232 research outputs found
Investigation on the role of red fox in tuberculosis maintenance community ¿ second opus: experimental infection with a virulent field Mycobacterium bovis strain
Trabajo presentado al: 69th Wildlife Disease Association and 14th European Wildlife Disease Association Conference. Cuenca, Spain. p. 135. 31 agosto-2 septiembre
Construction and validation of a questionnaire to assess student satisfaction with mathematics learning materials
Sixth Edition Technological Ecosystems for Enhancing MulticulturalityMathematics is an essential branch for the scientific development and its study is mandatory in most university degrees. However, currently the level of academic performance and motivation of students to learn this science is not the desired one. The students can use different learning tools inside and outside the math classroom, enhancing the quality of the learning materials that are designed essentially to facilitate the learning of mathematics. The present research project aims to determine the validity and reliability of a measurement instrument that allows theassessment of the satisfaction of the students with the availablelearning materials. To fulfill the objectives of this research, the method of survey was used. A study with a quantitative approach was developed, which led to the design and validation of a questionnaire by a group of 7 experts. The validation closed after applying a pilot study with 728 students. It concluded positively, obtaining nine factors that coincide with the revision of the literature: technological quality, quality of content, visual quality, didactic significance, adequacy of content, relationship between theory and practice, involvement, contribution to learning, relevance and interaction between educational actors. The results of this questionnaire provide to the international scientific community with relevant information for the design, selection, and use of study materials in the classrooms, which will contribute to raising the levels of student engagement, and their academic performance in mathematics, secondaril
Cartilage regeneration approach based on squid chitosan scaffolds : in-vitro assessment
During the past decades, marine organisms have been the focus of considerable attention as
potential source of valuable materials. For instance, chitosan is a biopolymer with high
potential in the biomedical field and can be produced from crustacean shells and squid pens
[1]. In this sense, we propose the use of chitosan to produce scaffolds for regenerative
medicine purposes. An alkaline solution was used to deproteinize squid pens and isolate β-
chitin (Chaussard 2004), which was further converted into chitosan through a deacetylation
reaction. Chitosan was then processed into porous structures by freeze-drying [3], where
chitosan solutions (4%) were submitted to different freezing temperature of -80ºC and -
196ºC. The produced structures were further submitted to neutralization methods with 4%
NaHO, including in some cases a pre-washing step using ethanol/water solutions (100:0;
90:10, 80:20; 70:30 and 50:50) [4]. The morphology of scaffolds produced using either squid
or commercial chitosan revealed a lamellar structure, independent of the source and/or
freezing temperature. All chitosan scaffolds produced exhibited no-cytotoxic behaviour over
L929 cells. To test the in vitro functionality of the scaffolds, cells from the mouse
chondrogenic cell line ATDC-5 were seeded in the scaffolds and cultured for different time
periods. Scaffolds made from squid chitosan were shown to promote better cell adhesion
than commercial chitosan scaffolds and comparable or better cell proliferation. This
demonstrates that squid chitosan is a valuable alternative to produce scaffolds for different
applications in regenerative medicine, namely the regeneration of cartilage
Development of marine-based nanocomposite scaffolds for biomedical applications
Despite
the
increasing
attention
that
marine
organisms
are
receiving,
many
of
those
are
not
efficiently
exploited
and
subproducts
with
valuable
compounds
are
being
discarded.
Two
examples
of
those
subproducts
are
the
endoskeleton
of
squid,
from
which
β-‐chitin
and
consecutively
chitosan
can
be
obtained;
and
fish-‐bones,
as
a
source
for
the
production
of
nano-‐
hydroxyapatite.
In
this
work,
inspired
in
the
nanocomposite
structure
of
human
bone,
marine-‐
based
nanocomposite
scaffolds
composed
by
chitosan
and
nano-‐hydroxyapatite
(nHA)
were
developed
using
particle
aggregation
methodology.
Chitosan
was
obtained
from
endoskeleton
of
giant
squid
Dosidicus
Gigas
while
fish
hydroxyapatite
nanoparticles
were
synthesized
from
fish-‐bones
by
pulsed
laser
in
deionized
water.
An
innovative
methodology
was
used
based
on
the
agglomeration
of
prefabricated
microspheres
of
chitosan/nHA,
generally
based
on
the
random
packing
of
microspheres
with
further
aggregation
by
physical
or
thermal
means
to
create
a
marine
nanocomposite
(CHA)
.The
morphological
analysis
of
the
developed
nanocomposites
revealed
a
low
porosity
structure,
but
with
high
interconnectivity,
for
all
produced
scaffolds.
Furthermore,
the
nanocomposite
scaffolds
were
characterized
in
terms
of
their
mechanical
properties,
bioactivity,
crystallinity
and
biological
behavior.
The
obtained
results
highlight
that
the
chitosan/nHA-‐based
marine
nanocomposite
can
be
a
good
candidate
for
biomedical
applications,
namely
on
bone
regeneration
Valorization of chitosan from squid pens and further use on the development of scaffolds for biomedical applications
Objectives: The aim of the present work is the valorization of squid pens
through the production of chitosan that can be used for the development of biomedical
applications. The present work is focused on !-chitin extraction from
squid pens of the species Dosidicus gigas and its further conversion into chitosan.
The biomedical potential of the isolated squid chitosan was assessed by
processing this polymer as scaffolds for tissue engineering strategies.
Methods: Alkali solution was used to deproteinized squid pens and thus isolate
!-chitin, which was further converted into chitosan through a deacetylation reaction.
The chitosan scaffolds were developed using a freeze-drying process,
from 3% and 4% chitosan solutions in acetic acid and freezing at temperatures
of -80ºC and -196ºC. Chitosan scaffolds were neutralized using two different
methods: M1 – NaHO solution; and M2 – ethanol/water and NaHO solution.
Morphology, Mechanical properties, degradation, cytotoxicity (L929 cells) and
cellular adhesion (ATDC5 Chondrocytes like cells) of squid chitosan scaffolds
were assessed and compared with the properties of scaffolds produced with
commercial chitosan.
Results: The morphology of scaffolds revealed a lamellar structure for all produced
scaffolds, independent of the origin and concentration of chitosan. The
treatment with sodium hydroxide and ethanol caused the formation of larger
pores and loose of some lamellar features. Different freezing temperatures gave
different pore morphology and the lower temperature a smaller pore size. The
in vitro cell culture and cell adhesion studies showed that all chitosan scaffolds
exhibited a non-cytotoxic effect over the mouse fibroblast-like cell line, L929
cells.
Conclusions: The chitosan produced from the endoskeletons of giant squid
Dosidicus Gigas has proven to be a valuable alternative to the commercial one
when considering its use as biomaterial for different biomedical applications
Influence of freezing temperature and deacetylation degree on the performance of freeze-dried chitosan scaffolds towards cartilage tissue engineering
Chitosan-based porous structures have been significantly studied across the world as potential tissue engineering scaffolds. Despite the differences in chitosan produced from squid pens or crustacean shells, with the former being more reactive and easily available with a higher degree of deacetylation (DD), most of the studies report the use of crab or shrimp chitosan as they are readily available commercial sources. The aim of this work was to highlight the great potential of chitosan produced from squid pens for biomedical application. From freeze-dried scaffolds for soft tissue engineering, we investigated the influence of the DD of chitosan and the freezing temperature during processing on their performance. Chitosan was obtained by deacetylation of β-chitin previously isolated from endoskeleton of giant squid Dosidicus gigas (DD 91.2%) and compared with a commercially available batch obtained from crab shells (DD 76.6%). Chitosan solutions were frozen at â 80° C or â 196° C and further freeze-dried to obtain 3D porous structures (scaffolds). Scaffolds prepared at â 196° C have a compact structure with smaller pores, while those prepared at â 80° C showed a lamellar structure with larger pores. The compressive modulus varied from 0.7 up to 8.8 MPa. Both types of scaffolds were stable on PBS, including in the presence of lysozyme, up to 4 weeks. Furthermore, the squid chitosan scaffolds processed at â 80° C promoted ATDC5 chondrocyte-like cells adhesion and proliferation. The results suggest that the developed squid chitosan scaffolds might be further exploited for ap- plications in cartilage tissue engineering.This work was partially funded by ERDF through POCTEP Projects 0330_IBEROMARE_1_P and 0687_NOVOMAR_1_P, Atlantic
Area Project 2011-1/164 MARMED and by European Union through European Research Council – Project ComplexiTE (ERC-2012-ADG 20120216-321266). Portuguese Foundation for Science and Technology is gratefully acknowledged for post-doc grants of R.P.
Pirraco (SFRH/BPD/101886/2014) and S.S. Silva (SFRH/BPD/112140/2015) and PhD grant of Lara L. Reys (SFRH/BD/112139/2015). The authors would also like to acknowledge to Dr. Julio Maroto, from Fundación CETMAR (Spain) and Roi Vilela, from
PESCANOVA S.A. (Spain), for the kind offer of squid pens.info:eu-repo/semantics/publishedVersio
Semiconductor gellan gum based composite hydrogels for tissue engineering applications
Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013)Semiconductor hydrogels can be developed by combining the intrinsic
electrical properties of semiconductors with the specific characteristics
of hydrogels. These hydrogels have recently attracted much attention
for applications in tissue engineering, especially formulations incorporating
pyrrole and excellent biocompatibility. Several studies have
reported that electrical stimulation influences the migration, proliferation
and differentiation of stem cells and other cell lines [1]. The goal
of this work is to use in situ chemical polymerization of polypyrrole
(PPy) with gellan gum (GG) in order to obtain a new generation of
semiconductor composite hydrogels. For the synthesis of GG/PPy composites,
GG at 1.25% (w/v) final concentration was prepared in distilled
water at room temperature. The solution was then heated under
stirring at 90°C for 20 min. Temperature was decreased to 65°C and Py
was added under vigorous agitation. The crosslinker solution (CaCl2,
0.18%) was added at 50°C. After 2 h, GG/Py composite hydrogels
were obtained. In a further step, GG/Py samples were immersed in a
solution of oxidizing agent in PBS and the reaction was carried out for
18 h under agitation at room temperature. Finally, the samples were
frozen at -80°C for 48 h and lyophilized. The characterization of GG,
GG/PPy and PPy samples was performed by scanning electron microscopy
(SEM). The incorporation of PPy in the gellan gum was confirmed
by SEM analysis. The coating with PPy increases the thickness of each
sheet in 3 fold when compared with GG samples. Conductivity tests
were also performed. For cytotoxicity assay, the samples were rehydrated
with complete culture medium. MTS and DNA quantification assays
were performed to evaluate the metabolic activity and proliferation of
L929 fibroblast cells after 1, 3 and 7 days in culture with GG, GG/PPy
and PPy samples. MTS assays clearly indicate a proportional relation
between the cell viability and the PPy concentration: higher concentrations
of PPy resulted in lower cell viability. These results show that
lower concentration of PPy incorporated in the GG hydrogels can provide
an adequate electrical stimulus to improve cell behavior. In conclusion,
semiconductor hydrogels can be an excellent platform for tissue
engineering and electrochemical therapy application
Evaluation of the potential of fucoidan-based microparticles for diabetes treatment
Abstract
INTRODUCTION: Marine organisms have in their constitution materials with a wide range of properties and characteristics inspiring their application within the biomedical field. One important example is fucoidan (Fu), an underexploited sulfated polysaccharide extracted from the cell wall of the brown seaweeds, with high solubility in water1. Fucoidan is composed of L- fucose and glucuronic acid including sulfate groups and has important bioactive properties such as antioxidative, anticoagulant, anticancer and in the reduction of blood glucose1,2. In this work, the biomedical potential of fucoidan was assessed by processing modified fucoidan (MFu) into microparticles by photocrosslinking using superhydrophobic surfaces and visible light3,4. Biological performance on the developed constructs using human pancreatic beta cells is currently under investigation.
METHODS: To design the materials structures, fucoidan was modified by methacrylation reaction3. Briefly, Fu aqueous solution 4% w/v was mixed with methacrylated anhydride (MA) in volume of 12% v/v at 50oC to react for 6h. Further, MFu particles with and without insulin (0.5% w/v) were produced by pipetting a solution of 5% MFu v/v with triethanolamine and eosin-y (photoinitiators) onto superhydrophobic surfaces4 (Fig. 1A) and then photocrosslinking using visible light4. MFu and developed particles were characterized using 1HNMR, turbidimetry and SEM to assess their chemistry and morphology, respectively. Moreover, the insulin release was evaluated in phosphate buffered saline (PBS) solution at pH 7and simulated intestinal fluid (SIF) at pH 5. The ability of the developed materials to support adhesion and proliferation of cells was assessed by suspension culture of human pancreatic cells 1.1B4 (3.5x105 cells/ml) in contact with MFu microparticles during up to 7 days. RESULTS: The chemical modification performed on Fu was confirmed by the presence of vinyl and additional methyl peaks in the 1HNMR of modified fucoidan, not present in Fu spectrum. Methacrylated fucoidan was obtained with a methacrylation degree of 17%. The produced fucoidan particles have round shape and average diameter of 1.53 mm (Fig. 1B). The insulin release in PBS and SIF demonstrate that the particles can release insulin in a sustained manner under the studied period. It seems that the insulin release is slower for SIF (pH5, Fig. 1C), than for PBS. The biological tests regarding the culture of pancreatic beta cells demonstrate that cells show a round-like shape and tend to form pseudo-islets during the culture period studied (Fig. 1D).
DISCUSSION & CONCLUSIONS: This work demonstrates the successful production of fucoidan- based-microparticles through the methacrylation of fucoidan, using visible light and superhydrophobic surfaces. The covalent crosslinking methacrylated fucoidan through visible light represents a promising method to obtain biocompatible fucoidan particles with a uniform round shape. The obtained insulin release profiles are sensitive to different pH (pH7 and pH5), mimicking the normal physiological pathway for insulin release. Furthermore, the results suggest these systems could be used for treatment of type I diabetes mellitus as they sustain beta cells viability and proliferation. The response also suggested, that the MFu particles could be a good candidate as drug delivery vehicles for the diabetes mellitus treatment.
REFERENCES: 1 Silva TH et al (2012), Biomatter 2(4): 278:289. 2Sezer Alidemir et al (2011), Fucoidan: A versatile biopolymer for biomedical applicatons (Springer Ber.Heid).pp377-406. 3Mihaila S.et al (2013), Adv. Health. Mat. 2(6): 895-907. 4Rial Hermida et al, Acta Biomater.(2014) 10(10) 4314-4322.
ACKNOWLEDGEMENTS: This work was partially funded by projects 0687_NOVOMAR_1_P (POCTEP), CarbPol_u_Algae (EXPL/MAR- BIO/0165/2013), ComplexiTE (ERC-2012-ADG 20120216-321266). Portuguese Foundation for Science and Technology is also gratefully acknowledged for doctoral grants of L. Reys and N. Oliveira and post- doctoral grants of S.S. Silva and D. Soares da Costafunded by projects 0687_NOVOMAR_1_P (POCTEP), CarbPol_u_Algae (EXPL/MARBIO/0165/2013)
, ComplexiTE(ERC-2012-ADG 20120216-321266). Portuguese Foundation for Science and Technologyinfo:eu-repo/semantics/publishedVersio
Marine algae sulfated polysaccharides for tissue engineering and drug delivery approaches
Biomedical field is constantly requesting for new biomaterials, with innovative properties. Natural polymers appear as materials of election for this goal due to their biocompatibility and biodegradability. In particular, materials found in marine environment are of great interest since the chemical and biological diversity found in this environment is almost uncountable and continuously growing with the research in deeper waters. Moreover, there is also a slower risk of these materials to pose illnesses to humans.
In particular, sulfated polysaccharides can be found in marine environment, in different algae species. These polysaccharides don’t have equivalent in the terrestrial plants and resembles the chemical and biological properties of mammalian glycosaminoglycans. In this perspective, are receiving growing interest for application on health-related fields. On this review, we will focus on the biomedical applications of marine algae sulfated polymers, in particular on the development of innovative systems for tissue engineering and drug delivery approaches.European Regional Development Fund (ERDF)Fundação para a Ciência e a Tecnologia (FCT
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