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Synthesis, Characterization, and Study of PLGA copolymer <i>in Vitro</i>Degradation

Journal of Biomaterials and Nanobiotechnology 2015年第1期6卷 8-19页

作者： anamaria teodora coêlho rios silva Barbara Camilla Oliveira Cardoso Maria Elisa Scarpelli Ribeiro e silva Roberto Fernando Souza Freitas Ricardo Geraldo Sousa Polymer Science and Technology Laboratory Chemical Engineering Department School of Engineering Federal University of Minas Gerais Belo Horizonte Brazil

The poly(lactic-co-glycolic acid), known as PLGA, is one of the main bioreabsorbable polymers used in the field of medicine today. This copolymer is widely applied in sutures, devices geared toward the controlled release of medication, and the guided regeneration of bone tissue as it presents a short degradation time. This work aimed to synthesize the 82/18 PLGA (expressed by the mass ratio of D,L-lactide and glycolide, respectively), to characterize and study the in Vitro degradation in the form of rods in phosphate buffer solution (PBS). The copolymer was synthesized by opening the cyclic dimer rings of the monomers D,L-lactide and glycolide, in the presence of the tin octanoate initiator and of the lauryl alcohol co-initiator. The characterization of the copolymer and the follow-up of its in vitro degradation were studied using: Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), Infrared Molecular Absorption Spectroscopy with Fourier Transform (FTIR), Rheometry, and Scanning Electron Microscopy (SEM). Through these characterization techniques, it was possible to obtain the glass transition temperature, thermal stability, chemical composition, morphology, and molar mass of both the synthesized and the degraded copolymer. The molar mass of the synthesized copolymer was, approximately, 106 g·mol-1. The degradation rate of PLGA significantly increased from the 19th to the 28th day in PBS. After 28 days in PBS, the glass transition temperature and the molar mass reduced from 45°C to 17°C and from 1.5 × 106 g·mol-1?to 7.5 × 104?g·mol-1, respectively. The pH of the medium has a significant influence on the copolymer degradation profile. When it diminishes, it accelerates the degradation process, resulting in smaller PLGA polymer chains. This pH dependent degradation can be useful for drug release systems.

关键词： Synthesis Characterization In Vitro Degradation PLGA

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Viscum Album Modulates Apoptotic Related Genes in Melanoma Tumor of Mice

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American Journal of Molecular Biology 2014年第2期4卷 49-58页

作者： anamaria da silva Facina Gil Facina Ismael Dale cotrim Guerreiro da silva Giovana Aparecida Goncalves Fernando Augusto de Almeida silvana Aparecida Alves correa de Noronha Samuel Marcos Ribeiro de Noronha Mary Uchiyama Nakamura Departament of Dermatology Federal University of Sao PauloSao PauloBrazil Department of Gynecology Federal University of Sao PauloSao PauloBrazil Department of Surgery Federal University of Sao PauloSao PauloBrazil Departament of Obstetrics Federal University of Sao PauloSao PauloBrazil

Cancer is a major public health problem throughout the world. It is estimated that one third of the American population will develop the disease at some time during their lifetimes. Among these, melanoma will account for 7% of the cases. In Brazil, in 2012, it is estimated that over six thousand new melanoma cases occurred. During recent years, the incidence of melanoma has increased, mainly due to a more constant exposure of the skin to sunlight. In this work, our aim is to assess the expression of apoptotis-related genes melanoma tumors in mice treated with Viscum album (VA). This will allow us to better understand the molecular mechanisms underlying tumor cell death activation caused by this compound. Our results clearly demonstrate upregulation of pro apoptotic genes (Trp53bp2, Nol3, Fadd, Tnfsf10, Traf1, Traf2, Cflar, Card10, Nod1, Casp 2, Casp7, Xiap, Dad1, and Dffb). Further bioinformatics-based tool analysis allowed us to assess which specific cell death-related intracellular pathways were activated by VA treatment. Two major effects of VA in melanoma cells could be observed: generation of an immunomudulatory Th-1 like action, recruiting several interleukines, and cell death activation through Caspase7, associated uspstream with Card10 and downstream with CAD. In summary, VA modulates apoptosis related genes in cancer melanoma cells. Although a deeper study should be conducted, VA seems to interfere with important signaling pathways within melanoma cells that control the cellular mechanisms of apoptosis activation. Therapeutic approaches using VA as an antineoplastic and adjuvant medication compounding should be considered.

关键词： Viscum Album Melanoma Apoptosis Pathways PCR Array Immunohistochemistry

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Rheological and Morphological Properties of composites Based on Polylactide and Talc

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材料科学与工程（中英文B版） 2013年第11期3卷 695-699页

作者： Talita F. Cipriano Ana Lucia Nazareth da silva Antonio Henrique Monteiro da Fonseca Thome da silva anamaria Furtado de Sousa Gustavo Monteiro da silva Christine Rabello do Nascimento Instituto de Macromol~culas Professora Eloisa Mano (IMA/UFRJ) Rio de Janeiro 21945-970 Brasil Departamento Agricola e Meio Ambiente (UFF) Niteroi 24210-240 Brasil Instituto de Quimica (IQ/UERJ) 20550-013 Brasil Programa de Engenharia Metalurgica (PEMM/coPPE/UFRJ) Rio de Janeiro 21941-908 Brasil

Polylactide (PLA) is an emerging material mainly because it can be synthesized from renewable resources and is thus environmentally and ecologically safe. In this study, composites of PLA and talc were prepared by melt-blending technique, using a twin screw extruder. The influence of talc content on the rheological properties of pure PLA and its composites were evaluated. Dynamic rheological tests show that the incorporation of talc particles into PLA decreased system viscosity due to the filler"s lubricant effect. However, as talc content increased, system"s viscosity tended also to increase and materials with higher elastic behavior were produced, further with a higher plastic behavior in relation to pure PLA. This behavior can be observed by SEM micrographs.

关键词：复合材料流变性能聚乳酸滑石形态特性扫描电子显微镜双螺杆挤出机粘度降低

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