Abstract Conventional orthodontic treatment with the use of stainless steel may be detrimental to oral health by promoting demineralizing lesions appearance and increasing adhesion and formation of bacterial biofilm, inducing the development of cavities. An alternative that has been researched to reduce the side effects of orthodontic treatment is the coating of materials with antimicrobial nanoparticles. Nanometric- sized particles increase their surface area and contact with the microbial membrane, consequently intensifying their bacteriostatic and bactericidal effect. In this work, hydrothermal synthesis, a “green” process was used to attach silver nanoparticles (AgNPs) to the surface of two different brands of orthodontic wires. The coated materials were analyzed for their physicochemical properties by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), which showed the distribution of AgNPs along the wires without modifying their properties. In the microbiological test, one of the brands showed a statistically significant difference in microbial adhesion and biofilm formation by Staphylococcus aureus and Streptococcus mutans. Results lead to the conclusion that antimicrobial orthodontic wires coated with silver nanoparticles through hydrothermal synthesis is a promising material for the improvement of orthodontic treatment.

Abstract In the last decade, bacterial cellulose (BC) has received considerable attention around the world, including in Brazil. The unique properties of BC, such as mechanical stability, tensile strength, thermostability, crystallinity, purity and biocompatibility make it a promising candidate for commercial applications in different areas. This article provides a comprehensive synthesis of commercial applications and studies related to BC around the world and shows the importance and development of Brazilian research during the last decade. In this review we present an overview of BC structure, biosynthesis and possible applications of BC mainly in the food, electronics, bioengineering, cosmetics and biomedical areas. The most significant contributions of Brazilian researchers using BC have been carried out in the biomedical area. Despite the increase in BC reserch, Brazil also needs to develop strategies to expand the use and commercialization of BC products, for which government financial support is extremely necessary.

ABSTRACT: The aim of the study was to evaluate the chemical composition and radiopacity of new calcium-silicatebased cements. Discs of 10 mm x 1 ± 0.1mm were prepared of BiodentineTM, TheraCal, Dycal and GC Fuji IX (n=5). The samples were radiographed directly on an PSP occlusal plate adjacent to an aluminium step wedge. The radiopacity of each specimen was determined according to ISO 9917/2007. Statistical analyses were carried out using ANOVA and Tukey’s test at a significance level of 5 %. The chemical constitution of materials was determined by scanning electron microscopy (SEM) and energy dispersive x-ray element mapping. The radiopacities of the materials in decreasing order were: GC Fuji IX (3.45 ± 0.16 mm), Dycal (3.18 ± 0.17), BiodentineTM (2.79 ± 0.22), and TheraCal (2.17 ± 0.17). TheraCal showed the lowest radiopacity compared to the other materials, followed by BiodentineTM. Dycal and GC Fuji IX radiopacity values did not present significant statistical differences. Scanning electron microscopy and energy dispersive X-ray analysis revealed the presence of zirconium in BiodentineTM; and strontium, barium and zirconium in TheraCal as radiopacifying elements. The new calcium silicate cements present distinctive chemical composition. BiodentineTM contains zirconium as a radiopacifying element and has higher radiopacity values than TheraCal, which contains barium and strontium as radiopacifiers.

RESUMEN: El objetivo de este estudio fue evaluar la composición química y la radiopacidad de nuevos cementos en base a silicato de calcio. Discos de 10 mm x 1 ± 0,1 mm fueron preparados con BiodentineTM, TheraCal, Dycal y GC Fuji IX (n=5). Las muestras fueron radiografiadas directamente en una película PSP oclusal adyacente a una cuña escalonada de aluminio. La radiopacidad de cada espécimen fue determinada de acuerdo a la norma ISO 9917/ 2007. Se realizaron los análisis estadísticos con las pruebas ANOVA y test de Tukey con un nivel de significancia de 5 %. La constitución química de los materiales fue determinada con microscopía electrónica de barrido y con mapeo por análisis con dispersión de energía de rayos X. La radiopacidad de los materiales en orden decreciente fue: GC Fuji IX (3,45 ± 0,16 mm), Dycal (3,18 ± 0,7 mm), BiodentineTM (2,79 ± 0,22 mm), y TheraCal (2,17 ± 0,17 mm). TheraCal mostró la menor radiopacidad comparada con los otros materiales, seguido de BiodentineTM. Los valores de radiopacidad de Dycal y GC Fuji IX no presentaron diferencias estadísticas significativas. Los análisis de microscopía electrónica de barrido y mapeo por análisis con dispersión de energía de rayos X revelaron la presencia de zirconio en BiodentineTM; y de estroncio, bario y zirconio en TheraCal, como elementos radiopacos. Los nuevos cementos en base a silicato de calcio presentan una composición química distintiva. BiodentineTM contienen zirconio como elemento que provee radiopacidad y tiene mayor valor de radiopacidad que TheraCal, el cual contiene bario y estroncio como agente radiopaco.

Resumo Este estudo avaliou a citotoxicidade de um cimento de aluminato de cálcio (EndoBinder) contendo diferentes radiopacificadores, Bi2O3, ZnO ou ZrO2, comparativamente ao trióxido mineral agregado (MTA). Seguindo a norma ISO 10993-12:2012 (E), 0,2 g de cada cimento foi aplicada em insertos transwell, que foram colocados em placas de cultura de 24 wells contendo 1 mL de meio de cultura (DMEM). Após 24 h de incubação, os extratos (DMEM contendo componentes liberados dos cimentos) foram aplicados sobre células pulpares imortalizadas MDPC-23. Viabilidade celular (teste de MTT), atividade da fosfatase alcalina (ALP), produção de proteína total e a morfologia das células (Microscópio Eletrônico de Varredura - MEV) foram avaliadas. Um volume de 50 µL do extrato foi utilizado para determinar, através de Espectroscopia de Energia Dispersiva (EDS), os elementos químicos liberados pelos cimentos. Os seguintes grupos foram estabelecidos (n=6): NC - controle negativo (sem tratamento); EB - EndoBinder sem radiopacificador; EBBO - EndoBinder+Bi2O3; EBZnO - EndoBinder+ZnO; EBZrO - EndoBinder+ZrO2 e WMTA - MTA branco. Os dados foram submetidos à análise estatística (teste de Kruskal-Wallis, nível de significância=5%). Células expostas às diferentes versões de EndoBinder apresentaram pequena redução na viabilidade, produção de proteína total e atividade da ALP, com valores semelhantes aos grupos NC e WMTA (p>0,05). Diversos elementos (C, O, Na, Al, P, Si, Cl, Bi, K) liberados pelos cimentos foram detectados nos extratos. Entretanto, as células não apresentaram alterações significativas em sua morfologia. EndoBinder e MTA, não afetaram negativamente o metabolismo das células odontoblastóides, mostrando-se citocompatíveis, independente do radiopacificador utilizado.

Abstract This study aimed to evaluate the cytotoxicity of a calcium aluminate cement (EndoBinder) containing different radiopacifiers, Bi2O3, ZnO or ZrO2, compared with Mineral Trioxide Aggregate (MTA). According to ISO 10993-12:2012 (E) recommendations, 0.2 g of each cement were applied in transwell inserts and placed in 24-well culture plates containing 1 mL of culture medium (DMEM). After 24 h of incubation, the extracts (DMEM containing components released from the cements) were applied to immortalized odontoblast-like MDPC-23 cells. Cell viability (MTT test), alkaline phosphatase activity (ALP), total protein production and cell morphology (Scanning Electron Microscopy - SEM) were evaluated. The volume of 50 µL of extract was used to determine the chemical elements released by the cements using Energy Dispersive Spectroscopy (EDS). The following groups were established (n=6): NC - negative control (without treatment); EB - EndoBinder without radiopacifier; EBBO - EndoBinder+Bi2O3; EBZnO - EndoBinder+ZnO; EBZrO - EndoBinder+ZrO2 and WMTA - White MTA. Data were subjected to statistical analysis (Kruskal-Wallis test, level of significance=5%). Cells exposed to the different versions of EndoBinder presented small reduction in viability, total protein production and ALP activity, with values similar to the NC and WMTA groups (p>0.05). Different elements (C, O, Na, Al, P, Si, Cl, Bi, K) released by the cements were detected in the extracts. However, the cells had no significant changes in their morphology. EndoBinder and MTA did not affect negatively the metabolism of the odontoblastic-like cells, showing it to be cytocompatible, irrespective of the used radiopacifier.

RESUMO Este trabalho almejou produzir celulose bacteriana (CB), obter nanocristais de celulose bacteriana (NCCB), incorporar NCCB como reforço em poli(L-ácido láctico) (PLLA) e avaliar propriedades destes bionanocompósitos. Foram produzidas membranas de CB provenientes da bactéria Gluconacetobacter hansenii. A partir das membranas foram obtidos NCCB por hidrólise com ácido sulfúrico (H2SO4), com base em 11 experimentos. Os parâmetros variados nos experimentos foram: concentração de H2SO4, temperatura e tempo. Pode-se definir critérios de obtenção de NCCB por análise termogravimétrica (TGA) e análise de espalhamento dinâmico de luz (DLS). Principais resultados indicam possibilidade de obtenção na condição de: 80% de concentração de H2SO4 (m/m), 60 ºC e 60 min. Para esta condição obteve-se tamanhos adequados dos NCCB (média de 388 nm), potencial zeta adequado (-38 mV) e estabilidade térmica adequada (Tonset2 = 301,9 ºC). Posteriormente, NCCB obtidos conforme critérios definidos foram incorporados ao PLLA em duas concentrações (2,5 e 5%), utilizando dois métodos (sem e com funcionalização dos NCCB). Os bionanocompósitos preparados foram caracterizados por TGA e calorimetria explanatória diferencial (DSC). Resultados das técnicas de caracterização dos bionanocompósitos foram comparados com resultados do PLLA puro. Principais resultados em relação aos métodos, revelam a importância da funcionalização dos NCCB antes de incorporá-los ao PLLA. Sobre a concentração de reforço utilizada, o aumento da estabilidade térmica foi gradual, conforme teor de reforço, sendo que para o bionanocompósito com 5% de NCCB funcionalizados o incremento foi de 10,4 ºC na Tonset2 em relação ao PLLA puro. Contudo, o grau de cristalinidade diminuiu (Xc do PLLA puro = 40,38% e Xc do bionanocompósito com 5% de NCCB funcionalizados = 24,73%). Conclui-se que a adição de NCCB em PLLA é ambientalmente viável e promove melhoria de propriedades.

ABSTRACT This work aimed to produce bacterial cellulose, to obtain bacterial cellulose nanocrystals, to incorporate nanocrystals as a reinforcement in poly(L-lactic acid) and to evaluate the properties of these bionanocomposites. Bacterial cellulose membranes from the bacterium Gluconacetobacter hansenii were produced. From the membranes were obtained nanocrystals by hydrolysis with sulfuric acid (H2SO4), based on 11 experiments. The parameters varied in the experiments were: concentration of H2SO4, temperature and time. It is possible to define criteria for obtaining nanocrystals by thermogravimetric analysis and analysis of dynamic scattering of light. Main results indicate the possibility of obtaining in the condition of: 80% concentration of H2SO4 (m/m), 60 °C and 60 min. For this condition, suitable sizes of the nanocrystals (mean 388 nm), suitable zeta potential (-38 mV) and adequate thermal stability (Tonset2 = 301.9 °C) were obtained. Subsequently, nanocrystals obtained according to defined criteria were incorporated into poly(L-lactic acid) in two concentrations (2,5 and 5%), using two methods (without and with functionalization of nanocrystals). The prepared bionanocomposites were characterized by thermogravimetric analysis and differential explanatory calorimetry. Results of the techniques of characterization of bionanocomposites were compared with results of pure poly(L-lactic acid). Main results regarding the methods, reveal the importance of the functionalization of the nanocrystals before incorporating them to the poly(L-lactic acid). On the reinforcement concentration used, the increase of the thermal stability was gradual, according to reinforcement content, and for the bionanocomposite with 5% functionalized nanocrystals the increase was of 10,4 ºC in the Tonset2 in relation to the poly(L-lactic acid) pure. However, the degree of crystallinity decreased (Xc of pure PLLA = 40,38% and Xc of bionanocomposite with 5% of functionalized nanocrystals = 24,73%). It is concluded that the addition of bacterial cellulose nanocrystals in poly(L-lactic acid) is environmentally feasible and improves properties.

Nas últimas décadas o uso de argilominerais nas áreas de Ciência e Engenharia de Materiais tem recebido notória atenção para a sua utilização no carreamento de fármacos. Dentre os diversos tipos de argilas, as fibrosas e as tubulares tem sido utilizadas na preparação de bionanocompósitos, devido as suas propriedades inerentes, como exemplo a elevada área superficial. Esta pesquisa visou o levantamento bibliográfico da utilização das argilas tubulares e fibrosas para o carreamento de fármacos. A busca por artigos foi realizado no banco de dados Web of Science, utilizando combinação dos termos: Fibrous Clay and drug delivery, Tubular Clay and drug delivery, Halloysite and drug delivery, Imogolite and drug delivery, Palygoskite and drug delivery e Sepiolite and drug delivery. Foram encontrados o total de 36 artigos durante a pesquisa. Observou-se que a maioria dos artigos utilizam as argilas em combinação com outros materiais (com formação de compósitos e blendas), principalmente polímeros, a fim de expandir as propriedades que melhoram a vetorização de insumos farmacêuticos ativos (IFAs), tais como a modificação do tamanho dos poros, do pH, da energia de ligação entre as moléculas, entre outros. Assim, evidencia-se que o interesse pela utilização das argilas no campo terapêutico tem aumentado, mostrando a relevância de pesquisas na área de medicamentos e materiais.

In recent decades the use of clay minerals in the areas of Materials Science and Engineering has received notable attention for its use in carrying of drugs. Among the various types of clay, and fibrous tubes have been used in the preparation of bionanocompósitos due to their inherent properties, for example high surface area. This research aimed a review at the literature of the use of tubular and fibrous clays for the carrying of drugs. The search for articles was conducted in the Web of Science database, using combination of terms: Fibrous Clay and drug delivery, Tubular Clay and drug delivery, Halloysite and drug delivery, imogolite and drug delivery, drug delivery and Palygoskite and Sepiolite and drug delivery. Found total of 36 articles during the search. It was observed that most of the clay articles used in combination with other materials (with formation of composites and blends), in particular polymers in order to extend the properties that improve the vectoring of active pharmaceutical ingredients (APIs), such as modification pore size, the pH, the binding energy between molecules, among others. Thus, it is clear that the interest in the use of clays in the therapeutic field has increased, showing the relevance of research in the area of drugs and materials.

This study compares a wound dressing based on bacterial cellulose/collagen (BC/COL) hydrogel in rat dorsum with commercial collagenase ointment and untreated wound. The hydrogel was characterized by Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Fourier transformed - Infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). According to the In vivo test and macroscopic evaluation, BC/COL hydrogel showed a better repair of wounds and promoted statistically significant differences of tissue repair between treatments on the 7th day after surgery. Better quality, quantity and orientation evaluation of collagen fibers (p=0.0001) were observed in the BC/COL hydrogel and collagenase ointment groups in relation to the control group. The BC/COL hydrogel promoted better wound healing than collagenase and the control group, therefore, it can be considered a potential wound dressing for skin regeneration.

The uses of polymer blends have stimulated research to promote a better performance of existing raw materials. The implementation of blends in the production of polymeric membranes has shown great results in regenerative medicine and consequently it has improved the application of biomaterials in this area. This study aimed to evaluate the morphology and wettability of a bacterial cellulose/corn starch polymeric membrane. In relation to biomaterials, wettability is an important property to be evaluated because it is possible to observe if the degradation is accelerated even when in contact with biological fluids. The membrane was morphologically evaluated by SEM. Results showed that there was interaction between the polymers. Additionally, by the technique of contact angle it was also possible to observe the ability to absorb water, being highly satisfactory, showing a complete wetting with a contact angle of 10.7° in the initial assessment and 6.6° in the evaluation after 5 seconds.

Bacterial cellulose produced from Gluconacetobacter xilinus was used to produce cellulose nanocrystals by sulfuric acid hydrolysis. Hydrolysis was performed with 64% sulfuric acid at 50 ºC with the hydrolysis time ranging between 5 and 90 min. The production of nanocrystals was observed to have size distributions that were dependent on hydrolysis times up to 10 min, after which time the suspensions showed distributions closer in size. Results from thermal analysis and X-ray diffraction showed that the amorphous cellulose was removed, leaving only the crystalline portion. Self-supported films were formed from the suspension of nanocrystals and had iridescence characteristics. The films were characterized by microscopy measures and specular reflectance.

In this work, methylcellulose (MC) was produced from bacterial cellulose (BC), using dimethyl sulfate in a 3 h (MC3h) or 5 h (MC5h) reaction under heterogeneous conditions, with reagent substitution at each hour. MC3h showed a degree of substitution (DS) of 2.26 ± 0.13 and MC5h showed a DS of 2.33 ± 0.05. The two samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), differential thermal analysis (DTA), thermal gravimetric analysis (TGA), 13C nuclear magnetic ressonance (NMR) and 1H NMR techniques. The FTIR spectra of the BC and MC samples present significant differences in the regions from 3750 to 2750 cm−1 and from 1500 to 750 cm−1, which evidence the methylation of the samples. Solid state NMR spectroscopy of the MC samples was used to identify the 13C NMR signals of substitution at sites C-2, C-3 or C-6 in the glucopyranose units. The modification of bacterial cellulose produced a material with a high DS, determined by three different techniques (chemically and using the liquid 1H and solid 13C NMR spectra). These samples also demonstrate high crystallinity and thermal stability. With the MC samples synthesized in this work, transparent and resistant films were prepared and also a highly porous sponge like material.

In recent years, the inappropriate disposal of polymeric materials has increased due to industrial development and increase of population consumption. This problem may be minimized by using biodegradable polymers, such as bacterial cellulose and poly(hydroxybutyrate), from renewable resources. This work was aimed at monitoring and evaluating degradation of bacterial cellulose, vegetable cellulose and poly(3-hydroxybutyrate) using Thermogravimetric Analysis and Scanning Electron Microscopy. Controlled mass polymer samples were buried in pots containing soil. Samples were removed in 30 day intervals up to 180 days. The results show that the mass of the polymer increased in the first month when in contact with the soil but then it was degraded as evidenced by mass loss and changes on the sample surface.

The aim of this study was to produce membranes using the adapted cuprammonium method. The cellulose utilized was obtained from recycled agroindustrial residues: sugarcane bagasse, corn stover and soybean hulls. The levels of Cu (II) ions in regenerated cellulose membranes produced with cellulose from bagasse, corn stover and soybean hulls were 0.0236 wt%, 0.0255 wt% and 0.0268 wt%, respectively. These levels were approximately 15 times lower than those observed in previous studies (0.3634 wt%). Cellular viability data show that membranes produced from bagasse cellulose do not present toxicity to the cellular cultures studied. These results demonstrate an evolution in production of regenerated cellulose membranes from agroindustrial residues mainly due to a decrease in the Cu (II) ions level, showing the possibility of application of these systems with improved membranes processing.

In this work, the effects of incorporating cellulose nanocrystals from soy hulls (WSH30) on the mechanical, thermal, and barrier properties of methylcellulose (MC) nanocomposites were evaluated. MC/WSH30 nanocomposite films with different filler levels (2, 4, 6, 8, and 10%) were prepared by casting. Compared to neat MC film, improvements in the mechanical and barrier properties were observed, while thermal stability was retained. The improved mechanical properties of nanocomposites prepared may be attributed to mechanical percolation of WSH30, formation of a continuous network of WSH30 linked by hydrogen interactions and a close association between filler and matrix.

Celulose bacteriana (BC) foi utilizada nesse estudo como molde na preparação de compostos do tipo hidrotalcita ou hidróxidos duplos lamelares (LDHs) pelo método da co-precipitação e submetida a três tempos de envelhecimento distintos. Os compósitos isolados contendo LDH suportado na BC (BC-LDH) foram calcinados para remoção da matriz orgânica. Os óxidos metálicos mistos formados após a decomposição térmica sofreram reação de reconstrução na presença de uma solução de Na2CO3 para produzirem novamente materiais do tipo hidrotalcita (RBC-LDH). Para avaliar a influência da BC na formação do LDH, também foram analisadas as frações de LDH que não aderiram às fibras da BC e, também, o LDH sintetizado na ausência da membrana polimérica. Os difratogramas de raios X dos compósitos BC-LDH exibem picos alargados relacionados com a matriz orgânica semi-cristalina, indicando um grande nível de interação entre as fases orgânica e inorgânica. A interação também é evidenciada pelas mudanças nos perfis de decomposição dos compósitos com relação ao polímero prístino. As imagens de microscopia eletrônica de varredura mostraram a formação de partículas arredondadas submicrométricas de LDH após a remoção da membrana (RBC-LDH), diferentemente do hábito de rosetas exibido pelo LDH prístino. O envelhecimento é uma componente chave no processo de crescimento de todas as amostras de LDH produzidas, resultando na formação de partículas inorgânicas maiores à medida que o tempo aumenta. O compósito RBC-LDH envelhecido por três dias apresenta um aumento significativo na área superficial (mais do que três vezes) se comparado ao LDH preparado na ausência de BC.

Bacterial cellulose (BC) was used as a template for preparation of Hydrotalcite-type compounds or layered double hydroxides (LDHs) by co-precipitation method, and submitted to three aging times. Isolated composites containing LDH supported on BC (BC-LDH) were calcined to remove the organic matrix. Mixed metal oxides formed after thermal decomposition underwent reconstruction reaction in Na2CO3 solution producing again hydrotalcite-like materials (RBC-LDH). To evaluate the influence of BC on the LDH formation, it was also analyzed LDH fractions not attached to the BC fibers and LDH synthesized in absence of the polymeric membrane. XRD pattern of BC-LDH composites show broadened peaks related to the organic semi-crystalline matrix, indicating a deep level of interaction between organic and inorganic phases. Interaction is also evidenced by changes in the composites thermal decomposition profiles compared to pristine polymer. SEM images revealed formation of submicrometrical round-shaped LDH particles after removal of membrane (RBC-LDH), differently from the plate-habit exhibited by pristine LDH. Aging plays a key role in growth of all LDHs samples, leading to the formation of larger inorganic particles as time is increased. RBC-LDH aging for three days shows significant improvement in the surface area (more than three times) if contrasted to LDH prepared in BC absence.

Commercial copolymers based on styrene and divinylbenzene containing sulfonic acid groups were used as support for the incorporation of silver nanoparticles. These nanoparticles were obtained in situ by the reduction of Ag+ by using hydroxylamine in the presence of a protective agent. These materials were characterized with determination of the silver content and their morphological characteristics. The antibacterial activity of the final products against Escherichia coli was evaluated and the results show that the synthesized copolymers had antibacterial effect varying from 54 to 100%. The most efficient composite was made with small, well distributed particles.