20 research outputs found
AFM study of morphology and mechanical properties of a chimeric 2 spider silk and bone sialoprotein protein for bone regeneration
Atomic force microscopy (AFM) was used to assess a
new chimeric protein consisting of a fusion protein of the consensus
repeat for Nephila clavipes spider dragline protein and bone sialoprotein
(6merþBSP). The elastic modulus of this protein in film
form was assessed through force curves, and film surface roughness
was also determined. The results showed a significant difference
among the elastic modulus of the chimeric silk protein, 6merþBSP,
and control films consisting of only the silk component (6mer). The
behavior of the 6merþBSP and 6mer proteins in aqueous solution in
the presence of calcium (Ca) ions was also assessed to determine
interactions between the inorganic and organic components related
to bone interactions, anchoring, and biomaterial network formation.
The results demonstrated the formation of protein networks in the
presence of Ca2þ ions, characteristics that may be important in the
context of controlling materials assembly and properties related to
bone formation with this new chimeric silk-BSP protein.Silvia Games thanks the Foundation for Science and Technology (FCT) for supporting her Ph.D. grant, SFRH/BD/28603/2006. This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283), the Chimera project (PTDC/EBB-EBI/109093/2008) funded by the FCT agency, the NIH (P41 EB002520) Tissue Engineering Resource Center, and the NIH (EB003210 and DE017207)
Solvent-Free Strategy Yields Size and Shape-Uniform Capsules
Capsules
with a liquefied core were fabricated via the assembly
of polymeric droplets induced by superamphiphobic surfaces. These
highly repellent substrates exhibit distinct features such as (i)
an easy and precise control over the particle size and shape, (ii)
a high encapsulation efficiency, (iii) mild processing conditions,
and (iv) the possibility to include any object in either a water or
oil-based liquid core, which are not found on the current available
strategies. As proof of concept, a photo-cross-linkable derivative
of chitosan was used to produce the polymeric shell while a wealth
variety of template cores were tested using a reversible cross-linking
mechanism, interfacial gelation process or ice. Owing to the widespread
application of polymeric capsules, the developed strategy is poised
to usher the development of the next generation of materials not only
for biomedical purposes but also for cosmetics, agriculture and electronics
Effect of Polyelectrolyte Multilayers Assembled on Ordered Nanostructures on Adhesion of Human Fibroblasts
Nanosphere lithography
(NSL) and the layer-by-layer (LbL) technique
are combined here for the first time to design a flexible system to
achieve nanotopographical control of cell adhesion. NSL is used to
generate regular patterns of tetrahedral gold nanodots of different
size and distance. Besides the change in topography, LbL is used to
generate a polyelectrolyte multilayer (PEM) system consisting of heparin
(HEP) and poly(ethylene imine) (PEI) on top of the gold dots. The
localized formation of PEM on gold dots is achieved by prior passivation
of the surrounding silicon or glass surface. Properties of PEM are
changed by adjusting the pH value of HEP solution to either acidic
or alkaline values. Studies with human dermal fibroblasts (HDF) reveal
that cells spread to a higher extent on PEM formed at pH 5.0 in dependence
on the structure dimension. Further, filopodia formation is highly
increased in cells on nanostructures exhibiting HEP as a terminal
layer. The new system offers a great potential to guide stem cell
differentiation in the future owing to its high degree of chemical
and topographical heterogeneity
Magnetically Multilayer Polysaccharide Membranes for Biomedical Applications
Self-standing
nanocomposite films based on biopolymers and functional
nanostructures have been widely used due to their potential applications
as active elements in biomedical devices. The coupling between chitosan
(CHI) and alginate (ALG) multilayered films and magnetic nanoparticles
(MNPs) allowed to fabricate magnetic responsive freestanding membranes
with a high structural control along the thickness, using the layer-by-layer
(LbL) methodology. The mechanical characterization evidenced a trend
for an increase of both Young modulus, and ultimate tensile strength
with the inclusion of MNPs, or by cross-linking with genipin. Additionally,
the multilayered membranes exhibited shape memory properties triggered
by hydration. The in vitro biological performance studies showed that
cells were more viable and adherent with higher proliferation rates
when MNPs were included in the membranes. Our results suggested the
potential of the developed magneto-active freestanding membranes for
biomedical applications, such as in tissue engineering and biomedical
applications
Magnetically Multilayer Polysaccharide Membranes for Biomedical Applications
Self-standing
nanocomposite films based on biopolymers and functional
nanostructures have been widely used due to their potential applications
as active elements in biomedical devices. The coupling between chitosan
(CHI) and alginate (ALG) multilayered films and magnetic nanoparticles
(MNPs) allowed to fabricate magnetic responsive freestanding membranes
with a high structural control along the thickness, using the layer-by-layer
(LbL) methodology. The mechanical characterization evidenced a trend
for an increase of both Young modulus, and ultimate tensile strength
with the inclusion of MNPs, or by cross-linking with genipin. Additionally,
the multilayered membranes exhibited shape memory properties triggered
by hydration. The in vitro biological performance studies showed that
cells were more viable and adherent with higher proliferation rates
when MNPs were included in the membranes. Our results suggested the
potential of the developed magneto-active freestanding membranes for
biomedical applications, such as in tissue engineering and biomedical
applications
Multilayered Hierarchical Capsules Providing Cell Adhesion Sites
Liquified capsules featuring (i) an external shell by
layer-by-layer
assembly of poly(l-lysine), alginate, and chitosan, and encapsulating
(ii) surface functionalized poly(l-lactic acid) (PLLA) microparticles
were developed. We hypothesize that, while the liquified environment
enhances the diffusion of essential molecules for cell survival, microparticles
dispersed in the liquified core of capsules provide the physical support
required for cellular functions of anchorage-dependent cells. The
influence of the incorporation of PLL on the regime growth, thickness,
and stability was analyzed. Results show a more resistant and thicker
film with an exponential build-up growth regime. Moreover, capsules
ability to support cell survival was assessed. Capsules containing
microparticles revealed an enhanced biological outcome in cell metabolic
activity and proliferation, suggesting their potential to boost the
development of innovative biomaterial designs for bioencapsulation
systems and tissue engineering products
Multilayered Hierarchical Capsules Providing Cell Adhesion Sites
Liquified capsules featuring (i) an external shell by
layer-by-layer
assembly of poly(l-lysine), alginate, and chitosan, and encapsulating
(ii) surface functionalized poly(l-lactic acid) (PLLA) microparticles
were developed. We hypothesize that, while the liquified environment
enhances the diffusion of essential molecules for cell survival, microparticles
dispersed in the liquified core of capsules provide the physical support
required for cellular functions of anchorage-dependent cells. The
influence of the incorporation of PLL on the regime growth, thickness,
and stability was analyzed. Results show a more resistant and thicker
film with an exponential build-up growth regime. Moreover, capsules
ability to support cell survival was assessed. Capsules containing
microparticles revealed an enhanced biological outcome in cell metabolic
activity and proliferation, suggesting their potential to boost the
development of innovative biomaterial designs for bioencapsulation
systems and tissue engineering products
Sequentially Moldable and Bondable Four-Dimensional Hydrogels Compatible with Cell Encapsulation
Hydrogels
have captivated the attention of several research and
industry segments, including bioengineering, tissue engineering, implantable/wearable
sensors and actuators, bioactive agent delivery, food processing,
and industrial processes optimization. A common limitation of these
systems is their fixed shape. The concept of hydrogel moldability
is often assigned to the injectability potential of liquid precursors,
and this feature is often lost right after hydrogel formation. Hydrogel
modulation is a recent trend that advocates the importance of designing
materials with shape fitting ability targeting on-demand responses
or defect filling purposes. Here, we present a compliant and cell
encapsulation-compatible hydrogel prepared from unmodified natural
origin polymers with the ability to undergo extreme sequential shape
alterations with high recovery of its mechanical properties. Different
fragments of these hydrogels could be bonded together in spatiotemporally
controlled shape- and formulation-morphing structures. This material
is prepared with affordable off-the-shelf polysaccharides of natural
origin using a mild and safe processing strategy based solely on polyelectrolyte
complexation followed by an innovative partial coacervate compaction
and dehydration step. These unique hydrogels hold potential for multifield
industrial and healthcare applications. In particular, they may find
application as defect filling agents or highly compliant wound healing
patches for cargo release and/or cell delivery for tissue regeneration
and cell-based therapies
Sequentially Moldable and Bondable Four-Dimensional Hydrogels Compatible with Cell Encapsulation
Hydrogels
have captivated the attention of several research and
industry segments, including bioengineering, tissue engineering, implantable/wearable
sensors and actuators, bioactive agent delivery, food processing,
and industrial processes optimization. A common limitation of these
systems is their fixed shape. The concept of hydrogel moldability
is often assigned to the injectability potential of liquid precursors,
and this feature is often lost right after hydrogel formation. Hydrogel
modulation is a recent trend that advocates the importance of designing
materials with shape fitting ability targeting on-demand responses
or defect filling purposes. Here, we present a compliant and cell
encapsulation-compatible hydrogel prepared from unmodified natural
origin polymers with the ability to undergo extreme sequential shape
alterations with high recovery of its mechanical properties. Different
fragments of these hydrogels could be bonded together in spatiotemporally
controlled shape- and formulation-morphing structures. This material
is prepared with affordable off-the-shelf polysaccharides of natural
origin using a mild and safe processing strategy based solely on polyelectrolyte
complexation followed by an innovative partial coacervate compaction
and dehydration step. These unique hydrogels hold potential for multifield
industrial and healthcare applications. In particular, they may find
application as defect filling agents or highly compliant wound healing
patches for cargo release and/or cell delivery for tissue regeneration
and cell-based therapies
Singularity of quantitative research: from collecting information to producing results
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