The development of polymeric fabrics with photoinduced antibacterial activity is important for different emerging applications, ranging from materials for medical and clinical practices to disinfection of objects for public use. In this work we prepared a series of cellulose acetate membranes, by means of phase inversion technique, introducing different additives in the starting polymeric solution. The loading of 5,10,15,20-tetraphenylporphyrin (TPP), a known photosensitizer, was considered to impart antibacterial photodynamic properties to the produced membranes. Besides, the addition of a surfactant (Pluronic F-127) allowed to modify the morphology of the membranes whereas the use of graphene oxide (GO) enabled further photo-activated antibacterial activity. The three additives were tested in various concentrations and in different combinations in order to carefully explore the effects of their mixing on the final photophysical and photodynamic properties. A complete structural/morphologycal characterization of the produced membranes has been performed, together with a detailed photophysical study of the TPP-containing samples, including absorption and emission features, excited state lifetime, singlet oxygen production, and confocal analysis. Their antibacterial activity has been assessed in vitro against S. aureus and E. coli, and the results demonstrated excellent bacterial inactivation for the membranes containing a combination of the three additives, revealing also a non-innocent role of the membrane porous structure in the final antibacterial capacity.

ABSTRACT: The physico-chemical properties of native oxide layers, spontaneously forming on crystalline Si wafers in air, can be strictly correlated to the dopant type and doping level. In particular, our investigations focused on oxide layers formed upon air exposure in a clean room after Si wafer production, with dopant concentration levels from ?1013 to ?1019 cm-3. In order to determine these correlations, we studied the surface, the oxide bulk, and its interface with Si. The surface was investigated using the contact angle, thermal desorption, and atomic force microscopy measurements which provided information on surface energy, cleanliness, and morphology, respectively. Thickness was measured with ellipsometry and chemical composition with X-ray photoemission spectroscopy. Electrostatic charges within the oxide layer and at the Si interface were studied with Kelvin probe microscopy. Some properties such as thickness, showed an abrupt change, while others, including silanol concentration and Si intermediate-oxidation states, presented maxima at a critical doping concentration of ?2.1 × 1015 cm-3. Additionally, two electrostatic contributions were found to originate from silanols present on the surface and the net charge distributed within the oxide layer. Lastly, surface roughness was also found to depend upon dopant concentration, showing a minimum at the same critical dopant concentration. These findings were reproduced for oxide layers regrown in a clean room after chemical etching of the native ones.

In membrane-based water purification technology, control of the membrane pore structure is fundamental to defining its performance. The present study investigates the effect of the preparation conditions on the final pore size distribution and on the dye removal efficiency of cellulose acetate membranes. The membranes were fabricated by means of phase inversion (using different speeds of film casting and different thicknesses of the casted solution) and introducing modifications in the preparation conditions, such as the use of a coagulation bath instead of pure water and the addition of a surfactant as a solution additive. Both isotropic and anisotropic membranes could be fabricated, and the membranes' pore size, porosity, and water permeability were found to be greatly influenced by the fabrication conditions. The removal capacity towards different types of water contaminants was investigated, considering, as model dyes, Azure A and Methyl Orange. Azure A was removed with higher efficiency due to its better chemical affinity for cellulose acetate, and for both dyes the uptake could be fitted using a pseudo-second order model, evidencing that the rate-limiting step is chemisorption involving valency forces through the sharing or exchange of electrons between the dye and the membrane.

The significant advances in synthesis and functionalization have enabled the preparation of high-quality nanoparticles that have found a plethora of successful applications. The unique physicochemical properties of nanoparticles can be manipulated through the control of size, shape, composition, and surface chemistry, but their technological application possibilities can be further expanded by exploiting the properties that emerge from their assembly. The ability to control the assembly of nanoparticles not only is required for many real technological applications, but allows the combination of the intrinsic properties of nanoparticles and opens the way to the exploitation of their complex interplay, giving access to collective properties. Significant advances and knowledge gained over the past few decades on nanoparticle assembly have made it possible to implement a growing number of strategies for reversible assembly of nanoparticles. In addition to being of interest for basic studies, such advances further broaden the range of applications and the possibility of developing innovative devices using nanoparticles. This review focuses on the reversible assembly of nanoparticles and includes the theoretical aspects related to the concept of reversibility, an up-to-date assessment of the experimental approaches applied to this field and the advanced computational schemes that offer key insights into the assembly mechanisms. We aim to provide readers with a comprehensive guide to address the challenges in assembling reversible nanoparticles and promote their applications.

We herein address the problem of polymorph selection by introducing a general and straightforward concept based on their ordering. We demonstrated the concept by the ordered patterning of four compounds capable of forming different polymorphs when deposited on technologically relevant surfaces. Our approach exploits the fact that, when the growth of a crystalline material is confined within sufficiently small cavities, only one of the possible polymorphs is generated. We verify our method by utilizing several model compounds to fabricate micrometric "logic patterns" in which each of the printed pixels is easily identifiable as comprising only one polymorph and can be individually accessed for further operations.

Here, we exploited the UV light and thermal triggered E <-> Z photoisomerization of an azobenzene compound to fabricate multimodal readable and rewritable data matrix based devices. We first demonstrated that the UV light sensing capabilities can be simultaneously monitored by the change in optical, spectroscopic, and electrical properties. Then we exploited this capability by integrating tetra(azobenzene)methane crystals in a micrometric TAG whose information can be modified and repristinated by local UV treatment and thermal annealing. The system was characterized by polarized optical microscopy, Raman spectroscopy, conductive atomic force microscopy and Kelvin Probe Force Microscopy.

Here, we applied rubbing on thiophene-basedorganic semiconductor thin films to induce a reversible mechanical amorphisation. Amorphisation is associated with fluorescence switching, which is regulated by the polymorphic nature of the film. Thermal annealing of rubbed films produces an opposite effect with respect to rubbing, inducing film crystallization. Notably, thermal crystallisation starts at a low temperature but generates the polymorph stable at a high temperature in the bulk. The mechanism of mechanical transformation is explained considering the mechanical properties of the material and demonstrated through combined X-ray diffraction, atomic force microscopy and photoluminescence at confocal microscopy.

Nanoparticles (NPs) have been studied for biomedical applications, ranging from prevention, diagnosis and treatment of diseases. However, the lack of the basic understanding of how NPs interact with the biological environment has severely limited their delivery efficiency to the target tissue and clinical translation. Here, we show the effective regulation of the surface properties of NPs, by controlling the surface ligand density, and their effect on serum protein adsorption, cellular uptake and cytotoxicity. The surface properties of NPs are tuned through the controlled replacement of native ligands, which favor protein adsorption, with ligands capable of increasing protein adsorption resistance. The extent and composition of the protein layer adsorbed on NPs are strongly correlated to the degree of ligands replaced on their surface and, while BSA is the most abundant protein detected, ApoE is the one whose amount is most affected by surface properties. On increasing the protein resistance, cellular uptake and cytotoxicity in mouse embryonic fibroblasts of NPs are drastically reduced, but the surface coating has no effect on the process by which NPs mainly induce cell death. Overall, this study reveals that the tuning of the surface properties of NPs allows us to regulate their biological outcomes by controlling their ability to adsorb serum proteins. This journal is

Materials possessing long-term antibacterial behavior and high cytotoxicity are of extreme interest in several applications, from biomedical devices to food packaging. Furthermore, for the safeguard of the human health and the environment, it is also stringent keeping in mind the need to gather good functional performances with the development of ecofriendly materials and processes. In this study, we propose a green fabrication method for the synthesis of silver nanoparticles supported on oxidized nanocellulose (ONCs), acting as both template and reducing agent. The complete structural and morphological characterization shows that well-dispersed and crystalline Ag nanoparticles of about 10-20 nm were obtained in the cellulose matrix. The antibacterial properties of Ag-nanocomposites (Ag-ONCs) were evaluated through specific Agar diffusion tests against E. coli bacteria, and the results clearly demonstrate that Ag-ONCs possess high long-lasting antibacterial behavior, retained up to 85% growth bacteria inhibition, even after 30 days of incubation. Finally, cell viability assays reveal that Ag-ONCs show a significant cytotoxicity in mouse embryonic fibroblasts.

Composite materials based on cellulose acetate matrices and porphyrinic photosensitizer (PS) dyes were prepared, characterized and tested as devices with antibacterial activity. Scope of the work is to use light to enable phototoxic bactericidal activity mediated by the production of reactive oxygen species, triggering oxidative damage to pathogens. The materials were fabricated as porous membranes by phase inversion process. Photosensitizers were loaded into the cellulose acetate fabrics as pre-loading, dissolving the dye into the polymer solution before membrane preparation. Different PS loading amounts were explored. We further prepared the fabrics also in the presence of a surfactant or graphene oxide (GO), the latter added to impart mechanical robustness to the final material. We will present the results of the morphological study of the prepared fabrics investigated by scanning electron microscopy and atomic force microscopy. We will further discuss the detailed photophysical characterization of the PS on the fabrics with and without GO performed for the composite materials by means of bulk and spatially resolved techniques. In particular absorption and time-resolved fluorescence data were collected evidencing high PS concentrations caused fluorescence lifetime shortening. Similar effects were observed in the presence of the surfactant. Confocal time-resolved fluorescence lifetime imaging (Figure 1) of the PSloaded fabrics confirmed aggregation phenomena at the basis of the short lifetimes. The most promising fabrics obtained loading the PS in different amounts were used to study the bactericidal effect of the fabrics on S. Aureus bacterial population illuminated with red light.

Subtracting technologies: Unconventional Nanolithography

Herein, we propose an easy and practical method for the fabrication of highly ordered supramolecular structures. The proposed approach combines fractional precipitation and wet lithography, to obtain a spatially-defined pattern of submicrometric structures with a high molecular order of poly(3-hexylthiophene). The process is demonstrated by XRD, confocal and time-resolved spectroscopy and by the performance of an effective field effect transistor.

Here we applied a novel concept of "sublimation-aided nanostructuring" to control the polymorphism of a model material. The process exploits fractional precipitation as a tool for crystallisation in confinement using a templating agent that sublimes away from the system at the end of the process.

Nanomaterials are being widely used in medical applications and consumer products such as cosmetics, fabrics, and food packaging, although their impact on health and the environment is yet to be understood. Strategies enabling reliable and reproducible safety assessment of nanomaterials are needed because predicting their toxic effects is challenging as there is no simple correlation between their properties and the interaction with living systems. Here, the real-time monitoring of toxic effects induced by nanoparticles on cells using organic electrochemical transistors (OECTs) is reported. Noteworthy, OECTs are able to assess the coating-dependent toxicity of nanoparticles on both barrier and non-barrier tissue cells and, moreover, to monitor the cell health status as a function of exposure time, allowing useful insight on the interaction processes between nanomaterials and cells. These results demonstrate that OECTs are effective devices for real-time cell monitoring and in vitro assessment of nanomaterial toxicity.

Polysulfone-based materials were fabricated as casted films, porous membranes, and nanofibers by solution casting, phase inversion process, and electrospinning technique, respectively. Photoactive rhodamine B hydrazide molecules were loaded into the fabrics either in preloading or postloading processes. The morphological structure of the fabrics was investigated by scanning electron microscopy and the wettability was determined by contact angle measurements. Detailed spectroscopic characterizations of the closed and open forms of rhodamine B was performed both in solution and in the solid-state composite materials. Theoretical investigations supported the depiction of the absorption and emission features of the two forms. The response of the prepared composite materials to Cu(II) ions has been tested by absorption and emission spectroscopy and confocal fluorescence imaging. The most effective materials for Cu(II) detection were found to be polysulfone films prepared by phase inversion and postloaded with 10% rhodamine B hydrazide. These results open the way to the development of composite sensory membranes. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48408.

Organic molecular beam deposition has been used to surpass the chemical approach commonly adopted for coating SiO surfaces, obtaining a smooth and uniform monomolecular layer of sexithiophene that fully covers the SiO surface on the centimetre length scale. This result has been achieved by submitting sexithiophene sub-monolayer films grown at different substrate temperatures to a post-deposition annealing process. Through Scanning Probe Microscopy techniques, morphological, tribological and mechanical measurements have highlighted the existence of face-on molecular aggregates on the SiO surface and their re-organization by means of a post-annealing process. Atomistic molecular dynamics simulations complement experimental observations, shedding light on the microscopic aspects of molecular diffusion and aggregates reorganization. Exploiting the molecular reorganization upon post-annealing, almost perfect 6 T monolayers were grown through a sequence of deposition and annealing steps. This preparation technique represents a new route for changing surface properties by using high controlled monomolecular layers.

Current technologies to monitor formation and disruption in in vitro cell cultures are based either on optical techniques or on electrical impedance/resistance measurement, which often rely on cumbersome and time-consuming measurements and data analyses. In this paper, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)-based organic electrochemical transistors (OECTs) are proposed with channel areas specifically designed and dimensioned as fast and real-time monitoring devices for a large variety of cell lines, with a broad range of tissue resistance. In particular, it is investigated how and why two device configurations provide a different response to leaky-barrier (NIH-3T3) and strong-barrier (CaCo-2) cell lines growth and detachment, achieving a continuous monitoring also for leaky-barrier cell layer growth and detachment. Data are collected using the transistor dynamic behavior to a DC potential pulse on the gate, providing an excellent time resolution and thus enhancing the amount of information that can be collected for fast biological processes (<5 s).

Here, we present a suitable advancement of parallel local oxidation nanolithography, demonstrating its feasibility in alternate current mode (AC-PLON). For demonstration, we fabricated model structures consisting of an array of parallel nanostripes of electrochemical SiOx with a controlled roughness. Besides, we proved the repeatability of AC-PLON and its integrability with conventional parallel local oxidation nanolithography.

The increasing scarcity of freshwater sources and the global demand for water is expected to grow in the oncoming decades which urge the need to develop alternative water supplies, including reuse and recycling of wastewater. Membrane-based separation for water treatment is playing an increasingly important role to provide adequate water resources of the desirable quality. H2020-MSCA-IF-project "Enhanced-MUMs" targets the development of advanced multifunctional and low-cost polymeric membranes for water treatment and desalination. The current work represents optimization of the preparation conditions of cellulose acetate membranes by phase inversion technique using automatic film applicator and water as a coagulation medium. The prepared bare membranes have a well-defined anisotropic microscopic structure with a pure water flux range from 150 L/m2.h to 990 L/m2.h using different membrane thicknesses and under different applied pressures. Modified membranes have been prepared using salt coagulation bath as well as in-situ salt addition to the polymer solution during the membrane fabrication. It was found that the preparation conditions greatly affect the microscopic and surface characteristics.The prepared membranes under different conditions were investigated for the separation organic dyes from their aquose solutions either by absorption or by rejection. Cationic and anionic dye models were investigated to understand the mechanism of the separation process. Other aims of the project are to improve the microscopic structure with regard to the pore size and structure and improve the mechanical properties of the modified membranes. In addition, the project aims also to study and control the fouling characteristics of the membranes by imparting photo-induced properties for enhanced antimicrobial and antifouling effects.

Access to clean water continues to be the most urgent and pressing global issue. The increasing scarcity of freshwater sources and the global demand for water is expected to grow in the oncoming decades which urge the need to develop alternative water supplies, including seawater desalination, reuse and recycling of wastewater. Membrane-based separations for water treatment and desalination are playing an increasingly important role to provide adequate water resources of desirable quality for a wide spectrum of designated applications. H2020-MSCA-IF-project "Enhanced-MUMs" targets the development of advanced multifunctional and low-cost polymeric membranes for water treatment and desalination. The project is a multidisciplinary one and its main innovation resides in the combination of (1) enhanced structural properties: high porosity and reinforcement, for improved water treatment and desalination characteristics and (2) light-induced antifouling and antimicrobial activity based on the loading of photosensitizers in the polymeric membrane. The current work represents optimization of the preparation conditions of cellulose acetate membranes by phase inversion technique using automatic film applicator and water as a coagulation medium. The prepared bare membranes have a well-defined anisotropic microscopic structure with a pure water flux range from 150 L/m2.h to 990 L/m2.h using different membrane thickness and under different applied pressure. Modified membranes have been prepared using salt coagulation bath as well as in-situ salt addition to the polymer solution during the membrane fabrication. It was found that the preparation conditions greatly affect the microscopic and surface characteristics. The project also aims to: improve the microscopic structure with regard to the pore size and structure and improve the mechanical properties of the modified membranes. In addition, the project aims also to study and control the fouling characteristics of the membranes by imparting photo-induced properties for enhanced antimicrobial and antifouling effects.