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Silicosis is a pneumoconiosis caused by inhaled crystalline silica microparticles, which trigger inflammatory responses and granuloma formation in pulmonary parenchyma, thus affecting lung function. Although systemic administration of mesenchymal stromal cells (MSCs) ameliorates lung inflammation and attenuates fibrosis in experimental silicosis, it does not reverse collagen deposition and granuloma formation. In an attempt to improve the beneficial effects of MSCs, magnetic targeting (MT) has arisen as a potential means of prolonging MSC retention in the lungs. In this study, MSCs were incubated with magnetic nanoparticles and magnets were used for in vitro guidance of these magnetized MSCs and to enhance their retention in the lungs in vivo. In vitro assays indicated that MT improved MSC transmigration and expression of chemokine receptors. In vivo, animals implanted with magnets for 48 hours had significantly more magnetized MSCs in the lungs, suggesting improved MSC retention. Seven days after magnet removal, silicotic animals treated with magnetized MSCs and magnets showed significant reductions in static lung elastance, resistive pressure, and granuloma area. In conclusion, MT is a viable technique to prolong MSC retention in the lungs, enhancing their beneficial effects on experimentally induced silicosis. MT may be a promising strategy for enhancing MSC therapies for chronic lung diseases., Magnetic targeting technique has emerged as a new strategy to aid delivery, increase retention, and enhance the effects of mesenchymal stromal cells (MSCs) but, so far, has not been performed in lung diseases. With the aid of magnets, magnetized MSCs remained longer in the lungs, and this was associated with increased beneficial effects for the treatment of silicosis in mice.

Paracoccidioidomycosis (PCM) is a disease caused by fungi of the genus Paracoccidioides. The disease is responsible for high rates of premature deaths and socioeconomic repercussions. The limitations of antifungal agents against PCM have motivated the search for new compounds. In our ongoing exploration of Cerrado plants as potential sources of new antifungal agents, we selected Copaifera langsdorffii oil (Copaíba resin oil) in order to explore its bioactive potential and test a formulation to increase oil stability and solubilization employing Pluronic F-127 to obtain the nanoemulsion of the oil. We aim at testing both Copaíba resin oil and its nanoemulsion against four species of the Paracoccidioides genus. We performed cytotoxicity test in Balb/C3T3 cells, hemolytic activity and interaction of Copaíba resin oil and Copaíba resin oil nanoemulsion (CopaPlu) with the antifungal agents such as amphotericin B, co-trimoxazole, and itraconazole. Moreover, the Copaíba resin oil was analyzed by mass spectrometry to identify its chemical profile. Eventually, a new methodology to prepare the nanoemulsion is presented. The Copaíba resin oil and CopaPlu nanoemulsion inhibited Paracoccidioides sp. growth efficiently, and no cytotoxicity or hemolytic effect was observed at minimum inhibitory concentration (MIC). When combined with amphotericin B, Copaíba resin oil and its nanoemulsion showed an additive effect with reduction of MIC values. The Copaíba resin oil and CopaPlu nanoemulsion is a promising antifungal agent against Paracoccidioides.

Citrate-coated iron oxide nanoparticles (IONPs) have potential use in environmental remediation, with possibilities in decontaminating aquatic environments exposed to toxic substances. This study analyzed IONPs associated to Roundup Original, a glyphosate-based herbicide (GBH), and pure glyphosate (GLY), through ultrastructural and histopathological biomarkers in liver tissue, from females of Poecilia reticulata exposed to: iron ions (0.3 mg/L) (IFe) and IONPs (0.3 mgFe/L) associated with GLY (0.65 mg/L) and GBH (0.65 mgGLY/L (IONP + GBH1) and 1.30 mgGLY/L (IONP + GBH2)) for a period of 7, 14 and 21 days, followed by an equal post-exposure period only in reconstituted water. For the assays, the synthetized IONPs had crystalline and rounded shape with an average diameter of 2,90 nm, hydrodynamic diameter 66,6 mV, zeta potential -55,4 and diffraction profile of maghemite (γ-Fe

Iron oxide nanoparticles (IONPs) have been tested to remediate aquatic environments polluted by chemicals, such as pesticides. However, their interactive effects on aquatic organisms remain unknown. This study aimed to investigate the genotoxicity and mutagenicity of co-exposure of IONPs (γ-Fe2O3 NPs) and glyphosate-based herbicide (GBH) in the fish Poecilia reticulata. Thus, fish were exposed to citrate-functionalized γ-Fe2O3 NPs (0.3 mg L-1; 5.44 nm) alone or co-exposed to γ-Fe2O3 NPs (0.3 mg L-1) and GBH (65 and 130 μg of glyphosate L-1) during 14 and 21 days. The genotoxicity (DNA damage) was analyzed by comet assay, while the mutagenicity evaluated by micronucleus test (MN test) and erythrocyte nuclear abnormalities (ENA) frequency. The co-exposure induced clastogenic (DNA damage) and aneugenic (nuclear alterations) effects on guppies in a time-dependent pattern. Fish co-exposed to NPs and GBH (130 μg glyphosate L-1) showed high DNA damage when compared to NPs alone and control group, indicating synergic effects after 21 days of exposure. However, mutagenic effects (ENA) were observed in the exposure groups after 14 and 21 days. Results showed the potential genotoxic and mutagenic effects of maghemite NPs and GBH co-exposure to freshwater fish. The transformation and interaction of iron oxide nanoparticles with other pollutants, as herbicides, in the aquatic systems are critical factors in the environmental risk assessment of metal-based NPs.

Citrate-coated iron oxide nanoparticles (IONPs) have potential use in environmental remediation, with possibilities in decontaminating aquatic environments exposed to toxic substances. This study analyzed IONPs associated to Roundup Original, a glyphosate-based herbicide (GBH), and pure glyphosate (GLY), through ultrastructural and histopathological biomarkers in liver tissue, from females of Poecilia reticulata exposed to: iron ions (0.3 mg/L) (IFe) and IONPs (0.3 mgFe/L) associated with GLY (0.65 mg/L) and GBH (0.65 mgGLY/L (IONP + GBH1) and 1.30 mgGLY/L (IONP + GBH2)) for a period of 7, 14 and 21 days, followed by an equal post-exposure period only in reconstituted water. For the assays, the synthetized IONPs had crystalline and rounded shape with an average diameter of 2,90 nm, hydrodynamic diameter 66,6 mV, zeta potential −55,4 and diffraction profile of maghemite (γ-Fe2O3). The data obtained by biomarkers indicated a high inflammatory response in all treatments. These same parameters, considered during the post-exposure period indicated recovery in reaction patterns of circulatory disturbances and regressive changes, resulting in average reductions of 37,53 points in IFe, 21 points in IONP + GBH1, 15 points in IONP + GBH2 and 11 points in IONP + GLY in total histopathological index of liver after 21 days post-exposure. However, although the cellular and tissue responses were significant, there was no change in the condition factor and hepatosomatic index, denoting resilience of the experimental model.

The environmental risk of nanomaterials (NMs) designed and used in nanoremediation process is of emerging concern, but their ecotoxic effects to aquatic organism remains unclear. In this study, the citrate-coated (maghemite) nanoparticles (IONPs) were synthesized and its genotoxic and mutagenic effects were investigated in the female guppy Poecilia reticulata . Fish were exposed to IONPs at environmentally relevant iron concentration (0.3 mg L −1 ) during 21 days and the animals were collected at the beginning of the experiment and after 3, 7, 14 and 21 days of exposure. The genotoxicity and mutagenicity were evaluated in terms of DNA damage (comet assay), micronucleus (MN) test and erythrocyte nuclear abnormalities (ENA) frequency. Results showed differential genotoxic and mutagenic effects of IONPs in the P. reticulata according to exposure time. The IONP induced DNA damage in P. reticulata after acute (3 and 7 days) and long-term exposure (14 and 21 days), while the mutagenic effects were observed only after long-term exposure. The DNA damage and the total ENA frequency increase linearly over the exposure time, indicating a higher induction rate of clastogenic and aneugenic effects in P. reticulata erythrocytes after long-term exposure to IONPs. Results indicated that the P. reticulata erythrocytes are target of ecotoxicity of IONPs.

Silver nanoparticles (Ag NPs) have been applied in several commercial products due to their antimicrobial properties, while their molluscicide properties, mode of action and toxicity to snail species remain unclear. In this study, the comparative toxicity of polyvinylpyrrolidone (PVP)-functionalized Ag NPs and their dissolved counterpart (Ag ions) was analyzed during the early developmental stages of the freshwater snail Biomphalaria glabrata, intermediate host of Schistosoma mansoni. Ag NPs were synthesized and characterized by multiple techniques, and the snail embryotoxicity was analyzed in terms of mortality, hatching, developmental stages and morphological alterations, while the acute toxicity to newly-hatched snails was analyzed by mortality and behavioral impairments. Results showed that both Ag forms induced mortality, hatching delay and morphological alterations (especially hydropic abnormalities) in snail embryos in a concentration and exposure time dependent patterns. Ag NPs showed low embryotoxic effects and similar toxicity for newly-hatched snails when compared to their dissolved counterparts, indicating that the nanotoxicity was dependent of snail developmental stages. The knowledge about the Ag NP toxicity to different early development stages of B. glabrata contributes to its potential use as molluscicide and control of neglected tropical diseases, including schistosomiasis.

Iron oxide nanoparticles (IONPs) are used in several medical and environmental applications, but their mechanism of action and hazardous effects to early developmental stages of fish remain unknown. Thus, the present study aimed to assess the developmental toxicity of citrate-functionalized IONPs (γ-Fe2O3 NPs), in comparison with its dissolved counterpart, in zebrafish (Danio rerio) after static and semi-static exposure. Embryos were exposed to environmental concentrations of both iron forms (0.3, 0.6, 1.25, 2.5, 5 and 10 mg L−1) during 144 h, jointly with negative control group. The interaction and distribution of both Fe forms on the external chorion and larvae surface were measured, following by multiple biomarker assessment (mortality, hatching rate, neurotoxicity, cardiotoxicity, morphological alterations and 12 morphometrics parameters). Results showed that IONPs were mainly accumulated on the zebrafish chorion, and in the digestive system and liver of the larvae. Although the IONPs induced low embryotoxicity compared to iron ions in both exposure conditions, these nanomaterials induced sublethal effects, mainly cardiotoxic effects (reduced heartbeat, blood accumulation in the heart and pericardial edema). The semi-static exposure to both iron forms induced high embryotoxicity compared to static exposure, indicating that the nanotoxicity to early developmental stages of fish depends on the exposure system. This is the first study concerning the role of the exposure condition on the developmental toxicity of IONPs on fish species.

The environmental risk of nanomaterials (NMs) designed and used in nanoremediation process is of emerging concern, but their ecotoxic effects to aquatic organism remains unclear. In this study, the citrate-coated (maghemite) nanoparticles (IONPs) were synthesized and its genotoxic and mutagenic effects were investigated in the female guppy Poecilia reticulata. Fish were exposed to IONPs at environmentally relevant iron concentration (0.3 mg L

Purpose Human embryonic stem (hES) cells are useful tools for regenerative medicine. Maintaining hES cells for research and clinical purposes remains a challenge. The hES cells have typically been grown on a mouse or human cell feeder layer, but these methods harbor potential health problems for the recipient. A culture system using magnetic field and iron oxide nanoparticles were previously demonstrated to sustain mouse embryonic stem cells in vitro . Now, by using the BG01v/hOG cell line, we could assess the effect of this culture system on the stemness of an embryonic stem cell of human origin. Methods Using a variant hES cell line, BG01V/hOG, expressing an emerald green fluorescent protein (EmGFP), we grown these cells in the presence of serum-free medium supplemented with magnetic nanoparticles functionalized with citrate. The cells were positioned over a circular magnet (4000 Gauss) and monitored daily by fluorescence microscopy. Results We discovered that hES cells can proliferate when labeled with magnetic nanoparticles and in the presence of a magnetic field without losing pluripotency. Conclusion These results establish an alternative method for maintaining hES cells which would minimize health concerns as well as label cells for subsequent clinical tracking.

Background Nanoparticles’ unique features have been highly explored in cellular therapies. However, nanoparticles can be cytotoxic. The cytotoxicity can be overcome by coating the nanoparticles with an appropriated surface modification. Nanoparticle coating influences biocompatibility between nanoparticles and cells and may affect some cell properties. Here, we evaluated the biocompatibility of gold and maghemite nanoparticles functionalized with 2,3-dimercaptosuccinic acid (DMSA), Au-DMSA and γ-Fe2O3-DMSA respectively, with human mesenchymal stem cells. Also, we tested these nanoparticles as tracers for mesenchymal stem cells in vivo tracking by computed tomography and as agents for mesenchymal stem cells magnetic targeting. Results Significant cell death was not observed in MTT, Trypan Blue and light microscopy analyses. However, ultra-structural alterations as swollen and degenerated mitochondria, high amounts of myelin figures and structures similar to apoptotic bodies were detected in some mesenchymal stem cells. Au-DMSA and γ-Fe2O3-DMSA labeling did not affect mesenchymal stem cells adipogenesis and osteogenesis differentiation, proliferation rates or lymphocyte suppression capability. The uptake measurements indicated that both inorganic nanoparticles were well uptaken by mesenchymal stem cells. However, Au-DMSA could not be detected in microtomograph after being incorporated by mesenchymal stem cells. γ-Fe2O3-DMSA labeled cells were magnetically responsive in vitro and after infused in vivo in an experimental model of lung silicosis. Conclusion In terms of biocompatibility, the use of γ-Fe2O3-DMSA and Au-DMSA as tracers for mesenchymal stem cells was assured. However, Au-DMSA shown to be not suitable for visualization and tracking of these cells in vivo by standard computed microtomography. Otherwise, γ-Fe2O3-DMSA shows to be a promising agent for mesenchymal stem cells magnetic targeting.

Nanosized maghemite (below 10 nm average diameter), surface-functionalized with meso-2,3-dimercaptosuccinic acid (DMSA), was investigated with respect to the content of DMSA molecules attached onto its surface and the onset of S-S bridges due to oxidation of neighboring S-H groups. To support our investigation, we introduced the use of photoacoustic spectroscopy to monitor thiol groups (S-H) conjugated with Raman spectroscopy to monitor the disulfide bridges (S-S). The normalized intensity (N(R)) of the Raman feature peaking at 500 cm(-1) was used to probe the S-S bridge whereas the normalized intensity (N(P)) of the photoacoustic band-S (0.42-0.65 μm) was used to probe the S-H moiety. The perfect linearity observed in the N(R) versus (1 - N(P)) plot strongly supports the oxidation process involving neighboring S-H groups as the DMSA surface grafting coefficient increases whereas the approach used in this report allows the evaluation of the [S-H]/[S-S] ratio. The observation of the reduction of the hydrodynamic diameter as the nominal DMSA-grafting increases supports the proposed model picture, in which the intraparticle (interparticle) S-S bridging takes place at higher (lower) DMSA-grafting values.

The in vitro growth of embryonic stem cells (ESCs) is usually obtained in the presence of murine embryonic fibroblasts (MEF), but new methods for in vitro expansion of ESCs should be developed due to their potential clinical use. This study aims to establish a culture system to expand and maintain ESCs in the absence of MEF by using murine embryonic stem cells (mECS) as a model of embryonic stem cell. Magnetic nanoparticles (MNPs) were used for growing mESCs in the presence of an external magnetic field, creating the magnetic field-magnetic nanoparticle (MF-MNP) culture system. The growth characteristics were evaluated showing a doubling time slightly higher for mESCs cultivated in the presence of the system than in the presence of the MEF. The undifferentiated state was characterized by RT-PCR, immunofluorescence, alkaline phosphatase activity and electron microscopy. Murine embryonic stem cells cultivated in presence of the MF-MNP culture system exhibited Oct-4 and Nanog expression and high alkaline phosphatase activity. Ultrastructural morphology showed that the MF-MNP culture system did not interfere with processes that cause structural changes in the cytoplasm or nucleus. The MF-MNP culture system provides a tool for in vitro expansion of mESCs and could contribute to studies that aim the therapeutic use of embryonic stem cells.

This study reports on the temperature dependence of hysteresis loops of magnetic nanocomposites consisting of iron oxide-based nanoparticles supported within exfoliated vermiculate. Two magnetic nanocomposite samples (IMFV and SMFV) were prepared by treating the exfoliated vermiculite with two magnetic fluid samples; an ionic magnetic fluid (IMF) and a surfacted magnetic fluid (SMF). X-ray diffraction and transmission electron microscopy of the magnetic phase powders provided the average diameter and diameter dispersity of the nanosized magnetic particles. The saturation magnetization, supported by the average nanoparticle size obtained from X-ray diffraction measurements, indicates the size-selectivity of the encapsulated nanoparticles by the hosting template. This finding is extremely interesting as it indicates the use of exfoliated vermiculite as a size-sort template for nanosized particles suspended as a colloid.

Magnetic nanoparticles surface-functionalized with meso-2,3-dimercaptosuccinic acid (MNPs-DMSA) constitute an innovative and promising approach for tissue- and cell-targeted delivery of therapeutic drugs in the lung. Transendothelial migration of leukocytes in the lung is a side effect of endovenous administration of MNPs-DMSA. Using cytologic and phenotypic analysis of murine bronchoalveolar lavage cells, we identified monocytes/macrophages as the main subpopulation of leukocytes involved in this process. Moreover, ultrastructural analysis revealed the presence of nanoparticles inside of numerous macrophages from bronchoalveolar lavage. MNPs-DMSA at concentrations as high as 1 x 10(15) nanoparticles/mL had no toxic effects on macrophages, as evidenced by 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay. Notably, MNPs-DMSA up-regulated the mRNA expression of E-, L- and P-selectin and macrophage-1 antigen in the murine lung. Upregulation of these cell adhesion molecules was associated with an increased concentration of tumor necrosis factor-alpha in lung. Finally, the critical relevance of the beta(2) integrin-dependent pathway in leukocyte transmigration elicited by MNPs-DMSA was demonstrated by use of knockout mice. Our results characterize mechanisms of the pro-inflammatory effects of MNPs-DMSA in the lung, and identify beta(2) integrin-targeted interventions as promising strategies to reduce pulmonary side effects of MNPs-DMSA during biomedical applications.

An undergraduate physical chemistry experiment based on the drop counting method for surface tension measurements is proposed to demonstrate adsorption isotherms of binary aqueous solutions of ethanol, n-propanol, and n-butanol. Excess surface is obtained by the derivative of surface tension taken with respect to alcohol activity, after this activity calculation using van Laar equation. Laboratory class contents are surface tension, excess surface, percolation of hydrogen bonds, micelle, activity, and ideal solution.

This text describes an experiment on fractional precipitation of a polymer together with determination of average degree of polymerization by NMR. Commercial sodium polyphosphate was fractionated by precipitation from aqueous solution by adding increasing amounts of acetone. The polydisperse salt and nine fractions obtained from it were analyzed by 31P Nuclear Magnetic Resonance and the degree of polymerization of the salts and of the fractions were calculated. Long-chain sodium polyphosphate was also synthesized and analyzed. This experiment was tested in a PChem lab course but it can be used also to illustrate topics of inorganic polymers and analytical chemistry.

This study reports on the pioneering use of the layer-by-layer (LbL) technique to produce multilayered (1 to 50 bilayers) bifunctional nanocomposite films consisting of negatively charged citrate-coated maghemite nanoparticle (cit-MAG) hosted in positively charged conducting polyaniline (doped-PANI). The aim is to use the LbL assembly to fabricate thin nanocomposite films displaying superparamagnetic and conductivity properties and with fine control of the end properties as a function of the preparation condition. Multilayered cit-MAG/PANI bifunctional nanocomposite films were systematically investigated in order to access information regarding the nanofilm structure, electrical conductivity, and magnetic properties. Using the isothermal adsorption of each individual electrolyte (cit-MAG dispersion and doped-PANI solution) onto solid substrates (silicon and glass) the average time for deposition of a single layer (cit-MAG or doped-PANI) was fixed in 3 min. Independent evaluation using UV−vis spectroscopy ...

In this study, the layer-by-layer technique is used to deposit nanostructured films exhibiting electrical conductivity and magnetic behavior, from poly( o -ethoxyaniline) (POEA), sulfonated polystyrene (PSS) and positively-charged maghemite nanoparticles. In order to incorporate the nanoparticles into the films, maghemite nanoparticles, in the form of magnetic fluid, were added to POEA solutions, and the resulting suspensions were used for film deposition. UV–Vis spectroscopy and atomic force microscopy images reveal that POEA remains doped in the films, even in the presence of the maghemite nanoparticles, and its typical globular morphology is also present. Electrical measurements show that a POEA/PSS film prepared from POEA solution containing 800 µL of the magnetic fluid exhibits a similar conductivity to that of the control film and, additionally, magnetic measurements indicated that nanosized maghemite phase was incorporated within the polymeric film.

For the first time nanocrystalline magnetic particles of Mg x Fe(3−x)O4 with x ranging from 0.5 to 1.5 have been synthesized by a combustion reaction method using iron nitrate Fe(NO3)3.9H2O, magnesium nitrate Mg(NO3)2.6H2O, and urea CO(NH2)2 as fuel without intermediate decomposition and/or calcining steps. X-ray diffraction patterns of all systems showed broad peaks consistent with cubic inverse spinel structure of MgFe2O4. The absence of extra reflections in the diffraction patterns of as-prepared materials ensures the phase purity. The mean crystallite sizes determined from the prominent (311) peak of the diffraction using Scherrer’s equation and transmission electron microscopy micrographs were c.a. 40 nm with spherical morphology. Fourier transform infrared spectra of the as-prepared material showed traces of organic and metallic salt by-products; however, these could be removed by washing with deionized water. Typical hysteresis curves were obtained for all specimens in magnetic field up to 14 T between 4 and 340 K. The saturation magnetization was 48.3 emu/g and 31.3 emu/g, 44.8 emu/g, and 28.4 emu/g for x=1.0 and 0.8 at 4 K and 340 K, respectively. The saturation magnetization, M s , of nanoparticles of the MgFe2O4 specimen is about 50% higher when compared to the bulk. The enhanced magnetization measured in our nanoparticles MgFe2O4 specimens may be attributed to the uncompensated magnetic moment of iron ions between the A- and B-sites, i.e., changes in the inversion factor. Our magnetization results of MgFe2O4 specimens are comparable to the existing data for the same compound but with different particle size and prepared by different synthesis methods.

In this study, we report on how surface-passivated and nonpassivated cobalt ferrite nanoparticles (8 nm diameter), suspended as ionic magnetic fluids and aged under low pH conditions, revealed different behavior as far as the time evolution of the iron/cobalt cation distribution, crystal quality, coercivity, and saturation magnetization are concerned. Different techniques were used to perform a detailed study regarding the chemical stability, structural stability, and surface and magnetic properties of the suspended nanoparticles as a function of the aging time. Properties of surface-passivated and nonpassivated nanoparticles were investigated by transmission electron microscopy, X-ray diffraction, atomic absorption spectrometry, magnetic measurements, Raman spectroscopy, and Mössbauer spectroscopy. Our data showed that the employed nanoparticle surface passivation process, besides the formation of an iron-rich surface layer, modifies the nanoparticle core as well, improving the crystal quality while modifying the Fe/Co cation distribution and the nanoparticle dissolution rate profile. Magnetic data showed that the saturation magnetization increases for surface-passivated nanoparticles in comparison to the nonpassivated ones, though coercivity decreases after passivation. These two observations were associated to changes in the cation distribution among the available tetrahedral and octahedral sites.

Nanocrystalline magnetic particles of CoxFe(3−x)O4, with x ranging from 0.79 to 1.15, has been synthesised by combustion reaction method using iron nitrate Fe(NO3)3.9H2O, cobalt nitrate Co(NO3)2·6H2O, and urea CO(NH2)2 as fuel without template and subsequent heat treatment. The process is quite simple and inexpensive since it does not involve intermediate decomposition and/or calcining steps. The maximum reaction temperature ranged from 850 to 1010 °C and combustion lasted less then 30 s for all systems. X-ray diffraction patterns of all systems showed broad peaks consistent with cubic inverse spinel structure of CoFe2O4. The absence of extra reflections in the diffraction patterns of as-prepared materials ensures phase purity. The average crystallite sizes determined from the prominent (3 1 1) peak of the diffraction using Scherre's equation and TEM micrographs consisted of ca. 27 nm in spherical morphology. FTIR spectra of the as-prepared material showed traces of organic and metallic salts byproducts. However, when the same material was washed with deionised water the byproducts were rinsed off, resulting in pure materials. Magnetic properties such as saturation magnetisation, remanence magnetisation and coercivity field measured at room temperature were 48 emu/g, 15 emu/g and 900 Oe, respectively.

Magnetic exfoliated vermiculite is a synthetic nanocomposite that quickly and efficiently absorbs organic compounds such as oil from water bodies. It was developed primarily to mitigate pollution, but the possible adverse impacts of its application have not yet been evaluated. In this context, the acute toxicity of magnetic exfoliated vermiculite and exfoliated vermiculite was herein assessed by genotoxic and histopathological biomarkers in zebrafish (Danio rerio). DNA fragmentation was statistically significant for all groups exposed to the magnetic exfoliated vermiculite and for fish exposed to the highest concentration (200mg/L) of exfoliated vermiculite, whereas the micronucleus frequency, nuclear abnormalities and histopathological alterations were not statistically significant for the fish exposed to these materials. In the intestinal lumen, epithelial cells and goblet cells, we found the presence of magnetic exfoliated vermiculite and exfoliated vermiculite, but no alterations or presence of the materials-test in the gills or liver were observed. Our findings suggest that the use of magnetic exfoliated vermiculite and exfoliated vermiculite during standard ecotoxicological assays caused DNA damage in D. rerio, whose alterations may be likely to be repaired, indicating that the magnetic nanoparticles have the ability to promote genotoxic damage, such as DNA fragmentation, but not mutagenic effects.

A detailed study of the surface passivation process in superparamagnetic cobalt ferrite nanoparticles has been carried out using micro Raman spectroscopy. In addition to Raman spectroscopy, X-ray diffraction and atomic absorption spectroscopy were also used to investigate passivated and non-passivated samples. The data were discussed in terms of changes in the structural characteristics of the samples considering the introduction of Fe ions during the passivation. We found an improvement of the nanoparticle crystallinity due to the passivation process.

Preparation and characterization of ultra-stable biocompatible cobalt ferrite-based magnetic fluids has been reported. Synthesized samples have core particle diameter in the range of 4.7 to 14.8 nm, as indicated by TEM. Chemical and crystalline data show that the prepared nanoparticles are cobalt ferrite with a slight deviation from the Fe : Co :: 2 : 1 stoichiometry. ATR-FTIR spectroscopy was used to investigate the citrate adsorption onto the nanoparticle surface. The fitted adsorption time-constants were 0.006 and 0.033 min− 1 for nanoparticle diameter of 4.7 and 14.8 nm, respectively.

In this study we evaluated the photophysical, photochemical properties of the zinc phthalocyanine/ magnetic fluid (ZnPC/MF) complex in liposomal medium. As a result of the present investigation we propose the liposome-encapsulated ZnPC/MF complex as a very promising nanostructured device for cancer treatment. The spectroscopy characterization and the in vitro dark toxicity of both ZnPC and ZnPC/MF complex in Hank's and in liposomal medium are reported. Our findings revealed that the spectroscopic properties of the ZnPC associated or not with MF presented little differences and are very close to what one expects from an ideal photosensitizer compound. Indeed, the ZnPC/MF complex in liposomal medium presented lower dark toxicity compared to the ZnPC/MF complex in Hank's, strongly supporting the use of the former for cancer treatment.

In this study the photoacoustic signal of cobalt-ferrite based particles has been investigated near the semiconductor band-edge and in the very small-size limit. In these limits we find that the photoacoustic signal scales with both the zero- and the three-dimensional density of states. In addition, we find that the relative contribution to the photoacoustic signal, due to the zero-dimension-like nanoparticles, decreases linearly with the increasing average nanoparticle size. From this linear behavior we estimate the electron-hole pair size in cobalt-ferrite nanoparticles around 1.6 nm.

In this study, we performed a comparative investigation of the binding properties of two surface-coated (carboxymethyldextran/glucuronic acid), magnetite-based biocompatible magnetic fluids with different biological macromolecules (BSA, HSA, and LDL). We also investigated the in vitro toxicity of the complex formed between the magnetic fluid and the biological macromolecule in the neoplastic cell line J774-A.

Zero-field birefringence was used to investigate maghemite-based biocompatible magnetic fluids surface-coated with citrate. The model used to analyze the birefringence signal considers the dipolar magnetic interaction among dimers and the onset of a nematic phase near the sample holder surface. The data show that zero-field birefringence grows with sample dilution.

The present study introduces a new class of material that allows the combined action of photodynamic therapy (PDT) and hyperthermia (HPT) therapies, designed to work in a synergetic way when used in vivo, with an expected enhancement in tumor damaging after minimum drug doses and based on heat dissipation and/or light photosensitization. With this purpose, we have investigated the spectroscopic and photophysical properties of the complex zinc phthalocyanine/magnetic fluid (ZnPC/MF) in homogeneous medium (ethanol). Our findings clearly indicate that the spectroscopic properties of ZnPC as a photosensitizer associated or not with MF present similar behavior working efficiently as a PDT drug.

In the present study we report on the chemical synthesis, the surface passivation process, the peptization in low pH aqueous medium, and the characterization of cobalt–ferrite nanoparticles. The as produced, passivated and peptized cobalt–ferrite nanoparticles were investigated by atomic absorption measurements, transmission electron microscopy, and Mossbauer spectroscopy. The liquid Helium Mossbauer spectra consist of three well-defined sextets in all the studied samples. The data are discussed in terms of the characteristics of the nanoparticle surface layer and the effects produced by the passivation and peptization/aging processes.

In this study the influence of the empirical passivation process of cobalt ferrite nanoparticles upon magneto-optical properties of magnetic fluid samples is investigated. The protective character of this process was evaluated for nanoparticles peptized in two perchloric acid concentrations (0.25M and 0.75M). In addition samples aged to different times (20 and 110 days) were also investigated. The results show that all samples present an increment in the number of particle aggregates due to passivation and aging time. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

X-ray high-resolution scanning electron microscopy was used to investigate the spatial distribution of magnetite nanoparticles chemically synthetized in mesoporous styrene-divinylbenzene copolymer microspheres. The parabolic-like spatial-distribution of magnetite along the microsphere diameter (200 μm average diameter) presents the lowest magnetite concentration at the microsphere center and the highest magnetite concentration at the microsphere surface. The magnetite spatial profile is claimed to be a result of normal diffusion of the chemical species throughout the porous template in contact with the aqueous solution during the incorporation step of the ferrous ions. We found that the aqueous-ion diffusion coefficient changes as the template is chemically-cycled from 1 to 15 cycles with the purpose of increasing the magnetite mass incorporation.

Transmission electron microscopy and scanning electron microscopy were used to investigate chemically cycled magnetite-based composites using mesoporous sulfonated styrene-divinylbenzene copolymer as template. The micron-sized morphology of the template was investigated using scanning electron microscopy, while transmission electron microscopy provided useful information concerning the nanoparticle size polydispersity profile and location of the magnetite nanoparticles inside the template. The narrowing of the nanoparticle size distribution and the linear dependence of the magnetite mass incorporation versus number of chemical cycles are supported by the transmission electron microscopy data.

Preparation of size-controllable magnetite (Fe3O4) nanoparticles by alkaline oxidation of ferrous ion adsorbed in sulfonated mesoporous styrenedivinylbenzene copolymer is described. It was observed that the magnetite nanoparticle size increases by ion-charging the sulfonated polymeric template with ferrous aqueous solution at increasing iron concentration. A simple model describing the amount of iron incorporation in the polymeric template is proposed. The magnetite-based composite was investigated by atomic absorption, transmission electron microscopy, Mo 1ssbauer spectroscopy, X-ray diffraction, and magnetization data.

Hydrous aluminum phosphates containing sodium were obtained by treating aluminum hydroxide with aqueous solutions of sodium orthophosphate or phosphoric acid and sodium hydroxide. The composition of the solids varied according to the initial concentration of reagents, pH of the reaction mixture, number of washings and reaction time. The properties of the solids upon heating are strongly dependent on their chemical compositions as P/Al and Na/Al ratios. Solids with high P/Al and Na/Al ratios are transformed into a closed cell foam in a temperature range 600°C to 1000°C, and solids with lower P/Al and Na/Al do not foam by heating up to 1000°C. The foams and powders were characterized by X-ray diffraction, infrared spectrophotometry, optical and scanning electron microscopy (SEM) and density determinations. The results suggest that the foam skeletal material consists of a glass–ceramic in which AlPO 4 crystalline phase is dispersed in a sodium-rich amorphous matrix.

Size-controlled synthesis of cobalt-ferrite nanoparticles, their passivation and peptization as stable ferrofluids are reported. Transmission electron microscopy and Mossbauer spectroscopy were used as characterization techniques. Particles with little change in size distribution, in the 10–15 nm diameter ranges, were obtained using stirring speeds between 2700 and 8100 rpm. The anomalous diffusion has been used to explain the nanoparticle size-control mechanism.

In this study the transmitted light intensity of three biocompatible magnetic fluid samples based on dimercaptosuccinic-coated maghemite nanoparticles was investigated using the typical birefringence experimental setup. The field dependence of the transmitted light intensity follows the typical second-order Langevin profile as the nanoparticle volume fraction reduces by dilution of the stock sample. As the stock sample is diluted the field dependence of the transmitted light intensity is analyzed in terms of changes in the sample morphology which is described by a distribution function of the chain-like structure length.

The aim of this study was to prepare bovine serum albumin-based beads containing maghemite nanoparticles incorporated via ionic magnetic fluid and to evaluate the cell toxicity of this biocompatible system using the J774-A1 cell line. Transmission electron micrographs obtained from the magnetic fluid sample were used to estimate the average particle diameter around 7.6 nm and diameter dispersion of 0.22. The BSA-based magnetic beads were prepared using the heat protein denaturation route. The nanoparticle concentration in the magnetic fluid sample used for the synthesis of the magnetic beads was in the range of 1.2 x 10(16) to 2.3 x 10(17) particle/ml. The methodology used to investigate the cell toxicity of the magnetic beads was the classical MTT assay. Our observation showed that the toxicity against the J774-A1 cell line depends upon the amount of magnetic material incorporated into the magnetic nanobeads and was found to be 14, 11, 9, 5, and 3% for 2.3 x 10(17), 1.2 x 10(17), 4.6 x 10(16), 2.3 x 10(16), and 1.2 x 10(16) particle/ml, respectively.

Static magnetic birefringence (SMB) and transmission electron microscopy were used to investigate maghemite-based magnetic fluids surface coated with citrate and dispersed in physiologic solution. The model used to investigate the birefringence signal considers the monomer and dimer contributions and dimer magnetic permeability dependence to the applied field. The particle size distribution obtained from the fit of the SMB data is compared to the data obtained from the microscopy. Zero-field birefringence, present in the birefringence data, was also taken into account, and analyzed by the dimer model.

Amorphous aluminum phosphates of various compositions were prepared by a precipitation reaction, using aqueous solutions of NaH 2 PO 4 , Al(NO 3 ) 3 , and NH 4 OH as reagents. The resulting solids were chemically characterized and tested in order to observe their capability to undergo closed-pore formation under heating at high temperatures (above 400°C). The formation of closed pores improves the particles’ light-backscattering power, making them useful as white pigments.

In this work, we investigated the interaction between different molecular-coated magnetite nanoparticles and the serum albumin protein. The investigation was based on the fluorescence quenching of the tryptophan residue of the serum albumin protein after the binding with the molecular-coated magnetite nanoparticles to specific sites. Three different biocompatible magnetic fluid samples based on magnetite nanoparticles surface-coated with carboxymethyldextran, tartrate, and polyaspartic were used. Significant differences in the values of binding constant (K/sub b/) and stoichiometry (n) were found as the surface-coating species are changed. The results obtained from the molecular-coated magnetite nanoparticles having different coatings indicate the effect of the coating material in the biological association of magnetite nanoparticles to biological macromolecules.

The formation of thermoreversible gels from aqueous aluminum polyphosphate solutions was previously assigned to hydration-dependent interionic associations, but these were not elucidated. In the present work, aluminum-phosphate interactions were examined by 31 P- and 27 Al-NMR spectroscopy of aqueous aluminum polyphosphate solutions and gels, at various P/Al ratios and temperatures. The fraction of aluminum and phosphate groups actually involved in the sol–gel transition is small, as evidenced by the comparison of spectra of solutions at various P/Al ratios and temperatures, in which only minor spectral changes are actually associated with gel formation. Chemical groups responsible for network formation are mainly Al- (H 2 O) 4 (PO 3 ) 2 groups, in which the phosphate ligands are polyphosphate chain-ends. Within the gels, a large fraction of total aluminum is found as hexaquoaluminum ions, as evidenced by 27 Al-NMR spectra; on the other hand, 31 P-NMR spectra show that most phosphate ions are associated. These data indicate that bonding and bridging involve both inner- and outer-coordination sphere interactions. The former depend on ligand exchange reactions with half-life on the order of magnitude of a few seconds, which explains the time dependence of thermoreversible sol–gel transformations, in this system.

In this paper, Raman spectroscopy was used to investigate the chemical and structural properties of citrate-coated Fe/sub 3/O/sub 4/ and CoFe/sub 2/O/sub 4/ nanoparticles. The Raman data obtained from the two samples investigated are compared with the Raman data from the literature of bulk maghemite and bulk hematite. The Raman data are used to discuss the higher structural stability of the CoFe/sub 2/O/sub 4/-based sample in comparison to the Fe/sub 3/O/sub 4/-based sample, when submitted to optical illumination at different intensities.

Incorporation of magnetite nanoparticles in mesoporous styrene−divinylbenzene microspheres, via oxidation of ferrous ion adsorbed in the template, is modeled in terms of the ferrous ion concentrati...

In this study dynamic susceptibility (DS) was used to investigate magnetite nanoparticles dispersed in styrene-divinylbenzene copolymer. Transmission electron microscopy (TEM) data have been used to support the DS data analysis. The field dependence of the peak position of the imaginary component of DS was analyzed using a picture of an asymmetric double well potential for the relaxation of the magnetic moment associated with the magnetite nanoparticle. The size dependence of the magnetic susceptibility was included in the data analysis. Nanoparticle-size parameters obtained from the analysis of the DS data (19.1 and 18.2 nm) are in excellent agreement with the values obtained from the fitting of the TEM data (19.2 and 20.1 nm).

In contrast to all magnetic resonance investigations previously performed using magnetic fluids (MFs) based on spinel ferrite nanoparticles, cadmium–ferrite-based MFs present an intense, relatively sharp resonance line near g=4, in addition to the typical, broad structure near g=2. The broad resonance structure is associated with larger cadmium–ferrite nanoparticles, whereas the sharp resonance line is associated with ultrasmall cadmium–ferrite nanoparticles. Transmission electron microscopy (TEM) data confirm the bimodal particle size distribution in the sample investigated. The temperature T dependence of the resonance field HR is almost linear, for both high-field (HF) and low-field (LF) resonance lines, in the range of 100–300 K. In support of the identification of the HF line (around g=2) and LF line (around g=4) with larger and smaller Cd–ferrite nanoparticles, respectively, the slope of the HR versus T curve is lower for the HF line (1.3 G/K) compared to the LF line (1.69 G/K), whereas the intercep...

In this work, we investigated the interaction between molecular-coated magnetic nanoparticles (MC-MNPs) and serum albumin proteins (BSA) through the fluorescence quenching of the tryptophan residue present in BSA after the binding of MC-MNPs to specific sites. Three different biocompatible magnetic fluid (BMF) samples based on magnetite or cobalt–ferrite MNPs coated with citric acid or dextran were used. The binding constant and the stoichiometry of the investigated MNPs indicate that the BMF based on cobalt–ferrite is more site specific and more strongly bound to the BSA than the BMFs based on magnetite. The results may direct the design of new magnetic drug-carriers based on BMFs.