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Synthesis and characterization of PVP nanogels prepared by gamma radiation using 60Co source
2019 - BALOGH, T.S.; KADLUBOWSKI, S.; BONTURIM, E.; VARCA, G.; LUGAO, A.B.
Nanogels are promising and innovative systems in nanometer scale, with particle size range varying from 0 to 100 nm, of great potential in nanomedicine, pharmaceutics and bionanotechnology. They present several advantages such as capacity of injection into the circulation reaching target tissues and ability to deliver their payloads locally and intracellularly. Nanogels are defined as two-component system on nanometer scale consisting of a permanent three-dimensional network of linked polymer chains, and molecules of a solvent filling the pores of this network. They are formed by intramolecular crosslinking that can be achieved by the use of ionizing radiation, this method allows the formation of nanogels free of additives, rendering them non-toxic, a fundamental requirement for biomedical application. In this work, five samples of nanogels were developed using a 25 mM PVP solution. The samples were saturated with argon and prepared in multipurpose cobalt-60 gamma irradiator using doses of 1, 2, 5, 10 and 25 kGy at a dose rate of 10 kGy/hour corresponding, respectively, to samples A, B, C, D and E. These samples were morphologically characterized using atomic force microscopy (AFM) as well as the pristine PVP solution. The mean particle size of the samples as well as the determination of polydispersity index was performed in equipment Zetasizer Nano ZS - Malvern® and the determination of radius of gyration and molecular weight was realized in equipment Heleos - Wyatt®. The mean particle size of the samples A, B, C, D and E, were, respectively, 41.89, 46.85, 61.04, 62.79 and 62.11 nm and the mean particle size of the pristine PVP solution was 43.28 nm. The AFM results revealed the presence of spherical nanostructures in the samples prepared with dose equal to or more than 5 kGy (samples C, D and E). Under the conditions evaluated in the study the morphological characterization of the nanogels revealed that the doses of 5 kGy, 10 and 25 kGy are the most suitable doses for the nanogel formation as it led to spherical structures when compared to the other conditions assayed.
Rare earth compounds as smart materials to biological application
2017 - FELINTO, M.C.F.C.; SALVADOR, F.F.S.; FRANCISCO, L.H.C.; BONTURIM, EVERTON; BRITO, H.F.; MALTA, O.M.L.; TEOTONIO, E.E.S.
Materials containing rare earth metals are receiving increasing attention due to its wide range of potential applications, including bioanalytical, images, dye-sensitized solar cells, nanobiotechnology, catalyses among others. The distinguished spectroscopic properties of lanthanides (intense emission bands, high color purity, long lifetime and high quantum efficiency) make them strong candidates for use as markers or bio- selective detectors. Besides the interest in developing nanoparticles ( NP ) associated with biological materials continues growing rapidly . This interest is mainly motivated by the desire to simultaneously exploit the properties of both the NP and biological components in new hybrid operating devices or materials that can be applied in strategic areas. In this work, we design various materials, synthesized and characterized in several laboratories that are part of the group fluoroimunoensaios inct - INAMI and NanoBio network and that have potential to use as biological markers .An attention to materials that emit in the regions of Vis and IR as the compound of Eu and Nd compounds, RE3 + compounds covered with silica and functionalized, RE3 + complexes dispersed in polymeric matrix and have sharp, etc. luminescence will be discussed. Also it will show these nanoparticles in - action , signaling biological materials at very low concentrations , on the order of nanomolar . The principal studies are connected to the diagnostic field and has been studied mainly Leishmania , PSA , LDL, sickle cell disease, estradiol and Chagas disease.
Preparation of luminescent Nd2(MoO4)3 amino-functionalized silica nanoparticles for bioconjugation
2017 - FELINTO, M.C.F.C.; DIAS, C.L.; FRANCISCO, L.H.C.; BONTURIM, EVERTON; BARBOSA, H.P.; BRITO, H.F.; MALTA, O.M.L.; TEOTONIO, E.E.S.
Nanomaterials are used in many areas of biological research. Nanoparticles can be used as active components in various functional materials and devices of interest for bio-applications. Nanoparticles have long been signaled as a potential revolution in the way we probe and interact with biological materials and organisms. This is because they are small enough to interact with their environment at a molecular level, but strong enough to maintain useful properties such as luminescence over extended periods. However, the physical properties of the host materials with nanometer dimensions may differ markedly from those of their bulk counterparts due to the particle size-dependent influences such as structure disordering and surface defects. The development of materials incorporated in the silica has been studied since these materials exhibit intrinsic luminescent properties of the inorganic part and characteristics of the silica matrix. In the present work Nd2(MoO4)3 compounds incorporated into silica particles were prepared using a microwave synthesis procedure. Then, the material was dispersed in ethyl alcohol and functionalized with APTES: 3-aminopropyltriethoxisilane. The emission spectra show broad bands when compared with the emission spectra of the own rare earth compound. The narrow lines are assigned to 4f–4f transitions from the emitting 4 F3/2 level to the 4 I9/2 and, 4 I11/2 levels, centered around 915 and 1060 respectively.. Emission spectrum of the Nd2(MoO4)3 @ Si dispersion showed an enlargement of the bands. It is also observed the broadened peak of the 4 F3/2 4 I9/2, 4 I11/2 transitions in the luminescent amino-functionalized silica particles as compared with the core compound spectrum. These materials were conjugated to anti-IgG antibody and presented high efficient performance in detect human antigen. They can concluded that particles are potential candidates for development of the bioassays acting as a biomarker.
Nuclear based techniques in multifunctional materials characterization
2017 - BONTURIM, E.; MAZZOCCHI, V.L.; PARENTEA, C.B.R.; MOREIRA, E.G.; SEO, E.S.M.; FELINTO, M.C.F.C.
The Nuclear Science and its technologies have provided fundamental tools for the understanding of new chemical and physical properties that help the development of the new age of multifunctional materials such as the Perovskites for photovoltaics and fuel cells, the luminescent oxides for lighting and biomarkers and the thin films in semiconductors. One of the most important parameters that defines key properties of the Perovskites to be applied as the cathode in fuel cells is their crystal structure and its point defects (e.g. oxygen vacancies), which can be determined by neutron diffraction (Fig. 1a). Photonic materials like luminescent nanoparticles, once doped with Rare Earth ions, they can emit light when excited with UV/IR, being used in probing bioassays. In this case, the precise determination of Rare Earth concentration by Instrumental Neutron Activation Analysis (INAA) leads to ensure the desired spectroscopy properties to prepare efficient probing nanoparticles (Fig.1b). Furthermore, nuclear based techniques such as Rutherford Backscattering Spectrometry (RBS) help us in determining the thickness and the elemental composition of thin films (Fig. 1c), which is not usually easy through other conventional techniques. In other words, the nuclear based techniques applied on materials characterization play a key role in providing a solid understanding on the physical and chemical properties of the condensed matter. In summary, this work presents three cases where the use of the Nuclear Techniques improves the characterization of different materials. All the data shown here were collect and published somehow, as indicated below.
Cashew gun resin doped with Eu(tta)3.(TPPO)2 and Eu(dbm)3.(TPPO) nanoparticle acting as biomaker
2017 - FELINTO, MARIA C.F.C.; SALVADOR, FRANCINE F.S.; BONTURIM, EVERTON; BRITO, HERMI F.; SANTOS, PAULO R.; TEOTONIO, ERCULES E.S.; FAUSTINO, WAGNER; MALTA, OSCAR M.L.
Anacardium occidentale L., a tree species from the Anacardiaceae family, is native in Brazil growing mostly in the northeastern region. Cashew gum (CG) is one such versatile naturally occurring biopolymer that is finding increasing applications in the pharmaceutical and biotechnology industry. It has been used successfully for many years in the food and beverage industry as a thickening agent and a colloidal stabilizer. Recently, the role of these gums in enveloping controlled drug delivery systems has increased significantly and CG has achieve lot of attraction towards this application [1]. In this work, nanoparticles of Eu(tta)3(TPPO)2 and Eu(dbm)3(TPPO) were tryed to solubilize in the CG water solution improving the dispersion of the nanoparticle complexes, and giving the opportunity to use these materials as biomarker. An 1%(w/w) of the Eu(tta)3(TPPO)2 or Eu(dbm)3(TPPO) nanoparticles were dispersed in a water solution of CG resin. After that, these materials were dried and the products obtained were films. These materials were characterized by infrared spectroscopy, XPD, TGA, SEM, absorption and photoluminescence spectroscopy. The results showed that the materials are crystalline and when doped increase the thermal stability of the CG resin. These films were soluble in water They also have intense luminescence, with emission spectra presenting characteristic internal transitions of 4f6-4f6 configuration of the Eu3+ ion even in water solution (Fig. 1). The addition of Ag0 in the solution improve the intensity of the fluorophore in solution. Intensity parameters in solid phase were determined and the quantum efficiency ~57% corroborate with the idea of use this green material as a biomarker[2].
Sr2MgSi2O7:Eu2+, Dy3+ long persistent luminescence material synthesized by microwave-assisted solid-state method (MASS)
2017 - MERIZIO, L.G.; BONTURIM, E.; SILVA, I.G.N.; RODRIGUES, L.C.V.; BRITO, H.F.
Persistent luminescence materials can emit light for several hours after ceasing an irradiation source. Studies involving these materials have increased in lasts years mainly due to their singular properties 1. Dissilicates (Sr2MgSi2O7) present promising results, however the ordinary processes require high annealing temperatures and time (~1200 °C, 5 h). A current challenge is find alternatives synthesis methods that can reduce these elevated time and temperatures required. Microwave-Assisted Solid-State synthesis (MASS) is an excellent alternative that can achieve high temperatures in only a few minutes allowing synthesis times around 25 minutes. In this work, Sr2MgSi2O7:Eu2+,Dy3+ was synthesized by MASS. The SrCO3, (MgCO3)4(Mg(OH)2), SiO2, and R2O3, (R3+: Eu, Dy) precursors were grinded and then annealed in a domestic microwave oven using carbon as susceptor at 1000 W for 10 minutes and 900 W for 15 minutes. The excitation spectrum (Fig.1 left red) shows a broad band from 250 to 450 nm assigned to the Eu2+ 4f65d1 ← 4f7 transitions. Several Eu3+ 4f – 4f absorption peaks are observed at e.g. 396, 420 and 450 nm. The emission spectra (Fig. 1, left blue) shows a broad band centered at 470 nm arising from Eu2+ parity allowed 4f65d1 → 4f7 transition with no Eu3+ emission, which indicates energy transfer from Eu3+ to Eu2+. The CIE chromaticity diagram (Fig. 1 right) shows a blue color (x: 0.105; y: 0.236). An important characteristic of this material is the possibility to excite efficiently in the visible range (blue region), allowing applications in the storage of sun light energy.
Submicron-crystals of BaWO4:Dy3+ and SrWO4:Dy3+ synthetized by green chemistry method
2017 - FELINTO, M.C.F.C.; GAIOLLO, E.; MOREIRA, R.P.; BONTURIM, E.; BARBOSA, H.P.; SILVA, I.G.N.; PEDROSO, C.C.S.; BRITO, H.F.; TEOTONIO, E.E.S.; MALTA, O.M.L.
Nowadays, the investigation of oxide based light emitting materials for white lightemitting diodes (w-LEDs) applications have generated interest due to the advantages such as long lifetime, low energy consumption, high luminescence efficiency and environmental friendliness [1]. These qualities make them a strong candidate for the solid state lighting, display devices, optoelectronic devices and light-emitting diodes (LEDs). In this work, we present results of Dy3+: BaWO4 and Dy3+: SrWO4 that present luminescence close to white color (Figure 1) left. They were synthetized using coprecipitation method. The emission spectra exhibit four emission transitions centered at around 486 nm, 576 nm, 665 nm and 760 nm corresponding to the transitions 4F9/26H15/2 (blue), 4F9/26H13/2 (yellow) 4F9/26H11/2 and 4F9/26H9/2 6F11/2 (red) respectively.Among these transitions 4F9/26H15/2 and 4F9/26H13/2 are observed to be strong whereas 4F9/26H11/2 transition is found to be relatively quite weak.The 4F9/26H13/2 transition is hypersensitive in nature and is strongly influenced by the environment around the Dy3+ ion site. It is observed in the luminescence spectra of these materials that the electric dipole transition is dominant compared to the magnetic dipole transition. The CIE diagram show emission close to white (Fig.1 right) for the five composition with little distortion of the color showing the influence of dopant concentration in the color of the emission.
Submicro-crystals of BaWO4:Eu3+ and BaMoO4:Eu3+ synthetized by Pechini Method
2017 - FELINTO, M.C.F.C.; MOREIRA, R.P.; BONTURIM, E.; BARBOSA, H.P.; BRITO, H.F.; TEOTONIO, E.E.S.; MALTA, O.M.L.
In the scheelite-related red phosphors, molybdate and tungstate are respectable high-quality host material. The central metal ions, Mo6+ and W6+, are coordinated to four oxygen atoms in tetrahedral symmetry (Td). Then, molybdate and tungstate demonstrate be chemically stable, red-emitting phosphors, very suitable for in lightening and bio-application.[1] Additionally, molybdate and tungstate phosphors have broad absorption bands owing to charge transfer (CT) from oxygen to metal in the near-UV region. Scheelite BaMoO4 and BaWO4 have almost ideal structure of the MO4 2− and display excellent thermal and hydrolytic stability [2-3]. Rare Earth Molybdates and Tungstate x%Eu:(BaMO4)3 submicron materials with smart photoluminescent properties were prepared using Pechini method. The powders were characterized by XRD, infrared absorption spectroscopy, thermal analyses, Scanning Electronic Microscopy and a criterions study of PL properties. These rare earth doped materials present highly intense red (Eu3+), luminescence under UV radiation. The structure change with the concentration of dopand, in this case concentration of Eu3+. The excitation spectra of these compounds presented broad bands arising from ligand–to–metal charge transfer (O→Mo6+, O→W6+ and O→Eu3+) and narrow bands related to 4f–4f intraconfigurational transitions. The emission spectra exhibited the 5D0→7FJ (J= 1–4) transitions, for the systems doped with Eu3+, while a broad band assigned to the LMCT (O→Mo;W) are observed when the excitation is monitored on the O→Mo;W LMCT state around 286 nm
Silver nanoparticle Plasmon Effect in the luminescence of X%Ag0@7.5%Eu(tta)3.TOPO-PVP system
2017 - FELINTO, MARIA C.F.C.; SOUZA, LUANA A.; BONTURIM, EVERTON; NAKAMURA, LIANA K.O.; CAMARGO, PEDRO; BRITO, HERMI F.; TEOTONIO, ERCULES E.S.; MALTA, OSCAR M.L.
Surface Plasmon’s (SP) are known as collective oscillations of the conduction electrons induced by incident light at a metallic interface. They attract increasing interest for their applications to surface enhanced Raman spectroscopy (SERS), metal enhanced fluorescence (MEF), non-linear optics (NLO), etc. In the MEF fluorophores are not covalently coupled to the silver nanoparticles, which can facilitate the control of the fluorophores-to-metal separation, using a polymer thin film as the spacer, to study this phenomenon. Nowadays Plasmon coupled RE ion sistems are of great scientific significance [1-2]. In this work, the polyvinylpyrrolidone polymer, PVP, powder (0.3 g) was dissolved in ethanol or water (50 mL) followed by the addition of the required amount (from 7.5% in mass) of the Ln3+-complex in ethanol and added 0.1-10%(w/w) of Ag0 nanoparticles in relation of Eu3+ mass. The mixed solution was stirred (30 minutes), then cast onto a Petri dish. The polymer film was obtained after the total evaporation of the solvent. These films were characterized using IR spectroscopy, XPD, TGA, TEM, absorption and photoluminescence spectroscopy. The luminescence spectra of the films doped with Ag0 have the same profile of undoped films, exhibiting characteristic bands assigned to 5D07FJ (J= 1-4) at 581, 596, 615 and 702 nm. The intensity parameters of the film with and without Ag0 in various concentrations of metallic nanoparticle were determined. The only difference in these systems remaining in the intensity of the bands of Eu3+ ion that increase in a factor of ~1000X (Fig. 1).
Investigation of rare earth distribution in Sr2MgSi2O7:Eu2+,Dy3+ nanophosphors prepared by wet-chemical routes
2017 - BONTURIM, E.; REIS, R. dos; MERIZIO, L.G.; RODRIGUES, L.C.V.; BRITO, H.F.; FELINTO, M.C.F.C.
Luminescent materials have been developed through ne chemistry methods that help to achieve a better control of parameters such as morphology, particle size, atomic homogeneity and high purity single phase in low temperature synthesis.[1, 2] In this work, the material Sr1:98MgSi2O7 nanoparticles doped with 0.01 mol of Eu2+ and codoped with 0.01 mol of Dy3+ was prepared via Pechini and Condensation methods. Post-annealing by microwave assisted method using granular coal as the susceptor/reducing agent [3] was applied on both materials and their luminescent properties were compared. The structural position of Eu2+ used as the activator ions determines photoluminescence properties. The luminescence spectra of Sr2MgSi2O7:Rn+ nanomaterial (R: Eu2+, Dy3+) shows a high emission broad band assigned to the intercon gurational transition 4f65d1 ! 4f7 centered around 460 nm, which is overlapped with a low emission lines attributed to the 4F9=2 ! 6H13=2 transition of Dy3+ ion (Fig. 1b). Elemental mappings obtained by Energy Dispersive X-Ray (EDX) presents dopants more likely to be found at the edge, indicating a possible segregation of rare earths to the grain boundaries during the synthesis (Fig. 1c). The persistent luminescence phenomenon emitting in a blue region was observed for both nanomaterials.

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