Investigations of the Toxic Effect of Silver Nanoparticles on Mammalian Cell Lines

Silver nanoparticles are widely used for many applications. In this study silver nanoparticles have been tested for their toxic effect on fibroblasts (NIH-3T3), on a human lung adenocarcinoma epithelial cell line (A-549), on PC-12-cells, a rat adrenal pheochromocytoma cell line, and on HEP-G2-cells, a human hepatocellular carcinoma cell line. The viability of the cells cultivated with different concentrations of silver was determined by the MTT assay, a photometric method to determine cell metabolism. Dose-response curves were extrapolated and IC50, total lethal concentration (TLC), and no observable adverse effect concentration (NOAEC) values were calculated for each cell line. As another approach, ECIS (electric-cell-substrate-impedance-sensing) an automated method to monitor cellular behavior in real-time was applied to observe cells cultivated with silver nanoparticles. To identify the type of cell death the membrane integrity was analyzed by measurements of the lactate dehydrogenase releases and by determination of the caspase 3/7 activity. To ensure that the cytotoxic effect of silver nanoparticles is not traced back to the presence of Ag+ ions in the suspension, an Ag+ salt (AgNO3) has been examined at the same concentration of Ag+ present in the silver nanoparticle suspension that is assuming that the Ag particles are completely available as Ag+ ions.

Nanotubos de carbono de parede simples funcionalizados com polietilenoglicol: avaliação de parâmetros in vivo e in vitro

Os nanomateriais apresentam uma escala na qual ao menos uma das dimensões varia entre 1 e 100 nm e possuem propriedades químicas, físicas ou biológicas dependentes da nanoestrutura e que lhes confere características funcionais de interesse para fins comerciais ou aplicações na área médica. Dentre os nanomateriais mais estudados e utilizados, destacam-se os de carbono, que incluem os fulerenos e os nanotubos de carbono (NT). Uma potencial utilização dos nanomateriais de carbono é na área biomédica, já que estes podem interagir com os sistemas biológicos em nível molecular e supramolecular com alto grau de especificidade. Em contrapartida, é importante considerar que os nanotubos de carbono podem exercer efeitos tóxicos, tendo como possível mecanismo o estresse oxidativo. Sendo assim, o objetivo desse trabalho foi investigar a ação dos nanotubos de carbono de parede única funcionalizados com polietilenoglicol (SWNT-PEG) em Danio rerio “zebrafish” (Teleostei, Cyprinidae). Avaliaram-se parâmetros bioquímicos, histológicos, comportamentais e de biodistribuição para entender como esse material se comporta in vitro e in vivo. Foi observado que o tipo de funcionalização é determinante para a ação desse material em meio biológico. No experimento in vitro o SWNT-PEG não mostrou efeito pró-oxidante nas avaliações de peroxidação lipídica, capacidade antioxidante total, conteúdo de GSH e atividade de GCL. Na exposição intraperitoneal em zebrafish constatou-se a agregação e geração de processo inflamatório, o que sugere que a cadeia de PEG utilizada para a funcionalização dos NT possui um tamanho inadequado e/ou uma funcionalização ineficiente para manter a estabilidade do material em meio biológico e evitar uma resposta inflamatória por parte do organismo exposto. Possivelmente devido a esta característica do nanomaterial, nas análises de biodistribuição, através de espectroscopia Raman, não se observou distribuição de SWNT-PEG no sistema nervoso central de zebrafish. No entanto, através da análise histológica foi observado processo inflamatório no tecido nervoso central, bem como alterações comportamentais avaliadas na tarefa de campo aberto.

Membrana de alumina anódica: comportamento da microestrutura e estudo das propriedades ópticas após tratamento térmico

Thin commercial aluminum electrolytic and passed through reactions was obtained with anodic alumina membranes nanopores. These materials have applications in areas recognized electronic, biomedical, chemical and biological weapons, especially in obtaining nanostructures using these membranes as a substrate or template for processing nanowires, nanodots and nanofibers for applications noble. Previous studies showed that the membranes that have undergone heat treatment temperature to 1300° C underwent changes in morphology, crystal structure and optical properties. This aim, this thesis, a study of the heat treatment of porous anodic alumina membranes, in order to obtain and to characterize the behavior changes structures during the crystallization process of the membranes, at temperatures ranging between 300 and 1700° C. It was therefore necessary to mount a system formed by a tubular furnace resistive alumina tube and controlled environment, applying flux with special blend of Ag-87% and 13% N2, in which argon had the role of carrying out the oxygen nitrogen system and induce the closing of the pores during the densification of the membrane. The duration of heat treatment ranged from 60 to 15 minutes, at temperatures from 300 to 1700° C respectively. With the heat treatment occurred: a drastic reduction of porosity, grain growth and increased translucency of the membrane. For the characterization of the membranes were analyzed properties: Physical - thermogravimetric, X-ray diffraction, BET surface area; morphological - SEM, EDS through compositional and, optical absorbance, and transmittance in the UV-VIS, and FTIR. The results using the SEM showed that crystallization has occurred, densification and significant changes in membrane structure, as well as obtaining microtube, the BET analysis showed a decrease in specific surface area of the membranes has to 44.381 m2.g-1 to less than 1.8 m2.g-1 and in the analysis of transmittance and absorbance was found a value of 16.5% in the range of 800 nm, characteristic of the near infrared and FTIR have confirmed the molecular groups of the material. Thus, one can say that the membranes were mixed characteristics and properties which qualify for use in gas filtration system, as well as applications in the range of optical wavelength of the infra-red, and as a substrate of nanomaterials. This requires the continuation and deepening of additional study

Multibiomarker assessment of cadmium-based quantum dots effects in the marine mussel Mytilus galloprovincialis

Tese de Doutoramento, Ciências do Mar, da Terra e do Ambiente, Ramo: Ciências e Tecnologias do Ambiente, Especialização em Ecotoxicologia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016

Design, Fabrication, and Mechanical Property Analysis of 3D Nanoarchitected Materials

Recent developments in micro- and nanoscale 3D fabrication techniques have enabled the creation of materials with a controllable nanoarchitecture that can have structural features spanning 5 orders of magnitude from tens of nanometers to millimeters. These fabrication methods in conjunction with nanomaterial processing techniques permit a nearly unbounded design space through which new combinations of nanomaterials and architecture can be realized. In the course of this work, we designed, fabricated, and mechanically analyzed a wide range of nanoarchitected materials in the form of nanolattices made from polymer, composite, and hollow ceramic beams. Using a combination of two-photon lithography and atomic layer deposition, we fabricated samples with periodic and hierarchical architectures spanning densities over 4 orders of magnitude from ρ=0.3-300kg/m³ and with features as small as 5nm. Uniaxial compression and cyclic loading tests performed on different nanolattice topologies revealed a range of novel mechanical properties: the constituent nanoceramics used here have size-enhanced strengths that approach the theoretical limit of materials strength; hollow aluminum oxide (Al₂O₃) nanolattices exhibited ductile-like deformation and recovered nearly completely after compression to 50% strain when their wall thicknesses were reduced below 20nm due to the activation of shell buckling; hierarchical nanolattices exhibited enhanced recoverability and a near linear scaling of strength and stiffness with relative density, with E∝ρ^1.04 and σy∝ρ^1.17 for hollow Al₂O₃ samples; periodic rigid and non-rigid nanolattice topologies were tested and showed a nearly uniform scaling of strength and stiffness with relative density, marking a significant deviation from traditional theories on “bending” and “stretching” dominated cellular solids; and the mechanical behavior across all topologies was highly tunable and was observed to strongly correlate with the slenderness λ and the wall thickness-to-radius ratio t/a of the beams. These results demonstrate the potential of nanoarchitected materials to create new highly tunable mechanical metamaterials with previously unattainable properties.

Synthesis of porous graphene/TiO2 by use of recycled graphite

Graphene-based nanomaterials are a kind of new technological materials with high interest for physicists, chemists and materials scientists. Graphene is a two-dimensional (2-D) sheet of carbon atoms in a hexagonal configuration with atoms bonded by sp2 bonds. These bonds and this electron configuration provides the extraordinary properties of graphene, such as very large surface area, a tunable band gap, high mechanical strength and high elasticity and thermal conductivity [1]. Graphene has also been investigated for preparation of composites with various semiconductors like TiO2, ZnO, CdS aiming at enhanced photocatalytic activity for their use for photochemical reaction as water splitting or CO2 to methanol conversion [2-3]. In this communication, the synthesis of porous graphene@TiO2 obtained from a powder graphite recycled, supplied by ECOPIBA, is presented. This graphite was exfoliated, using a nonionic surfactant (Triton X-100) and sonication. Titanium(IV) isopropoxide was used as TiO2 source. After removing the surfactant with a solution HCl/n-propanol, a porous solid is obtained with a specific area of 358 m2g-1. The solid was characterized by XRD, FTIR, XPS, EDX and TEM. Figure 1 shows the graphene 2D layer bonded with nanoparticles of TiO2. When a water suspension of this material is exposed with UV-vis radiation, water splitting reaction is carried out and H2/O2 bubbles are observed (Figure 2)

Pirólise de borras oleosas de petroleo utilizando nanomateriais

The oily sludge is a complex mix of hydrocarbons, organic impurities, inorganic and water. One of the major problems currently found in petroleum industry is management (packaging, storage, transport and fate) of waste. The nanomaterials (catalysts) mesoporous and microporous are considered promising for refining and adsorbents process for environment protection. The aim of this work was to study the oily sludge from primary processing (raw and treated) and vacuum residue, with application of thermal analyses technique (pyrolysis), thermal and catalytic pyrolysis with nanomaterials, aiming at production petroleum derived. The sludge and vacuum residue were analyzed using a soxhlet extraction system, elemental analysis, thin layer chromatography, thermogravimetry and pyrolysis coupled in gas chromatography/mass spectrometry (Py GC MS). The catalysts AlMCM-41, AlSBA-15.1 e AlSBA-15.2 were synthesized with molar ratio silicon aluminum of 50 (Si/Al = 50), using tetraethylorthosilicante as source of silicon and pseudobuhemita (AlOOH) as source of aluminum. The analyzes of the catalysts indicate that materials showed hexagonal structure and surface area (783,6 m2/g for AlMCM-41, 600 m2/g for AlSBA-15.1, 377 m2/g for AlSBA-15.2). The extracted oily sludge showed a range 65 to 95% for organic components (oil), 5 to 35% for inorganic components (salts and oxides) and compositions different of derivatives. The AlSBA-15 catalysts showed better performance in analyzes for production petroleum derived, 20% increase in production of kerosene and light gas oil. The energy potential of sludge was high and it can be used as fuel in other cargo processed in refinery

Avaliação ecotoxicológica de fármacos psicotrópicos e suas possíveis interações com nanomateriais usando embriões de peixe-zebra

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2016.

Positive biocompatibility of nanocrystalline glass-like carbon thin films

The interest in carbon nanomaterials with high transparency and electrical conductivity has grown within the last decade in view of a wide variety of applications, including biocompatible sensors, diagnostic devices and bioelectronic implants. The aim of this work is to test the biocompatibility of particular nanometer-thin nanocrystalline glass-like carbon films (NGLC), a disordered structure of graphene flakes joined by carbon matrix (Romero et al., 2016). We used a cell line (SN4741) from substantia nigra dopaminergic cells derived from transgenic mouse embryo cells (Son et al., 1999). Some cells were cultured on top of NGLC films (5, 20 and 80 nm) and other with NGLC nanoflakes (approx. 5-10 mm2) in increasing concentrations: 1, 5, 10, 20 and 50 μg/ml, during 24 h, 3 days and 7 days. Cells growing in normal conditions were defined under culture with DMEM supplemented with 10% FCS, Glucose (0,6%), penicillin-streptomycin (50U/ml) and L-glutamine (2mM) at 5%CO2 humidified atmosphere. Nanoflakes were resuspended in DMEM at the stock concentration (2 g/l). The experiments were conducted in 96 well plates (Corning) using 2500 cells per well. For MTT analysis, the manufacturer recommendations were followed (Roche, MTT kit assay): a positive control with a 10% Triton X-100 treatments (15 minutes) and a negative control without neither Triton X-100 nor NGLC. As apoptosis/necrosis assay we used LIVE/DEAD® Viability/Cytotoxicity Assay Kit (Invitrogen). In a separate experiment, cells were cultured on top of the NGLC films for 7 days. Primary antibodies: anti-synaptophysin (SYP, clone SY38, Chemicon) and goat anti-GIRK2 (G-protein-regulated inward-rectifier potassium channel 2 protein) (Abcom) following protocol for immunofluorescence. WB for proteins detection performed with a polyclonal anti-rabbit proliferating cell nuclear antigen (PCNA). Results demonstrated the biocompatibility with different concentration of NGLC varying the degree of survival from a low concentration (1 mg/ml) in the first 24 h to high concentrations (20-50 g/ml) after 7 days as it is corroborated by the PCNA analysis. Cells cultured on top of the film showed after 7 days axonal-like alignment and edge orientation as well as net-like images. Neuronal functionality was demonstrated to a certain extent through the analysis of coexistence between SYP and GIRK2. In conclusion, this nanomaterial could offer a powerful platform for biomedical applications such as neural tissue engineering

Compositional effects of large graphene oxide sheets on the spinnability and properties of polyurethane composite fibers

Recent advances in wearable electronics, technical textiles, and wearable strain sensing devices have resulted in extensive research on stretchable electrically conductive fibers. Addressing these areas require the development of efficient fiber processing methodologies that do not compromise the mechanical properties of the polymer (typically an elastomer) when nanomaterials are added as conductive fillers. It is highly desirable that the addition of conductive fillers provides not only electrical conductivity, but that these fillers also enhance the stiffness, strength, stretchability, and toughness of the polymer. Here, the compatibility of polyurethane (PU) and graphene oxide (GO) is utilized for the study of the properties of elastomeric conductive fibers prepared by wet-spinning. The GO-reinforced PU fibers demonstrate outstanding mechanical properties with a 200-fold and a threefold enhancement in Young's modulus and toughness, respectively. Postspinning thermal annealing of the fibers results in electrically conductive fibers with a low percolation threshold (≈0.37 wt% GO). An investigation into optimized fiber's electromechanical behavior reveals linear strain sensing abilities up to 70%. Results presented here provide practical insights on how to simultaneously maintain or improve electrical, mechanical, and electromechanical properties in conductive elastomer fibers.

Optical actuation of inorganic/organic interfaces: comparing peptide-azobenzene ligand reconfiguration on gold and silver nanoparticles

Photoresponsive molecules that incorporate peptides capable of material-specific recognition provide a basis for biomolecule-mediated control of the nucleation, growth, organization, and activation of hybrid inorganic/organic nanostructures. These hybrid molecules interact with the inorganic surface through multiple noncovalent interactions which allow reconfiguration in response to optical stimuli. Here, we quantify the binding of azobenzene-peptide conjugates that exhibit optically triggered cis-trans isomerization on Ag surfaces and compare to their behavior on Au. These results demonstrate differences in binding and switching behavior between the Au and Ag surfaces. These molecules can also produce and stabilize Au and Ag nanoparticles in aqueous media where the biointerface can be reproducibly and reversibly switched by optically triggered azobenzene isomerization. Comparisons of switching rates and reversibility on the nanoparticles reveal differences that depend upon whether the azobenzene is attached at the peptide N- or C-terminus, its isomerization state, and the nanoparticle composition. Our integrated experimental and computational investigation shows that the number of ligand anchor sites strongly influences the nanoparticle size. As predicted by our molecular simulations, weaker contact between the hybrid biomolecules and the Ag surface, with fewer anchor residues compared with Au, gives rise to differences in switching kinetics on Ag versus Au. Our findings provide a pathway toward achieving new remotely actuatable nanomaterials for multiple applications from a single system, which remains difficult to achieve using conventional approaches.

Optical actuation of inorganic/organic interfaces: comparing peptide-azobenzene ligand reconfiguration on gold and silver nanoparticles

Photoresponsive molecules that incorporate peptides capable of material-specific recognition provide a basis for biomolecule-mediated control of the nucleation, growth, organization, and activation of hybrid inorganic/organic nanostructures. These hybrid molecules interact with the inorganic surface through multiple noncovalent interactions which allow reconfiguration in response to optical stimuli. Here, we quantify the binding of azobenzene-peptide conjugates that exhibit optically triggered cis-trans isomerization on Ag surfaces and compare to their behavior on Au. These results demonstrate differences in binding and switching behavior between the Au and Ag surfaces. These molecules can also produce and stabilize Au and Ag nanoparticles in aqueous media where the biointerface can be reproducibly and reversibly switched by optically triggered azobenzene isomerization. Comparisons of switching rates and reversibility on the nanoparticles reveal differences that depend upon whether the azobenzene is attached at the peptide N- or C-terminus, its isomerization state, and the nanoparticle composition. Our integrated experimental and computational investigation shows that the number of ligand anchor sites strongly influences the nanoparticle size. As predicted by our molecular simulations, weaker contact between the hybrid biomolecules and the Ag surface, with fewer anchor residues compared with Au, gives rise to differences in switching kinetics on Ag versus Au. Our findings provide a pathway toward achieving new remotely actuatable nanomaterials for multiple applications from a single system, which remains difficult to achieve using conventional approaches.