Publications by authors named "Gustavo R Castro"

This study describes the synthesis and characterization of chlorambucil (CLB)-functionalized mesoporous silica nanoparticles (MSNs) for potential application in cancer therapy. The nanoparticles were designed with a diameter between 20 and 50 nm to optimize cellular uptake and avoid rapid clearance from the bloodstream. The synthesis method involved modifying a previously reported technique to reduce particle size.

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Functional nanomaterials have attracted attention by producing different structures in any field. These materials have several potential applications, including medicine, electronics, and energy, which provide many unique properties. These nanostructures can be synthesized using various methods, including self-assembly, which can be used for the same applications.

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Background: Prostate cancer cells have very high PCA3 messenger RNA levels, which turns them into one of the new biomarkers for prostate cancer prognosis and diagnosis.

Objective: Our goal here is to develop a new aptasensor to detect PCA3 release by the cancer cell.

Methods: DNA hairpin containing PCA3 aptamer was thiolated, conjugated to methylene blue (MB) redox probe, and immobilized on gold electrode through self-assembly to detect label-free cancer cells.

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We have developed a clean route for the modification of polyvinylchloride surface (PVC) with 4-amino-5-hydrazino-1,2,4-triazole-3-thiol molecule. The modification reaction was investigated through Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analysis. According to our findings, S-H groups are responsible to the molecule attachment and nitrogen atoms are directly involved in metal ion coordination.

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Gold nanoparticles (AuNPs) can provide a simple, easy-to-use, inexpensive, at hand point-of-care (POC) fast to diagnose; however, AuNPs have the predisposition to form aggregations. Since the nanoparticles stability is an important issue, this article is aiming to study the long-term stability associated with the development of an immunosensor for clinical diagnosis. Here, we assessed two previous methods commonly described in the literature to prevent the formation of aggregate by studying pH and Tween® 20 (polysorbates) addition as surfactant.

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The aim of the present research is to propose a new method based on localized surface plasmon resonance (LSPR) for fast dengue virus detection. A pool with four dengue serotypes (DENV-1, -2, -3, -4) was detected through antigen-antibody binding using gold nanoparticles (AuNPs) as signaling antibody carriers. Such result was confirmed through surface plasmon resonance (SPR), transmission electron microcopy (TEM), and dynamic light scattering (DLS) techniques.

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Early prostate cancer (PCa) diagnostic is crucial to enhance patient survival rates; besides, non-invasive platforms have been developed worldwide in order to precisely detect PCa biomarkers. Therefore, the aim of the present study is to develop a new aptamer-based biosensor through the self-assembling of thiolated aptamers for PSA and VEGF on the top of gold electrodes. This biosensor was tested in three prostate cell lines (RWPE-1, LNCaP and PC3).

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This work reports the sol-gel synthesis of a SBA-15 silica, and its functionalization with 4-amino-2-mercaptopyrimidine to perform adsorption of metal species from aqueous media. The functionalization of the material was confirmed by FTIR and superficial area measurements. The final material was tested through batch experiments to uncover its adsorptive properties towards the adsorption of Cu(II), Cd(II), Zn(II), Pb(II) and Ni(II).

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Background: Insulin-like growth factor I (IGF-I) is produced almost entirely by the liver and is the main promoter of anabolic growth hormone (GH) effects on protein, carbohydrate, and lipid metabolism. IGF-I is significantly decreased in patients with liver cirrhosis. Our objective was to determine the relationship between circulating IGF-I and MELD (Model for End-stage Liver Disease) in cirrhotics subjected to orthotopic liver transplantation (OLT).

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The purpose of this work was to determine the concentration of copper in samples of farmed Nile tilapia (Oreochromis niloticus L.) fillets purchased in the city of Botucatu (São Paulo, Brazil) and in fillet and liver samples of Tilapia fed diets supplemented with different concentrations of Cu from the Laboratory of Aquatic Organism Nutrition/FMVZ-UNESP (Botucatu, Brazil). The fillet samples were prepared by lyophilisation and cryogenic grinding into particles smaller than 60 µm, and copper was extracted ultrasonically using 0.

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An investigation was made into calcium, iron and zinc in protein spots in samples of Nile tilapia (Oreochromis niloticus) liver tissue obtained after protein separation by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and subsequent qualitative and quantitative evaluation by synchrotron radiation X-ray fluorescence (SRXRF) and Flame Atomic Absorption Spectrometry (FAAS). An analysis of the fluorescence spectra indicated the presence of calcium, iron and zinc in 12, 6 and 8 liver protein spots, respectively. The metal ions found were distributed mainly in proteins with a molar mass of less than 40.

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This paper reports on a preliminary evaluation of the grain size distribution of cadmium, lead and copper in sediment from Catarina Beach, Ilha Solteira, in the state of São Paulo, Brazil. Surface sediments were fractionated with <63 microm nylon sieves and subjected to three digestion procedures: the proposed open digestion, the standard USEPA-3050B and closed digestion in a Teflon tube. The metals were determined by atomic absorption spectrometry.

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Background: The influence of hypothyroidism in liver regeneration has been a controversial opinions.

Purpose: The aim of this study is to identify the relationship between hypothyroidism and liver regeneration in rats.

Methods: Forty male Wistar rats divided into two groups of 20 specimens each.

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A rapid and sensitive method was developed to determine trace levels of Cd2+ ions in an aqueous medium by flame atomic absorption spectrometry, using on-line preconcentration in a mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT). The Cd2+ ions were sorbed at pH 5.0.

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