JAQUELINE JAMARA SOUZA SOARES

JAQUELINE JAMARA SOUZA SOARES

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The effect of gamma radiation on the structure of graphene oxide and graphene oxide functionalized with amino-PEG
2019 - SOARES, J.J.S.; JACOVONE, R.M.S.; SANTOS, P.S.; ZAIM, M.H.; FARIA, D.L.A.; SAKATA, S.K.
Covalent functionalization of graphene oxide (GO) with polyethylene glycol (PEG) has been widely used in drug delivery systems. This nanocomposite exhibits excellent stability in the presence of high concentrations of salts and proteins and shows low toxicity compared to its raw form. However, it must be sterilized prior to use in medical devices, and for this purpose, the gamma irradiation shows a promising option. Sterilization by ionizing energy through gamma rays, generated by Cobalt-60 self-disintegration, consists in exposing the materials to short electromagnetic waves. The irradiation process provides substantial advantages when compared to thermal and chemical processes, such as, more precise control of the process, lower energy consumption, and less environmental pollution. In this work the effects of gamma radiation on GO and GO functionalized with amino-PEG (GO-PEG-NH2) irradiated with doses (15, 25, 35 and 50 kGy) at rate dose of 7.3 kGy.h-1 were evaluated. The analyses were performed by Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The results showed that gamma radiation up to 50 kGy did not cause any defects on the nanomaterials.
The effect of gamma radiation on the stability of aqueous dispersions of graphene oxide and graphene oxide functionalized with amino-peg
2018 - SOARES, J.J.S.; SANTOS, P.S.; ZAIM, M.H.; SAKATA, S.K.
Nanocomposites based on graphene have been prominent in the field of biomedicine due to the biocompatibility with the physiological medium and the possibility of being functionalized by a series of biocompatible polymers, such as chitosan, polyethylene glycol, poly (caprolactone), among others. However, there is a need for sterilization of these nanomaterials in the medical field and gamma irradiation is a promising option. In the present work graphene oxide (GO), produced by the modified Hummers method, was functionalized with amino-PEG (GO-PEG-NH2) through the amidation process. The objective of this study was to evaluate the aqueous dispersions stability of these nanomaterials before and after gamma radiation (Cobalt 60) at a dose of 25 kGy. Dynamics light scattering (DLS) was used to determine the zeta potential. The results showed no significant differences between the zeta potentials of the non-irradiated and irradiated graphene oxide. The dispersion of the functionalized graphene oxide showed to be stable and the irradiated unstable.
Gamma radiation assisted reduction of graphene oxide in unoxidized environment
2017 - MOURA, TIAGO S.; GOTO, PAULA T.; GARCIA, RAFAEL H.L.; SALVADOR, PABLO A.V.; SANTOS, PAULO S.; SOARES, JAQUELINE J.S.; NODA, LUCIA; SAKATA, SOLANGE K.
Graphene is a honeycomb like structure of carbon atoms of sp2 hybridization, with remarkable physical and chemical properties. Perhaps, the most desirable properties of a such material is the quasi-ballistic electronic transport and its excellent thermal conductivity that make graphene an excellent alternative to build electronic devices related to silicon, for instance. However, the lack of organic functions and the strong bonds between carbons in graphene nano-sheets make them unable to undergo functionalization reactions, that is important for many applications such as gas and biochemical sensors or nanoparticles decoration. So, in order to allow the functionalization of graphene nano-sheets and make possible a variety of new applications it was developed a nanomaterial based on the oxidation and exfoliation of graphite: the graphene oxide. This new material has epoxide and hydroxyl groups in the basal planes, with carboxyl groups in the borders, improving the hydrophilic properties and potential for chemical functionalization. Graphene oxide also serves as a starting material to graphene production by reduction routes. Partial reduction of graphene oxide leads to reduced graphene, a nanomaterial that combines both proprieties of graphene and graphene oxide: an excellent electrical and thermal conductivity, high superficial area and remaining oxygen groups that allow its functionalization. In the literature is described different ways to produce reduced oxide graphene from graphene oxide, such as chemical reduction using hydrazine hydrate or NaBH4, thermal reduction using high temperatures and plasma hydrogenation. Here in it is described a sustainable process to reduce graphene oxide in sodium bisulfite solution using gamma radiation. Exfoliated Graphene oxide (1-100mg/L) with NaHSO3 under inert medium was submitted to gamma radiation. The radiation dose ranged from 50 to 500 kGy and the product was centrifuged and analyzed by X-ray diffraction (XRD), Raman and infra-red (FT-IR) spectroscopies. It was observed that depending on the dose total or partial reduction was achieved. This methodology does not produce any toxic residue.
The effect of gamma radiation on the structure of graphene oxide and graphene oxide functionalized with amino-PEG
2017 - SOARES, JAQUELINE J.S.; JACOVONE, RAYNARA M.S.; SANTOS, PAULO S.; ZAIM, MARCIO H.; FARIA, DALVA L.A. de; SAKATA, SOLANGE K.
The functionalization of graphene oxide (GO) with polyethylene glycol (PEG) has been widely used in drug delivery systems. This nanocomposite exhibits excellent stability in the presence of high concentrations of salts and proteins and shows to be less toxic than its raw form in vitro and in vivo. However, it must be sterilized before use in the medical field and the gamma irradiation shows a promising option for this purpose. Sterilization by ionizing energy through gamma rays, generated by Cobalt-60 self-disintegration, consists in exposing the materials to short electromagnetic waves. The irradiation process provides substantial advantages when compared to thermal and chemical processes such as more precise control of the process, production of products with superior qualities, lower energy consumption and less environmental pollution. In this work the effect of gamma radiation on the structure of GO and GO functionalized com Amino-PEG (GO-PEG-NH2) irradiated with different doses (15, 25, 35 and 50 kGy) and rate dose 7.31 kGy.h-1 was evaluated. The analyses were performed by Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The results showed that the methods for the synthesis of GO and GO-PEG-NH2 was effective since there was confirmation of the surface oxidation of materials and functionalization with the PEG-NH2 and the sterilization by gamma radiation does not caused any defects on materials.