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1.
Nanomaterials (Basel) ; 14(6)2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38535702

RESUMO

High-entropy alloys (HEAs) are a class of metal alloys consisting of four or more molar equal or near-equal elements. HEA nanomaterials have garnered significant interest due to their wide range of applications, such as electrocatalysis, welding, and brazing. Their unique multi-principle high-entropy effect allows for the tailoring of the alloy composition to facilitate specific electrochemical reactions. This study focuses on the synthesis of high-purity HEA nanoparticles using the method of femtosecond laser ablation synthesis in liquid. The use of ultrashort energy pulses in femtosecond lasers enables uniform ablation of materials at significantly lower power levels compared to longer pulse or continuous pulse lasers. We investigate how various femtosecond laser parameters affect the morphology, phase, and other characteristics of the synthesized nanoparticles. An innovative aspect of our solution is its ability to rapidly generate multi-component nanoparticles with a high fidelity as the input multi-component target material at a significant yielding rate. Our research thus focuses on a novel synthesis of high-entropy alloying CuCoMn1.75NiFe0.25 nanoparticles. We explore the characterization and unique properties of the nanoparticles and consider their electrocatalytic applications, including high power density aluminum air batteries, as well as their efficacy in the oxygen reduction reaction (ORR). Additionally, we report a unique nanowire fabrication phenomenon achieved through nanojoining. The findings from this study shed light on the potential of femtosecond laser ablation synthesis in liquid (FLASiL) as a promising technique for producing high-purity HEA nanoparticles.

2.
Materials (Basel) ; 16(6)2023 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-36984315

RESUMO

The synthesis of contaminant-free silver@linear carbon chains (Ag@LCCs) nanohybrid systems, at different Ag/LCCs ratios, by pulsed laser ablation was studied. The ablation products were first characterized by several diagnostic techniques: conventional UV-Vis optical absorption and micro-Raman spectroscopies, as well as scanning electron microscopy, operating in transmission mode. The experimental evidence was confirmed by the theoretical simulations' data. Furthermore, to gain a deeper insight into the factors influencing metal@LCCs biological responses in relation to their physical properties, in this work, we investigated the bioproperties of the Ag@LCCs nanosystems towards a wound-healing activity. We found that Ag@LCC nanohybrids maintain good antibacterial properties and possess a better capability, in comparison with Ag NPs, of interacting with mammalian cells, allowing us to hypothesize that mainly the Ag@LCCs 3:1 might be suitable for topical application in wound healing, independent of (or in addition to) the antibacterial effect.

4.
Materials (Basel) ; 15(10)2022 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-35629727

RESUMO

Gold nanoparticles (Au NPs) have received great attention owing to their biocompatible nature, environmental, and widespread biomedical applications. Au NPs are known as capable to regulate inflammatory responses in several tissues and organs; interestingly, lower toxicity in conjunction with anti-inflammatory effects was reported to occur with Au NPs treatment. Several variables drive this benefit-risk balance, including Au NPs physicochemical properties such as their morphology, surface chemistry, and charge. In our research we prepared hybrid Au@LCC nanocolloids by the Pulsed Laser Ablation, which emerged as a suitable chemically clean technique to produce ligand-free or functionalized nanomaterials, with tight control on their properties (product purity, crystal structure selectivity, particle size distribution). Here, for the first time to our knowledge, we have investigated the bioproperties of Au@LCCs. When tested in vitro on intestinal epithelial cells exposed to TNF-α, Au@LCCs sample at the ratio of 2.6:1 showed a significantly reduced TNF gene expression and induced antioxidant heme oxygenase-1 gene expression better than the 1:1 dispersion. Although deeper investigations are needed, these findings indicate that the functionalization with LCCs allows a better interaction of Au NPs with targets involved in the cell redox status and inflammatory signaling.

5.
Data Brief ; 38: 107306, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34466636

RESUMO

This data paper reports data obtained from the fitting of Raman spectra obtained during a laser reduction process for graphene oxide under different processing and material conditions. In particular, we show examples of fitting curves of three different representative reduced graphene oxide spectra, as well as fitting curves for a graphene oxide spectrum. Moreover, we show and compare cumulative distributions of the ID/IG values (intensity ratio of peaks D and G) obtained from spectra acquired from different samples. Fittings and distributions were obtained using the OriginPro 8.5 software package. Such data may be the starting point of further experiments on the laser induced reduction of graphene oxide.

6.
Materials (Basel) ; 14(13)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34279246

RESUMO

In this work, raw halloysite mineral from Dunino (Poland) has been characterized and tested as an efficient and low-cost adsorbent for dye removal from water. The morphology and structure of this clay were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and the chemical composition was evaluated by means of X-ray fluorescence spectroscopy (XRF), energy dispersive X-ray spectroscopy (EDX), and electron energy loss spectroscopy (EELS). The results showed that it is made up of both platy and tubular structures, mainly composed of Si, Al, and O. Iron oxide particles covering the platy structures were also observed. The surface charge of halloysite was measured by z-potential measurements and by the evaluation of the point of zero charge. The clay was tested as an adsorbent for the removal of positively and negatively charged dye molecules, i.e., methylene blue (MB) and methyl orange (MO), both separately and in a mixed-dye solution. Halloysite showed the ability to efficiently and selectively remove MB molecules by adsorption, both in a single-dye solution and in a mixed one. The adsorption of positive dyes on the clay surface mainly occurred through ion exchange at negatively charged sites on its surface. The possibility of regenerating the clay for further dye removal processes is also shown.

7.
Nanomaterials (Basel) ; 10(11)2020 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-33238455

RESUMO

Laser synthesis emerges as a suitable technique to produce ligand-free nanoparticles, alloys and functionalized nanomaterials for catalysis, imaging, biomedicine, energy and environmental applications. In the last decade, laser ablation and nanoparticle generation in liquids has proven to be a unique and efficient technique to generate, excite, fragment and conjugate a large variety of nanostructures in a scalable and clean way. In this work, we give an overview on the fundamentals of pulsed laser synthesis of nanocolloids and new information about its scalability towards selected applications. Biomedicine, catalysis and sensing are the application areas mainly discussed in this review, highlighting advantages of laser-synthesized nanoparticles for these types of applications and, once partially resolved, the limitations to the technique for large-scale applications.

8.
Chemistry ; 26(42): 9206-9242, 2020 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-32311172

RESUMO

Although oxide nanoparticles are ubiquitous in science and technology, a multitude of compositions, phases, structures, and doping levels exist, each one requiring a variety of conditions for their synthesis and modification. Besides, experimental procedures are frequently dominated by high temperatures or pressures and by chemical contaminants or waste. In recent years, laser synthesis of colloids emerged as a versatile approach to access a library of clean oxide nanoparticles relying on only four main strategies running at room temperature and ambient pressure: laser ablation in liquid, laser fragmentation in liquid, laser melting in liquid and laser defect-engineering in liquid. Here, established laser-based methodologies are reviewed through the presentation of a panorama of oxide nanoparticles which include pure oxidic phases, as well as unconventional structures like defective or doped oxides, non-equilibrium compounds, metal-oxide core-shells and other anisotropic morphologies. So far, these materials showed several useful properties that are discussed with special emphasis on catalytic, biomedical and optical application. Yet, given the endless number of mixed compounds accessible by the laser-assisted methodologies, there is still a lot of room to expand the library of nano-crystals and to refine the control over products as well as to improve the understanding of the whole process of nanoparticle formation. To that end, this review aims to identify the perspectives and unique opportunities of laser-based synthesis and processing of colloids for future studies of oxide nanomaterial-oriented sciences.

9.
Sci Total Environ ; 718: 137457, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32325618

RESUMO

We report the presence of microplastics on the external surface and in the gastrointestinal tract of white late-larval and juvenile stages (fry) of clupeid fishes caught in the Southern Tyrrhenian Sea. The average highest number of plastics debris was recorded on Sardina pilchardus (0.53 items/specimen); a lower average number of items was observed for Engraulis encrasicolus (0.26 items/specimen). The plastics were characterized by fibers that differed in shape, colour and composition. Polyester, polypropylene, polyacrylonitrile, polyethylene, polyamide, nylon, rayon and polyurethane segments were detected by Raman and FTIR spectroscopies. Traces of organic components and dyes, compounds that are generally included in the polymer matrix to modify its base properties, were also identified on microplastics. Our results raise concerns for the potential transfer of synthetic materials through the marine food web and into humans, given the prominent role of S. pilchardus and E. encrasicolus within the food web as main food source for many marine species.


Assuntos
Peixes , Animais , Monitoramento Ambiental , Cadeia Alimentar , Larva , Plásticos , Poluentes Químicos da Água
10.
Eur Biophys J ; 49(2): 175-191, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32123956

RESUMO

Protein misfolding and subsequent self-association are complex, intertwined processes, resulting in development of a heterogeneous population of aggregates closely related to many chronic pathological conditions including Type 2 Diabetes Mellitus and Alzheimer's disease. To address this issue, here, we develop a theoretical model in the general framework of linear stability analysis. According to this model, self-assemblies of peptides with pronounced conformational flexibility may become, under particular conditions, unstable and spontaneously evolve toward an alternating array of partially ordered and disordered monomers. The predictions of the theory were verified by atomistic molecular dynamics (MD) simulations of islet amyloid polypeptide (IAPP) used as a paradigm of aggregation-prone polypeptides (proteins). Simulations of dimeric, tetrameric, and hexameric human-IAPP self-assemblies at physiological electrolyte concentration reveal an alternating distribution of the smallest domains (of the order of the peptide mean length) formed by partially ordered (mainly ß-strands) and disordered (turns and coil) arrays. Periodicity disappears upon weakening of the inter-peptide binding, a result in line with the predictions of the theory. To further probe the general validity of our hypothesis, we extended the simulations to other peptides, the Aß(1-40) amyloid peptide, and the ovine prion peptide as well as to other proteins (SOD1 dimer) that do not belong to the broad class of intrinsically disordered proteins. In all cases, the oligomeric aggregates show an alternate distribution of partially ordered and disordered monomers. We also carried out Surface Enhanced Raman Scattering (SERS) measurements of hIAPP as an experimental validation of both the theory and in silico simulations.


Assuntos
Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Desnaturação Proteica , Dobramento de Proteína , Coloides/química , Simulação por Computador , Eletrólitos , Humanos , Cinética , Modelos Teóricos , Simulação de Dinâmica Molecular , Peptídeos/química , Multimerização Proteica , Estrutura Secundária de Proteína , Reprodutibilidade dos Testes , Solventes , Análise Espectral Raman , Termodinâmica
11.
Mar Pollut Bull ; 146: 408-416, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31426175

RESUMO

The present study investigates the occurrence of plastic pollution in two commercially important marine teleosts (Zeus faber and Lepidopus caudatus) from the northern coasts of Sicily (Tyrrhenian Sea). Plastics occurrence in the gastrointestinal tract was higher in Lepidopus caudatus (78.1%) than Zeus faber (51.4%). Debris characterization, carried out by micro-Raman spectroscopy, allowed identified the main types of found polymers as: polypropylene (PP), polyamide (PA), nylon and, to a lesser extent, polyethylene (PE). Of the two fish species studied, the silver scabbardfish appeared to be the more vulnerable to plastic ingestion. Our study represents a starting point that may pave the way for future investigation of the fate, accumulation and transfer of plastic debris to upper trophic levels, to verify their potential toxicity and to better understand strategies to mitigate this phenomenon.


Assuntos
Trato Gastrointestinal/química , Perciformes , Plásticos/análise , Poluentes Químicos da Água/análise , Animais , Exposição Dietética/análise , Monitoramento Ambiental/métodos , Mar Mediterrâneo , Plásticos/química , Sicília , Análise Espectral Raman , Resíduos/análise , Poluentes Químicos da Água/química
12.
Data Brief ; 23: 103798, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31372443

RESUMO

In this data paper we share the absorption spectrum of Ag NP ablated in pure water and in presence of trisodium citrate (TSC). We also share the full emission spectrum of the irradiation lamp used for the reshaping process described in the related research paper. The data is related to the research article "Plasmon Sensing and enhancement of laser prepared silver colloids" [1].

13.
Sci Total Environ ; 691: 455-465, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31323590

RESUMO

Pollution deriving from textile wastes, including industrial and household waste, is recently of great interest due to their environmental impacts. Anthropogenic and synthetic fibers are responsible for negative effects on the quality of water and soil, and, also, their presence damages plant and animal health. In this work, the authors revealed the occurrence of man-made cellulose fibers in specimens of Boops boops from the Northern Sicilian coasts. Bogue was chosen as target species as it has been used as an indicator within the European Marine Strategy Framework Directive (MSFD 2008/56/EC) in order to value the "microplastics status" in the stomach contents. Of the 30 specimens examined, 63.3% of these had ingested fibers items. The number of fibers ranged from 1 to 10 per specimens with an average of 2.7 items/specimen. Fibers length ranged from 0.5 to 30 mm, most of them were black (95%), and a small percentage was red (5%). The ingestion of man-made cellulose fibers, observed for the first time, in Boops boops in the Mediterranean Sea wake-up call and it should attract the attention of the EU for new guidelines where this new type of contaminant is classified harmful as well as plastics.


Assuntos
Monitoramento Ambiental , Perciformes , Plásticos/análise , Poluentes da Água/análise , Animais , Conteúdo Gastrointestinal , Mar Mediterrâneo , Sicília
14.
Phys Chem Chem Phys ; 20(31): 20588-20596, 2018 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-30059089

RESUMO

We report a structural investigation on IAPP, Aß(1-40) and their equi-molar mixture aggregation pathway at nano-molar concentration using the Surface Enhanced Raman Spectroscopy (SERS) effect induced by silver metal colloids prepared by laser processes in solution and molecular dynamics simulations. Our data show the ability of silver NPs coupled with SERS to detect secondary structures of IAPP, Aß(1-40) and their 1 : 1 molar ratio mixture in the oligomeric state. The preparation of silver colloids shows superior performance with respect to chemically prepared nano-particles. SERS spectroscopy shows both selectivity and sensitivity in detecting the secondary structures of hIAPP and Aß(1-40) and to recognize both proteins in their mixture. On the other hand, molecular dynamics simulations confirm SERS structural data and the given atomistic details about the structural organization of IAPP and Aß(1-40) oligomers. Our study shows an inhomogeneity in the chemical composition of IAPP/Aß(1-40) oligomer aggregates.

15.
Phys Chem Chem Phys ; 19(32): 21759-21768, 2017 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-28782765

RESUMO

Laboratory experiments have shown that the energetic processing, i.e. ion bombardment and UV photolysis, of interstellar grain mantles and cometary surfaces is efficient in the production of formamide. To explain its presence in the gas-phase in these astrophysical environments, a desorption mechanism has to be taken into account. In this work we show experimental results on the thermal evolution of formamide when deposited at 17 K as pure and in mixture with water or carbon monoxide. In these samples, we observed formamide desorption at 220 K. Moreover, we discuss its synthesis in a mixture containing molecular nitrogen, methane and water (N2:CH4:H2O) deposited at 17 K and bombarded with 200 keV H+. Heating the sample, we observed that the newly formed formamide remains trapped in the refractory residue produced after the ion bombardment up to 296 K. To analyse the samples we used Fourier transform-infrared spectroscopy (FT-IR) that allowed us to study the infrared spectra between the deposition and the complete desorption of formamide. Here we discuss the experimental results in view of their astrophysical relevance.

16.
J Colloid Interface Sci ; 489: 131-137, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-27554175

RESUMO

We have measured the photocatalytic water splitting activity of several titania colloids, modified by nanosecond pulsed laser irradiation. Photocatalysis has been tested using UV and visible light. We have found that laser irradiation increases the hydrogen production efficiency up to a factor of three for anatase, rutile and P25. A hydrogen production rate as high as 30mmolg-1h-1 has been obtained with good stability, tested by repeated runs. The chemical and morphological properties of the nanoparticles have been studied by electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy, showing that laser irradiation promotes the formation of disordered surface state and lattice distortion which could be responsible for the observed enhanced photocatalytic activity.

17.
Nanotechnology ; 27(24): 245704, 2016 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-27158973

RESUMO

The antibacterial activity and possible toxicity of graphene oxide and laser-irradiated graphene oxide (iGO) were investigated. Antibacterial activity was tested on Escherichia coli and shown to be higher for GO irradiated for at least three hours, which seems to be correlated to the resulting morphology of laser-treated GO and independent of the kind and amount of oxygen functionalities. X-ray photoelectron spectroscopy, Raman spectroscopy, dynamic light scattering and scanning electron microscopy (SEM) show a reduction of the GO flakes size after visible laser irradiation, preserving considerable oxygen content and degree of hydrophilicity. SEM images of the bacteria after the exposure to the iGO flakes confirm membrane damage after interaction with the laser-modified morphology of GO. In addition, a fish embryo toxicity test on zebrafish displayed that neither mortality nor sublethal effects were caused by the different iGO solutions, even when the concentration was increased up to four times higher than the one effective in reducing the bacteria survival. The antibacterial properties and the absence of toxicity make the visible laser irradiation of GO a promising option for water purification applications.


Assuntos
Grafite/química , Animais , Antibacterianos , Escherichia coli , Óxidos , Análise Espectral Raman
18.
J Phys Chem B ; 119(14): 4898-904, 2015 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-25781213

RESUMO

Cysteine is a sulfur-containing amino acid that easily coordinates to soft metal ions and grafts to noble metal surfaces. Recently, chiroptical activity of Ag(+)/cysteine coordination polymers has been widely studied, while, on the other hand, the appearance of a plasmon-enhanced circular dichroic signal (PECD) at the plasmonic spectral region (λ > 400 nm) has been observed for AgNPs capped with chiral sulfur-containing amino acids. These two events are both potentially exploited for sensing applications. However, the presence of Ag(+) ions in AgNP colloidal solution deals with the competition of cysteine grafting at the metal NP surface and/or metal ion coordination. Herein we demonstrate that the chiroptical activity observed by adding cysteine to AgNP colloids prepared by pulsed laser ablation in liquids (PLAL) is mainly related to the formation of CD-active Ag(+)/cysteine supramolecular polymers. The strict correlation between supramolecular chirality and hierarchical effects, driven by different chemical environments experienced by cysteine when different titration modalities are used, is pivotal to validate cysteine as a fast and reliable probe to characterize the surface oxidation of AgNPs prepared by pulsed laser ablation in liquids by varying the laser wavelengths.


Assuntos
Complexos de Coordenação/química , Cisteína/química , Polímeros/química , Prata/química , Nanopartículas Metálicas/química , Modelos Moleculares , Conformação Molecular , Nitrato de Prata/química , Estereoisomerismo
19.
Nanoscale ; 6(4): 2381-9, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24435549

RESUMO

Porous graphene (PG) and graphene quantum dots (GQDs) are attracting attention due to their potential applications in photovoltaics, catalysis, and bio-related fields. We present a novel way for mass production of these promising materials. The femtosecond laser ablation of highly oriented pyrolytic graphite (HOPG) is employed for their synthesis. Porous graphene (PG) layers were found to float at the water-air interface, while graphene quantum dots (GQDs) were dispersed in the solution. The sheets consist of one to six stacked layers of spongy graphene, which form an irregular 3D porous structure that displays pores with an average size of 15-20 nm. Several characterization techniques have confirmed the porous nature of the collected layers. The analyses of the aqueous solution confirmed the presence of GQDs with dimensions of about 2-5 nm. It is found that the formation of both PG and GQDs depends on the fs-laser ablation energy. At laser fluences less than 12 J cm(-2), no evidence of either PG or GQDs is detected. However, polyynes with six and eight carbon atoms per chain are found in the solution. For laser energies in the 20-30 J cm(-2) range, these polyynes disappeared, while PG and GQDs were found at the water-air interface and in the solution, respectively. The origin of these materials can be explained based on the mechanisms for water breakdown and coal gasification. The absence of PG and GQDs, after the laser ablation of HOPG in liquid nitrogen, confirms the proposed mechanisms.


Assuntos
Grafite/química , Lasers , Pontos Quânticos/química , Porosidade
20.
Phys Chem Chem Phys ; 15(9): 3022-6, 2013 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-23138867

RESUMO

Today, nanoparticles are widely implemented as functional elements onto surfaces, into volumes and as nano-hybrids, resulting for example in bioactive composites and biomolecule conjugates. However, only limited varieties of materials compatible for integration into advanced functional materials are available: nanoparticles synthesized using conventional gas phase processes are often agglomerated into micro powders that are hard to re-disperse into functional matrices. Chemical synthesis methods often lead to impurities of the nanoparticle colloids caused by additives and precursor reaction products. In the last decade, laser ablation and nanoparticle generation in liquids has proven to be a unique and efficient technique to generate, excite, fragment, and conjugate a large variety of nanostructures in a scalable and clean manner. This editorial briefly highlights selected recent advancements and critical aspects in the field of pulsed laser-based nanoparticle generation and manipulation, including exemplary strategies to harvest the unique properties of the laser-generated nanomaterials in the field of biomedicine and catalysis. The presented critical aspects address future assignments such as size control and scale-up.


Assuntos
Lasers , Nanopartículas/química , Nanotecnologia/métodos , Catálise , Eletroforese , Galvanoplastia , Nanocompostos/química , Tamanho da Partícula , Polímeros/química
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