperthermia treatments. Since the main safety concerns of MNPs are represented by their inherent instability in a biological medium, strategies to both achieve longterm stability and monitor hazardous MNP degradation are needed. We combined a dynamic approach relying on flow field flow fractionation (FFF)-multidetection with conventional techniques to explore frame-by-frame changes of MNPs injected in simulated biological medium, hypothesize the interaction mechanism they are subject to when surrounded by a saline, protein-rich environment, and understand their behaviour at the most critical point of intravenous administration. In the first moments of MNPs administration in the patient, MNPs change their surrounding from a favorable to an unfavorable medium, i.e., a complex biological fluid such as blood; the particles evolve from a synthetic identity to a biological identity, a transition that needs to be carefully monitored. The dynamic approach presented herein represents an optimal alternative to conventional batch techniques that can monitor only size, shape, surface charge, and aggregation phenomena as an averaged information, given that they cannot resolve different populations present in the sample and cannot give accurate information about the evolution or temporary instability of MNPs. The designed FFF method equipped with a multidetection system enabled the separation of the particle populations providing selective information on their morphological evolution and on nanoparticle- proteins interaction in the very first steps of infusion. Results showed that in a dynamic biological setting and following interaction with serum albumin, PP-MNPs retain their colloidal properties, supporting their safety profile for intravenous administration.

For the first time, we exploited the antiviral and antibacterial properties of Ag NPs stabilised by quaternized hydroxyethyl cellulose (Ag-HEC) against SARS-CoV-2 and Escherichia coli through an eco-friendly process at room temperature in three different environments: 1) water, where Ag was dispersed as a nanosol, 2) textiles, where Ag was applied as a coating, and 3) hydrogel where Ag is embedded. The antiviral performance of Ag-HEC nanosols was quantified through the selectivity index (SI), defined as the ratio between 50% cytotoxic and inhibitory concentration, in order to evaluate the ability to be active in a concentration range below the cytotoxicity value. The collected results pointed out an actual enhanced risk/benefit profile of Ag-HEC NPs with respect to chloroquine, with an SI of 22.2 and 8.4, respectively. Antibacterial and antiviral activities of Ag-HEC NPs immobilized on textiles or mucosa-like hydrogels were also assessed and their efficacy in potential application as protective clothing or nasal molecular masks was verified. This work demonstrated that a modern, safe and sustainable design allows traditional colloidal silver-based technologies to be efficiently exploited for a broad spectrum of antimicrobial solutions against bacterial and viral infections.

Industrial spray coating processes are known to produce excellent coatings on large surfaces and are thus often used for in-line production. However, they could be one of the most critical sources of worker exposure to ultrafine particles (UFPs). A monitoring campaign at the Witek s.r.l. (Florence, Italy) was deployed to characterize the release of TiO2 NPs doped with nitrogen (TiO2-N) and Ag capped with hydroxyethyl cellulose (AgHEC) during automatic industrial spray-coating of polymethyl methacrylate (PMMA) and polyester. Aerosol particles were characterized inside the spray chamber at near field (NF) and far field (FF) locations using on-line and off-line instruments. Results showed that TiO2-N suspension produced higher particle number concentrations than AgHEC in the size range 0.3-1 µm (on average 1.9 10 p/cm and 2.5 10 p/cm, respectively) after background removing. At FF, especially at worst case scenario (4 nozzles, 800 mL/min flow rate) for TiO2-N, the spray spikes were correlated with NF, with an observed time lag of 1 minute corresponding to a diffusion speed of 0.1 m/s. The averaged ratio between particles mass concentrations in the NF position and inside the spray chamber was 1.7% and 1.5% for TiO2- N and for AgHEC suspensions, respectively. The released particles' number concentration of TiO2- N in the size particles range 0.3-1 ?m was comparable for both PMMA and polyester substrates, about 1.5 and 1.6 10 p/cm. In the size range 0.01-30 µm, the aerosol number concentration at NF for both suspensions was lower than the nano reference values (NRVs) of 16?10 p/cm.

A new class of bio-nano hybrid catalyst useable in downstream wastewater treatment was developed. We combined the sorption potentialities of Chlorella vulgaris microalgae with the photocatalytic properties of TiO NPs in order to investigate unexplored synergistic effects that could push the algal remediation technology toward a more promising cost-effective balance. We exploited non-living C. vulgaris, which keeps the biosorption properties of the living microalgae, but greatly enhancing the overall processability. C. vulgaris biomass was coupled with TiO NPs and the nanosols were then dried by means of a spray freeze drying (SFD) process able to produce highly reactive granules. A widespread physicochemical characterization supported the preparation and the performance evaluation, so highlighting the key-role of C. vulgaris/TiO interaction at the colloidal state. Heavy metal adsorption, tested for copper ions, and photocatalytic activity, assessed for Rhodamine B (RhB) photodegradation, were evaluated as key performances. The results pointed out a positive synergistic effect for hybrid samples consistent with the enhancement of metal biosorption which ranges from 103 mg g, for pristine C. vulgaris, to about 4000 mg g, when the biomass was coupled with the inorganic nanophase. The photocatalytic activity was well preserved with a complete RhB conversion after 1 h and even advanced in presence of SiONPs into the inorganic counterpart, so increasing the kinetic constant from 8.70 to 10.7 10 min. The results pave the way for the integration of these sorbent/photocatalytic hybrid materials into water remediation systems in an innovative sustainable design perspective.

An automatic lab-scaled spray-coating machine was used to deposit Ag nanoparticles (AgNPs) on textile to create antibacterial fabric. The spray process was monitored for the dual purpose of (1) optimizing the process by maximizing silver deposition and minimizing fluid waste, thereby reducing suspension consumption and (2) assessing AgNPs release. Monitoring measurements were carried out at two locations: inside and outside the spray chamber (far field). We calculated the deposition efficiency (E), finding it to be enhanced by increasing the spray pressure from 1 to 1.5 bar, but to be lowered when the number of operating sprays was increased, demonstrating the multiple spray system to be less efficient than a single spray. Far-field AgNPs emission showed a particle concentration increase of less than 10% as compared to the background level. This finding suggests that under our experimental conditions, our spray-coating process is not a critical source of worker exposure.

The use of nano-photocatalysts for the water/wastewater purifications, particularly in de-veloping regions, offers promising advantages over conventional technologies. TiO2-based photo-catalysts deposited on fabrics represent an efficient solution for obtaining heterogeneous photocata-lysts, which are easily adaptable in the already installed water treatment plants or air purification systems. Despite the huge effort spent to develop and characterize novel nano-photocatalysts, which are especially active under solar light, knowledge gaps still persist for their full-scale appli-cation, starting from the reactor design and scale-up and the evaluation of the photocatalytic efficiency in pre-pilot scenarios. In this study, we offered easily scalable solutions for adapting TiO2-based photocatalysts, which are deposited on different kinds of fabrics and implemented in a 6 L semi-pilot plant, using the photodegradation of Rhodamine B (RhB) as a model of water pollution. We took advantage of a multi-variable optimization approach to identify the best design options in terms of photodegradation efficiency and turnover frequency (TOF). Surprisingly, in the condition of use, the irradiation with a light-emitting diode (LED) visible lamp appeared as a valid alternative to the use of UV LED. The identification of the best design options in the semi-pilot plant allowed scaling up the technology in a 100 L pilot plant suitable for the treatment of industrial wastewater.

Biocompatible coating based on bovine serum albumin (BSA) was applied on two different TiO nanoparticles (aeroxide P25 and food grade E171) to investigate properties and stability of resulting TiO@BSA composites, under the final perspective to create a "Safe-by-Design" coating, able to uniform, level off and mitigate surface chemistry related phenomena, as naturally occurring when nano-phases come in touch with proteins enriched biological fluids. The first step towards validating the proposed approach is a detailed characterization of surface chemistry with the quantification of amount and stability of BSA coating deposited on nanoparticles' surfaces. At this purpose, we implemented an orthogonal multi-techniques characterization platform, providing important information on colloidal behavior, particle size distribution and BSA-coating structure of investigated TiO systems. Specifically, the proposed orthogonal approach enabled the quantitative determination of bound and free (not adsorbed) BSA, a key aspect for the design of intentionally BSA coated nano-structures, in nanomedicine and, overall, for the control of nano-surface reactivity. In fact, the BSA-coating strategy developed and the orthogonal characterisation performed can be extended to different designed nanomaterials in order to further investigate the protein-corona formation and promote the implementation of BSA engineered coating as a strategy to harmonize the surface reactivity and minimize the biological impact.

In response to the nowadays battle against SARS-CoV-2, we designed a new class of high performant filter media suitable to advance the facemask technology and provide new efficient widespread solutions against virus propagation. By means of the electrospinning technology we developed filter media based on polyvinyl alcohol (PVA) nanofibers doped with AgNPs combining three main performance requirements: high air filtration efficiency to capture nanometer-size particles, low airflow resistance essential to ensure breathability and antimicrobial activity to inactivate aerosolized microorganisms. PVA/AgNPs electrospun nanofibers were produced by electrospinning the dispersion of colloidal silver into the PVA water solution. A widespread physicochemical characterization was addressed to the Ag colloidal suspension. The key functional performances of the electrospun nanofibers were proven by water stability, antibacterial activity, and filtration efficiency and pressure drop measurements performed under conditions representative of facemasks. We assessed a total bacterial depletion associated to a filtering efficiency towards nano-aerosolized particles of 97.7% higher than required by the EN149 standard and a pressure drop in line with FFP1 and FFP2 masks, even at the highest filtration velocity. Such results pave the way to the application of PVA/AgNPs electrospun nanofibers in facemasks as advanced filtering media for protecting against airborne microorganisms.

The photocatalytic oxidation of biomass-derived building blocks such as 5-hydroxymethylfurfural (HMF) is a promising reaction for obtaining valuable chemicals and the efficient long-term storage of solar radiation. In this work, we developed innovative TiO2-based materials capable of base-free HMF photo-oxidation in water using simulated solar irradiation. The materials were prepared by combining microemulsion and spray-freeze drying (SFD), resulting in highly porous systems with a large surface area. The effect of titania/silica composition and the presence of gold-copper alloy nanoparticles on the properties of materials as well as photocatalytic performance were evaluated. Among the lab-synthesized photocatalysts, Ti15Si85 SFD and Au3Cu1/Ti15Si85 SFD achieved the higher conversions, while the best selectivity was observed for Au3Cu1/Ti15Si85 SFD. The tests with radical scavengers for both TiO2-m and Au3Cu1/Ti15Si85 SFD suggested that primary species responsible for the selective photo-oxidation of HMF are photo-generated electrons and/or superoxide radicals.

Titanium dioxide (TiO) nanoparticles (NPs) are produced in high volume and widely used in manufacturing processes, raising potential occupational health concerns. Here, workers' exposure was assessed during production of antibacterial textiles, where TiO NPs were impregnated onto 65% polyester 35% cotton textile surface by spray-coating. The influence of pressure, web speed and number of working spray nozzles to TiO particles release was studied under different experimental conditions. Real-time monitoring was used to measure size-resolved particle concentration and lung-deposited surface area (LDSA) concentration using an optical particle counter and a diffusion charger, respectively, from both near- and far-field. Particles were sampled from the working area for off-line electron microscopy characterization, and suspensions of sampled particles were characterized by dynamic light scattering. Post-campaign data analysis was carried out and used for quantitative exposure safety assessment. Particle number concentration and LDSA results showed that pressure at the spraying nozzles (P) is the main parameter that influences the release of particles in the environment. Other process parameters studied (web speed and number of working spray nozzles) did not appear to significantly affect the release of particles. The particle number concentration in default experimental conditions (intermediate values for all process parameters; P = 2.3 bar, web speed = 6 m/min and number of working spray nozzles = 2) was quantified as 1.19 10 # L. Upon increasing the pressure, from 1.5 to 4.0 bar, near-field average mass and LDSA concentrations increased from 0.90 to 1.76 mg/m, and from 51.8 to 290.5 ?m/cm, respectively. Average (avg) mass concentrations were well below the maximum recommended exposure limit of 2.4 mg/m for fine TiO particles proposed by the US National Institute for Occupational Safety and Health.

This study was aimed at the production and characterization of coated cotton textiles with luminescent ceramic nanophases doped with cationic Ir(III) tetrazole complexes. We confirmed that SiO nanoparticles (NPs) do not affect the phosphorescent properties of the complexes that maintain their emission (610 and 490 nm). For the first time we transferred the luminescence feature from nanosol to textile surface, highlighting the advantages of using nanosilica as an encapsulating and stabilizing matrix. The optimized Ir@SiO suspensions were homogenously applied onto the cotton surface by dip-pad-dry-cure technique, as proved by the 2p-fluorescence microscope analysis. Once we verified the self-marker properties of the Ir(III) complex, we observed an excellent washing fastness of the coating with a very limited release. SiO in the washing water was quantified at maximum around 1.5 wt% and Ir below the inductively coupled plasma optical emission spectrometry (ICP-OES) detection limit of 1 ppm. A Franz cell test was used to evaluate any possible ex-vivo uptake of Ir@SiO nanoparticles across human skin tissues, showing that epidermis and dermis stop over 99% of Ir, implying a reduced impact on human health. The light-induced antimicrobial potential of the Ir@SiO were assessed toward both Gram(-) and Gram(+) bacteria. The results encouraged further developments of such functional textiles coated by self-markers and antibacterial active nanophases.

Length and aspect ratio represent important toxicity determinants of fibrous nanomaterials. We have previously shown that anatase TiO nanofibers (TiO NF) cause a dose-dependent decrease of cell viability as well as the loss of epithelial barrier integrity in polarized airway cell monolayers. Herein we have investigated the impact of fiber shortening, obtained by ball-milling, on the biological effects of TiO NF of industrial origin. Long TiO NF (L-TiO NF) were more cytotoxic than their shortened counterparts (S-TiO NF) toward alveolar A549 cells and bronchial 16HBE cells. Moreover, L-TiO NF increased the permeability of 16HBE monolayers and perturbed the distribution of tight-junction proteins, an effect also mitigated by fiber shortening. Raw264.7 macrophages efficiently internalized shortened but not long NF, which caused cell stretching and deformation. Compared with L-TiO NF, S-TiO NF triggered a more evident macrophage activation, an effect suppressed by the phagocytosis inhibitor cytochalasin B. Conversely, a significant increase of inflammatory markers was detected in either the lungs or the peritoneal cavity of mice exposed to L-TiO NF but not to S-TiO NF, suggesting that short-term macrophage activation in vitro may not be always a reliable indicator of persistent inflammation in vivo. It is concluded that fiber shortening mitigates NF detrimental effects on cell viability and epithelial barrier competence in vitro as well as inflammation development in vivo. These data suggest that fiber shortening may represent an effective safe-by-design strategy for mitigating TiO NF toxic effects.

Organic-inorganic hybrid (ceramer) coatings were synthesized and deposited on the polyester nonwoven fabrics through the sol-gel process. This promoted the formation of an insulating barrier that was able to enhance the thermal stability and the hydrophobicity of fabrics. The hybrid phase is made of an organic network arising from different alkoxysilane precursors (trimethoxymethylalkoxysilane (TMEOS), 3-aminopropyl-trimethoxyalkoxysilane (APTMS), and tetraethylorthosilicate (TEOS)) and inorganic phase made of titanium dioxide TiO2 nanoparticles (NPs) and, in some cases, coated by P-based compound. The characterization of hybrid phase at liquid (size distribution and zeta potential of dispersed nanoparticles), dried state (crystalline phase, thermogravimetric (TGA), and Fourier transform infrared spectroscopic (FTIR) analyses), and on deposited coatings (contact angle, burn-out tests) aimed to find a correlation between the physicochemical properties of ceramer and functional performances of coated fabrics (thermal stability and hydrophobicity). The results showed that all ceramer formulations were able to improve the char formation after burn-out, in particular the highest thermal stability was obtained in the presence of TMEOS precursor and TiO2 NPs coated by P-based compound, which also provided the highest hydrophobicity. In conclusion, we presented an environmentally friendly and easily scalable process for the preparation of ceramer formulations capable of being formed into transparent, thermal-resistant, and hydrophobic fabric coatings, whose functions are extremely challenging for the textile market.

The great antimicrobial action of copper oxide nanoparticles (CuO NPs) and their consequent use in many applications in the biomedical field have caused concern about the potentially negative effects of human skin exposure to CuO NPs. However, so far, very few studies have investigated the toxic action of CuO NPs toward humans, with a special focus on the skin penetration route of entry. This study considers for the first time the absorption of topically applied CuO NPs through the human skin, using a Franz static diffusion cell model. We characterised the colloidal behaviour and static dissolution of commercial bare CuO NPs, evaluating both intact and damaged skins. We tested physiological solutions as the receiving phase; as the donor phase, CuO NPs were dispersed in synthetic sweat and exposed to the outer surface of the skin (0.11 mg cm(-2)) for 24 hours. The Cu elemental analysis in the receptor fluid and in the exposed skin allowed us to quantify the copper translocation within the epidermis and dermis. The experimental data showed that the CuO NPs absorption through intact skin was negligible. However, in damaged skin, we observed an increasing permeation of copper. The latter would justify the capacity of CuO NPs to pass the first skin layers and release Cu2+ ions into the stratum corneum, reaching the receptor fluid in the in vitro diffusion cell system.

The spray-freeze-drying (SFD) approach was successfully applied for the preparation of nanostructured porous mixed oxides with high surface area. The preparation of different composite materials and the encapsulation of metal nanoparticles in inorganic matrix was easily obtained using this interesting technique. In particular, TiO2-SiO2 mixed-oxides were produced at different compositions using the colloidal heterocoagulation of very stable sols, associated with SFD. Moreover, its versatility allowed the incorporation of metal. This synthetic approach led to the preparation of porous micro-granules characterised by a high homogeneity in the phase distribution. The prepared materials were active and selective in the reduction of 5-hydroxymethyl-2-furfural (HMF) to 2,5- bishydroxymethylfuran (BHMF) and in the photodegradation of rhodamine B (RhB), used as a as a stain model. These encouraging results pave the way for the use of this method for the homogeneous embedding of different typologies of catalytic active phases (metal nanoparticles, inorganic complexes, enzyme) into any kind of support (inorganic, organic, polymeric) minimizing the possibility of phase separation on a molecular scale, as also demonstrated for drugs.

The enormous technological relevance of titanium dioxide (TiO2) nanoparticles (NPs) and the consequent concerns regarding potentially hazardous effects that exposure during production, use, and disposal can generate, encourage material scientists to develop and validate intrinsically safe design solution (safe-by-design). Under this perspective, the encapsulation in a silica dioxide (SiO2) matrix could be an effective strategy to improve TiO2 NPs safety, preserving photocatalytic and antibacterial properties. In this work, A549 cells were used to investigate the toxic effects of silica-encapsulated TiO2 having different ratios of TiO2 and SiO2 (1:1, 1:3, and 3:1). NPs were characterized by electron microscopy and dynamic light scattering, and cell viability, oxidative stress, morphological changes, and cell cycle alteration were evaluated. Resulting data demonstrated that NPs with lower content of SiO2 are able to induce cytotoxic effects, triggered by oxidative stress and resulting in cell necrosis and cell cycle alteration. The physicochemical properties of NPs are responsible for their toxicity. Particles with small size and high stability interact with pulmonary cells more effectively, and the different ratio among silica and titania plays a crucial role in the induced cytotoxicity. These results strengthen the need to take into account a safe(r)-by-design approach in the development of new nanomaterials for research and manufacturing.

Building safe production places can protect workers more effectively than managing risks in a plant that has been conceived without taking into account safety upfront. In this paper, we describe an approach to assessing potential risks already at the stage of design of production processes of nano-enabled products. In a chemical plant, risk results from the combination of hazard of the chemicals and exposure of workers to them. Toxicological profiles of novel nanomaterials, however, are generally unknown; in addition, the impossibility of measuring exposure in a plant that does not exist yet exacerbates the challenge of designing safe production processes. This paper describes a simple method to formulate realistic hypotheses about the toxicity of untested nanoparticles and derives a simplified model of exposure that enables non-specialists (e.g., managers, engineers) to analyze potential risks in projects of future production plants. As an example of analysis of risk in the absence of experimental data, the paper describes the procedure to generate maps of risks of two envisaged production chains of antibacterial textiles: 1) sonochemical synthesis and deposition of bactericidal nanoparticles, and 2) spray deposition of suspension of bactericidal nanoparticles.