Navegando por Autor "Marques, Rodrigo Fernando Costa"

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    Magnetic Nanoparticles Obtained by Homogeneous Coprecipitation Sonochemically Assisted
    (2015) Freitas, Juliana Cristina de; Branco, Rogerio Mendes; Lisboa, Isabella Garcia Oliveira; Costa, Taciane Pereira da; Campos, Maria Gabriela Nogueira; Jafelicci Júnior, Miguel; Marques, Rodrigo Fernando Costa
    The present work demonstrates preparation of magnetic nanoparticles by a novel method. Magnetic nanoparticles with potential for biomedical and environmental applications were obtained by homogeneous coprecipitation method sonochemically assisted. The effect of ultrasonic cavitation on changing the reaction environment was studied. The chemical reaction media used here was very similar to those used for Sono-Fenton process. The ultrasonic energy has driven the growth of particles; smaller diameter nanoparticles were obtained by applying a higher power. For the first time, it was demonstrated the iron oxide nanoparticles synthesis at pH lower than 6.
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    Morphological and mechanical characterization of chitosan-calcium phosphate composites for potential application as bone-graft substitutes
    (2015) van de Graaf, Guilherme Maia Mulder; De Zoppa, Andre Luis do Valle; Moreira, Rodrigo Crispim; Maestrelli, Sylma Carvalho; Marques, Rodrigo Fernando Costa; Campos, Maria Gabriela Nogueira
    Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP) - a component of natural bone, and chitosan (CS) - a biocompatible biopolymer. Methods CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C) on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours) on the mechanical properties - compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction) and the chemical composition of the samples, confirmed by FTIR. Conclusion Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.
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    Preparation and Characterization of Chitosan/mPEG-PCL Blended Membranes for Wound Dressing and Controlled Gentamicin Release
    (2018) Brianezi, Samira Faleiros Silva; Castro, Karine Cappuccio; Piazza, Rodolfo Debone; Melo, Maria do Socorro Fernandes; Pereira, Rafael Matsumoto; Marques, Rodrigo Fernando Costa; Campos, Maria Gabriela Nogueira
    In this paper, a novel wound dressing membrane for controlled release of gentamicin (GE), while covering and protecting the wound was investigated. Chitosan (CHI) was associated with methoxy polyethylene glycol - polycaprolactone copolymer (mPEG-PCL) to prepare the blended wound dressing membranes. The use of copolymer mPEG-PCL was necessary to improve the compatibility between CHI and PCL. The association of CHI and PCL was required to control the water retention and release rate of encapsulated GE. In vitro release studies were performed with the mPEG-PCL/CHI-GE membranes in order to evaluate the effect of copolymer concentration on the kinetics of GE release and water uptake. Reduced burst release rates and swelling ratios were observed for the 1/2 and 1/4 mPEG-PCL/CHI-GE membranes. In addition, all gentamicin-loaded membranes inhibited S. aureus and E. coli growth, and demonstrated color, moisture and thermal stability. Therefore, mPEG-PCL/CHI-GE membranes showed important features for potential wound dressing and drug delivery applications.