Bacterial nanocellulose in dentistry: Perspectives and challenges

Bacterial cellulose (BC) is a natural polymer that has fascinating attributes, such as biocompatibility, low cost, and ease of processing, being considered a very interesting biomaterial due to its options for moldability and combination. Thus, BC-based compounds (for example, BC/collagen, BC/gelatin, BC/fibroin, BC/chitosan, etc.) have improved properties and/or functionality, allowing for various biomedical applications, such as artificial blood vessels and microvessels, artificial skin, and wounds dressing among others. Despite the wide applicability in biomedicine and tissue engineering, there is a lack of updated scientific reports on applications related to dentistry, since BC has great potential for this. It has been used mainly in the regeneration of periodontal tissue, surgical dressings, intraoral wounds, and also in the regeneration of pulp tissue. This review describes the properties and advantages of some BC studies focused on dental and oral applications, including the design of implants, scaffolds, and wound-dressing materials, as well as carriers for drug delivery in dentistry. Aligned to the current trends and biotechnology evolutions, BC-based nanocomposites offer a great field to be explored and other novel features can be expected in relation to oral and bone tissue repair in the near future.Fil: de Oliveira Barud, Hélida Gomes. BioSmart Nanotechnology, LTDA; BrasilFil: da Silva, Robson Rosa. Chalmers University of Technology; SueciaFil: Costa Borges, Marco Antonio. University of Araraquara; BrasilFil: Castro, Guillermo Raul. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: José Lima Ribeiro, Sidney. São Paulo State University; BrasilFil: da Silva Barud, Hernane. University of Araraquara; Brasi

Near-infrared/visible-emitting nanosilica modified with silylated Ru(II) and Ln(III) complexes

Three luminescent silica-based nanohybrids were fabricated by grafting of silylated Ru(II)andNd/Yb(III)complexes onto mesoporous silica nanoparticles obtained by microemulsion method.The prepared nanohybrids were characterized by Fourier transform-Raman spectroscopy, solidstate-nuclear magnetic resonance, high resolution-transmission electron microscopy andscanning and transmission electron microscopy techniques. The chemical integrity and thegrafting of all complexes inside MSNs nanopores as well as a good distribution of metalcomplexes onto MSNs surface were achieved for all nanohybrids. Photophysical results revealedthat by monitoring the excitation on Ru(II)moieties from SiO2–RuNd and SiO2–RuYb nanohybrids, the sensitization of NIR-emitting Nd/Yb(III)ions were successfully detected viaenergy transfer processes. Energy transfer rates(kEnT)of 0.20×107and 0.11×107s−1 and efficiencies of energy transfer(ηEnT)of 40% and 27.5% were obtained for SiO2–RuNd and SiO2–RuYb nanohybrids, respectively. These results confirm the preparation of promising dual(near-infrared/visible)-emitting silica-based nanohybrids as new nanotools for applications asnanosensores and nanomarkers

Microbial Cellulose — Biosynthesis Mechanisms and Medical Applications

Currently some principles of sustainability, eco-efficiency and green chemistry are guiding the development of a new generation of materials as an alternative to conventional polymers based on petroleum. Then, in the field of biodegradable polymers one of the most promising investigations is focused on the use of microbial cellulose (MC), biocellulose or bacterial cellulose. MC has received substantial interest since it is synthesized from the bacterium Gluconacetobacter genus from a variety of carbon sources such as glucose, fructose, galactose, etc. MC is an interesting emerging biomaterial, with no toxicity, and since its discovery has shown tremendous potential in various fields, because the structural aspect of MC is far superior to those of plant cellulose. Thus, the main focus of the chapter review involves detailed aspects about the biosynthesis and recent advances on microbial production, including mechanism for the biochemistry of the cellulose synthesis, new sources for culture medium, main aspects about static and air-reactor productions and genetic modifications. We also revised microbial cellulose devices for biomedical applications: artificial skin, artificial blood vessels and microvessels, wound dressing of second- or third-degree burn ulcers, scaffolds for tissue engineering, drug delivery systems, dental implants, among others

Luminescent nanohybrids based on silica and silylated Ru(II)—Yb(III) heterobinuclear complex: new tools for biological media analysis

Lanthanide (Ln) complexes emitting in the near-infrared (NIR) region have fostered great interest as upcoming optical tags owing to their high spatial and temporal resolution emission as well deeper light penetration in biological tissues for non-invasive monitoring. For use in live-cell imaging, lanthanide complexes with long-wavelength absorption and good brightness are especially critical. Light-harvesting ligands of Ln complexes are typically excited in the ultraviolet region, which in turn trigger simultaneously autofluorescence and long-exposition damage of living systems. The association of d-metalloligands rather than organic chromophores enables the excitation of NIR-emitting Ln complex occurs in the visible region. Taking advantage of the long-lived excited states and intense absorption band in the ultraviolet (UV) to NIR region of Ru(II), we successfully design a dual-emitting (in the visible and NIR region) d–f heterobinuclear complex based on Ru(II) metalloligand and Yb(III) complex. In addition, we developed luminescent nanohybrids by grafting of Ru(II)–Yb(III) heterobinuclear complexes containing silylated ligands on the surface of mesoporous and dense silica matrix. The nanomarkers were successfully applied for imaging of murine melanoma B16-F10 and neonatal human dermal fibroblast HDFn cell cultures by one-photon or two-photon absorption using laser scanning confocal microscopy. Great cellular uptake, low cytotoxicity and the possibility to achieve visible and NIR emission via two-photons excitation show that the nanohybrids are remarkable markers for in vitro and a potential tool for in vivo applications

Strong Electronic Identification: Survey & Scenario Planning

The deployment of more high-risk services such as online banking and government services on the Internet has meant that the need and demand for strong electronic identity is bigger today more than ever. Different stakeholders have different reasons for moving their services to the Internet, including cost savings, being closer to the customer or citizen, increasing volume and value of services among others. This means that traditional online identification schemes based on self-asserted identities are no longer sufficient to cope with the required level of assurance demanded by these services. Therefore, strong electronic identification methods that utilize identifiers rooted in real world identities must be provided to be used by customers and citizens alike on the Internet. This thesis focuses on studying state-of-the-art methods for providing reliable and mass market strong electronic identity in the world today. It looks at concrete real-world examples that enable real world identities to be transferred and used in the virtual world of the Internet. The thesis identifies crucial factors that determine what constitutes a strong electronic identity solution and through these factors evaluates and compares the example solutions surveyed in the thesis. As the Internet become more pervasive in our lives; mobile devices are becoming the primary devices for communication and accessing Internet services. This has thus, raised the question of what sort of strong electronic identity solutions could be implemented and how such solutions could adapt to the future. To help to understand the possible alternate futures, a scenario planning and analysis method was used to develop a series of scenarios from underlying key economic, political, technological and social trends and uncertainties. The resulting three future scenarios indicate how the future of strong electronic identity will shape up with the aim of helping stakeholders contemplate the future and develop policies and strategies to better position themselves for the future

A ética do silêncio racial no contexto urbano: políticas públicas e desigualdade social no Recife, 1900-1940

Mais de meio século após o preconceito racial ter se tornado o principal alvo dos movimentos urbanos pelos direitos civis nos Estados Unidos e na África do Sul, e décadas depois do surgimento dos movimentos negros contemporâneos no Brasil, o conjunto de ferramentas legislativas criado no Brasil para promover o direito à cidade ainda adere à longa tradição brasileira de silêncio acerca da questão racial. Este artigo propõe iniciar uma exploração das raízes históricas desse fenômeno, remontando ao surgimento do silêncio sobre a questão racial na política urbana do Recife, Brasil, durante a primeira metade do século XX. O Recife foi eé um exemplo paradigmático do processo pelo qual uma cidade amplamente marcada por traços negros e africanos chegou a ser definida política e legalmente como um espaço pobre, subdesenvolvido e racialmente neutro, onde as desigualdades sociais originaram na exclusão capitalista, e não na escravidão e nas ideologias do racismo científico. Neste sentido, Recife lança luzes sobre a política urbana que se gerou sob a sombra do silêncio racial.More than half a century after racial prejudice became central to urban civil rights movements in the United States and South Africa, and decades after the emergence of Brazil’s contemporary Black movements, Brazil's internationally recognized body of rights-to-the-city legislation still adheres to the country's long historical tradition of racial silence. This article explores the historical roots of this phenomenon by focusing on the emergence of racial silence in Recife, Brazil during the first half of the 20th Century. Recife was and remains a paradigmatic example of the process through which a city marked by its Black and African roots came to be legally and politically defined as a poor, underdeveloped and racially neutral space, where social inequalities derived from capitalist exclusion rather than from slavery and scientific racism. As such, Recife'sexperience sheds light on the urban policies that were generated in the shadow of racial silence