Navegação Periódicos - Artigos por assunto "nanoparticles"

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  • IPEN-DOC 23168

    GALANTE, RAQUEL; REDIGUIERI, CAROLINA F.; KIKUCHI, IRENE S.; VASQUEZ, PABLO A.S. ; COLACO, ROGERIO; SERRO, ANA P.; PINTO, TEREZINHA J.A.. About the sterilization of chitosan hydrogel nanoparticles. Plos One, v. 11, n. 12, 2016. DOI: 10.1371/journal.pone.0168862

    Abstract: In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP) associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility) with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS) hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation), a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP) hydrogel nanoparticles (CS-HNP), with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol). Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

    Palavras-Chave: sterilization; oligosaccharides; hydrogels; nanoparticles; drug delivery; biological materials

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  • IPEN-DOC 25111

    CUNICO, PATRICIA ; KUMAR, ANU; ALCANTARA, RAQUEL R. ; FUNGARO, DENISE A. . Adsorption of solophenyl dyes from aqueous solution by modified nanozeolite from bottom ash and its toxicity to C. dubia. Current Nanomaterials, v. 2, n. 2, p. 95-103, 2017. DOI: 10.2174/2405461503666180201152351

    Abstract: Background: It is known that wastewater from textile industries are responsible for producing large amounts of highly contaminated effluents by various types of synthetic dyes. These compounds can be toxic, and in some cases, are carcinogenic and mutagenic and its removal is recommended. Application: In the area of water purification, nanomaterials have been applied for removal of several compounds. Of the four classes of nanomaterials, zeolites have demonstrated good results for the removal of dyes. Nanozeolite synthesized from bottom ash and modified with hexadecyltrimethylamonium (ZMB) was used as adsorbent to removal of Solophenyl Navy (SN), Solophenyl Turquoise (ST) and their hydrolyzed forms (SNH and STH, respectively) from simulated textile wastewater. Method: The physical-chemical characterization of materials was presented by using relevant analytical methods (XRD, SEM, BET surface area, etc.). Effects of parameters such as initial dye concentration, contact time and equilibrium adsorption were evaluated. The adsorption kinetics followed the pseudo-second-order model. Results: Langmuir isotherm model shows the best fit for most dyes-ZMB systems. In order to identify if ZMB presented toxicity for the environment, bioassay and toxicity identification evaluation (TIE) with C. dubia were performed. The leached of ZMB was toxic to daphinids (11.3 TU). Conclusion: TIE results appointed that the main cause of the toxicity could be due the surfactant and metal ions presents in aqueous solution.

    Palavras-Chave: toxicity; textile industry; waste water; nanoparticles; zeolites; copper; dyes; adsorption

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  • IPEN-DOC 27828

    PARRA, DUCLERC F. ; MARCHINI, LEONARDO G. ; KOMATSU, LUIZ G.H. ; OLIVEIRA, CAMILA B. de ; OLIANI, WASHINGTON L. ; RANGARI, VIJAYA K.. AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect. SN Applied Sciences, v. 3, n. 4, 2021. DOI: 10.1007/s42452-021-04365-2

    Abstract: This paper presents research results of biocidal effect of thermoplastic- polyester-elastomer (TPE-E) with incorporation of hybrid Ag/ZnO/SiO2 NPs (silver/Zinc oxide/SiO2 nanoparticles). These results were compared with various gamma-irradiated doses and processing techniques including extrusion, injection molding and compression molding. In all these processing techniques the TPE-E was mixed with mineral oil and Ag/ZnO/SiO2 nanoparticles. The TPE-E nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Infrared FT spectroscopy (FTIR), surface enhanced Raman technique (SERS), FESEM (Field emission scanning electron microscopy), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), TEM (transmission electronic microscopy) and antimicrobial test. Antibacterial activity against E. coli and S. aureus, are reported and these results showed potential application in health care products.

    Palavras-Chave: gamma radiation; irradiation; antibiotics; nanoparticles; silver; processing; thermoplastics

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  • IPEN-DOC 21212

    GONCALVES, KARINA de O.; SILVA, MONICA N. da; SICCHIERI, LETICIA B. ; SILVA, FLAVIA R. de O. ; MATOS, RICARDO A. de; COURROL, LILIA C. . Aminolevulinic acid with gold nanoparticles: a novel theranostic agent for atherosclerosis. Analyst, v. 140, n. 6, p. 1974-1980, 2015.

    Palavras-Chave: aminolevulinic acid; gold; nanoparticles; arteriosclerosis; polyethylene glycols; rabbits; porphyrins; fluorescence spectroscopy; histological techniques; biochemistry; animals

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  • IPEN-DOC 26399

    ROVANI, SUZIMARA ; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A. . An alternative and simple method for the preparation of bare silica nanoparticles using sugarcane waste ash, an abundant and despised residue in the Brazilian industry. Journal of the Brazilian Chemical Society, v. 30, n. 7, p. 1524-1533, 2019. DOI: 10.21577/0103-5053.20190049

    Abstract: Sugarcane waste ash, a Si-rich waste product, is generated in large quantities and creates a serious disposal problem in the Brazilian ethanol-sugar industry, affecting the environment and public health. Here, a simple method capable of generating bare silica nanoparticles utilizing this residue is demonstrated. Firstly, the crystalline silica present in sugarcane waste ash (SWA) was converted into amorphous by melting a mixture of sodium hydroxide and SWA at 550 °C for 1 h. The silica nanoparticles (SiO2NPs) were formed by lowing pH. This production process of SiO2NPs from SWA was optimized varying the ash:NaOH mass ratio, increasing the silica extraction up to 96%. The sample’s composition was characterized by total X-ray fluorescence spectroscopy, morphology and physical-chemical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, specific surface area measurements, Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), followed by use as adsorbent for the removal of methylene blue dye. With this process of extraction, nanoparticles smaller than 100 nm were generated, with a surface area of 63 m2 g-1 and a maximum adsorption capacity of 37 mg g-1 for methylene blue. The results indicate a successful process for obtaining an adsorbent from an industrial waste product using a cost effective and rapid synthesis procedure rendering renewable product.

    Palavras-Chave: sugar cane; wastes; adsorbents; silica; nanoparticles; ethanol fuels; ashes; sodium hydroxides; agriculture; agricultural wastes

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  • IPEN-DOC 26862

    GARCIA, PAULO R.A.F.; PRYMAK, OLEG; GRASMIK, VIKTORIA; PAPPERT, KEVIN; WLYSSES, WAGNER; OTUBO, LARISSA ; EPPLE, MATTHIAS; OLIVEIRA, CRISTIANO L.P.. An in situ SAXS investigation of the formation of silver nanoparticles and bimetallic silver–gold nanoparticles in controlled wet-chemical reduction synthesis. Nanoscale Advances, v. 2, n. 1, p. 225-238, 2020. DOI: 10.1039/c9na00569b

    Abstract: We present a study on the formation of silver (Ag) and bimetallic silver–gold (AgAu) nanoparticlesmonitored by in situ SAXS as well as by ex situ TEM, XRD and UV-vis analysis in a flow reactor at controlled reaction temperature. The formation mechanism of the nanoparticles is derived from the structural parameters obtained from the experimental data. The evolution of the average particle size of pure and alloyed nanoparticles shows that the particle growth occurs initially by a coalescence mechanism. The later growth of pure silver nanoparticles is well described by Ostwald ripening and for the alloyed nanoparticles by a process with a significantly slower growth rate. Additionally, the SAXS data of pure silver nanoparticles revealed two major populations of nanoparticles, the first one with a continuous crystal growth to a saturation plateau, and the second one probably with a continuous emergence of small new crystals. The particle sizes obtained by SAXS agree well with the results from transmission electron microscopy and X-ray diffraction. The present study demonstrates the capability of an in situ investigation of synthesis processes using a laboratory based SAXS instrument. Online monitoring of the synthesis permitted a detailed investigation of the structural evolution of the system.

    Palavras-Chave: nanoparticles; small angle scattering; x-ray diffraction; silver; bimetals; gold; monte carlo method; nanostructures; alloys

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  • IPEN-DOC 25206

    FREITAS, LUCAS F. de ; VARCA, GUSTAVO H.C. ; BATISTA, JORGE G. dos S. ; LUGAO, ADEMAR B. . An overview of the synthesis of gold nanoparticles using radiation technologies. Nanomaterials, v. 8, n. 11, 2018. DOI: 10.3390/nano8110939

    Abstract: At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.

    Palavras-Chave: gold; nanoparticles; gamma radiation; electron beams; x-ray sources; radiolysis; nanotechnology; medicine; diagnostic uses; ionizing radiations

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  • IPEN-DOC 26718

    JACOVONE, RAYNARA M.S. ; SOARES, JAQUELINE J.S. ; SOUSA, THAINA S. ; SILVA, FLAVIA R.O. ; GARCIA, RAFAEL H.L. ; NGUYEN, HANG N.; RODRIGUES, DEBORA F.; SAKATA, SOLANGE K. . Antibacterial activity of silver/reduced graphene oxide nanocomposite synthesized by sustainable process. Energy, Ecology and Environment, v. 4, n. 6, p. 318-324, 2019. DOI: 10.1007/s40974-019-00136-3

    Abstract: Traditional methods to incorporate metals into graphene oxide (GO) usually require toxic reagents or high temperatures. This study proposes an innovative and sustainable method to incorporate silver (Ag) into graphene oxide using electron beam and evaluate its antibacterial activities. The method is based on green synthesis, without toxic reagents or hazardous wastes, and can be carried out at room temperature, in short reaction times. To synthesize the Ag/rGO nanocomposite, a water/isopropanol solution with dispersed graphene oxide and silver nitrate was submitted to a dose range from 150 to 400 kGy. The product was characterized by thermogravimetry analysis, X-ray diffraction and transmission electron microscopy. The antibacterial activity of Ag/rGO was observed against Gram-negative Escherichia coli by plate count method and atomic force microscopy. The results showed that concentrations as low as 100 lg/mL of produced Ag/rGO were enough to inactivate the cells.

    Palavras-Chave: graphene; nanocomposites; antimicrobial agents; atomic force microscopy; silver; nanoparticles; electron beams; oxides; sustainability; thermal gravimetric analysis; bacteria; antibiotics; escherichia coli

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  • IPEN-DOC 27124

    COURROL, LILIA C.; ESPINOZA-CULUPÚ, ABRAHAM; SILVA JUNIOR, PEDRO I. da; GONÇALVES, KARINA de O.; SILVA, FLAVIA R. de O. ; BORGES, MONAMARIS M.. Antibacterial and antitumoral activities of the spider acylpolyamine Mygalin silver nanoparticles. BioNanoScience, v. 10, n. 2, p. 463-472, 2020. DOI: 10.1007/s12668-020-00738-w

    Abstract: Mygalin is a synthetic analog of polyamine spermidine isolated from spider hemocytes. Polyamines show potential therapeutic activity against a wide range of human diseases such as cancer and microbial infections. In this work, we analyzed the antibacterial and antitumoral activities of Mygalin silver nanoparticles synthesized by the photoreduction method. The formation and distribution of MygAgNPs were confirmed by UV-visible spectroscopy, zeta potential, and transmission electron microscopy. The obtained nanoparticles were mostly spherical with a particle size distribution in the range of ~ 10–60 nm. We have demonstrated that MygAgNPs increased the effectiveness of the native Mygalin by approximately 6400-fold. Cytotoxicity tests were performed, and it was possible to reach a concentration that was not toxic to healthy cells (NHI-3T3) and at the same time toxic to the tumor cell line (MCF-7). The obtained results suggest that this system shows potential enhanced antibacterial activity against Escherichia coli, DH5α and anticancer activity against MCF-7 cell line.

    Palavras-Chave: drugs; neoplasms; antibiotics; spiders; silver; nanoparticles; cell cultures; drugs; amines; bacteria

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  • IPEN-DOC 27589

    GONCALVES, FLAVIA; CAMPOS, LUIZA M. de P. ; SANCHES, LUCIANA K.F.; SILVA, LARISSA T.S.; SANTOS, TAMIRIS M.R. dos ; VARCA, GUSTAVO H.C. ; LOPES, DIANA P.; COGO-MULLER, KARINA; PARRA, DUCLERC F. ; BRAGA, ROBERTO R.; SANTOS, MARCELO dos; BOARO, LETICIA C.C.. Antimicrobial activity and physicochemical performance of a modified endodontic sealer / Atividade antimicrobiana e desempenho físico-químico de um cimento endodôntico modificado. Research, Society and Development, v. 9, n. 11, p. 1-16, 2020. DOI: 10.33448/rsd-v9i11.9401

    Abstract: Introduction: this study aimed to evaluate the antimicrobial and physicochemical properties of a commercial endodontic sealer modified by the addition of montmorillonite (MMT) nanoparticles loaded with two different drugs: chlorhexidine (CHX) or metronidazole (MET). Methods: 5 wt% MMT/CHX or MMT/MET nanoparticles were added to the sealer AH-Plus. The experimental materials were evaluated for drug release, antimicrobial activity, flow, flexural strength, and flexural modulus. Data were subjected to one-way ANOVA, Kruskal-Wallis, and Mann-Whitney tests. Results: The drug incorporation into MMT particles was 9% and 10% for CHX and MET, respectively. At 20 days after manipulation, 16.5% of the drug was released by the sealer with MMT/MET and 0.4% by MMT/CHX. The addition of both nanoparticles decreased the flow of materials, but they were still in compliance with ISO 6876-2012. The conversion, flexural strength, and flexural modulus of MMT/MET (87%, 37±7 MPa, 2.3 GPa) and MMT/CHX (78%, 29±2 MPa, 2.7 GPa) were similar in both groups but lower than in the control group (100%, 54±7 MPa, 4.0±0.7 GPa). Both experimental materials were able to form an inhibition halo for E. faecalis bacteria (CHX: 4.8±1.4 and MET: 4.0±1.6 mm), whereas the control group did not inhibit the microorganism. Conclusion: both formulations proposed as endodontic sealer presented effective antimicrobial activity and acceptable flow. The addition of MMT/CHX and MMT/MET particles decreased the conversion and mechanical properties, but further studies are required to clarify the clinical relevance of these properties.

    Palavras-Chave: antimicrobial agents; metronidazole; organic chlorine compounds; dentistry; drugs; sealing materials; montmorillonite; nanoparticles; teeth; seals

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  • IPEN-DOC 29085

    FRANZOLIN, MARCIA R.; COURROL, DANIELLA dos S.; SILVA, FLAVIA R. de O. ; COURROL, LILIA C.. Antimicrobial activity of silver and gold nanoparticles prepared by photoreduction process with leaves and fruit extracts of Plinia cauliflora and Punica granatum. Molecules, v. 27, n. 20, p. 1-16, 2022. DOI: 10.3390/molecules27206860

    Abstract: The increased number of resistant microbes generates a search for new antibiotic methods. Metallic nanoparticles have emerged as a new platform against several microorganisms. The nanoparticles can damage the bacteria membrane and DNA by oxidative stress. The photoreduction process is a clean and low-cost method for obtaining silver and gold nanoparticles. This work describes two original insights: (1) the use of extracts of leaves and fruits from a Brazilian plant Plinia cauliflora, compared with a well know plant Punica granatum, and (2) the use of phytochemicals as stabilizing agents in the photoreduction process. The prepared nanoparticles were characterized by UV-vis, FTIR, transmission electron microscopy, and Zeta potential. The antimicrobial activity of nanoparticles was obtained with Gram-negative and Gram-positive bacteria, particularly the pathogens Staphylococcus aureus ATCC 25923; Bacillus subtilis ATCC 6633; clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis; Escherichia coli ATCC 25922; Escherichia coli O44:H18 EAEC042 (clinical isolate); Klebsiella pneumoniae ATCC 700603, Salmonella Thiphymurium ATCC 10231; Pseudomonas aeruginosa ATCC 27853; and Candida albicans ATCC 10231. Excellent synthesis results were obtained. The AgNPs exhibited antimicrobial activities against Gram-negative and Gram-positive bacteria and yeast (80–100%), better than AuNPs (0–87.92%), and may have the potential to be used as antimicrobial agents.

    Palavras-Chave: gold; nanoparticles; microorganisms; antimicrobial agents; silver; reduction

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  • IPEN-DOC 27171

    FONTES, E.H. ; NANDENHA, J. ; SOUZA, R.F.B. de ; ANTONIO, F.C.T.; HOMEM-DE-MELLO, P.; NETO, A.O. . Au core stabilizes CO adsorption onto Pd leading to CO2 production. Materials Today Advances, v. 6, p. 1-9, 2020. DOI: 10.1016/j.mtadv.2020.100070

    Abstract: Au core and Pd shell supported on carbon structure Au@Pd/C can cleave the CeC bond of ethanol molecules leading to the production of a relatively high amount of CO2 when compared with Pd/C electrocatalyst as the attenuated total reflectance - Fourier transform infrared (ATR-FTIR) experiment shows. Density functional theory (DFT) calculations showed that this could be explained by the oxidation of CO species adsorbed into Pd sites that has a modified electronic structure compared with Pd/C. In terms of DFT analysis, the highest thermodynamical stability of CO in Pd shell with Au core atoms, when compared with Pd/C is because of the increase of virtual orbital states near Fermi level that can be occupied by valence electrons of CO molecule. The d-band center shift is experimentally verified using the valence band X-ray photoelectron spectroscopy and theoretically predicted by the Generalized Koopmans’ Theorem. Besides that, Au@Pd/C electrocatalyst has a better electrochemical activity when compared with Pd/C.

    Palavras-Chave: ethanol; oxidation; calculation methods; density; nanoparticles; adsorption; carbon dioxide; density functional method

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  • IPEN-DOC 26620

    LEAL, GEORGIA B. ; SILVA, DANIELA C.L. da ; WATACABE, BEATRIZ N. ; CIOTTI, LIGIA ; ANTONIASSI, RODOLFO M. ; GIUDICI, REINALDO; LINARDI, MARCELO ; VAZ, JORGE M. ; SPINACE, ESTEVAM V. . Au/TiO2 catalysts prepared by borohydride reduction for preferential CO oxidation at near-ambient temperature. Catalysis for Sustainable Energy, v. 6, n. 1, p. 6-12, 2019. DOI: 10.1515/cse-2019-0002

    Abstract: Au nanoparticles were prepared in solution using HAuCl4.3H2O as Au precursor, sodium citrate as stabilizing agent and sodium borohydride as reducing agent. The influence of synthesis parameters such as BH4:Au and Citrate:Au ratios were studied. In a further step, the stabilized Au nanoparticles were supported on TiO2 with different Au loadings (wt%). The resulting Au/ TiO2 catalysts were characterized by Energy-dispersive X-ray spectroscopy, X-ray diffraction and Transmission Electron Microscopy and tested for the preferential oxidation of carbon monoxide in hydrogen-rich stream. Au nanoparticles stabilized in solution were obtained with sizes in the range of 3-4 nm. After supported on TiO2, the Au nanoparticles size did not change and the Au/TiO2 catalysts exhibited excellent performance and stability in the temperature range of 20 - 50 °C.

    Palavras-Chave: gold; hydrogen; nanoparticles; carbon monoxide; titanium oxides; borohydrides; reduction; catalysts

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  • IPEN-DOC 27899

    ALENCAR, C.S.L. ; PAIVA, A.R.N. ; SILVA, L.G.A. ; SOMESSARI, E.S.R. ; VAZ, J.M. ; SPINACE, E.V. . AuCu/TiO2 catalysts prepared using electron beam irradiation for the preferential oxidation of carbon monoxide in hydrogen-rich mixtures. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-16, 2021. DOI: 10.15392/bjrs.v9i1A.1497

    Abstract: The major part of the world production of hydrogen (H2) is originated from a combination of methane steam reforming and water gas shift reaction resulting in an H2 rich mixture known as reformate gas, which contains about 1% vol (10,000 ppm) of carbon monoxide (CO). The preferential oxidation reaction of CO in H2 rich mixtures (CO PROX) has been considered a very promising process for H2 purification, reducing CO for values below 50 ppm allowing its use in PEMFC Fuel Cells. Au nanoparticles supported on TiO2 (Au/TiO2) catalysts have been shown good activity and selectivity for CO PROX reaction in the temperature range between 20 80 ºC; however, the catalytic activity strongly depends on the preparation method. Also, the addition of Cu to the Au/TiO2 catalyst could increase the activity and selectivity for CO PROX reaction. In this work, AuCu/TiO2 catalysts with composition 0.5%Au0.5%Cu/TiO2 were prepared in a single step using electron beam irradiation, where the Au3+ and Cu2+ ions were dissolved in water/2 propanol solution, the TiO2 support was dispersed and the obtained mixture was irradiated under stirring at room temperature using different dose rates (8 64 kGy s 1) and total doses (144 576 kGy). The catalysts were characterized by energy dispersive X ray analysis, X ray diffraction transmission electron microscopy, temperature programmed reduction and tested for CO PROX reaction. The best result was obtained with a catalyst prepared with a dose rate of 64 kGy s 1 and a total dose of 576 kGy showed a CO conversion of 45% and a CO2 selectivity of 30% at 150 ºC.

    Palavras-Chave: absorbed radiation doses; carbon monoxide; catalysts; copper; dose rates; electron beams; gold; hydrogen; irradiation; mixtures; nanoparticles; oxidation; titanium oxides

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  • IPEN-DOC 28435

    JUNIOR, ALEXANDRE F.; RIBEIRO, CHARLENE A.; LEYVA, MARIA E.; MARQUES, PAULO S.; SOARES, CARLOS R.J. ; QUEIROZ, ALVARO A.A. de . Biophysical properties of electrospun chitosan-grafted poly(lactic acid) nanofibrous scaffolds loaded with chondroitin sulfate and silver nanoparticles. Journal of Biomaterials Applications, v. 36, n. 6, p. 1098-1110, 2022. DOI: 10.1177/08853282211046418

    Abstract: The aim of this work was to study the biophysical properties of the chitosan-grafted poly(lactic acid) (CH-g-PLA) nanofibers loaded with silver nanoparticles (AgNPs) and chondroitin-4-sulfate (C4S). The electrospun CH-g-PLA:AgNP:C4S nanofibers were manufactured using the electrospinning technique. The microstructure of the CH-g-PLA:AgNP:C4S nanofibers was investigated by proton nuclear magnetic resonance (1H-NMR), scanning electron microscopy (SEM), UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR and 1H-NMR confirm the CH grafting successfully by PLA with a substitution degree of 33.4%. The SEM measurement results indicated apparently smooth nanofibers having a diameter range of 340 ± 18 nm with porosity of 89 ± 3.08% and an average pore area of 0.27 μm2. UV-Vis and XRD suggest that silver nanoparticles with the size distribution of 30 nm were successfully incorporated into the electrospun nanofibers. The water contact angle of 12.8 ± 2.7° reveals the hydrophilic nature of the CH-g-PLA:AgNP:C4S nanofibers has been improved by C4S. The electrospun CH-g-PLA:AgNP:C4S nanofibers are found to release ions Ag+ at a concentration level capable of rendering an antimicrobial efficacy. Gram-positive bacteria (S.aureus) were more sensitive to CH-g-PLA:AgNP:C4S than Gram-negative bacteria (E. coli). The electrospun CH-g-PLA:AgNP:C4S nanofibers exhibited no cytotoxicity to the L-929 fibroblast cells, suggesting cytocompatibility. Fluorescence microscopy demonstrated that C4S promotes the adhesion and proliferation of fibroblast cells onto electrospun CH-g-PLA:AgNP:C4S nanofibers.

    Palavras-Chave: silver; nanoparticles; nanofibers; lactic acid

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  • IPEN-DOC 24857

    SANTOS, JONNATAN J. ; LEAL, JESSICA ; DIAS, LUIS A.P. ; TOMA, SERGIO H.; CORIO, PAOLA; GENEZINI, FREDERICO A. ; KATTI, KATTESH V.; ARAKI, KOITI; LUGAO, ADEMAR B. . Bovine serum albumin conjugated gold-198 nanoparticles as model to evaluate the damage caused by ionizing radiation to biomolecules. ACS Applied Nano Materials, 2018. DOI: 10.1021/acsanm.8b01174

    Abstract: Gold nanoparticles (AuNPs) have several applications including in medicine. Considering cancer as one of the most common diseases for men and women, new treatments and more specific and effective drugs, which cause less side effects, have been actively pursued. Among them, gold-198 can be engineered as theranostic agents, working as contrast (exploiting gamma emission) and treatment agents (beta emission). Accordingly, a new procedure for the production of 14 nm diameter radioactive citrate protected gold-198 nanoparticles, that were then conjugated with bovine serum albumin utilizing 3-mercaptopropionic acid directly bound to AuNPs surface as anchoring groups, generating fully dispersible nanoparticles in aqueous media, are described. The effect of gamma and beta radiation on grafted BSA was evaluated by direct irradiation of the corresponding cold material and comparing with the damage caused on BSA grafted gold-198 nanoparticles prepared from a neutron activated gold foil. The investigation by fluorescence and Raman spectroscopy indicated that the damage to BSA chromophore groups is proportional to the dose (from 0.1 to 1 kGy) and that chromophores groups close to the particle surface are more prone to damage. Gold-198 nanoparticles conjugated with bovine serum albumin showed that process is much more localized next to nanoparticles surface since each gold core acts as a punctual radiation source. In short, AuNPs can enhance the damage caused by irradiation of cold nanoparticles and AuNPs@MPA-BSA is a suitable model to probe the effect of gamma and beta emitter on biomolecules. Furthermore, the strategy of diluting the gold-198 with cold gold atoms was shown to be suitable to control the activity of 198AuNPs aiming medical applications, since the damage to BSA was found to be proportional to the relative concentration of gold-198.

    Palavras-Chave: gold 198; cattle; blood serum; albumins; nanoparticles; ionizing radiations; therapy; gamma spectroscopy; neoplasms

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  • IPEN-DOC 23203

    SHRIVASTAVA, NAVADEEP; KHAN, L.U.; KHAN, Z.U.; VARGAS, J.M.; MOSCOSO-LONDONO, O.; OSPINA, CARLOS; BRITO, H.F.; JAVED, YASIR; FELINTO, M.C.F.C. ; MENEZES, A.S.; KNOBEL, MARCELO; SHARMA, S.K.. Building block magneto-luminescent nanomaterials of iron-oxide/ZnS@LaF3:Ce3+,Gd3+,Tb3+ with green emission. Journal of Materials Chemistry C, v. 5, n. 9, p. 2282-2290, 2017. DOI: 10.1039/c6tc05053k

    Abstract: The preparation of novel triply-doped bifunctional Fe3O4/ZnS@LaF3:xCe3+,xGd3+,yTb3+ (x = 5; y = 5, 10 and 15 mol%) nanocomposites with efficient optical and magnetic features has been reported. The ZnS semiconductor functionalized Fe3O4 particles were coated with LaF3:RE3+ materials via a chitosanassisted co-precipitation method. The size of iron oxide B7.2 nm and trigonal structures of bifunctional nanostructures were confirmed through X-ray diffraction and high-resolution transmission electron microscopy. The static magnetic measurements supported and manifested the superparamagnetic behavior of the materials at 300 K. A broad emission band was observed in the blue region (400–550 nm) due to the sulphur vacancy on the surface of the Fe3O4/ZnS nanocomposite. For a triply doped bifunctional nanostructure, the excitation spectra revealed broad absorption bands centered at around 270 nm, which were attributed to the 4f(7F7/2) - 5d interconfigurational transition of the Ce3+ ion accompanied by narrow absorption lines arising from the 4f–4f intraconfigurational transitions of the Tb3+ ion. The emission spectra of the nanocomposites showed characteristic narrow emission lines assigned to the 5D4 - 7FJ transitions (J = 6–0) of the Tb3+ ion. The energy transfer process from the Ce3+ - Gd3+ - Tb3+ ions has also been presented and discussed. Furthermore, the structural, photoluminescence and magnetic properties of Fe3O4/ZnS@LaF3:RE3+ suggested that it may be an efficient candidate for magnetic light-converting molecular devices (MLMCDs) and high energy radiation detection.

    Palavras-Chave: fluorescence; nmr imaging; iron oxides; buildings; building materials; nanoparticles; zinc sulfides; lanthanum fluorides; cerium ions; gadolinium ions; terbium ions; nanocomposites

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  • IPEN-DOC 24305

    ANTONIASSI, R.M. ; SILVA, J.C.M. ; LOPES, T. ; OLIVEIRA NETO, A. ; SPINACE, E.V. . Carbon-supported Pt nanoparticles with (100) preferential orientation with enhanced electrocatalytic properties for carbon monoxide, methanol and ethanol oxidation in acidic medium. International Journal of Hydrogen Energy, v. 42, n. 8, p. 28786-28796, 2017. DOI: 10.1016/j.ijhydene.2017.10.036

    Abstract: The relationship between atomic arrangement (morphology) and catalytic activity/selectivity in heterogeneous catalysis is an actual hot research topic concerning a range of reactions. This article evaluates one-pot synthesized carbon-supported Pt nanoparticles with preferential Pt(100) orientation prepared with an environmentally friendly shape-directing agent and compares this with Pt/C polycrystalline towards CO, methanol and ethanol electrooxidation reactions. The preferentially cubic nanomaterial (Pt-(100)) interacts differently with CO molecule and presents distinct hydrogen adsorption/desorption characteristics. Pt/C polycrystalline exhibits a CO-stripping profile with one peak at 0.86 V in contrast to three peaks between 0.75 and 0.86 V and a pre-peak at about 0.40.6 V for the Pt/C-(100), which may be associated to the unique surface characteristics of the cubic material. The onset potentials towards carbon monoxide, methanol and ethanol electro-oxidation reactions on Pt/C-(100) are 22%, 21% and 54% lower than on Pt/C polycrystalline. The ratio between the forward per backward peak current densities for the electrooxidation of ethanol and methanol are higher on Pt/C-(100), which suggests that Pt(100) domains are more tolerant to undergo poisoning by the intermediates/by-products formed in these reactions. Proton exchange membrane fuel cells fed with pure hydrogen and with a H-2/CO mixture show superior performance using Pt/C-(100) as anode in comparison to Pt/C polycrystalline catalyst. These results evidence that controlling the morphology of Pt nanoparticles is a key factor to improve the catalytic activity of the polymer electrolyte fuel cell fueled with fuels that involve the electro-oxidation of CO.

    Palavras-Chave: nanoparticles; ethanol; methanol; carbon; proton exchange membrane fuel cells; platinum; oxidation; stripping

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  • IPEN-DOC 25713

    ICHIKAWA, RODRIGO U. ; PARRA, JOAO P.R.L.L.; VALLCORBA, ORIOL; PERAL, INMA; YOSHITO, WALTER K. ; SAEKI, MARGARIDA J.; TURRILLAS, XAVIER; MARTINEZ, LUIS G.. Cation distribution of Mn-Zn ferrite nanoparticles using pair distribution function analysis and resonant X-ray scattering. EPL, v. 124, n. 5, p. 56001-p1 - 56001-p5, 2018. DOI: 10.1209/0295-5075/124/56001

    Abstract: Mn-Zn ferrite nanoparticles were synthesized by chemical co-precipitation method and analysed using X-ray synchrotron diffraction data. Pair distribution function (PDF) analysis was used to probe the local structure and revealed that the first-neighbour distances of Fe-Fe and Mn-Zn in the 3.0 up to 3.5˚A range are different from the ones usually reported in the literature. For the sample with the best magnetic behaviour, resonant X-ray scattering (RXS) using three energies close to the absorption edges of Mn, Zn and Fe was applied to determine the cation distribution which explained the previous result from PDF analysis.

    Palavras-Chave: nanoparticles; distribution functions; scattering; x-ray diffraction; ferrite; zinc compounds; manganese compounds; magnetic resonance; nmr imaging; images

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  • IPEN-DOC 27228

    BRANT, ANTONIO J.C. ; NAIME, NATALIA ; LUGAO, ADEMAR B. ; PONCE, PATRICIA . Cellulose nanoparticles extracted from sugarcane bagasse and their use in biodegradable recipients for improving physical properties and water barrier of the latter. Materials Sciences and Applications, v. 11, n. 1, p. 81-133, 2020. DOI: 10.4236/msa.2020.111007

    Abstract: The present work firstly aimed to obtain cellulose from sugarcane bagasse by using alkaline methods in pulping/delignifying and, at bleaching stages, using sodium chlorite, glacial acetic acid, and hydrogen peroxide, associated to NaOH/KOH. The process was carried out at temperatures varying from 55˚C to 110˚C, under magnetic stirring in various steps lasting from 2 h to 12 h. The yields of the two cellulose extracted, SCB24-Na-I and SCB24-Na-II, were 37% and 41%, respectively, from samples of ca. 15 g of the bagasse. Secondly, it is to extract nanoparticles from the obtained celluloses via acid hydrolysis (with 77% H2SO4) to lately be tested as reinforcement in biodegradable packagings. Both celluloses and their respective nanoparticles were characterized by several techniques, among them ATR-FTIR, DSC-TGA, XRD, SEM, and TEM. Despite that the yields of cellulose nanoparticles have been low, the preliminary studies of their use in biodegradable films coated on biodegradable pots were promising.

    Palavras-Chave: sugar cane; bagasse; cellulose; biomass; acid hydrolysis; nanoparticles; delignification; biodegradation; packaging; suspensions; films

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A elaboração do projeto do RI do IPEN foi iniciado em novembro de 2013, colocado em operação interna em julho de 2014 e disponibilizado na Internet em junho de 2015. Utiliza o software livre Dspace, desenvolvido pelo Massachusetts Institute of Technology (MIT). Para descrição dos metadados adota o padrão Dublin Core. É compatível com o Protocolo de Arquivos Abertos (OAI) permitindo interoperabilidade com repositórios de âmbito nacional e internacional.

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