1,721,213 research outputs found
Nickel ferrite nanoparticles for simultaneous use in magnetic resonance imaging and magnetic fluid hyperthermia
Full text linkWe demonstrate magnetic resonance imaging (MRI) contrast enhancement and ac-field induced heating abilities of tetramethylammoniumhydroxide (TMAH) coated nickel ferrite (NiFe2O4) nanoparticles and discuss the underlying physical mechanisms. The structural characterization revealed that the NiFe2O4 particles synthesized with a modified co-precipitation method have a very narrow size distribution with a 4.4 nm magnetic core and 15 nm hydrodynamic diameters, with relatively small fraction of agglomerates. The as-prepared particles presented superparamagnetic behavior at room temperature. The in vitro hyperthermia experiments, performed in ac-field conditions under human tolerable limits, showed that the suspensions of the synthesized nanoparticles exhibit a maximum specific absorption rate (SAR) value of 11 W/g. The 1H nuclear magnetic resonance (NMR) relaxometry measurements indicated the suspensions of NiFe2O4 have a transverse-to-longitudinal relaxivity ratio r2/r1 greater than two, as required for superparamagnetic MRI contrast agents. On the basis of the parameters obtained from the magnetic measurements, by comparing the relevant theoretical models with the experimental results, we found that the presence of agglomerates, and particularly the interactions within the agglomerated nanoparticles, caused a significant increase in the hyperthermia and MRI efficiencies. On the other hand, from an applicative point of view, both the MRI contrast enhancement and the heating capabilities allow the simultaneous use of nickelferrites in diagnostic and therapeutic applications as theranostic agents
New Methodologies for the Conservation of Cultural Heritage: Micellar Solutions, Microemulsions, and Hydroxide Nanoparticles
No full textModern civilization’s inherited artworks have a powerful impact on society, from political, sociological, and anthropological points of view, so the conservation of our Cultural Heritage is fundamental for conveying to future generations our culture, traditions, and ways of thinking and behaving. In the conservation of cultural artifacts, scientists intervene in the degradation of often unique handcrafts, resulting from a delicate balance of aging, unpredicted events, environmental conditions, and sometimes incorrect previous restoration treatments, the details of which are often not precisely known.
Nanoscience and nanotechnology are revolutionizing materials science in a pervasive way, in a manner similar to polymer chemistry’s revolution of materials science over the preceding century. The continuous development of novel nanoparticle-based materials and the study of physicochemical phenomena at the nanoscale are creating new approaches to conservation science, leading to new methodologies that can “revert” the degradation processes of the works of art, in most cases “restoring” them to their original magnificent appearance.
Until recently, serendipity and experiment have been the most frequent design principles of formulations for either cleaning or consolidation of works of art. Accordingly, the past has witnessed a number of actively detrimental treatments, such as the application of acrylic and vinyl resins to wall paintings, which can irreversibly jeopardize the appearance (or even the continued existence) of irreplaceable works of art. Current research activity in conservation science is largely based on the paradigm that compatibility of materials is the most important prerequisite for obtaining excellent and durable results.
The most advanced current methodologies are (i) the use of water-based micelles and microemulsions (neat or combined with gels) for the removal of accidental contaminants and polymers used in past restorations and (ii) the application of calcium hydroxide nanoparticles for the consolidation of works of art. In this Account, we highlight how conservation science can benefit from the conceptual and the methodological background derived from both soft (micro- emulsions and micelles for cleaning) and hard (nanoparticles for consolidation) nanoscience.
A combination of different nanotechnologies allows today’s conservators to provide, in each restoration step, interventions respectful of the physicochemical characteristics of the materials used by artists. The “palette” of methods provided by nanoscience is continuously enriching the field, and the development of novel nanomaterials and the study of nanoscale physicochemical phenomena will further improve the performance of restoration formulations and our comprehension of degradation mechanism
Interaction of nanoparticles with lipid membranes: a multiscale perspective
No full textFreestanding lipid bilayers were challenged with 15 nm Au nanospheres either coated by a citrate layer or passivated by a protein corona. The effect of Au nanospheres on the bilayer morphology, permeability and fluidity presents strong differences or similarities, depending on the observation length scale, from the colloidal to the molecular domains. These findings suggest that the interaction between nanoparticles and lipid membranes should be conveniently treated as a multiscale phenomenon
Nanostructured Surfactant-Based Systems for the Removal of Polymers from Wall Paintings: A Small-Angle Neutron Scattering Study
No full textNanostructured soft matter systems represent effective and long-lasting solutions with respect to traditional and often obsolete methodologies for the conservation of works of art. In particular, complex fluids such as micelles and microemulsions are the most performing media for the removal of organic materials from porous supports, like wall paintings or stones. In this Article, we report on the characterization of two systems, EAPC and XYL, which have shown good to optimal performances in the removal of organic polymers from wall paintings. EAPC is a five-components fluid composed of water, sodium dodecylsulfate (SDS), 1-pentanol (PeOH), propylene carbonate (PC), and ethyl acetate (EA), while XYL is a “classical” o/w microemulsion, where p-xylene droplets are stabilized in water by SDS and PeOH. Small-angle neutron scattering (SANS) with contrast variation is used to infer a detailed picture of the structure of these complex fluids, with a particular focus on the partition of the components between the bulk phase and the nanocompartments. We found that, differently from XYL, the EAPC system is neither a microemulsion nor a simple micellar solution, with the cosolvents partitioned between the dispersing phase and the disperse droplets. These different structural features play a key role in defining the cleaning effectiveness and specifically the kinetics of interaction between the nanofluid and the polymeric coating to be removed, which is of paramount importance for the application in the field. Both of these nanofluids are effective in polymer removal, but EAPC is considerably more efficient and versatile. The composition and the structure at the nanoscale determine the capability of removing a broad range of different polymer coatings from porous materials. A representative case study is here described, addressing a particularly challenging conservative issue, which is the removal of a multilayered aged coating that was irreversibly damaging the pictorial layer of the Annunciation Basilica in Nazareth
Smart cleaning of cultural heritage: a new challenge for soft nanoscience
No full textThe search for innovative, smart and performing cleaning agents is one of the main issues of modern
conservation science. Nanosciences do not only provide solutions to this scientific field in terms of new
materials but also change radically the approach to problems and challenges. In this feature article we
review the most innovative nanostructured systems developed in the last decade for the cleaning of
artworks together with some noteworthy case studies. Micelles, microemulsions, thickened complex
fluids, and responsive gels that constitute the new ‘‘cleaning palette’’ for modern conservators are here
presented and critically analyzed. The development of these smart nanostructured systems requires the
comprehension of their behavior and interactions with other materials down to the nanoscale. In the
last section of this manuscript we report on the most recent results from a study about the mechanism of
polymer removal from porous artifacts using nanofluids, such as micelles or microemulsions. The rules
of classical detergency do not fully address the polymer removal mechanism and a schematic model of
the process is proposed
Chapter 13 Soft Hybrid Nanostructures Composed of Phospholipid Liposomes Decorated with Oligonucleotides
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Polymer films removed from solid surfaces by nanostructured fluids: Microscopic mechanism and implications for the conservation of cultural heritage
No full textComplex fluids based on amphiphilic formulations are emerging, particularly in the field of conservation of works of art, as effective and safe liquid media for the removal of hydrophobic polymeric coatings. The comprehension of the cleaning mechanism is key to designing tailored fluids for this purpose. However, the interaction between nanostructured fluids and hydrophobic polymer films is still poorly understood. In this study, we show how the combination of confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) provides interesting and complementary insight into this process. We focused on the interaction between an ethyl methacrylate/methyl acrylate 70:30 copolymer film deposited onto a glass surface and a water/nonionic surfactant/2-butanone (MEK) ternary system, with MEK being a good solvent and water being a nonsolvent for the polymer. Our results indicate a synergy between the organic solvent and the surfactant assemblies: MEK rapidly swells the outer layers of the polymer film allowing for the subsequent diffusion of solvent molecules, while the amphiphile decreases the interfacial energy between the polymeric coating and the liquid phase, favoring dewetting and dispersion of swollen polymer droplets in the aqueous phase. The chemical nature of the surfactant and the microstructure of the assemblies determine both the kinetics and the overall efficiency of polymer removal, as assessed by comparing the behavior of similar formulations containing an anionic surfactant (sodium dodecyl sulfate, SDS)
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