Titanium surface modification by laser to enhance the anti-biofilm effect of dental implants

Dissertação de mestrado integrado em Engenharia BiomédicaPeri-implant diseases are one the main causes of dental implant failure. Throughout the years, new strategies for dental implants fabrication have been developed in order to prevent such infections to occur. In one hand, the increase of the surface roughness and hydrophilicity can promote a better connection of the bone cells with the implant. Consequently, the healing time is shortened. On the other hand, those alterations also promote bacteria to adhere and proliferate. Therefore, another strategy is to incorporate organic or inorganic elements with antibacterial properties onto the surface of implants. The intend of this work was to develop and test surfaces that generate a dipole repellent for the bacteria when immersed in an aqueous solution. Two approaches were developed for that purpose. In one approach a pattern of different titanium dioxide thickness was created on the titanium surface, using a Q-Switched Nd:YAG laser system operating at 1064 nm. The other strategy was to incorporate silver particles on a laser textured titanium surface. The incorporation of the silver was performed by laser sintering and through hot-pressing. The antibacterial properties of the samples with different oxide thickness and the samples with hot-pressed silver were tested against 14 bacterial strains. The surface characteristics of the samples were also evaluated by optical and scanning electronical microscopy, the wettability and roughness were also measured, and the oxides were characterized by Energy Dispersive X-ray Spectroscopy. The tests performed on the samples showed that the surfaces were hydrophilic and moderately rough. The oxide present in the samples with different oxide thickness was mostly in the rutile form. Those samples also showed no signs of antibacterial effects when compared to polished samples. The samples with silver, on the other hand, showed a reduction of Porphyromonas gingivalis and Prevotella intermedia strains. A reduction of the biofilm was also noticed on the surface of those samples.As doenças periimplantares são uma das principais causas de falhas em implantes. Ao longo dos anos, novas estratégias têm sido desenvolvidas com o intuito de prevenir a ocorrência de infecções. Por um lado, o aumento da rugosidade e hidrofílicidade das superfícies dos implantes promove uma melhor ligação entre as células ósseas e os implantes. Por conseguinte, o tempo de recuperação é reduzido. Por outro lado, essas características também promovem a adesão e proliferação de bactérias. Consequentemente, outras estratégias desenvolvidas incluem a incorporação de elementos antibacterianos orgânicos ou inorgânicos na superfície dos implantes. Com este trabalho pretendeu-se desenvolver e testar superfícies que gerem dipolos repelentes para bactérias, quando imersas em soluções aquosas. Duas abordagens foram desenvolvidas. Uma das abordagens correspondeu a criar um padrão com diferentes espessuras de dióxido de titânio através da utilização de um sistema laser Q-Switched Nd:YAG que opera a 1064 nm. Outra estratégia correspondeu à incorporação de partículas de prata numa superfície de titânio previamente texturizada por laser. A incorporação da prata foi efectuada através de laser e de prensagem a quente. As propriedades antibacterianas das amostras produzidas foram testadas numa cultura com 14 diferentes estirpes bacterianas. As características das superfícies foram também examinadas por microscopia óptica e electrónica, a molhabilidade e rugosidade foram também medidas, e os óxidos caracterizados por Espectroscopia de Raios-X por Dispersão de Energia. Os testes realizados revelaram que as superfícies apresentavam características hidrofílicas e eram moderadamente rugosas. O óxido presente nas amostras com diferentes espessuras de óxido encontrava-se maioritariamente na forma rutile. Estas também não revelaram propriedades antibacterianas comparativamente a uma superfície polida. Por outro lado, as amostras com prata mostraram-se eficazes a reduzir a adesão das estirpes de Porphyromonas gingivalis e Prevotella intermedia. Também se revelaram inibidoras da formação de biofilme na sua superfície.This work is supported by Fundação para a Ciência e Tecnologia (FCT) with the reference project UID/EEA/04436/2019, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941 and POCI-01-0145-FEDER-030498 and the project with reference NORTE-01-0145-FEDER-000018-HAMaBIC

Organ-on-a-chip platforms for drug screening and delivery in tumor cells: a systematic review

The development of cancer models that rectify the simplicity of monolayer or static cell cultures physiologic microenvironment and, at the same time, replicate the human system more accurately than animal models has been a challenge in biomedical research. Organ-on-a-chip (OoC) devices are a solution that has been explored over the last decade. The combination of microfluidics and cell culture allows the design of a dynamic microenvironment suitable for the evaluation of treatments’ efficacy and effects, closer to the response observed in patients. This systematic review sums the studies from the last decade, where OoC with cancer cell cultures were used for drug screening assays. The studies were selected from three databases and analyzed following the research guidelines for systematic reviews proposed by PRISMA. In the selected studies, several types of cancer cells were evaluated, and the majority of treatments tested were standard chemotherapeutic drugs. Some studies reported higher drug resistance of the cultures on the OoC devices than on 2D cultures, which indicates the better resemblance to in vivo conditions of the former. Several studies also included the replication of the microvasculature or the combination of different cell cultures. The presence of vasculature can influence positively or negatively the drug efficacy since it contributes to a greater diffusion of the drug and also oxygen and nutrients. Co-cultures with liver cells contributed to the evaluation of the systemic toxicity of some drugs metabolites. Nevertheless, few studies used patient cells for the drug screening assays.This work has been supported by the projects NORTE-01-0145-FEDER-030171 (project reference PTDC/EME-SIS/30171/2017), NORTE-01-0145-FEDER-029394 (project reference PTDC/EMDEMD/29394/2017), through the COMPETE2020, the Lisb@2020, the Programa Operacional Regional do Norte–Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement through the European Regional Development Fund (FEDER) and by Fundação para a Ciência e Tecnologia (FCT), and through FEDER and FCT, project references EXPL/EMD-EMD/0650/2021 and PTDC/EEI-EEE/2846/2021. The authors also acknowledge the partial financial support within the R&D Units Project Scope: UIDB/00319/2020, UIDB/04077/2020, UIDB/00690/2020, UIDB/04436/2020. This work was also funded by AMED-CREST Grant Number JP20gm1310001h0002. Raquel O. Rodrigues (R.O.R.) thanks FCT for her contract funding provided through 2020.03975.CEECIND

3D printing techniques and their applications to organ-on-a-chip platforms: a systematic review

Three-dimensional (3D) in vitro models, such as organ-on-a-chip platforms, are an emerging and effective technology that allows the replication of the function of tissues and organs, bridging the gap amid the conventional models based on planar cell cultures or animals and the complex human system. Hence, they have been increasingly used for biomedical research, such as drug discovery and personalized healthcare. A promising strategy for their fabrication is 3D printing, a layer-by-layer fabrication process that allows the construction of complex 3D structures. In contrast, 3D bioprinting, an evolving biofabrication method, focuses on the accurate deposition of hydrogel bioinks loaded with cells to construct tissue-engineered structures. The purpose of the present work is to conduct a systematic review (SR) of the published literature, according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, providing a source of information on the evolution of organ-on-a-chip platforms obtained resorting to 3D printing and bioprinting techniques. In the literature search, PubMed, Scopus, and ScienceDirect databases were used, and two authors independently performed the search, study selection, and data extraction. The goal of this SR is to highlight the importance and advantages of using 3D printing techniques in obtaining organ-on-a-chip platforms, and also to identify potential gaps and future perspectives in this research field. Additionally, challenges in integrating sensors in organs-on-chip platforms are briefly investigated and discussed.The authors are grateful for the funding of FCT through the projects NORTE-01-0145- FEDER-029394, NORTE-01-0145-FEDER-030171 funded by COMPETE2020, NORTE2020, PORTUGAL2020, and FEDER. This work was also supported by Fundação para a Ciência e a Tecnologia (FCT) under the strategic grants UIDB/04077/2020, UIDB/00319/2020, UIDB/04436/2020 and UIDB/00532/2020. This work was also funded by AMED-CREST Grant Number JP20gm1310001h0002.Violeta Carvalho acknowledges the PhD scholarship UI/BD/151028/2021 attributed by FCT. Inês Gonçalves acknowledges the PhD scholarship BD/08646/2020 attributed by FCT

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Extensional flow for assessing the effect of nanocarriers on the mechanical deformability of red blood cells

The effect of nanoparticles on the mechanical behavior of red blood cells (RBCs) under an extensional flow has not been extensively studied. In this work, by using a microfluidic hyperbolic contraction, it is assessed the deformability of healthy RBCs in contact with ∼20 nm nanoparticles of magnetic iron and non-magnetic cerium. The results showed that, under a controlled extensional flow, the healthy RBCs deformability index depended on the cells’ velocity along the microfluidic contraction. Additionally, the results showed that the deformability index of the RBCs decreased when the cells got in contact with the nanoparticles, being that difference higher for the magnetic nanoparticles and for the longer exposition times. The RBCs presented a logarithmic deformability index vs velocity trend, with variations according to the magnetic or non-magnetic properties of the nanoparticles, to the concentration and to the exposure time. Thus, the representation of the deformation index as a function of velocity seems to be a promising method to evaluate the mechanical behavior of the cells. Such knowledge will be essential for further understanding how the cell-nanoparticle interactions occur in RBCs disorders, and will open new possibilities regarding future applications of these nanocarriers in targeted drug delivery systems for therapeutics.FCT -Fundação para a Ciência e a Tecnologia(2020.00215

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

Bioenergia: desenvolvimento, pesquisa e inovação

Com 27 trabalhos produzidos por pesquisadores do Instituto de Pesquisa em Bioenergia (Bioen), da Unesp, este livro oferece uma ampla visão sobre as áreas que compõem o segmento. Seu principal objetivo é contribuir para melhorar a compreensão dos vários aspectos da bioenergia, em especial no Brasil, que figura entre os países com maior nível de desenvolvimento tecnológico no setor. Os artigos abordam uma série abrangente de questões relacionadas à bioenergia, como a construção genética das plantas de cana-de-açúcar visando ao aumento de produtividade, a disseminação de sementes para estimular a propagação de espécies com potencial energético, etapas de produção de bioenergia, usos do combustível e seus efeitos nos diversos tipos de motores. Agrupados por assunto, os textos estão distribuídos em cinco partes: Biomassa para bioenergia; Produção de biocombustíveis; Utilização de bioenergia; Biorrefinaria, alcoolquímica e oleoquímica e Sustentabilidade dos biocombustíveis