Biomedical Engineering Reference
In-Depth Information
Stainless steels (SS) are extensively used in biomaterials researches and other applications
involving contact with biologic compounds, owing to their adaptable mechanical properties,
their manufacturability and their outstanding corrosion resistance. For instance, SS may be
used in the manufacture of vascular stents, guide wires, or other orthopedic implants
(Hanawa, 2002, Ratner, 2004). In these conditions, SS are subjected to the adsorption of
biomolecules (proteins, polysaccharides, lipids) and biological materials (cellular debris).
The surface modification of SS may thus be important to orient the host response as desired.
The present work is dedicated to the surface composition of 316L SS surfaces at different
stages of the procedure used to graft a protein via the use of APTES and of a bifunctional agent
expected to link the NH
2
-terminated silane with NH
2
groups of the protein. Glucose oxidase
was chosen as a model protein for reasons of convenience owing to previous works related to
microbiologically influenced corrosion (Dupont et al., 1998, Landoulsi et al., 2009, Landoulsi et
al., 2008b, Landoulsi et al., 2008c). A particular attention is given to (i) the real state of the
interface (composition, depth distribution of constituents) at different stages and (ii) the mode
of protein retention. Therefore, X-ray photoelectron spectroscopy is used in a way (angle
resolved measurements, reasoned peak decomposition, validation by quantitative
relationships between spectral data) to provide a speciation in terms of classes of compounds
(silane, protein, contaminants), using guidelines established in previous works (Genet et al.,
2008; Rouxhet & Genet, 2011). Water contact angle measurements are used to address the issue
of the presence of contaminants and the perspectives of avoiding it.
Substrate
Linker
Biomolecule
Reference
a. Substrate preparation
b. APTES treatment
c. Evaluation of efficiency regarding biomolecule activity. Substrate taken as blank
d. Interface characterization
Stainless steel
EDC
Alginate
Yoshioka et al., 2003
a. Sonication in acetone, 5 min; heating 2 h at 500°C in air.
b. In toluene, 1h; rinsing in toluene and ethanol; sonication in ethanol, 5 min; drying in air;
curing 10 min at 105°C.
c. Preventing adsorption of blood-clotting proteins. Blanks = native, silanized.
d. XPS: elemental concentration, consistent evolution according to reaction steps; C 1s
peak, demonstration of alginate retention, majority of carbon of C-(C,H) type at all stages.
Stainless steel
GA
Lysozyme
Minier et al., 2005
a. Acid etching at 60 °C; rinsing in water; drying under N
2
gas flow.
b. In ethanol/water, 3 min; curing 1 h at 100-150 °C in air; rinsing with water.
c. Increase of the enzymatic activity in bacterial lysis. Blanks = native + enzyme, silanized
+ enzyme.
d. IRRAS: Characteristic bands of APTES. XPS: elemental concentration, consistent
evolution according to reaction steps; N/Si ratio vs photoelectron collection angle,
consistent evolution.
Stainless steel stent
none
Chitosan/heparin
LbL film
Meng et al., 2009
a. Cleaning in ethanol/water (1/1, v/v); rinsing in water; drying under reduced pressure,
24 h at 30 °C.
b. In ethanol, 4 h at 37 °C; rinsing in water, drying in air at 50 °C.
c. Promoting re-endothelialization after stent implantation, improvement of
