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Silva C.S.R.,Polytechnic University of Valencia | Luz G.M.,University of Minho | Luz G.M.,PT Government Asociate Laboratory | Gamboa-Martinez T.C.,Polytechnic University of Valencia | And 5 more authors.
Journal of Macromolecular Science, Part B: Physics | Year: 2014

Polycaprolactone (PCL) scaffolds were produced by electrospinning. Polymeric solutions in a mix of dichloromethane (DCM) and dimethylformamide were electrospun to form fibers in the sub-micron range. Physical properties of the PCL solutions were characterized with respect to density, viscosity, conductivity and surface tension. Processing was optimized following Taguchi's methodology to select the set of processing parameters that resulted in producing fibers with the smallest diameters, minimum number of defects and with the narrowest distribution of fiber diameter. Morphology of electrospun fibers was qualitatively and quantitatively analyzed for the different sets of processing parameters. The optimum conditions found to electrospun PCL were used to process PCL solutions containing nanoparticles of hydroxyapatite (HA) or bioactive glass (BG). Bioactivity of nanocomposite electrospun membranes in simulated body fluid (SBF) was analyzed and biological response was tested by assessing proliferation and viability of MT3C3-E1 preosteoblasts cultured on PCL and its nanocomposite membranes. © 2014 Taylor and Francis Group, LLC. Source


Rodrigues P.L.,PT Government Asociate Laboratory | Rodrigues P.L.,University of Minho | Rodrigues P.L.,Polytechnic Institute of Cavado and Ave | Rodrigues N.F.,University of Minho | And 6 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2015

Background: Kidney stone is a major universal health problem, affecting 10% of the population worldwide. Percutaneous nephrolithotomy is a first-line and established procedure for disintegration and removal of renal stones. Its surgical success depends on the precise needle puncture of renal calyces, which remains the most challenging task for surgeons. This work describes and tests a new ultrasound based system to alert the surgeon when undesirable anatomical structures are in between the puncture path defined through a tracked needle. Methods: Two circular ultrasound transducers were built with a single 3.3-MHz piezoelectric ceramic PZT SN8, 25.4 mm of radius and resin-epoxy matching and backing layers. One matching layer was designed with a concave curvature to work as an acoustic lens with long focusing. The A-scan signals were filtered and processed to automatically detect reflected echoes. Results: The transducers were mapped in water tank and tested in a study involving 45 phantoms. Each phantom mimics different needle insertion trajectories with a percutaneous path length between 80 and 150 mm. Results showed that the beam cross-sectional area oscillates around the ceramics radius and it was possible to automatically detect echo signals in phantoms with length higher than 80 mm. Conclusions: This new solution may alert the surgeon about anatomical tissues changes during needle insertion, which may decrease the need of X-Ray radiation exposure and ultrasound image evaluation during percutaneous puncture. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. © 2015 SPIE. Source


Francesko A.,Polytechnic University of Catalonia | Fernandes M.M.,Polytechnic University of Catalonia | Ivanova K.,Polytechnic University of Catalonia | Amorim S.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | And 9 more authors.
Acta Biomaterialia | Year: 2016

This work reports on the development of infection-preventive coatings on silicone urinary catheters that contain in their structure and release on demand antibacterial polycationic nanospheres. Polycationic aminocellulose conjugate was first sonochemically processed into nanospheres to improve its antibacterial potential compared to the bulk conjugate in solution (ACSol). Afterward the processed aminocellulose nanospheres (ACNSs) were combined with the hyaluronic acid (HA) polyanion to build a layer-by-layer construct on silicone surfaces. Although the coating deposition was more effective when HA was coupled with ACSol than with ACNSs, the ACNSs-based coatings were thicker and displayed smoother surfaces due to the embedment of intact nanospheres. The antibacterial effect of ACNSs multilayers was 40% higher compared to ACSol coatings. This fact was further translated into more effective prevention of Pseudomonas aeruginosa biofilm formation. The coatings were stable in the absence of bacteria, whereas their disassembling occurred gradually during incubation with P. aeruginosa, and thus eradicate the biofilm upon release of antibacterial agents. Only 5 bilayers of HA/ACNSs were sufficient to prevent the biofilm formation, in contrast to the 10 bilayers of ACSol required to achieve the same effect. The antibiofilm efficiency of (HA/ACNSs)10 multilayer construct built on a Foley catheter was additionally validated under dynamic conditions using a model of the catheterized bladder in which the biofilm was grown during seven days. Statement of Significance Antibacterial layer-by-layer coatings were fabricated on silicone that efficiently prevents Pseudomonas aeruginosa biofilm formation during time beyond the useful lifetime of the currently employed urinary catheters in medical practice. The coatings are composed of intact, highly antibacterial polycationic nanospheres processed from aminated cellulose and bacteria-degrading glycosaminoglycan hyaluronic acid. The importance of incorporating nanoscale structures within bacteria-responsive surface coatings to impart durable antibacterial and self-defensive properties to the medical indwelling devices is highlighted. ©2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source


Santos N.C.,University of Minho | Santos N.C.,PT Government Asociate Laboratory | Costa P.S.,University of Minho | Costa P.S.,PT Government Asociate Laboratory | And 12 more authors.
PLoS ONE | Year: 2015

Here we focus on factor analysis from a best practices point of view, by investigating the factor structure of neuropsychological tests and using the results obtained to illustrate on choosing a reasonable solution. The sample (n=1051 individuals) was randomly divided into two groups: one for exploratory factor analysis (EFA) and principal component analysis (PCA), to investigate the number of factors underlying the neurocognitive variables; the second to test the "best fit" model via confirmatory factor analysis (CFA). For the exploratory step, three extraction (maximum likelihood, principal axis factoring and principal components) and two rotation (orthogonal and oblique) methods were used. The analysis methodology allowed exploring how different cognitive/psychological tests correlated/discriminated between dimensions, indicating that to capture latent structures in similar sample sizes and measures, with approximately normal data distribution, reflective models with oblimin rotation might prove the most adequate. © 2015 Santos et al. Source


Oliveira M.B.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Oliveira M.B.,PT Government Asociate Laboratory | Neto A.I.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Neto A.I.,PT Government Asociate Laboratory | And 6 more authors.
ACS Applied Materials and Interfaces | Year: 2014

We suggest the use of biomimetic superhydrophobic patterned chips produced by a benchtop methodology as low-cost and waste-free platforms for the production of arrays of cell spheroids/microtissues by the hanging drop methodology. Cell spheroids have a wide range of applications in biotechnology fields. For drug screening, they allow studying 3D models in structures resembling real living tissues/tumors. In tissue engineering, they are suggested as building blocks of bottom-up fabricated tissues. We used the wettability contrast of the chips to fix cell suspension droplets in the wettable regions and evaluated on-chip drug screening in 3D environment. Cell suspensions were patterned in the wettable spots by three distinct methods: (1) by pipetting the cell suspension directly in each individual spot, (2) by the continuous dragging of a cell suspension on the chip, and (3) by dipping the whole chip in a cell suspension. These methods allowed working with distinct throughputs and degrees of precision. The platforms were robust, and we were able to have static or dynamic environments in each droplet. The access to cell culture media for exchange or addition/removal of components was versatile and opened the possibility of using each spot of the chip as a mini-bioreactor. The platforms' design allowed for samples visualization and high-content image-based analysis on-chip. The combinatorial analysis capability of this technology was validated by following the effect of doxorubicin at different concentrations on spheroids formed using L929 and SaOs-2 cells. © 2014 American Chemical Society. Source

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