Jairo P. Oliveira

Resin from Virola oleifera Protects Against Radiocontrast-Induced Nephropathy in Mice.

Contrast-induced nephropathy (CIN) is an iatrogenic medical event for which there is not yet a successful therapy. Increasing evidence in rodents has suggested that this disease is associated with renal tubular and vascular injury that is triggered directly by oxidative stress. In the present study, we evaluated whether the antioxidant resin from Virola oleifera (RV) could attenuate renal damage in an experimental mouse model of CIN. Adult male Swiss mice were divided into six groups and pre-treated orally with RV (10, 100 and 300 mg/kg), N-acetylcysteine (200 mg/kg) or vehicle for 5 days before the induction of CIN and Control group. Renal function was assessed by measuring plasma creatinine and urea levels. Additionally, renal oxidative stress and apoptosis/cell viability were determined with flow cytometry. Finally, kidney tissues were sectioned for histopathological examination. In this CIN model, pre-treatment with RV improved renal function, lowered the mortality rate, and reduced oxidative stress and apoptosis in both the medulla and cortex renal cells in a dose-dependent manner. Moreover, the RV treatment had beneficial effects on kidney histopathology that were superior to the standard treatment with N-acetylcysteine. These data suggest that because of its antioxidative and antiapoptotic effects and its ability to preserve renal function, resin from Virola oleifera may have potential as a new therapeutic approach for preventing CIN.

Extracellular biosynthesis of silver nanoparticles using the cell-free filtrate of nematophagous fungus Duddingtonia flagrans

The biosynthesis of metallic nanoparticles (NPs) using biological systems such as fungi has evolved to become an important area of nanobiotechnology. Herein, we report for the first time the extracellular synthesis of highly stable silver NPs (AgNPs) using the nematophagous fungus Duddingtonia flagrans (AC001). The fungal cell-free filtrate was analyzed by the Bradford method and 3,5-dinitrosalicylic acid assay and used to synthesize the AgNPs in the presence of a 1 mM AgNO3 solution. They have been characterized by UV–Vis spectroscopy, X-ray diffraction, transmission electron microscopy, dynamic light scattering, Zeta potential measurements, Fourier-transform infrared, and Raman spectroscopes. UV–Vis spectroscopy confirmed bioreduction, while X-ray diffractometry established the crystalline nature of the AgNPs. Dynamic light scattering and transmission electron microscopy images showed approximately 11, 38 nm monodisperse and quasispherical AgNPs. Zeta potential analysis was able to show a considerable stability of AgNPs. The N–H stretches in Fourier-transform infrared spectroscopy indicate the presence of protein molecules. The Raman bands suggest that chitinase was involved in the growth and stabilization of AgNPs, through the coating of the particles. Our results show that the NPs we synthesized have good stability, high yield, and monodispersion.

Virtual Reconstruction and Three-Dimensional Printing of Blood Cells as a Tool in Cell Biology Education

The cell biology discipline constitutes a highly dynamic field whose concepts take a long time to be incorporated into the educational system, especially in developing countries. Amongst the main obstacles to the introduction of new cell biology concepts to students is their general lack of identification with most teaching methods. The introduction of elaborated figures, movies and animations to textbooks has given a tremendous contribution to the learning process and the search for novel teaching methods has been a central goal in cell biology education. Some specialized tools, however, are usually only available in advanced research centers or in institutions that are traditionally involved with the development of novel teaching/learning processes, and are far from becoming reality in the majority of life sciences schools. When combined with the known declining interest in science among young people, a critical scenario may result. This is especially important in the field of electron microscopy and associated techniques, methods that have greatly contributed to the current knowledge on the structure and function of different cell biology models but are rarely made accessible to most students. In this work, we propose a strategy to increase the engagement of students into the world of cell and structural biology by combining 3D electron microscopy techniques and 3D prototyping technology (3D printing) to generate 3D physical models that accurately and realistically reproduce a close-to-the native structure of the cell and serve as a tool for students and teachers outside the main centers. We introduce three strategies for 3D imaging, modeling and prototyping of cells and propose the establishment of a virtual platform where different digital models can be deposited by EM groups and subsequently downloaded and printed in different schools, universities, research centers and museums, thereby modernizing teaching of cell biology and increasing the accessibility to modern approaches in basic science.

CARACTERIZAÇÃO FÍSICO-QUÍMICA DE RESÍDUOS OLEOSOS DO SANEAMENTO E DOS ÓLEOS E GRAXAS EXTRAÍDOS VISANDO A CONVERSÃO EM BIOCOMBUSTÍVEIS

Oily waste from sanitation processes was characterized for its potential use in the generation of biofuels. The waste residues studied showed high levels of oil and grease, reaching up to 87% (m/m) in a grease trap of a food company, showing that these residues can be utilized for the production of biofuels. The results revealed high levels of moisture and saponification as well as high levels of free fatty acids (FFA). Analysis of chromatographic profiles (HPLC) showed great heterogeneity of the fatty acids contained in the sample, and a predominance of palmitic, oleic, linoleic and linolenic acids.

Surface-Enhanced Raman Plasmon in Self-Assembled Sulfide-Coated Gold Nanoparticle Arrays

This paper investigates the surface-enhanced Raman plasmon in self-assembled gold nanoparticle arrays. The self-assembly process reported in this paper is triggered by the addition of sulfide in a sample of citrate-stabilized gold nanoparticles (AuNPs). The characterization of gold nanoparticle arrays was carried out by UV-visible absorption spectrum, transmission electron microscopy (TEM), and Raman map. Results demonstrate an aggregation of AuNPs with a peculiar physical docking resembling nanowires. Moreover, these nanostructures exhibited intense Raman scattering signal when compared with regular AuNPs. This simple technique is a candidate for future applications such as sensors for detecting sulfide compounds and nanosystem fabrication.

Comparison between the synthesis of gold nanoparticles with sodium citrate and sodium tetraboreto

Background With gold nanoparticles (AuNPs) is possible to develop nanoscale devices that can interact with chemical and biological systems. The phenomenon explored in these nanosystems is called Localized Surface Plasmon Resonance (LSPR), which promotes electromagnetic wave oscillation electronics on these small metallic structures. It is interesting to note that this resonance is directly linked to the size of the nanoparticles, the nature of the dielectric material and support environment where the device is being studied [1,2]. This work makes a comparison between results obtained in the synthesis of AuNP’s reduction method using a Sodium Citrate (Na3C6H5O7) and Sodium Borohydride (NaBH4). Was expected to demonstrate the viability of these two reducing agents and highlight the potential differences obtained in each of the mechanisms. Since knowledge is the ability of stabilizing citrate ions and the strong reducing action of NaBH4 [3]. The dominance of this knowledge will provide the development of systems with particle size specific for various applications in biosensors.

Ultrasound-assisted extraction of Achyrocline satureioides prevents contrast-induced nephropathy in mice

Achyrocline satureioides or Macela, has been largely used in traditional folk medicine in Brazil as an anti-inflammatory agent and to treat various digestive disorders. The aim of the present study was to evaluate the preventive action of the extracts of A. satureioides obtained by maceration and ultrasound-assisted extraction, quercetin and N-acetylcysteine against contrast-induced nephropathy in mice. The antioxidant activity, cytotoxicity and inhibition of nitric oxide (NO) production in macrophages were evaluated. Also, chemical analyses of phenolic compounds, total flavonoids, and quercetin by LC-MS/MS present in various extracts of A. satureioides were performed. Thirty six mice were divided into six groups: control group (C), Contrast-Induced Nephropathy group (CIN), Group N-acetylcysteine 200mg/kg (NAC); Group quercetin 10mg/kg (Q), Group Macela 10mg/kg (M10), and Group Macela 50mg/kg (M50). The serum levels of urea and creatinine, advanced oxidation protein products (AOPP) and renal ultrastructure were evaluated by electron microscopy scanning. Ultrasound-assisted extraction improved the quality of extract (with 100% ethanol), since did not show toxicity to fibroblasts, and showed potent antioxidant activity and a high content of phenolic compounds, flavonoids, and quercetin, in addition to being able to reduce the production of NO in dose-dependent effect in macrophages. Results showed that animals treated with Macela extracts maintained normal levels of urea, creatinine, and AOPP, while preserving ultrastructure of the renal cells. The obtained results were more promising than NAC and Q groups in protecting against renal failure caused by CIN, showing that the plant can be a promising drug for preventing this disease.

Ultrasensitive nanosensor based on silver nanoparticles to detect hydrogen peroxide

Studies to determine the concentration of hydrogen peroxide (H2O2) are important in biological system due to cellular damages provoked by reative oxygen species that include H2O2. An alternative to detect H2O2 is through an optical nanosensors based on silver nanoparticles, which have great potential for chemical and biological sensing applications. Here we demonstrate that attenuated total reflectance (ATR) from interaction of silver nanoparticles and hydrogen peroxide were able to detect very low levels of H2O2 around 0,001mM.

Quantification of Inter-particle Spacing Caused by Thiol Self-Assembled Monolayers Using Transmission Electron Microscopy

AbstractNano-surface modification techniques have been increasingly reported in a multitude of applications. However, the metal-ligand interface can be difficult to characterize, mainly due to the inadequacy of analytical methodologies. Here, we analyze this interface using transmission electron microscopy, which can determine the thickness of the linkers. This work presents a comprehensive physical characterization of gold nanoparticles with modified surfaces using conventional transmission electron microscopy. We have successfully demonstrated a simple and reliable protocol for the quantification of inter-particle spacing caused by SAM thiol ligands bound onto AuNPs. This approach is based on the linear correlation of the distance between the gold nanoparticles and the length of 3-mercaptopropionic acid (MPA), 11-mercaptoundecanoic acid (MUA), and 16-mercaptohexadecanoic acid (MHA). Graphical Abstract

Virola oleifera-capped gold nanoparticles showing radical-scavenging activity and low cytotoxicity

The development of effective nanoparticle therapeutics has been hindered by their surface characteristics, such as hydrophobicity and charge. Therefore, the success of biomedical applications with nanoparticles is governed by the control of these characteristics. In this article, we report an efficient green capping method for gold nanoparticles (AuNPs) by a reduction with sodium citrate and capping with Virola oleifera (Vo), which is a green exudate rich in polyphenols and flavonoids. The Vo-capped AuNPs were characterized by UV, DLS, FTIR, Raman, TEM, DPPH, FRAP and their cytotoxicity was evaluated on the viability of Murine macrophage cell. The AuNPs had an average particle size of 15 nm and were stable over a long time, as indicated by their unchanged SPR and zeta potential values. These nanoparticles were assessed for their antioxidant potential using DPPH and FRAP and demonstrated the highest antioxidant activities and low cytotoxicity. We propose that the Virola oleifera-capped AuNPs have potential biomedical applications.