15 research outputs found
Application of layered poly (L-lactic acid) cell free scaffold in a rabbit rotator cuff defect model
<p>Abstract</p> <p>Background</p> <p>This study evaluated the application of a layered cell free poly (L-lactic acid) (PLLA) scaffold to regenerate an infraspinatus tendon defect in a rabbit model. We hypothesized that PLLA scaffold without cultivated cells would lead to regeneration of tissue with mechanical properties similar to reattached infraspinatus without tendon defects.</p> <p>Methods</p> <p>Layered PLLA fabric with a smooth surface on one side and a pile-finished surface on the other side was used. Novel form of layered PLLA scaffold was created by superimposing 2 PLLA fabrics. Defects of the infraspinatus tendon were created in 32 rabbits and the PLLA scaffolds were transplanted, four rabbits were used as normal control. Contralateral infraspinatus tendons were reattached to humeral head without scaffold implantation. Histological and mechanical evaluations were performed at 4, 8, and 16 weeks after operation.</p> <p>Results</p> <p>At 4 weeks postoperatively, cell migration was observed in the interstice of the PLLA fibers. Regenerated tissue was directly connected to the bone composed mainly of type III collagen, at 16 weeks postoperatively. The ultimate failure load increased in a time-dependent manner and no statistical difference was seen between normal infraspinatus tendon and scaffold group at 8 and 16 weeks postoperatively. There were no differences between scaffold group and reattach group at each time of point. The stiffness did not improve significantly in both groups.</p> <p>Conclusions</p> <p>A novel form of layered PLLA scaffold has the potential to induce cell migration into the scaffold and to bridge the tendon defect with mechanical properties similar to reattached infraspinatus tendon model.</p
Highly Water Repellent but Highly Adhesive Surface with Segregation of Poly(ethylene oxide) Side Chains
Polymer
surfaces were modified using methacrylate terpolymers containing
both perfluoroalkyl (R<sub><i>f</i></sub>) groups and poly(ethylene
oxide) (PEO) as side chains in the same molecule. The structure and
properties of the modified surfaces were evaluated using X-ray photoelectron
spectroscopy and by measuring the dynamic contact angles and 90°
peel strength. It was found that not only R<sub><i>f</i></sub> groups but also PEO side chains were segregated on the surface
being against the order of the surface free energy. The terpolymer
modified surface is hydrophobic in air because R<sub><i>f</i></sub> groups are predominant, but it becomes hydrophilic in water
because the surface is covered with PEO side chains. This response
to the environment is rapid and reversible. The modified surface showed
high water repellency because of the surface R<sub><i>f</i></sub> groups and high adhesive strength because of the side chains
Change in the Crystallite Orientation of Poly(ethylene oxide)/Cellulose Nanofiber Composite Films
The crystallite orientation and crystallographic
domain structure
of poly(ethylene oxide) (PEO) in cellulose nanofiber-incorporated
(CNF-incorporated) PEO films developed for packaging materials were
observed using wide-angle X-ray diffraction for different CNF filling
ratios. When a CNF filling ratio of <10 wt % was used, the molecular
chains in the PEO crystallite region were oriented in a direction
perpendicular to the surface of the film; however, when the ratio
was >50 wt %, the PEO molecular chains were oriented in a direction
parallel to the surface of the film. The fiber axis of the CNFs became
parallel to the surface of the PEO/CNF composite film when the filling
ratio was >25 wt %. The change in the orientation of the PEO crystals
occurred because increasing the amount of CNF in the composite films
decreased the space in which the PEO could be crystallized. Furthermore,
the hydrogen bonds between the PEO and the CNF may behave as crystallization
nuclei for the PEO. Our results thus pave the way toward the development
of packaging materials that are more impermeable to gases than the
current materials
Change in the Crystallite Orientation of Poly(ethylene oxide)/Cellulose Nanofiber Composite Films
The crystallite orientation and crystallographic
domain structure
of poly(ethylene oxide) (PEO) in cellulose nanofiber-incorporated
(CNF-incorporated) PEO films developed for packaging materials were
observed using wide-angle X-ray diffraction for different CNF filling
ratios. When a CNF filling ratio of <10 wt % was used, the molecular
chains in the PEO crystallite region were oriented in a direction
perpendicular to the surface of the film; however, when the ratio
was >50 wt %, the PEO molecular chains were oriented in a direction
parallel to the surface of the film. The fiber axis of the CNFs became
parallel to the surface of the PEO/CNF composite film when the filling
ratio was >25 wt %. The change in the orientation of the PEO crystals
occurred because increasing the amount of CNF in the composite films
decreased the space in which the PEO could be crystallized. Furthermore,
the hydrogen bonds between the PEO and the CNF may behave as crystallization
nuclei for the PEO. Our results thus pave the way toward the development
of packaging materials that are more impermeable to gases than the
current materials