MARGARETH KAZUYO KOBAYASHI DIAS FRANCO

MARGARETH KAZUYO KOBAYASHI DIAS FRANCO

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Structural characterization of silver nanoparticles produced by biogenic synthesis using SAXS
2024 - RIBEIRO JUNIOR, ARI; YOKAICHIYA, FABIANO; MONERJAN, ENELI; LEMKE, KARINA; GUILGER-CASAGRANDE, MARIANA; LIMA, RENATA; FRACETO, LEONARDO; FRANCO, MARGARETH K.K.D.; KELLERMANN, GUINTHER
Nanotechnology applied to the agricultural sector has highlighted in recent decades, making important contributions, including systems for pest control as biogenic nanoparticles. These nanoparticles are used to control phytopathogens, demonstrating the need to understand its composition, mechanisms of action and toxicity. Their capping of biomolecules, derived from the organism used in the synthesis, contributes to their stability and biological activity. Ag nanoparticles were produced by the fungus Trichoderma harzianum in aqueous solutions containing silver nitrate as a precursor for the silver nanoparticles. Some of the samples were exposed to the phytopathogenic fungus Sclerotinia sclerotiorum responsible for the white mold. After preparation, a fraction of the samples was submitted to physico-chemical processes to remove organic cap layer on nanoparticles surface formed during the preparation process. In this study we determined the effect of the phytopathogenic fungus and cap removal process in the average radius, radius dispersion, number density of the nanoparticles using small angle X-ray scattering (SAXS), where we considered their almost spherical shape in aqueous solution obtained by the biogenic route. The SAXS data analyses suggest that the presence of the pathogenic fungus results in a diminution of number and total volume of Ag NPs without significant effects on average radius and radius dispersion. Our results also indicate that the physic-chemical process to remove the organic cap surrounding the Ag NPs leads to a decrease in the fraction of the smaller nanoparticles.
Corrosion characterization of the 6061 Al–Mg–Si alloy in synthetic acid rain using neutron tomography
2022 - MILAGRE, MARIANA X.; PEREIRA, MARCO S.; GOMES, ANTONIO A.; SCAPIN, MARCOS; FRANCO, MARGARETH; YOKAICHIYA, FABIANO; GENEZINI, FREDERICO; COSTA, ISOLDA
Neutron tomography has gained increasing importance as an imaging technique for materials characterization. In general, neutron beams are able to show microstructure features of hydrogenous materials, even enfolded with thick metal layers. In the present paper, neutron tomography and observation of cross section images were successfully applied to investigate the corrosion features of the 6061 Al–Mg–Si alloy. The results showed good agreement between neutron 3D tomography and the cross section images obtained in the high attenuation areas of the samples, whereas significant differences in depth of corrosion penetration were obtained between the results from Neutron Tomography and 3D optical profilometry.
Supramolecular structure of temperature-dependent polymeric hydrogels modulated by drug incorporation
2020 - FRANCO, MARGARETH K.K.D.; SEPULVEDA, ANDERSON F.; VIGATO, ARYANE A.; OSHIRO, ALISSON; MACHADO, IAN P.; KENT, BEN; CLEMENS, DANIEL; YOKAICHIYA, FABIANO; ARAUJO, DANIELE R. de
Poloxamers or Pluronics® (PL) have been described as promising pharmaceutical and cosmetics matrices. Herein, we have explored the structural organization of hydrogel formulations composed of PL F‐127 and PL L‐81, considering their different hydrophilic‐lipophilic balances and interactions with an antimigraine drug, sumatriptan succinate (SMT). Hydrogels phase organizations were investigated by X‐ray diffraction (XRD) and Small Angle Neutron Scattering (SANS) to establish the relationship between structural features and drug release modulation. XRD analysis revealed very low intensity peaks for hydrogels containing SMT due to the presence of small amounts of SMT as crystalline form, which is an evidence of drug incorporation into hydrogels. At physiological temperature, a structural transition from lamellar to hexagonal was observed after SMT incorporation. In addition, SANS patterns displayed a distorted hexagonal structure, (calculated q2 >experimental q2), indicating the presence of a comprised structure compared to a perfect hexagonal assembly. This structural shift however have no influence on the drug release mechanism, allowing the SMT molecules to access the micellar and intermicellar hydrophilic spaces, with release mechanism dependent on the drug diffusion (R2=0.998 ≥ 0.986) from the hydrogel to the medium and release constant (Krel) values from 9.8 to 14.7 %.h−1; 31.5 to 39.1 %.h−1/2; 0.84 to 1.2 %.h−n for Zero‐order, Higuchi and Korsmeyer‐Peppas models, respectively. Using SMT as a drug model, it could be concluded that the drug access to the micellar/intermicellar hydrophilic spaces can be modulated by interplaying the polarity of binary PL‐based hydrogels. Therefore, drug release constants and mechanisms will be then dependent on the hydrogels physico‐chemical and structural properties, which determine the drug diffusion from the hydrogel to the release medium.
Influence of chitosan-tripolyphosphate nanoparticles on thermosensitive polymeric hydrogels
2020 - MARIANO, KELLI C.F.; NASCIMENTO, MONICA H.M. do; QUEROBINO, SAMYR M.; CAMPOS, ESTEFANIA V.R.; OLIVEIRA, JHONES L. de; YOKAICHIYA, FABIANO; FRANCO, MARGARETH K.K.D.; ALBERTO-SILVA, CARLOS; PAULA, ENEIDA de; LOMBELLO, CHRISTIANE B.; LIMA, RENATA de; FRACETO, LEONARDO F.; ARAUJO, DANIELE R. de
Chitosan-tripolyphosphate (CS-TPP) nanoparticles containing naproxen (NPX) were dispersed in poloxamer (PL) as unique (PL407) or binary (PL407-PL403) systems. Nanoparticles presented diameter of 250nm and zeta potential of 35mV with drug loading and encapsulation efficiency of 98.4 ± 0.3% and 36.9 ± 0.12%, respectively. NPX-CS-TPP shifted the sol-gel transition and micellization temperatures. PL407-PL403 systems presented G0 >G00 compared to PL407. SAXS patterns revealed transitions from lamellar to hexagonal phase organizations with low drug release rates, in the presence of CS-TPP nanoparticles. NPX-CS-TPP-PL407 induced lower cytotoxicity compared to PL407-PL403 in fibroblasts and osteoblasts, making them promising systems for intra-articular delivery.
Influence of the irradiation in cement for the Brazilian radioactive waste repositories
2018 - FERREIRA, EDUARDO G.A.; YOKAICHIYA, FABIANO; MARUMO, JULIO T.; VICENTE, ROBERTO; GARCIA-MORENO, FRANCISCO; KAMM, PAUL H.; KLAUS, MANUELA; RUSSINA, MARGARITA; GUNTHER, GERRIT; JIMENEZ, CATALINA E.; FRANCO, MARGARETH K.K.D.
Powerful characterization techniques have allowed detailing the investigation of cementitious materials that must endure for millennia as an engineered barrier in radioactive waste repositories. Cement is used in the repository, as waste immobilization matrix, structural material and an additional barrier against the contact of the waste with the biosphere. The material properties have to comply with requirements in respect to a number of parameters including homogeneity, permeability, and leachability, as well as withstand mechanical stress, heat, chemical and microbial attack, and the effects of ionizing radiation. The present study aims to investigate the behavior of cementitious materials contributing to the understanding of the processes that occur in hydrated cement under the environmental conditions of a repository and to estimate the durability of these materials. In this study was observed the changes caused by radiation, to which the material was exposed. A reference Portland cement paste and grout samples were compared with irradiated ones by X-ray diffraction and Tomography. Original and valuable results concerning the investigation of the influence of radiation on cement samples were also obtained by quasielastic scattering. These results are not accessible by others techniques.
Effects of doxorubicin on the structural and morphological characterization of solid lipid nanoparticles (SLN) using small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS)
2018 - YOKAICHIYA, FABIANO; SCHMIDT, CHRISTIAN; STORSBERG, JOACHIM; VOLLRATH, MONT K.; ARAUJO, DANIELE R. de; KENT, BEN; CLEMENS, DANIEL; WINGERT, FRIEDRICH; FRANCO, MARGARETH K.K.D.
Cancer is still a major public health problem. Leaving detection of early stages of tumors and other issues aside, minimizing unwarranted side effects, for example after clinical usage of a liposomal anticancer drug doxorubicin (Dox) formulation, is an unmet clinical problem and the focus of many studies. Using compounds typically used in the preparation of food and/or cosmetics to prepare drug carrier systems, we observed that sodium tetradecyl sulfate (STS) containing and soybean-oil based carriers are more efficient in reducing the viability of HeLa cells tumor cells in comparison to their respective counterparts. Here, we probe the doxorubicin (Dox) loading on structural properties of either soybean oil or coconut oil (Mygliol 812) formulations. Small angle neutron scattering (SANS) assays were performed using V16 instrument at Helmholtz-Zentrum Berlin (HZB) at 25, 37 and 40 C with two or 11m distance between detector and sample to assess a wide range in scattering vector Q. Combined with previous measurement using small angle X-ray scattering (SAXS), our results show that the Dox has different influence in the surface structure of the solid lipid nanoparticles (SLN) and also affects the fractality in the vesicle aggregates when the concentration of the drug is altered, for Mygliol and soybean oil SLN drug delivery carrier systems.
Complexation of oxethazaine with 2-hydroxypropyl-bcyclodextrin: increased drug solubility, decreased cytotoxicity and analgesia at inflamed tissues
2017 - PRADO, ANDRESSA R.; YOKAICHYIA, FABIANO; FRANCO, MARGARETH K.K.D.; SILVA, CAMILA M.G. da; OLIVEIRA-NASCIMENTO, LAURA; FRANZ-MONTAN, MICHELLE; VOLPATO, MARIA C.; CABECA, LUIS F.; PAULA, ENEIDA de
ObjectivesOxethazaine (OXZ) is one of the few local anaesthetics that provides analgesia at low pH, but presents poor solubility, cytotoxicity and no parenteral formulations. To address these issues, we aimed to prepare OXZ host-guest inclusion complex with hydroxypropyl-beta-cyclodextrin (HP--CD). MethodsThe inclusion complex was formed by co-solubilization, followed by a job plot analysis to determine stoichiometry of complexation and dialysis equilibrium analysis (based on UV/VIS absorption and fluorescence profiles of OXZ). Complex formation was confirmed by phase-solubility data, X-ray, Scanning Electron Microscopy and DOSY-H-1-NMR experiments. In vitro cytotoxicity was analysed by MTT test in 3T3 fibroblasts. In vivo analgesia was tested by Von Frey test (inflammatory wounds - rats). Key findingsOxethazaine complexed (1 : 1 molar ratio) with HP--CD, as indicated by loss of OZX crystalline structure (X-ray) and strong host: guest interaction (NMR, K = 198/M), besides increased solubility. In vitro cell survival improved with the complex (IC50 OXZ = 28.9 m, OXZ : HP--CD = 57.8 m). In addition, the complex (0.1% OXZ) promoted in vivo analgesia for the same time that 2% lidocaine/epinephrine did. Conclusion Our results show that complexation improved physicochemical and biological properties of OXZ, allowing its application to inflamed tissues by parenteral routes.
Assessing the pozzolanic activity of cements with added sugar cane straw ash by synchrotron X-ray diffraction and Rietveld analysis
2015 - CALLIGARIS, GUILHERME A.; FRANCO, MARGARETH K.K.D.; ALDRIGE, LAURENCE P.; RODRIGUES, MICHELLE S.; BERALDO, ANTONIO L.; YOKAICHIYA, FABIANO; TURRILLAS, XAVIER; CARDOSO, LISANDRO P.
Sugar and alcohol industries generate large amount of wastes that could produce ashes of great reactivity with pozzolan properties. The objective of this paper is to evaluate the pozzolanicity of Sugar Cane Straw Ashes (SCSA), thermal treated, at different curing times. Employing Synchrotron X-ray radiation for XRD measurements, scans from 10 to 110 (h 2h setup) allowed the quantification of several phases of the cement pasts through Rietveld analysis. The SCSA substitution of 20% (weight) in Ordinary Portland Cement (OPC) has improved the AFt (Ettringite) formation up to 47% for 90 days curing time. The Portlandite concentration analysis allowed concluding that this addition of SCSA in OPC has caused a delay in the cement setting time. Moreover, the behaviour of the C3S and Calcite contents in both OPC and OPC/SCSA samples were determined by refinement of the XRD pattern using the Rietveld method.