Correia C.O.,University of Minho |
Correia C.O.,Pt Government Associ Laboratory |
Mano J.F.,University of Minho |
Mano J.F.,Pt Government Associ Laboratory
Journal of Materials Chemistry B | Year: 2014
We demonstrate that chitosan-based porous scaffolds can present a shape memory effect triggered by hydration. The shape memory effect of non-crosslinked (CHT0) and genipin-crosslinked (CHT1) scaffolds was followed by innovative hydromechanical compressive tests and dynamic mechanical analysis (DMA), while the sample was immersed in varying compositions of water-ethanol mixtures. By dehydration with higher contents of ethanol, the vitreous-like nature of the amorphous component of chitosan allows the fixation of the temporary shape of the scaffold. The presence of water disrupts inter-molecular hydrogen bonds permitting large-scale segmental mobility of the chitosan chains upon the occurrence of glass transition and thus the recovery of the permanent shape of a pre-deformed scaffold. Results showed that chitosan possesses shape memory properties, characterized by a fixity ratio above 97.2% for CHT0 and above 99.2% for CHT1 and a recovery ratio above 70.5% for CHT0 and 98.5% for CHT1. In vitro drug delivery studies were also performed to demonstrate that such devices can also be loaded with molecules. We show that the developed chitosan scaffolds are candidates of biomaterials for applications in minimally invasive surgery for tissue regeneration or for drug delivery. © the Partner Organisations 2014.
Costa R.R.,University of Minho |
Costa R.R.,Pt Government Associ Laboratory |
Mano J.F.,University of Minho |
Mano J.F.,Pt Government Associ Laboratory
Chemical Society Reviews | Year: 2014
Layer-by-layer (LbL) was first introduced as a surface modification technique based on the sequential spontaneous adsorption of at least two distinct materials onto planar substrates. In the last two decades, this technique has been expanded to the coating of more convoluted geometries with high levels of tailored functionalization or with structural purposes. In this review, the potential uses of LbL films in biomedical engineering based mainly on the assembly of polyelectrolytes are reviewed. Examples of recent developments are provided, from the modification of substrates to improve their biointegration or to add specialized properties, to the three-dimensional extrapolation of this technique to more complex structures for cell seeding, drug delivery devices, biosensors and customizable microreactors. Future strategies and opportunities are compared with current medical and laboratorial methodologies. Through them, it is expected that LbL will contribute greatly to the development of new functional devices with high perspectives of return for the administration of active agents, supports for cells in regenerative medicine and tissue engineering, biosensing and construction of microtissues and disease models in the laboratory. © 2014 the Partner Organisations.
Santos N.C.,University of Minho |
Santos N.C.,Pt Government Associ Laboratory |
Santos N.C.,Clinical Academic Center |
Costa P.S.,University of Minho |
And 21 more authors.
Age | Year: 2013
Identification of predictors of cognitive trajectories through the establishment of composite or single-parameter dimensional categories of cognition and mood may facilitate development of strategies to improve quality of life in the elderly. Participants (n= 487, aged 50+ years) were representative of the Portuguese population in terms of age, gender, and educational status. Cognitive and mood profiles were established using a battery of neurocognitive and psychological tests. Data were subjected to principal component analysis to identify core dimensions of cognition and mood, encompassing multiple test variables. Dimensions were correlatedwith age and with respect to gender, education, and occupational status. Cluster analysis was applied to isolate distinct patterns of cognitive performance and binary logistic regression models to explore interrelationships between aging, cognition, mood, and socio-demographic characteristics. Four main dimensions were identified: memory, executive function, global cognitive status, and mood. Based on these, strong and weak cognitive performers were distinguishable. Cluster analysis revealed further distinction within these two main categories into very good, good, poor, and very poor performers. Mood was the principal factor contributing to the separation between very good and good, as well as poor and very poor, performers. Clustering was also influenced by gender and education, albeit to a lesser extent; notably, however, female gender × lower educational background predicted significantly poorer cognitive performance with increasing age. Mood has a significant impact on the rate of cognitive decline in the elderly. Gender and educational level are early determinants of cognitive performance in later life. © 2012 American Aging Association.
Santos N.,University of Minho |
Santos N.,Pt Government Associ Laboratory |
Santos C.,University of Minho |
Santos C.,Pt Government Associ Laboratory |
And 5 more authors.
PLoS ONE | Year: 2015
Environmental contamination with Mycobacterium tuberculosis complex (MTC) has been considered crucial for bovine tuberculosis persistence in multi-host-pathogen systems. However, MTC contamination has been difficult to detect due to methodological issues. In an attempt to overcome this limitation we developed an improved protocol for the detection of MTC DNA. MTC DNA concentration was estimated by the Most Probable Number (MPN) method. Making use of this protocol we showed that MTC contamination is widespread in different types of environmental samples from the Iberian Peninsula, which supports indirect transmission as a contributing mechanism for the maintenance of bovine tuberculosis in this multi-host-pathogen system. The proportion of MTC DNA positive samples was higher in the bovine tuberculosis-infected than in presumed negative area (0.32 and 0.18, respectively). Detection varied with the type of environmental sample and was more frequent in sediment from dams and less frequent in water also from dams (0.22 and 0.05, respectively). The proportion of MTC-positive samples was significantly higher in spring (p<0.001), but MTC DNA concentration per sample was higher in autumn and lower in summer. The average MTC DNA concentration in positive samples was 0.82 MPN/g (CI95 0.70-0.98 MPN/g). We were further able to amplify a DNA sequence specific of Mycobacterium bovis/caprae in 4 environmental samples from the bTB-infected area. © 2015 Santos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Gomes A.P.,University of Beira Interior |
Mano J.F.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine |
Mano J.F.,Pt Government Associ Laboratory |
Queiroz J.A.,University of Beira Interior |
Gouveia I.C.,University of Beira Interior
Journal of Applied Polymer Science | Year: 2014
The aim of this study was to investigate a method of embedding l-cysteine (l-cys), an antimicrobial agent, between layers of chitosan (CH) and sodium alginate (ALG) onto cotton samples obtained via a layer-by-layer electrostatic deposition technique via several embedding methods. The results show that the best way to incorporate l-cys into the layers was the one that used the property of gelling ALG. To monitor the l-cys embedding into the CH/ALG multilayer film, different methods were used: energy-dispersive X-ray spectrometry analysis to assess the presence of sulfur on the sample, Ellman's reagent method to analyze l-cys release from the sample, and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR) to compare the ATR-FTIR spectra of the pure l-cys and l-cys embedded in the CH/ALG multilayer film to study the interaction between the l-cys and the CH/ALG multilayer films. Functionalized CH/ALG cotton samples were also investigated for their antibacterial properties toward Staphylococcus aureus and Klebsiella pneumonia with the Japanese Industrial Standard method JIS L 1902:2002, and the results show an enhancement of the antibacterial effect due to the presence of l-cys. © 2014 Wiley Periodicals, Inc.