Time filter

Source Type

Costa R.R.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Costa R.R.,PT Government Associated Laboratory | Testera A.M.,University of Valladolid | Testera A.M.,CIBER ISCIII | And 6 more authors.
Journal of Physical Chemistry B | Year: 2013

Nanostructured films consisting of polysaccharides and elastin-like recombinamers (ELRs) are fabricated in a layer-by-layer manner. A quartz-crystal microbalance with dissipation monitoring (QCM-D) is used to follow the buildup of hybrid films containing one polysaccharide (chitosan or alginate) and one of several ELRs that differ in terms of amino acid content, length, and biofunctionality in situ at pH 4.0 and pH 5.5. The charge density of the ingredients at each pH is determined by measuring their ζ-potential, and the thickness of a total of 36 different films containing five bilayers is estimated using the Voigt-based viscoelastic model. A comparison of the values obtained reveals that thicker films can be obtained when working at a pH close to the acidity constant of the polysaccharide used (near-pKa conditions), suggesting that the construction of such films is more favorable when based on the presence of hydrophobic interactions between ELRs and partially neutralized polysaccharides. Further analysis shows that the molecular weight of the ELRs plays only a minor role in defining the growth tendency. When taken together, these results point to the most favorable conditions for constructing nanostructured films from natural and distinct recombinant polypeptides that can be tuned to exhibit specialized biofunctionality for tissue-engineering, drug-delivery, and biotechnological applications. © 2013 American Chemical Society. Source

Pereira P.,University of Aveiro | Pereira P.,IPMA Portuguese Institute for the Sea and Atmosphere | Pereira P.,University of Minho | Pereira P.,PT Government Associated Laboratory | And 5 more authors.
Science of the Total Environment | Year: 2014

Fish eyes and brain are highly susceptible to environmental Hg exposure but this issue is still scarcely investigated, mainly regarding methylmercury (MeHg) accumulation. Yet, Hg levels in fish lens have not been previously examined under field conditions. Total Hg (tHg), MeHg and inorganic Hg (iHg) levels were assessed in the brain, eye wall and lens of the golden grey mullet (Liza aurata) from an Hg contaminated area, both in winter and summer, together with water and sediment levels. Sampling was performed at Aveiro lagoon (Portugal) where a confined area (LAR) is severely contaminated by Hg. Fish brain, eye wall and lens accumulated higher levels of tHg, MeHg and iHg at LAR than the reference site, reflecting faithfully environmental spatial differences. The brain and eye wall responded also to the winter-summer changes found in water and sediment, accumulating higher levels of MeHg (and tHg) in winter. Contrarily, lens was unable to reflect seasonal changes, probably due to its composition and structural stability over time. The three neurosensory structures accumulated preferentially MeHg than iHg (MeHg was higher than 77% of tHg). Lens exhibited a higher retention capacity of MeHg (mean around 1μgg-1 at LAR), accumulating higher levels than the other two tissues. Interestingly, MeHg and iHg levels were significantly correlated for the brain and eye wall but poorly associated within the two analysed eye components. The high levels of MeHg found in the brain, eye wall and lens could compromise their functions and this needs further research. © 2014. Source

Custodio C.A.,University of Minho | Custodio C.A.,PT Government Associated Laboratory | Reis R.L.,University of Minho | Reis R.L.,PT Government Associated Laboratory | And 2 more authors.
Advanced Healthcare Materials | Year: 2014

Engineered cell instructive microenvironments with the ability to stimulate specific cellular responses are a topic of high interest in the fabrication and development of biomaterials for application in tissue engineering. Cells are inherently sensitive to the in vivo microenvironment that is often designed as the cell "niche." The cell "niche" comprising the extracellular matrix and adjacent cells, influences not only cell architecture and mechanics, but also cell polarity and function. Extensive research has been performed to establish new tools to fabricate biomimetic advanced materials for tissue engineering that incorporate structural, mechanical, and biochemical signals that interact with cells in a controlled manner and to recapitulate the in vivo dynamic microenvironment. Bioactive tunable microenvironments using micro and nanofabrication have been successfully developed and proven to be extremely powerful to control intracellular signaling and cell function. This Review is focused in the assortment of biochemical signals that have been explored to fabricate bioactive cell microenvironments and the main technologies and chemical strategies to encode them in engineered biomaterials with biological information. This Review is focused on the assortment of biochemical signals that have been explored to fabricate bioactive cell microenvironments. The main receptor molecules that the cell has available on its surface that interacts with external ligands are also considered. Existing tools to pattern and functionalize cell microenvironments with active biologic motifs are described in the last part. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Santo V.E.,University of Minho | Santo V.E.,PT Government Associated Laboratory | Rodrigues M.T.,University of Minho | Rodrigues M.T.,PT Government Associated Laboratory | And 2 more authors.
Expert Review of Molecular Diagnostics | Year: 2013

The current limitations of regenerative medicine strategies may be overcome through the use of magnetic nanoparticles (MNPs), a class of nanomaterial typically composed of magnetic elements that can be manipulated under the influence of an external magnetic field. Cell engineering approaches following the internalization of these MNPs by cells and/or the incorporation of these nanosystems within 3D constructs (scaffolds or hydrogels) may constitute a new attractive approach to achieve a magnetically responsive system enabling remote control over tissue-engineered constructs in an in vivo scenario. Moreover, the incorporation of bioactive factors within these MNPs also enables a targeted and smart delivery of biomolecules to specific regions and/or triggering specific cell responses upon external magnetic stimulation. Certainly, one of the most attractive properties of MNPs is their ability to be used as theranostic tools for regenerative medicine applications, enabling live monitoring and tracking of the system while simultaneously acting as a therapeutic stimulation. © 2013 Informa UK Ltd. Source

Costa R.R.,University of Minho | Costa R.R.,PT Government Associated Laboratory | Castro E.,University of Minho | Castro E.,PT Government Associated Laboratory | And 6 more authors.
Biomacromolecules | Year: 2013

Inspired by the cells' structure, we present compartmentalized capsules with temperature and magnetic-based responsiveness and hierarchical organization ranging from the nano-to the visible scales. Liquefied alginate macroscopic beads coated with a layer-by-layer (LbL) chitosan/alginate shell served as containers both for model fluorophores and microcapsules, which in their turn encapsulated either another fluorophore or magnetic nanoparticles (MNPs). The microcapsules were coated with a temperature-responsive chitosan/elastin-like recombinamer (ELR) nanostructured shell. By varying the temperature from 25 to 37 C, the two-hour release of rhodamine encapsulated within the microcapsules and its diffusion through the external compartment decreased from 84% and 71%. The devices could withstand handling and centrifugal stress, with 50% remaining intact at a rotation speed of 2000g. MNPs attributed magnetic responsiveness toward external magnetic fields. Such a customizable system can be envisaged to transport bioactive agents and cells in tissue engineering applications. © 2013 American Chemical Society. Source

Discover hidden collaborations