63 research outputs found
Differential attraction and repulsion of Staphylococcus aureus and Pseudomonas aeruginosa on molecularly smooth titanium films
Magnetron sputtering techniques were used to prepare molecularly smooth titanium thin films
possessing an average roughness between 0.18â
nm and 0.52â
nm over 5 ÎŒm Ă 5 ÎŒm AFM scanning
areas. Films with an average roughness of 0.52â
nm or lower were found to restrict the extent
of P. aeruginosa cell attachment, with less than 0.5% of all available cells being
retained on the surface. The attachment of S. aureus cells was also limited on films
with an average surface roughness of 0.52â
nm, however they exhibited a remarkable propensity
for attachment on the nano-smoother 0.18â
nm average surface roughness films, with the
attachment density being almost twice as great as that observed on the nano-rougher film.
The difference in attachment behaviour can be attributed to the difference in morphology of
the rod-shaped P. aeruginosa compared to the spherical S. aureus cells
Influence of packing density and surface roughness of vertically-aligned carbon nanotubes on adhesive properties of gecko-inspired mimetics.
We have systematically studied the macroscopic adhesive properties of vertically aligned nanotube arrays with various packing density and roughness. Using a tensile setup in shear and normal adhesion, we find that there exists a maximum packing density for nanotube arrays to have adhesive properties. Too highly packed tubes do not offer intertube space for tube bending and side-wall contact to surfaces, thus exhibiting no adhesive properties. Likewise, we also show that the surface roughness of the arrays strongly influences the adhesion properties and the reusability of the tubes. Increasing the surface roughness of the array strengthens the adhesion in the normal direction, but weakens it in the shear direction. Altogether, these results allow progress toward mimicking the gecko's vertical mobility.The authors acknowledge funding from the EC project Technotubes.This is the accepted manuscript. The final version is available at http://pubs.acs.org/doi/abs/10.1021/am507822b
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
(6merĂŸBSP). 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, 6merĂŸBSP,
and control films consisting of only the silk component (6mer). The
behavior of the 6merĂŸBSP 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 Ca2ĂŸ 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)
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