Sebastião William da Silva

Effect of Fe2O3 concentration on the structure of the SiO2-Na2O-Al2O3-B2O3 glass system.

The structural properties of the glass matrix 40SiO(2)·30Na(2)O·1Al(2)O(3)·(29-x)B(2)O(3)·xFe(2)O(3) (mol%), 0.0≤x≤29.0 were studied by X-ray diffraction (XRD), differential thermal analysis (DTA) and Raman and infrared spectroscopy (FT-IR). XRD demonstrated Fe(3)O(4) crystal formation for Fe(2)O(3) concentrations of 29.0 mol%. DTA showed that glass transition and crystallization temperatures changed as a function of Fe(2)O(3) concentration and that these alterations were related to structural change in the glass system. Interesting aspects of Raman and FT-IR spectra were found, and this gives information about of the structure changes in Si-O-Si units of these glasses as a function of Fe(2)O(3) concentration.

Raman spectroscopy in magnetic fluids.

In this work Raman spectroscopy was used to investigate uncoated magnetic fluids (UMFs) and coated magnetic fluids (CMFs). The coating agents were N-oleoylsarcosine, dodecanoic acid, and ethoxylated polyalcohol. The Raman probe is the hydroxyl (OH) group chemisorbed at the magnetic nanoparticle surface and the measurements were performed in the typical OH bending and OH stretching regions. The room temperature Raman data obtained from the UMFs and CMFs are compared to each other and with the data obtained from liquid water. Suppression of Raman modes from the MFs are discussed in terms of symmetry reduction and in terms of the interaction between the chemisorbed OH-group and the surrounding medium. The relative grafting coefficient associated to different coatings are estimated from the Raman data. The highest grafting coefficient is achieved with a single coating of dodecanoic acid in the hydrocarbon-based MF. The surface-grafting coefficient of the N-oleoylsarcosine-coated MF reduces when the polar liquid carrier replaces the non-polar liquid carrier. In comparison to liquid water, it was found that the hydrogen bonding between the chemisorbed OH-group and the solvent was enhanced in UMFs and reduced in CMFs.

Shell Thickness Modulation in Ultrasmall CdSe/CdSxSe1–x/CdS Core/Shell Quantum Dots via 1-Thioglycerol

In this study, we report on the synthesis of CdSe/CdS core-shell ultrasmall quantum dots (CS-USQDs) using an aqueous-based wet chemistry protocol. The proposed chemical route uses increasing concentration of 1-thioglycerol to grow the CdS shell on top of the as-precipitated CdSe core in a controllable way. We found that lower concentration of 1-thioglycerol (3 mmol) added into the reaction medium limits the growth of the CdSe core, and higher and increasing concentration (5-11 mmol) of 1-thioglycerol promotes the growth of CdS shell on top of the CdSe core in a very controllable way, with an increase from 0.50 to 1.25 nm in shell thickness. The growth of CS-USQDs of CdSe/CdS was confirmed by using different experimental techniques, such as optical absorption (OA) spectroscopy, fluorescence spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Data collected from OA were used to obtain the average values of the CdSe core diameter, whereas Raman data were used to assess the average values of the CdSe core diameter and CdS shell thicknesses.

Anti-CEA loaded maghemite nanoparticles as a theragnostic device for colorectal cancer.

Nanosized maghemite particles were synthesized, precoated (with dimercaptosuccinic acid) and surface-functionalized with anticarcinoembryonic antigen (anti-CEA) and successfully used to target cell lines expressing the CEA, characteristic of colorectal cancer (CRC) cells. The as-developed nanosized material device, consisting of surface decorated maghemite nanoparticles suspended as a biocompatible magnetic fluid (MF) sample, labeled MF-anti-CEA, was characterized and tested against two cell lines: a high-CEA expressing cell line (LS174T) and a low-CEA expressing cell line (HCT116). Whereas X-ray diffraction was used to assess the average core size of the as-synthesized maghemite particles (average 8.3 nm in diameter), dynamic light scattering and electrophoretic mobility measurements were used to obtain the average hydrodynamic diameter (550 nm) and the zeta-potential (−38 mV) of the as-prepared and maghemite-based nanosized device, respectively. Additionally, surface-enhanced Raman spectroscopy (SERS) was used to track the surface decoration of the nanosized maghemite particles from the very first precoating up to the attachment of the anti-CEA moiety. The Raman peak at 1655 cm−1, absent in the free anti-CEA spectrum, is the signature of the anti-CEA binding onto the precoated magnetic nanoparticles. Whereas MTT assay was used to confirm the low cell toxicity of the MF-anti-CEA device, ELISA and Prussian blue iron staining tests performed with both cell lines (LS174T and HCT116) confirm that the as-prepared MF-anti- CEA is highly specific for CEA-expressing cells. Finally, transmission electron microscopy analyses show that the association with anti-CEA seems to increase the number of LS174T cells with internalized maghemite nanoparticles, whereas no such increase seems to occur in the HCT116 cell line. In conclusion, the MF-anti-CEA sample is a biocompatible device that can specifically target CEA, suggesting its potential use as a theragnostic tool for CEA-expressing tumors, micrometastasis, and cancer-circulating cells.

SERS Investigation of Cancer Cells Treated with PDT: Quantification of Cell Survival and Follow-up

In this study Surface Enhanced Raman Spectroscopy (SERS) data recorded from mouse mammary glands cancer cells (4T1 cell line) was used to assess information regarding differences between control, death and viable cells after Photodynamic Therapy (PDT) treatment. The treatment used nanoemulsions (NE/PS) loaded with different chloroaluminumphthalocyanine (ClAlP) photosensitizer (PS) contents (5 and 10 µmol × L−1) and illumination (660 nm wavelength) at 10 J × cm−2 (10 minutes). The SERS data revealed significant molecular alterations in proteins and lipids due to the PDT treatment. Principal Component Analysis (PCA) was applied to analyze the data recorded. Three-dimensional and well reproductive PCA scatter plots were obtained, revealing that two clusters of dead cells were well separated from one another and from control cluster. Overlap between two clusters of viable cells was observed, though well separated from control cluster. Moreover, the data analysis also pointed out necrosis as the main cell death mechanism induced by the PDT, in agreement with the literature. Finally, Raman modes peaking at 608 cm−1 (proteins) and 1231 cm−1 (lipids) can be selected for follow up of survival rate of neoplastic cells after PDT. We envisage that this finding is key to contribute to a quick development of quantitative infrared thermography imaging.

Fe-doping effects on the structural, vibrational, magnetic, and electronic properties of ceria nanoparticles

In this work, we report on a single-pot synthesis route based on a polymeric precursor method used for successfully producing undoped and iron-doped CeO2 nanoparticles with iron contents up to 10.0 mol. %. The formation of high-crystalline nanoparticles with a cubic fluorite structure is determined for all the studied samples. Meanwhile, the magnetic measurements of the undoped ceria nanoparticles revealed the occurrence of ferromagnetism of bound magnetic polarons of a fraction of Ce3+ at room temperature, and only a paramagnetic behavior of Fe3+ ions was determined for Fe-doped ceria nanoparticles. A monotonous reduction of the effective magnetic moment of the Fe3+ ions was determined. It suggests a change from a high-spin to low-spin state of Fe ions as the Fe content is increased. The 3+ valence state of the iron ions has been confirmed by the Fe K-edge X-ray absorption near-edge structure (XANES) and Mossbauer spectroscopy measurements. X-ray photoelectron spectroscopy data analysis evidenced a coexi...

Nanocapsules for the co-delivery of selol and doxorubicin to breast adenocarcinoma 4T1 cells in vitro

Abstract Nanocapsules (NCS-DOX) with an oily core of selol and a shell of poly(methyl vinyl ether-co-maleic anhydride) covalently conjugated to doxorubicin were developed. These nanocapsules are spherical, with an average hydrodynamic diameter of about 170 nm, and with negative zeta potential. NCS-DOX effectively co-delivered the selol and the doxorubicin into 4T1 cells and changed the intracellular distribution of DOX from the nuclei to the mitochondria. Moreover, a significantly increased cytotoxicity against 4T1 cells was observed, which is suggestive of additive or synergic effect of selol and doxorubicin. In conclusion, PVM/MA nanocapsules are suitable platforms to co-deliver drugs into cancer cells.

Evidence of competition in the incorporation of Co2+ and Mn2+ ions into the structure of ZnTe nanocrystals

Glass-embedded Zn1−x−yMnxCoyTe nanocrystals (with x = 0.01 and y varying from 0.000 to 0.800) were successfully synthesized using a protocol based on the melting–nucleation synthesis route and herein investigated by several experimental techniques. Optical absorption (OA) provides evidence of the incorporation of substitutional Co2+ ions in the semiconducting Zn1−x−yMnxCoyTe lattice and shows that with increasing Co concentration these ions may also be dispersed into the glass matrix, causing structural disorder. Atomic force microscopy (AFM) images reveal the size of the nanocrystals and magnetic force microscopy (MFM) gives evidence of the paramagnetic behavior of the doped samples. X-ray diffraction (XRD) and Raman scattering reveal that high Co concentrations increase the structural disorder in the host glass matrix. Electron paramagnetic resonance (EPR) spectroscopy reveals the presence of Mn2+ ions inside and at (or near) the surface of the ZnTe nanocrystals, and also that the increase of Co doping concentration reduces the incorporation of Mn2+ ions into the ZnTe structure, simultaneously increasing their dispersion into the glass matrix.

Polyethyleneglycol nanoparticles adsorbed to glycine as a bioengineered neomaterial for application in inflammatory processes

Polyethylene glycol nanoparticles (NP-PEG) have good adsorption in bioactive compounds and are considered promising vehicles. Several studies have reported the importance of the amino acid for several treatments, among them glycine that has immunomodulatory, cytoprotective and anti-inflammatory effects. The objective of this work was to evaluate the efficiency of the synthesis of polyethylene glycol (PEG) nanoparticles adsorbed with glycine (NANO-PEG/GLY) on functional activity of colostrum macrophages. Human colostrum cells were obtaining from 18 clinically healthy women and used for bioassays of cell viability, phagocytosis, microbicidal activity and cytokines concentration. It was observed that the cell viability index in the presence of NANO-PEG/GLY was above 85%. Phagocytosis rates in colostrum cells treated with glycine and in the presence of EPEC, wheareas the higest microbicidal index were observed in macerophages treated with PEG-NANO-GLY. IL-1β and TNF-α levels increased in GLY and NANO-PEG/GLY groups. The levels of IL-12 and IL-17 also increased in the macrophages cultures under the NANO-PEG/GLY treatment. In the supernatant cell culture IL-8 and IFN-γ levels were similar among the treatments. The date suggest that NANO-PEG particles produced were able to adsorb the amino acid glycine, and this new bioengineered material is capable of modulating the functional activity of human colostrum macrophages and represents an alternative route for the treatment of inflammatory deseases.

Magnetic nanohydrogel obtained by miniemulsion polymerization of poly(acrylic acid) grafted onto derivatized dextran

This study describes the synthesis of magnetic nanohydrogels by miniemulsion polymerization technique. Dextran was derivatized by the glycidyl methacrylate to anchor vinyl groups on polysaccharides backbone, allowing its use as a macromonomer for miniemulsion polymerization, as confirmed by proton nuclear magnetic resonance spectroscopy (13C NMR). Magnetite nanoparticles were synthesized by coprecipitation, followed by air oxidation to maghemite. The results of X-ray diffractometry (XRD), Raman and transmission electron microscopy (TEM) analysis showed that maghemite nanoparticles were obtained with a diameter of 5.27nm. The entrapment of iron oxide nanoparticles in a dextran nanohydrogel matrix was confirmed by thermogravimetric analysis (TGA), scanning transmission electron microscopy (STEM) and Zeta potential data. The magnetic nanohydrogels presented superparamagnetic behavior and were colloidal stable in physiological during 30days. Our findings suggest that the synthesized magnetic nanohydrogel are potential candidates for use in drug delivery systems due to its physicochemical and magnetic properties.