ADRIANA KUCHINSKI CAVALCANTE
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Artigo IPEN-doc 27201 Comparison between gold nanoparticles synthesized by radiolysis and by EGCG-driven gold reduction2020 - FREITAS, LUCAS F. de; CRUZ, CASSIA P.C. da; CAVALCANTE, ADRIANA K.; BATISTA, JORGE G. dos S.; VARCA, GUSTAVO H.C.; MATHOR, MONICA B.; LUGAO, ADEMAR B.Radiolytic synthesis and phytochemical-driven gold reduction for the generation of nanoparticles are successful examples of Green Chemistry applied for nanomaterials. The present work compares these two green approaches focusing on hydrodynamic size, stability over time, optical properties and toxicity in NIH 3T3 (ATCC® CRL- 1658™) cells and Danio rerio (Zebra Fish). The radiolytic synthesis was performed by mixing 1 mM NaAuCl4; polyvinyl pyrrolidone 0.5%, AgNO3 6×10−5 M, propan-2-ol 0.2 M and acetone 0.06 M, followed by irradiation at 15 kGy (5 kGy h−1, 60Co source). The EGCG-functionalized nanoparticles were synthesized by mixing 1.6 mM of Au with 0.8 mM of EGCG in phosphate buffer (10 mM) for 2 h. Both methods yield the formation of gold nanoparticles featuring plasmon resonance bands at 520–530 nm, polydispersity above 0.3 was relevant only for the radiolytic protocol. Regarding stability over time, after 30 days, the nanoparticles synthesized radiolytically presented no relevant size changes, while some aggregation was observed for the EGCG-particles. The same nanoparticles demonstrated a lack of stability in high ionic strength medium. Slight toxicity was observed for the EGCG-nanoparticles in Danio rerio, with an IC50 calculated as 40.49%, while no IC50 was established within the concentration range of radiolysis-AuNPs used in this study. In conclusion, both green methods generated nanoparticles with good control of size and optical properties, especially via reduction by EGCG. However, the stability and toxicity results were found to be more promising for the radiolytically synthesized gold nanoparticles.Artigo IPEN-doc 25728 In vitro and in vivo toxicity of coal fly Ash Lechatee2018 - DAMASCENO, K.C.; CAVALCANTE, A.K.; MAZIERO, J.S.; MARTINI, G.A.; ORMENIO, M.B.; MAMEDE, F.C.; MIRANDA, C.S.; CAMPELLO, F.A.; IZIDORO, J.C.; ROGERO, S.O.; FUNGARO, D.A.; LOPES-FERREIRA, M.; ROGERO, J.R.Coal Fly ash is a major solid waste from coal-fired power stations. In Brazil, more than 4 million tons per year of fly ash are generated and only 30% is applied as raw material for cement and concrete production. The remaining is disposed in on-site ponds, nearby abandoned or active mine sites and landfills. The inadequate disposal of fly ash may pose a significant risk to the environment due to the possible leaching of hazardous pollutants into the surrounding soil and groundwater. A combination of leaching tests, cytotoxicity and ecotoxicological assays were used in this studyin order toevaluate the possible adverse effects of coal fl y ash in non-target organisms. The sample was collected from coal-fi red power plant located in Southern Brazil and the coal fly ash was submitted to a leaching procedure using USEPA SW 864 Method 1311. The leachate was prepared in six dilutions: 1.56%, 3.12%, 6.25%, 12.5%, 25% and 50%. Acute toxicity tests were performed on NCTC clone 929 (CCIAL-020) culture cells by neutral red uptake cytotoxicity method; acute ecotoxicity usingDaphnia similisand Danio rerio embryos according to ABNT NBR 12713 and OECD 236, respectively were employed. The cytotoxicity index (CI50) obtained was 33%; the EC50of D. similis after 48 h of exposure to the leachate was 7.25% and the LC50of D. rerio after 96 h of exposure was 4.39%. The results of these bioassays indicated toxicity of the coal fly ash leachate toward exposed organisms.Resumo IPEN-doc 25275 Radiolytic synthesis of non-toxic, size-homogeneous gold nanoparticles2018 - FREITAS, L.F.; KUCHINSKI, A.C.; LUGAO, A.B.Radiolytic synthesis of nanoparticles is one of the successful examples of Green Chemistry (the use of non-toxic chemicals, environmentally benign solvents and renewable materials during the chemical processes), in which the reducing agents responsible for the particle nucleation are no other than the reactive species generated by the radiolysis of the solvent itself (i.e. water, acetone or alcohols). This study consists on the radiolytic synthesis and characterization of gold nanoparticles, as well as the assessment of their toxicity levels to Zebrafish embryos (Danio rerio), as an indication of a possible environmental effect. The nanoparticles were synthesized by mixing: NaAuCl4 2 x 10-3 M; polyvinylpyrrolidone 100 kDa 0.5% (as size stabilizer); propan-2-ol 0.2 M and acetone 0.06 M (for the generation of propyl radicals); and AgNO3 6 x 10-5 M (another size stabilizer), followed by 10 kGy of gamma radiation (5 kGy h-1) [1]. The particles were characterized by their absorption spectra in the UV and visible, and the dynamic light scattering (DLS) technique was used to assess their hydrodynamic size. Finally, the impact on the development of Zebrafish embryos was investigated for different dilutions of the nanoparticles suspension, according to the OECD protocol nº 236 (Guideline on Fish Embryo Acute Toxicity Test – FET), as a means of assessing the environmental impact of the nanomaterial. An acute (96 hours of exposition to gold nanoparticles) and a chronic (168 hours of exposition) assay were performed. The particles were successfully synthesized in a nuclear reactor, with an absorption peak at 532 nm and a narrow size distribution (around 25 nm). There was no evident toxicity for the fish in any tested concentration, leading to the conclusion that this green method of nanoparticle synthesis generates a potentially environment-safe material, with good control of size and optical properties.