Nanotecnologia : considerações em materiais, saúde e meio ambiente

Qualquer leitor, com o mínimo de interesse em Tecnologia, não pode ficar alheio à Nanociência e Nanotecnologia (N&N), que representam importantes fronteiras do conhecimento científico e tecnológico. O traço da N&N é a transversalidade de sua atuação e o impacto que protagoniza nos dias de hoje, em franco crescimento. Este livro foi concebido e produzido para fornecer ao leitor informações básicas e aplicadas sobre a N&N. O livro destaca duas vertentes importantes da N&N: síntese e caracterização de nanomateriais e aplicações em saúde e meio ambiente. O texto não pretende cobrir todo o universo da N&N, porém inclui tópicos relevantes, organizados dos fundamentos para as aplicações, oferecendo ao leitor um marco introdutório, que por iniciativas individuais poderá se aprofundar em diferentes direções da N&N. O texto reflete parte da experiência acumulada pela rede de N&N, organizada a partir do trabalho conjunto de diferentes laboratórios e unidades acadêmicas pertencentes à Universidade de Brasília (UnB), com foco no ensino de pós-graduação, pesquisa, desenvolvimento e inovação. Esta rede foi organizada a partir do final da década de 1990, e nos anos subsequentes estendeu-se muito além da UnB, envolvendo cerca de duas dezenas de instituições parceiras no país e no exterior, coletando o saldo de quase um milhar de patentes e artigos publicados em revistas científicas indexadas e cerca de cinco centenas de orientações de alunos de pós-graduação

Liposomal photosensitizers : potential platforms for anticancer photodynamic therapy

Photodynamic therapy is a well-established and clinically approved treatment for several types of cancer. Antineoplastic photodynamic therapy is based on photosensitizers, i.e., drugs that absorb photons translating light energy into a chemical potential that damages tumor tissues. Despite the encouraging clinical results with the approved photosensitizers available today, the prolonged skin phototoxicity, poor selectivity for diseased tissues, hydrophobic nature, and extended retention in the host organism shown by these drugs have stimulated researchers to develop new formulations for photodynamic therapy. In this context, due to their amphiphilic characteristic (compatibility with both hydrophobic and hydrophilic substances), liposomes have proven to be suitable carriers for photosensitizers, improving the photophysical properties of the photosensitizers. Moreover, as nanostructured drug delivery systems, liposomes improve the efficiency and safety of antineoplastic photodynamic therapy, mainly by the classical phenomenon of extended permeation and retention. Therefore, the association of photosensitizers with liposomes has been extensively studied. In this review, both current knowledge and future perspectives on liposomal carriers for antineoplastic photodynamic therapy are critically discussed

PVM/MA-shelled selol nanocapsules promote cell cycle arrest in A549 lung adenocarcinoma cells

Background: Selol is an oily mixture of selenitetriacylglycerides that was obtained as a semi-synthetic compound containing selenite. Selol is effective against cancerous cells and less toxic to normal cells compared with inorganic forms of selenite. However, Selol’s hydrophobicity hinders its administration in vivo. Therefore, the present study aimed to produce a formulation of Selol nanocapsules (SPN) and to test its effectiveness against pulmonary adenocarcinoma cells (A549). Results: Nanocapsules were produced through an interfacial nanoprecipitation method. The polymer shell was composed of poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA) copolymer. The obtained nanocapsules were monodisperse and stable. Both free Selol (S) and SPN reduced the viability of A549 cells, whereas S induced a greater reduction in non-tumor cell viability than SPN. The suppressor effect of SPN was primarily associated to the G2/M arrest of the cell cycle, as was corroborated by the down-regulations of the CCNB1 and CDC25C genes. Apoptosis and necrosis were induced by Selol in a discrete percentage of A549 cells. SPN also increased the production of reactive oxygen species, leading to oxidative cellular damage and to the overexpression of the GPX1, CYP1A1, BAX and BCL2 genes. Conclusions: This study presents a stable formulation of PVM/MA-shelled Selol nanocapsules and provides the first demonstration that Selol promotes G2/M arrest in cancerous cells

Antitumor effect and toxicity of free rhodium (II) citrate and rhodium (II) citrate-loaded maghemite nanoparticles in mice bearing breast cancer

Background: Magnetic fluids containing superparamagnetic iron oxide nanoparticles represent an attractive platform as nanocarriers in chemotherapy. Recently, we developed a formulation of maghemite nanoparticles coated with rhodium (II) citrate, which resulted in in vitro cytotoxicity enhanced up to 4.6 times when compared to free rhodium (II) citrate formulation on breast carcinoma cells. In this work, we evaluate the antitumor activity and toxicity induced by these formulations in Balb/c mice bearing orthotopic 4T1 breast carcinoma. Methods: Mice were evaluated with regard to the treatments’ toxicity through analyses of hemogram, serum levels of alanine aminotransferase, iron, and creatinine; DNA fragmentation and cell cycle of bone marrow cells; and liver, kidney and lung histology. In addition, the antitumor activity of rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate was verified by tumor volume reduction, histology and immunohistochemistry. Results: Regarding the treatments’ toxicity, no experimental groups had alterations in levels of serum ALT or creatinine, and this suggestion was corroborated by the histopathologic examination of liver and kidney of mice. Moreover, DNA fragmentation frequency of bone marrow cells was lower than 15% in all experimental groups. On the other hand, the complexes rhodium (II) citrate-functionalized maghemite and free rhodium (II) citrate led to a marked growth inhibition of tumor and decrease in CD31 and Ki-67 staining. Conclusions: In summary, we demonstrated that both rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate formulations exhibited antitumor effects against 4T1 metastatic breast cancer cell line following intratumoral administration. This antitumor effect was followed by inhibition of both cell proliferation and microvascularization and by tumor tissue injury characterized as necrosis and fibrosis. Remarkably, this is the first published report demonstrating the therapeutic efficacy of maghemite nanoparticles coated with rhodium (II) citrate. This treatment prolonged the survival period of treated mice without inducing apparent systemic toxicity, which strengthens its use for future breast cancer therapeutic applications

Antibacterial, antibiofilm and cytotoxic activities of Terminalia fagifolia Mart. extract and fractions

Background: The methicillin resistance of bacteria from the genus Staphylococcus and its ability to form biofilms are important factors in pathogenesis of these microorganisms. Thus, the search for new antimicrobials agents, especially from plants, has been intensified. In this context, Terminalia species have been the subject of research for many pharmacological activities. In this study we evaluated the antibacterial, antibiofilm and cytotoxic activities of the ethanol extract (EtE) from Terminalia fagifolia stem bark as well as that of three fractions of the extract (AqF, HaF and WSF). Methods: We determined the minimum inhibitory concentration (MIC) by microdilution in 96-well plates, where the strains were exposed to serial dilutions of the ethanol extract and fractions, ranging from 12.5 to 400 μg/mL. We then determined the minimum bactericidal concentration (MBC), seeding the inoculum (10 μL) with concentrations equal to or greater than the MIC in Mueller-Hinton agar. To test the antibiofilm activity biofilm formation was induced in the presence of concentrations equivalent to 1/2, 1/4 and 1/8 of the MIC extract or fraction tested. In addition, the effect of the EtE and the fractions on cell viability was tested by the MTT assay on human MCF-7 breast cancer and mouse fibroblast NIH/3T3. To obtain high-resolution images of the effect of the aqueous fraction on the bacterial morphology, atomic force microscopy (AFM) imaging of treated S. aureus cells was performed. Results: We observed antibacterial activity of EtE and fractions with MICs ranging from 25–200 μg/mL and MBCs ranging from 200–400 μg/mL. Regarding antibiofilm activity, both the EtE as the AqF, HaF and WSF fractions showed significant inhibition of the biofilm formation, with inhibition of biofilms formation of over 80% for some strains. The EtE and fractions showed a moderate cytotoxicity in cell line NIH/3T3 viability and potential antitumoral activity on human breast cancer cell line MCF-7. The microscopic images obtained revealed morphological changes to the S. aureus ATCC 29213 surface caused by AqF, as well as significant size alterations. Conclusions: The results show potential antibacterial, antibiofilm and antitumoral activities of the ethanol extract and fractions of T. fagifolia

In vivo efficacy and toxicity of curcumin nanoparticles in breast cancer treatment : a systematic review

Breast cancer is one of the most prevalent types of malignant tumors in the world, resulting in a high incidence of death. The development of new molecules and technologies aiming to apply more effective and safer therapy strategies has been intensively explored to overcome this situation. The association of nanoparticles with known antitumor compounds (including plant-derived molecules such as curcumin) has been considered an effective approach to enhance tumor growth suppression and reduce adverse effects. Therefore, the objective of this systematic review was to summarize published data regarding evaluations about efficacy and toxicity of curcumin nanoparticles (Cur-NPs) in in vivo models of breast cancer. The search was carried out in the databases: CINAHL, Cochrane, LILACS, Embase, FSTA, MEDLINE, ProQuest, BSV regional portal, PubMed, ScienceDirect, Scopus, and Web of Science. Studies that evaluated tumor growth in in vivo models of breast cancer and showed outcomes related to Cur-NP treatment (without association with other antitumor molecules) were included. Of the 528 initially gathered studies, 26 met the inclusion criteria. These studies showed that a wide variety of NP platforms have been used to deliver curcumin (e.g., micelles, polymeric, lipid-based, metallic). Attachment of poly(ethylene glycol) chains (PEG) and active targeting moieties were also evaluated. Cur-NPs significantly reduced tumor volume/weight, inhibited cancer cell proliferation, and increased tumor apoptosis and necrosis. Decreases in cancer stem cell population and angiogenesis were also reported. All the studies that evaluated toxicity considered Cur-NP treatment to be safe regarding hematological/biochemical markers, damage to major organs, and/or weight loss. These effects were observed in different in vivo models of breast cancer (e.g., estrogen receptor-positive, triple-negative, chemically induced) showing better outcomes when compared to treatments with free curcumin or negative controls. This systematic review supports the proposal that Cur-NP is an effective and safe therapeutic approach in in vivo models of breast cancer, reinforcing the currently available evidence that it should be further analyzed in clinical trials for breast cancer treatments

Efeitos citostáticos e citotóxicos do inibidor de proteases - BTCI - e peptídeos derivados em células de câncer de mama (MCF-7)

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2008.O câncer de mama é o tipo de câncer que apresenta as maiores taxas de incidência e mortalidade em mulheres no Brasil e no mundo. Atualmente, os tratamentos existentes para esse tipo de câncer têm eficiência moderada e causam efeitos colaterais severos que diminuem a qualidade de vida do paciente. Dessa forma, existe uma busca constante por novos tratamentos e moléculas anticarcinogênicas eficientes e não indutoras de efeitos colaterais severos. Diversos compostos purificados de plantas têm seus efeitos anticarcinogênicos relatados na literatura. Dentre essas moléculas, destacam-se os inibidores de protease da família Bowman-Birk. O presente trabalho teve como objetivo analisar os efeitos do inibidor de proteases da família Bowman-Birk BTCI, purificado de sementes de Vigna unguiculata, e de peptídeos sintéticos derivados em células de câncer de mama (MCF-7), in vitro. O tratamento de BTCI e do peptídeo com atividade de inibição para quimotripsina (PCHY) em células MCF-7 por 72 horas mostraram os seguintes efeitos: redução do potencial de membrana mitocondrial e da viabilidade e proliferação celular; aumento da fragmentação de DNA; condensação de cromatina; e alterações do ciclo celular, integridade da membrana plasmática e morfologia das células. Os efeitos citostáticos e citotóxicos observados no tratamento de BTCI e PCHY sugerem a indução da via de morte celular da apoptose associada a ativação do processo de autofagia. Além de seus efeitos anticarcinogênicos, outras características promissoras dessas moléculas, como elevada estabilidade (BTCI), ausência de toxicidade para fibroblastos (PCHY), solubilidade em solução aquosa e ausência de efeitos na lise de hemáceas (BTCI e PCHY), corroboram para sua potencial utilização como agentes anticarcinogênicos alternativos ou complementares aos tratamentos convencionais empregados atualmente para o câncer de mama.Breast cancer is the type of cancer with the highest incidence and mortality rates among women in Brazil and around the world. Currently, breast cancer treatments employed have moderate efficiency and cause severe side effects which reduce the patients life quality. Therefore, there is constant research for new and efficient treatments and anticarcinogenic molecules with low or no side effects. Several purified compounds of plants and their anticarcinogenic effects have been reported in literature. Among these compounds, the Bowman-Birk family protease inhibitors stand out. The objective of the present work was to analyze the effects of a Bowman-Birk family protease inhibitor named BTCI, extracted from Vigna unguiculata seeds, and of BTCI-derived peptides in breast cancer cells (MCF-7), in vitro. The 72 hours treatment of BTCI and its derived peptide with chymotrypsin inhibitor properties (PCHY) showed the following results: mitochondrial membrane potential, cell viability, and proliferation reductions; DNA fragmentation increase; chromatin condensation; cell cycle, plasma membrane integrity, and morphology alterations. The cytostatic and cytotoxic effects observed in BTCI and PCHY treatments suggested the induction of apoptosis cell death associated with autophagy activation. In addition to their anticarcinogenic effects, other promising characteristics of these molecules are that they presented elevated stability (BTCI), no toxicity to fibroblasts (PCHY), aqueous solution solubility, and no induction of erythrocytes lyses (BTCI and PCHY). These additional properties contribute to their potential use as alternative anticarcinogenic agents for conventional breast cancer treatments employed at the present moment

Efeitos de extrato de sementes de Vigna unguiculata e do inibidor de proteases BTCI, livre e encapsulado em nanopartículas, em células de câncer de mama e na prevenção de câncer de pele

Tese (doutorado)—Universidade de Brasília, Programa de Pós-Graduação em Biologia Animal, 2012.O câncer de mama e de pele não-melanoma são neoplasias com altas taxas de incidência e mortalidade no Brasil e no mundo. Atualmente, os tratamentos existentes para esses tipos de câncer têm eficiência moderada e causam efeitos cadversos severos que diminuem a qualidade de vida do paciente. Dessa forma, existe uma busca constante por novos tratamentos e moléculas anticarcinogênicas eficientes e não indutoras de efeitos adversos severos. Estudos recentes mostraram que o inibidor de proteases BTCI, purificado de sementes de Vigna unguiculata (feijão-de-corda) e pertencente à família Bowman-Birk, induziu efeitos citostáticos e citotóxicos em células de câncer de mama, sem causar alterações na viabilidade de células de mama normais. Considerando esses resultados promissores, os principais objetivos do presente trabalho foram o de otimizar os efeitos do BTCI em células de câncer de mama MCF-7, in vitro; e o de avaliar os efeitos do extrato de sementes de V. unguiculata (EB) e do BTCI na prevenção de câncer de pele não-melanoma, in vivo. O BTCI foi encapsulado em nanopartículas (micelas ou lipossomos) para reduzir sua agregação em meio de cultura e otimizar a entrega do inibidor diretamente no citoplasma das células MCF-7. Os resultados mostraram que lipossomos catiônicos foram as plataformas mais adequadas para a encapsulação do BTCI; mas, apesar dessas nanopartículas entregarem o inibidor no citoplasma das células MCF-7, não houve alteração na viabilidade das mesmas. A presença de outros compostos bioativos em amostras de BTCI foi investigada e mostrou que amostras com diferentes padrões de citotoxicidade em células tumorais apresentam o mesmo perfil protéico, mas quantidades de ácidos graxos diferentes. Ao longo do processo de indução química de câncer de pele não-melanoma em camundongos, observou-se que a aplicação tópica de EB ou BTCI livres reduziu significativamente: a incidência e o volume de lesões pré-malígnas; a freqüência de alterações histopatológicas; e a produção de mediadores inflamatórios envolvidos na progressão do tumor. Considerando os dados apresentados acima, concluiu-se que mais estudos precisam ser realizados visando esclarecer as moléculas e os mecanismos de ação envolvidos no efeito citotóxico do BTCI em células de câncer de mama. Com relação aos efeitos preventivos, o EB e o BTCI foram capazes de retardar a progressão do câncer de pele não-melanoma, provavelmente exercendo efeitos anti-inflamatórios. A confirmação desse novo dado será útil para auxiliar no desenho de novas estratégias preventivas no tratamento desse tipo de câncer e também de outras doenças relacionadas às inflamações agudas ou crônicas. _______________________________________________________________________________ ABSTRACTBreast and non-melanoma skin cancer have shown high incidence and mortality rates in Brazil and around the world. Currently, the treatments available for these types of cancer show moderate efficiency and cause severe side effects reducing the patient’s life quality. Therefore, there is a constant research for new and efficient treatments and anticarcinogenic molecules with low or no side effects. Recent studies reported that the Bowman-Birk protease inhibitor BTCI, extracted from Vigna unguiculata (feijão-de-corda) seeds, induced cytostatic and cytotoxic effects on breast cancer cells; while no effect on was observed on normal breast cells. In view of these promising data, the main objectives of the present work was to optimize the therapeutic effects of BTCI on breast cancer cells (MCF-7), in vitro; and to evaluate the effects of a crude extract (EB) from V. unguiculata seeds and BTCI on nonmelanoma skin cancer prevention, in vivo. BTCI was encapsulated in nanoparticles (micelles or liposomes) in order to reduce its aggregation on culture media and to optimize the delivery of this inhibitor to the cytoplasm of MCF-7 cells. The results showed that cationic liposomes were suitable platforms for BTCI encapsulation; however, despite of delivering the inhibitor to the cytoplasm of MCF-7 cells, no cytotoxicity was observed. The presence of other bioactive compounds in BTCI samples were investigated and showed that BTCI samples with different cytotoxic patterns on cancer cells have similar protein profile, but distinct amounts of fatty acids. During the chemical induction of non-melanoma skin cancer in mice, it was shown that topic applications of BTCI or EB significantly reduced: the incidence and volume of premalignant lesions; the number of histopathological features; and the production of inflammatory mediators involved in tumor progression. Considering the data presented above, it was concluded that more studies are necessary to clarify the molecules and mechanisms of action involved in BTCI cytotoxicity on breast cancer cells. Regarding the preventive effects, EB and BTCI treatments were able to retard the progression of nonmelanoma skin cancer, probably inducing anti-inflammatory effects. The confirmation of this new BTCI feature can be helpful to design new strategies for skin cancer prevention and also for other diseases involving acute or chronic inflammation