Biocompatible superparamagnetic poly(thioether-ester) nanoparticles via miniemulsion technique

Biocompatible polymeric nanoparticles were obtained via thiol-ene polymerization of a biobased monomer in miniemulsion. The α,ω-diene-diester monomer was synthesized through esterification reaction of a glycerol derivative, namely 1,3-propanediol, with 10-undecenoic acid, a long-chain diene carboxylic acid. The biobased poly(thioether-ester), PTEE, nanoparticles were submitted to cytotoxicity and hemolysis analyses. High cell viability and no significant changes in cell morphology were observed. Lastly, hemolysis assays revealed blood compatibility and therefore PTEE nanoparticles have been shown to be a potential alternative drug delivery vector for intravenous administration. The poly(thioether-ester) was also employed to encapsulate magnetic nanoparticles (MNPs) by miniemulsification technique. Please click Additional Files below to see the full abstract

Encapsulation of superparamagnetic nanoparticles and 4-nitrochalcone in poly(thioether-ester) for biomedical applications

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2018.O câncer é uma das principais causas de morbidade e mortalidade no mundo, sendo hoje considerado um problema de saúde pública. A maior dificuldade durante o tratamento destas doenças é destruir as células tumorais sem afetar o tecido saudável. As nanopartículas poliméricas magnéticas têm sido consideradas como um sistema eficaz para estes tratamentos, pois contribuem para uma entrega precisa do fármaco, reduzindo os efeitos colaterais e aumentando a eficácia terapêutica. As chalconas são compostos polifenólicos da classe dos flavonóides associados a diversas atividades farmacológicas, cujas propriedades levaram os pesquisadores a considerá-las como potenciais anticarcinogênicos. A polimerização tiol-eno é um novo e promissor campo de estudo devido aos seus atributos, incluindo condições suaves e rápidas taxas de reação sem a formação de subprodutos. Neste trabalho, nanopartículas superparamagnéticas de poli(tioéter-éster) (PTEe) juntamente com o encapsulamento de 4-nitrochalcona (4NC) foram sintetizadas pela primeira vez. A polimerização tiol-eno em miniemulsão foi aplicada usando um monômero a,?-dieno totalmente renovável obtido a partir do ácido 10-undecenóico e 1,3-propanodiol, ambos derivados do óleo de mamona. Nanopartículas superparamagnéticas foram sintetizadas com sucesso por miniemulsificação e evaporação de solvente, apresentando morfologia esférica, diâmetros em torno de 135 nm e baixos índices de polidispersão. Análises de FT-IR mostraram as bandas de absorção do polímero e das MNPs. Análises de TGA mostraram uma eficiência de encapsulação (EE%) de MNPs maior que 99%. Ensaios de citotoxicidade e microscopia de fluorescência em células HeLa demonstraram que o material não é citotóxico e que, quando exposto a um campo magnético externo, a internalização celular é até três vezes maior. A EE% da 4NC foi maior que 90%. O perfil de liberação de 4NC foi obtido em pH 7,4 e 6,0, utilizando-se uma amostra de MNPs e 4NC encapsuladas simultaneamente. Observou-se que a liberação ocorre por difusão e mais rápida em pH 6,0. As nanopartículas também foram sintetizadas pela polimerização em miniemulsão, que tem a vantagem de incorporar compostos inorgânicos em apenas uma etapa. Características como morfologia, diâmetro e índice de polidispersão não apresentaram diferenças significativas considerando a aplicação final desejada. A 4NC foi encapsulada sozinha, obtendo-se uma EE% maior que 99%. O perfil de liberação da 4NC também foi obtido para pH 7,4 e ocorreu por difusão. As MNPs foram encapsuladas em diferentes concentrações e, por meio de TGA, observou-se que quanto maior a porcentagem inicial de MNPs, menor a EE%. Além disso, pode-se observar que usando um tetratiol na formulação, em vez de um ditiol, a EE% também é maior. Desta forma, os materiais sintetizados demonstraram potencial para serem aplicados na área biomédica e, mais especificamente, no tratamento do câncer.Abstract : Cancer is one of the leading causes of morbidity and mortality in the world, thus it is nowadays considered as a public health problem. The greatest difficulty during the treatment is to destroy the tumor cells without affecting the healthy tissue. Magnetic polymeric nanoparticles have been considered as an effective system as they contribute to a precise drug delivery, reducing side effects and increasing the therapeutic efficacy. Chalcones are polyphenolic compounds of the flavonoid class associated with various pharmacological activities, whose properties led researchers to consider them as potential anticarcinogens. Thiol-ene polymerization is a new and promising field of study due to its attributes, including mild conditions and rapid reaction rates without the formation of byproducts. Herein, superparamagnetic poly(thioether-ester) nanoparticles along with the encapsulation of 4-nitrochalcone (4NC) were synthesized for the first time. Thiol-ene polymerization in miniemulsion was applied using a fully renewable a,?-diene monomer obtained from 10-undecenoic acid and 1,3-propanediol, both derived from castor oil. Superparamagnetic nanoparticles were successfully synthesized by miniemulsification and solvent evaporation, presenting spherical morphology, diameters around 135 nm and low polydispersity indexes. FT-IR analyses showed the absorption bands of both the polymer and the MNPs. TGA analyses showed an encapsulation efficiency (EE%) of MNPs greater than 99%. Cytotoxicity and fluorescence microscopy assays in HeLa cells have demonstrated that the material is not cytotoxic and that, when exposed to an external magnetic field, the cell uptake is up to three times higher. The EE% of 4NC was greater than 90%. The release profile of 4NC was obtained at pH 7.4 and 6.0, using a sample of MNPs and 4NC simultaneously encapsulated. It was observed that the release occurs by diffusion and faster at pH 6.0. Nanoparticles were also synthesized by mininemulsion polymerization, which has the advantage of incorporating inorganic compounds in only one step. Characteristics such as morphology, diameter and polydispersity index did not present significant differences considering the desired final application. The 4NC was encapsulated alone, obtaining an EE% greater than 99%. The 4NC release profile was also obtained for pH 7.4 and it occurred by diffusion. The MNPs were encapsulated at different concentrations and, through TGA, it was observed that the higher the initial percentage of MNPs, the lower the EE%. In addition, it could be seen that using a tetrathiol in the formulation, rather than a dithiol, the EE% of MNPs was greater. In this way, the synthesized materials demonstrated potential to be applied in the biomedical area and, more specifically, in the treatment of cancer

Aggregative adherent strains of Corynebacterium pseudodiphtheriticum enter and survive within HEp-2 epithelial cells

Corynebacterium pseudodiphtheriticum is a well-known human pathogen that mainly causes respiratory disease and is associated with high mortality in compromised hosts. Little is known about the virulence factors and pathogenesis of C. pseudodiphtheriticum. In this study, cultured human epithelial (HEp-2) cells were used to analyse the adherence pattern, internalisation and intracellular survival of the ATCC 10700 type strain and two additional clinical isolates. These microorganisms exhibited an aggregative adherence-like pattern to HEp-2 cells characterised by clumps of bacteria with a "stacked-brick" appearance. The differences in the ability of these microorganisms to invade and survive within HEp-2 cells and replicate in the extracellular environment up to 24 h post infection were evaluated. The fluorescent actin staining test demonstrated that actin polymerisation is involved in the internalisation of the C. pseudodiphtheriticum strains. The depolymerisation of microfilaments by cytochalasin E significantly reduced the internalisation of C. pseudodiphtheriticum by HEp-2 cells. Bacterial internalisation and cytoskeletal rearrangement seemed to be partially triggered by the activation of tyrosine kinase activity. Although C. pseudodiphtheriticum strains did not demonstrate an ability to replicate intracellularly, HEp-2 cells were unable to fully clear the pathogen within 24 h. These characteristics may explain how some C. pseudodiphtheriticum strains cause severe infection in human patients