MARA TANIA SILVA ALCANTARA
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Artigo IPEN-doc 26505 Simultaneous hydrogel crosslinking and silver nanoparticle formation by using ionizing radiation to obtain antimicrobial hydrogels2019 - ALCANTARA, M.T.S.; LINCOPAN, N.; SANTOS, P.M.; RAMIREZ, P.A.; BRANT, A.J.C.; RIELLA, H.G.; LUGAO, A.B.Hydrogel dressings are crosslinked hydrophilic polymers able of swelling in presence of water and can be used in many different types of wound care. In turn, in wound care, silver has been used for a long time as an effective antimicrobial agent. Recent studies have demonstrated an increase of its antimicrobial action when it is used at nanometer scale, that is, as silver nanoparticles (AgNPs), which have anti-inflammatory effect on infected wounds, rashes, and mesh skin grafts. The objective of this work was to study hydrogel dressings containing AgNPs from silver nitrate, synthesized by radiation involving the formation of silver nanoparticles with simultaneous occurrence of crosslinking and sterilization of the polymer systems. One of the hydrogels was prepared with poly(N-vinyl-2- pyrrolidone) (PVP) and the other with poly(vinyl alcohol) (PVA) as main studied polymers. An aqueous solution of AgNO3 was added to both polymer systems separately. The AgNPs synthesis, polymer crosslinking and dressing sterilization were achieved simultaneously by irradiating the resultant solutions with gamma-rays from a 60Co source. Gel fraction, swelling in reverse osmosis water, SEM-EDS, UVvisible spectroscopy, and antimicrobial activity were performed and characterized. The obtained results showed that the dressings have a soft consistency, high degree of crosslinking and swelling, homogeneous distribution of AgNPs with peaks of plasmonic bands about 400 nm, but only PVP hydrogel showed antimicrobial properties to P. aeruginosa and normal S. aureus. Moreover, this hydrogel also showed antimicrobial properties to S. aureus strain multiresistant to penicillins, cephalosporins, carbapenems, sulfonamides, tetracyclines, quinolones, and aminoglycosides, whereas the PVA hydrogel showed antimicrobial properties to P. aeruginosa and bacteriostatic activity to S. aureus. The results suggest that both synthesized dressings have potential for use in wounds and burns infected with gram-positive and gram-negative bacteria.Resumo IPEN-doc 24823 Obtaining of a hydrogel gel dressing of PVP with nanosilver for deep and complex wounds2017 - ALCANTARA, MARA T.S.; COUTINHO, CAMILA M.; OLIVEIRA, MARIA J.A.; MUNHOZ, MARA M.L.; LUGAO, ADEMAR B.Introduction Chronic and some acute wounds of difficult treatment that challenge medical and nursing teams are classificadas como Complex wound (Ferreira et al., 2006). Due to the long cicatrization time and successive relapses, cause a problem social on patients' lives and economic a major impact on the health system (Azoubel et al., 2017). Throughout the world there has been a growing interest in the use of hydrogels for application as dressings in view that they are able to maintain the humidity of the wound, favoring the epithelialization of lesions and favoring the relief of pain. On the other hand, silver is an agent that has been used since ancient times, but it has been replaced after the discovery of antibiotics. However, with the advent of bacterial resistance to antibiotics and the development of nanotechnology, it has regained notoriety, since the clinical incidence of silver resistance remains low (Chopra, 2007).In addition to its bactericidal properties, silver nanoparticles (AgNPs) also have anti-inflammatory properties, which, allied to hydrogels’ advantages of maintaining moisture in the wound, represent a great advantage for use as a dressing. However, conventional dressings do not address the need for direct contact with the wound when this is a deep wound. The objective of this work was to obtain a hydrogel gel with silver nanoparticles for wound dressing, synthesized in situ by using ionizing radiation for gelation (crosslinking of PVP-Ag+ aqueous solution), synthesis of the AgNPs and simultaneous sterilization of the final product, able to fill the cavity of deep wounds, thus allowing the direct contact of the dressing with the lesioned walls. Methodology The gel was prepared from the mixture of PVP with plasticizers, water, and silver ions; next, the mixture was irradiated / sterilized by gamma-irradiation from a 60-Co source at a dose of 20 kGy. . Results The result of this work is a viscous and transparent gel (Fig. 1), easy to be applied, able to control pain since it reduces the local temperature due to evaporation of water. Fig. 1 - Hydrogel gel of PVP with silver nanoparticles for wound dressing. The studies are being continued with the aim of evaluating its stability and bactericidal activity.