Tailoring properties and functionalities of TiO2 and Ag nanoparticles involved in surfaces engineering processes

The functionalization of substrates through the application of nanostructured coatings allows to create new materials, with enhanced properties. In this work, the development of self-cleaning and antibacterial textiles, through the application of TiO2 and Ag based nanostructured coatings was carried out. The production of TiO2 and Ag functionalized materials was achieved both by the classical dip-padding-curing method and by the innovative electrospinning process to obtain nanofibers doped with nano-TiO2 and nano-Ag. In order to optimize the production of functionalized textiles, the study focused on the comprehension of mechanisms involved in the photocatalytic and antibacterial processes and on the real applicability of the products. In particular, a deep investigation on the relationship between nanosol physicochemical characteristics, nanocoating properties and their performances was accomplished. Self-cleaning textiles with optimized properties were obtained by properly purifying and applying commercial TiO2 nanosol while the studies on the photocatalytic mechanism operating in self-cleaning application demonstrated the strong influence of hydrophilic properties and of interaction surface/radicals on final performance. Moreover, a study about the safety in handling of nano-TiO2 was carried out and risk remediation strategies, based on “safety by design” approach, were developed. In particular, the coating of TiO2 nanoparticles by a SiO2 shell was demonstrated to be the best risk remediation strategy in term of biological response and preserving of photoreactivity. The obtained results were confirmed determining the reactive oxygen species production by a multiple approach. Antibacterial textiles for biotechnological applications were also studied and Ag-coated cotton materials, with significant anti-bacterial properties, were produced. Finally, composite nanofibers were obtained merging biopolymer processing and sol-gel techniques. Indeed, electrospun nanofibers embedded with TiO2 and Ag NPs, starting from aqueous keratin based formulation were produced and the photocatalytic and antibacterial properties were assessed. The results confirmed the capability of electrospun keratin nanofibers matrix to preserve nanoparticle properties

Assessing occupational risk in designs of production processes of nano-materials

Abstract 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

Encapsulation of cationic iridium(iii) tetrazole complexes into a silica matrix: Synthesis, characterization and optical properties

Herein we report the easy incorporation of brightly phosphorescent cationic iridium(iii) tetrazole complexes into a silica based matrix via an easily scalable colloidal process. For this purpose, two cationic Ir(iii) emitters bearing 5-aryl tetrazole ligands (R-CN4) were selected: blue [F2IrPTZ-Me]+(C^N = F2ppy; N^N = PTZ-Me-2-(2-methyl-2H-tetrazol-5-yl)pyridine) and red [IrQTZ-Me]+(C^N = ppy; N^N = QTZ-Me-2-(2-methyl-2H-tetrazol-5-yl)quinoline). The cationic complexes were readily adsorbed to negatively charged silica nanoparticles and trapped in the sol-gel matrix. The sol-to-solid phase transfer was performed by using an innovative spray-freeze-drying technique, leading to the formation of phosphorescent solid micro-granules. The structural and optical characterisation of the Ir(iii) complexes together with SiO2nanoparticles, nanosols (Ir@SiO2) and powders (Ir@SiO2powders), revealed how the presence of the Ir(iii)-based complexes did not alter the morphology of the colloidal silica or granulated phases. Moreover, the silica matrix did not interfere with the optical properties of the embedded complexes. The distribution of [F2IrPTZ-Me]+and [IrQTZ-Me]+in the spray-freeze-dried powders was qualitatively evaluated by fluorescence microscopy, revealing how the luminescent particles were homogeneously dispersed all over the silica matrix. Interestingly, in aqueous solution the release of complex [F2IrPTZ-Me]+from the corresponding Ir@SiO2powder is almost negligible, therefore suggesting that a strong interaction occurs between the host-silica matrix and the Ir(iii) guest complex

TiO2@BSA nano-composites investigated through orthogonal multi-techniques characterization platform.

Abstract Biocompatible coating based on bovine serum albumin (BSA) was applied on two different TiO2 nanoparticles (aeroxide P25 and food grade E171) to investigate properties and stability of resulting TiO2@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 TiO2 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

Hollow-fiber flow field-flow fractionation and multi-angle light scattering investigation of the size, shape and metal-release of silver nanoparticles in aqueous medium for nano-risk assessment

open11siAvailable online 22 November 2014 The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) through the project SANOWORK under Grant Agreement no. 280716. The HRTEM has been made available under the INSPIRE programme, funded by Irish Government's Programme for Research in Third Level Institutions, Cycle 4, National Development Plan 2007–2013, which is supported by European Union Structural Fund. Drs. Abbasi Gandhi and Vishnu Mogili of the University of Limerick are acknowledged for generating HRTEM data.Due to the increased use of silver nanoparticles in industrial scale manufacturing, consumer products and nanomedicine reliable measurements of properties such as the size, shape and distribution of these nano particles in aqueous medium is critical. These properties indeed affect both functional properties and biological impacts especially in quantifying associated risks and identifying suitable risk-mediation strategies. The feasibility of on-line coupling of a fractionation technique such as hollow-fiber flow field flow fractionation (HF5) with a light scattering technique such as MALS (multi-angle light scattering) is investigated here for this purpose. Data obtained from such a fractionation technique and its combination thereof with MALS have been compared with those from more conventional but often complementary techniques e.g. transmission electron microscopy, dynamic light scattering, atomic absorption spectroscopy, and X-ray fluorescence. The combination of fractionation and multi angle light scattering techniques have been found to offer an ideal, hyphenated methodology for a simultaneous size-separation and characterization of silver nanoparticles. The hydrodynamic radii determined by fractionation techniques can be conveniently correlated to the mean average diameters determined by multi angle light scattering and reliable information on particle morphology in aqueous dispersion has been obtained. The ability to separate silver (Ag+) ions from silver nanoparticles (AgNPs) via membrane filtration during size analysis is an added advantage in obtaining quantitative insights to its risk potential. Most importantly, the methodology developed in this article can potentially be extended to similar characterization of metal-based nanoparticles when studying their functional effectiveness and hazard potential.partially_openembargoed_20151122Marassi, Valentina; Casolari, Sonia; Roda, Barbara; Zattoni, Andrea; Reschiglian, Pierluigi; Panzavolta, Silvia; Tofail, Syed A.M.; Ortelli, Simona; Delpivo, Camilla; Blosi, Magda; Costa, Anna LuisaMarassi, Valentina; Casolari, Sonia; Roda, Barbara; Zattoni, Andrea; Reschiglian, Pierluigi; Panzavolta, Silvia; Tofail, Syed A.M.; Ortelli, Simona; Delpivo, Camilla; Blosi, Magda; Costa, Anna Luis

Native Study of the Behaviour of Magnetite Nanoparticles for Hyperthermia Treatment during the Initial Moments of Intravenous Administration

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

Insulating Thermal and Water-Resistant Hybrid Coating for Fabrics

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

TiO2 Nanosols Applied Directly on Textiles Using Different Purification Treatments

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