Influence of oxygen content on the antibacterial effect of Ag-O coatings deposited by magnetron sputtering

Ag and AgOx thin films were deposited by pulsed DC magnetron sputtering, for medical devices, in order to provide antibacterial properties. During the deposition process, oxygen flow, and, consequently, oxygen fraction, was varied (0â15 sccm) to understand the influence of oxygen species in the physical, chemical and structural properties of thin films. Coatings morphology was observed by scanning electron microscopy (SEM) and their nanostructure and composition were assessed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS), respectively. XRD and XPS analyses revealed that Ag thin films are composed by metallic Ag, which crystallizes in fcc-Ag phase; whereas AgOx showed a mixture of Ag2O and AgO phases for low oxygen fraction that became single AgO with the increase of oxygen fraction in the discharge. Surface wettability and surface tension of the coatings were also determined showing hydrophobic character. Halo inhibition zone tests were performed against Staphylococcus epidermidis, in order to evaluate the antibacterial behavior of coatings, and silver ion release was measured. Only AgOx presented antibacterial behavior, showing that the presence of silver oxide are the main reasons for the antibacterial effect, probably due to the increased production of ROS (Reactive Oxygen Species),making these coatings promising for medical applications.The authors acknowledgments the financial support of FCTFundação para a Ciência e Tecnologia through grant SFRH/BD/90321/2012. Also thank support by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, and projects ERA-SIINN/0004/2013 through the “Fundo Europeu de Desenvolvimento Regional” (FEDER)

Ant species that remove diaspores alone are more efficient removers

Secondary diaspore removal on the ground is an important ecosystem process. In this process, solitary foraging ants with larger body sizes are more efficient because they may remove more diaspores, faster and carry them at greater distances. Therefore, we sought to test the effects of the sizes of the morphological traits of ants, removal strategy, and nest distance on secondary diaspore removal, testing hypotheses related to the efficiency of this process. We evaluated the removal of artificial diaspores by ants in 15 areas of Cerrado sensu stricto (tropical savanna), collecting data on diaspore removal strategy (solitary or group), nest distance, diaspore discovery time, diaspore removal time, and the number of diaspores removed. Larger ants tended to remove diaspores alone and remove diaspores faster than smaller ones. Ants that removed diaspores alone removed more diaspores than ants that removed diaspores in groups. However, we did not find a linear relationship between ant size and diaspore removal. This is likely due to a limitation on, or a preference by larger ants for removing larger diaspores, while the smaller diaspores may have hindered manipulation or been less attractive to larger ants. Thus, the removal strategy was the best predictor of efficient diaspore removal performance, where the solitary foraging ants discover and remove diaspores quickly and remove more diaspores, mainly from the closest nests to the sampling point. However, the benefits (or not) of removing more diaspores still need to be evaluated

Evaluating biomaterial-and microfluidic-based 3D tumor models

Cancer is a major cause of morbidity and mortality worldwide, with a disease burden estimated to increase in the coming decades. Disease heterogeneity and limited information on cancer biology and disease mechanisms are aspects that 2D cell cultures fail to address. We review the current "state-of-the-art" in 3D Tissue Engineering (TE) models developed for and used in cancer research. Scaffold-based TE models and microfluidics, are assessed for their potential to fill the gap between 2D models and clinical application. Recent advances in combining the principles of 3D TE models and microfluidics are discussed, with a special focus on biomaterials and the most promising chip-based 3D models.The authors would like to thank the European Union's Seventh Framework Program (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and QREN (ON.2 - NORTE-01-0124-FEDER-000016) co-financed by North Portugal Regional Operational Program (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF) for providing financial support to this project. The FCT distinction attributed to J.M.O. under the Investigator FCT program (IF/00423/2012) Is also greatly acknowledged

Investigation of Dendrimer-based nanoparticles cellular uptake and cell tracking in a semiautomated microfluidic platform

A microfluidic device such as Kima Pump and Vena8 biochip is able to realize functions that are not easily imaginable in conventional biological analysis, such as highly parallel, sophisticated high-throughput analysis and single-cell analysis in a well-defined manner [1]. Cancer cell tracking within the microfluidic model will be achieved by grafting fluorescent label probe Fluorescein-5(6)-isothiocyanate (FITC) to dendrimer nanoparticles allowing cell visualization by immunofluorescent staining followed by fluorescence microscopy. In this study, synthesis and physicochemical characterization of Carboxymethyl-chitosan/poly(amidoamine) dendrimer nanoparticles (CMCht/PAMAM NPâ s) were performed[2].  Several cancer cell lines such as a HeLA (cervical carcinoma cell line), HTTC-116 (Colon Carcinoma) and Glioblastome cell line (GBM) were exposed to different concentrations of CMCht/PAMAM dendrimer nanoparticles over a period of 7d. After finding the adequate NP concentration, the internalization efficiency was tested, as well as cellular trafficking, in static and dynamic conditions (Kima Pump bioreactor).Portuguese Foundation for Science and Technology (FCT) through the project PEst­C/SAU/LA0026/20

Longitudinally aligned inner-patterned silk fibroin conduits for peripheral nerve regeneration

Published 18 April 2023Peripheral nerve injuries represent a major clinical challenge, if nerve ends retract, there is no spontaneous regeneration, and grafts are required to proximate the nerve ends and give continuity to the nerve. The nerve guidance conduits (NGCs) presented in this work are silk fibroin (SF)-based, which is biocompatible and very versatile. The formation of conduits is obtained by forming a covalently cross-linked hydrogel in two concentric moulds, and the inner longitudinally aligned pattern of the SF NGCs is obtained through the use of a patterned inner mould. SF NGCs with two wall thicknesses of ~ 200 to ~ 400 μm are synthesized. Their physicochemical and mechanical characteristics have shown improved properties when the wall thickness is thicker such as resistance to kinking, which is of special importance as conduits might also be used to substitute nerves in flexible body parts. The Young modulus is higher for conduits with inner pattern, and none of the conduits has shown any salt deposition in presence of simulated body fluid, meaning they do not calcify; thus, the regeneration does not get impaired when conduits have contact with body fluids. In vitro studies demonstrated the biocompatibility of the SF NGCs; proliferation is enhanced when iSCs are cultured on top of conduits with longitudinally aligned pattern. BJ fibroblasts cannot infiltrate through the SF wall, avoiding scar tissue formation on the lumen of the graft when used in vivo. These conduits have been demonstrated to be very versatile and fulfil with the requirements for their use in PNR.Open access funding provided by FCT|FCCN (b-on)

Advanced structural characterization of biocompatible Ag-TiCN coatings

One of the main reasons for biomedical implants failure is the generation of wear debris together with microbial infection. To overcome this problem it has been proposed the use of very low wear coatings as diamond-like carbon (DLC), transitionmetal carbides (MeCx) or nitrides (MeNx) in combination with antibacterial elements such silver, gold or copper. The present work explores the potentialities of silver-containing carbon/nitride (Ag-TiCN) based coatings to be used as protective thin films for biomedical implants. Samples were prepared by DC unbalanced reactive magnetron sputtering with contents of Ag ranging from 0 to 20 at.% and Ti from 35 to 15 at.% while keeping C, N and O content constant. The coatings were fully characterized in terms of structure (XRD, Raman) and depth profiling composition by GDOES and RBS (using the nitrogen resonance at 3.70 MeV He+ ions). In particular, we have selected three samples with different Ag contents (0, 6 and 20%) and carried out and advanced surface characterization using XPS, ARXPS and HR-SEM to study the segregation of silver towards the surface. We have correlated the structure and composition of the films with their biological properties. Microbial adhesion was assessed for both bacteria (Staphylococcus epidermidis) and yeast (Candida albicans)

Dendrimers in tissue engineering

Dendrimers are highly branched and multivalent, and monodispersive making them perfect candidates for a myriad of controlled drug delivery applications. Dendrimers possess many other advantages, such as the possibility of modulating surface chemistry and charge, and biodegradation rate and to be processed as scaffolds that can emulate natural extracellular matrices thus opening up unique applications in tissue engineering. The combination of dendrimers and other macromolecules (proteins and carbohydrates), as well as other traditional scaffold polymers, has led to the creation of hybrid scaffolds with new physical, mechanical, and biochemical properties. However, despite the widespread use of dendrimers in biomedical applications, their use in the fabrication of tissue engineering scaffolds remains some-how narrow. The most promising applications of dendritic macromolecules in TE area such as drug delivery strategies, cell differentiation and/or tissue regeneration, 3D/Dynamic platforms and ex vivo/in vivo testing are overviewed and discussed herein.JMO for the financial support provided under the program “Investigador FCT” (IF/01285/2015). MCR acknowledges the IET Institution of Engineering and Technology for the financial support provided under the IET Harvey Research Prize 2017. IMO thanks the financial support under the Norte2020 project (“NORTE-08-5369-FSE-000044”)

A semiautomated microfluidic platform for real-time investigation of nanoparticles' cellular uptake and cancer cells' tracking

Aims: develop a platform composed of labeled dendrimer nanoparticles and a microfluidic device for real-time monitoring of cancer cells fate. Materials and Methods: The physicochemical and biological characterization of the developed Carboxymethyl-chitosan/poly(amidoamine) (CMCht/PAMAM) dendrimer nanoparticles were performed using TEM, AFM, Zeta Sizer, DSC and cytotoxicity screening. Cancer cell lines derived from different tumor types, including HeLa (Cervical Carcinoma), HCT-116 (Colon Carcinoma) and U87MG (Glioblastoma), were exposed to different concentrations of CMCht/PAMAM dendrimer nanoparticles over a period of 3 days (MTS/DNA). Results: Nanoparticles were successfully modified with an average size of 50 nm. Internalization levels go from 87% to 100% in static and from 95% to 100% in dynamic conditions. Viability levels range from 95% to 100% in static and from 90% to 100% in dynamic conditions, being HCT the most sensitive to the presence of the NP. Conclusions: the results show different responses to the presence of 0.5 mg.mL-1 dendrimer nanoparticles when comparing static to dynamic conditions, with a tendency towards higher sensitivity when subjected to confinement. This work demonstrated that the proposed microfluidic-based platform allows real-time cell monitoring, which, upon more studies, namely the assessment of the drug release effect, could be used for cancer theranostics.FR Maia acknowledges ERC-2012-ADG 20120216–321266 (ComplexiTE) for her Postdoc scholarship. JM Oliveira thanks Portuguese Foundation for Science and Technology (FCT) for his distinction attributed under the FCT Investigator program (IF/00423/2012). BM Costa also thanks Portuguese Foundation for Science and Technology (PTDC/SAU-GMG/113795/2009 and IF/00601/2012 to BM Costa), Fundação Calouste Gulbenkian (BM Costa) and Liga Portuguesa Contra o Cancro (BM Costa). MR Carvalho also thanks the funding through the LA ICVS/3Bs project (UID/Multi/50026/2013). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.info:eu-repo/semantics/publishedVersio

Methodology evaluation of pin microrelief meter

The effects of natural weathering and different managements performed in agriculture may best be understood by studying the soil roughness. The aim of this study was to evaluate the optimization of the use of pin microrelief meter, an instrument used to determine the soil surface roughness, as the number of readings collected over traditional methodology proposed in the bibliography. The study was conducted in Rio Paranaiba (MG), in a Haplustox soil. The experimental design was completely randomized in a 2×3 factorial design with four replications. There were combined two types of primary tillage: conventional tillage with disc plow (PCAD) and harrow (PCGA), and three amounts of readings (100, 200, and 300 reading points) sampled in each experimental unit. Independently of the soil tillage, disc plow and harrow, the collection of 100 readings using a pin microrelief meter of a square meter, was sufficient to determine the surface roughness before and after soil preparation, without accuracy loss compared with the traditional method

New perspectives of Juglans regia L. phytochemicals against Candida species

Opportunistic fungal infections have deserved special relevance in the last decades, presenting itself, a serious problem in terms of public health. Despite Candida albicans was considered the main agent responsible for those infections, other non-albicans Candida species have also been described in the last years [1-3]. Most of the species are susceptible to antimicrobial drugs, but recently it has been observed a growing number of microorganisms with drug resistance. Therefore, the discover/use of alternative therapies is crucial [4]. Juglans regia L. (walnut) leaves are commonly used in traditional medicine as antiseptic, antimicrobial and anti-inflammatory [5]; those benefits could be related with its richness in phenolic compounds [6]. In the present work, the antifungal potential of the hydroalcoholic extract prepared from walnut leaves was evaluated against a total of nineteen Candida strains (from the species: C.albicans, C.glabrata, C.parapsilosis and C.tropicalis), using the disc diffusion halo assay. All the tested strains were sensible to the plant extract. The obtained values of the inhibitory zones ranged between 0.9-1.4 cm, being the halo maintained after 48h. The observed antifungal activity is certainly related to the phenolic compounds previously determined in the extract [6]: five phenolic acid derivatives- caffeoylquinic and p-coumaroylquinic acid derivatives, two dimers and one trimer of procyanidins, twelve flavonols- quercetin, myricetin and kaempferol derivatives, and five taxifolin O-pentoside isomers; 3-O-caffeoylquinic acids and quercetin O-pentoside were the main phenolic compounds. Further studies are necessaries in order to elucidate the most active compounds and the specific role of each one. REFERENCES [1] Kim J, Sudbery P. (2011) J Microbiol. 49, 171-177. [2] Tsai P-W, Chen Y-T, Hsu P-C, Lan C-Y. (2013) BioMedicine. 3, 51–64. [3] Vázquez-González D, Perusquía-Ortiz AM, Hundeiker M, Bonifaz A. (2013) J Ger Soc Dermatology. 11, 381–94. [4] Kanafani ZA, Perfect JR. (2008) Clin Infect Dis - Antimicrob Resist. 46, 120–128. [5] Murray MT. (2004) 2nd ed. New York, NY. Random House. [6] Santos A, Barros L, Calhelha RC, Dueñas M, Carvalho AM, Santos-Buelga C, Ferreira ICFR. (2013) Ind Crops Prod. 51, 430-436.Instituto Nacional de Saúde Dr. Ricardo Jorg