1. Nanostructured surfaces for blood proteins selective adsorption
Inês C Gonçalves1,2, Mª Cristina L Martins1, Mário A Barbosa1,2
1 INEB - Instituto de Engenharia Biomédica, Lab. Biomateriais, Porto, Portugal
2 Univ. Porto, Fac. Engenharia, Dep. Eng. Metalúrgica & Materiais, Univ. Porto, Porto, Portugal
1º Encontro Ciência em Portugal – Ciência 2007
Lisboa, 12 Abril 2007

2. Blood-material interactions
Bacterial Adhesion
Infection
Thrombosis
Platelet Adhesion and Activation
Coagulation System Activation
Inflammation
Complement System Activation
Leukocyte Adhesion and Activation
Protein Adsorption
Biomaterial
Heart valves
Catheters
Stents

3. Model surfaces - SAMs
Self-assembled monolayers (SAMs) are well-organized organic surfaces, very useful to study the properties of the interface between a material and biological media, at the molecular scale.
Form highly ordered systems
Easy to prepare
Wide range of functional groups to be explored X S
X- (CH2)n- SH
(X = OH; COOH; CH3; NH2; SO3H; etc...)
gold

4. Research purpose
Develop a model surface that binds albumin in a selective and reversible way in order to decrease the adhesion and activation of platelets.
O=C=N-(CH2)17CH3
selective for albumin
C18 ligand
C18 SAMs (0-10%)
inhibit non-specific protein adsorption
EG4 SAMs
gold
HS-(CH2)11-(O-CH2CH2)4-OH

5. EG4-C18 SAMs Contact angle
Fourier transform infrared reflection absorption spectroscopy - IRAS
X-ray photoelectron spectroscopy - XPS
Atomic Force Microscopy - AFM
Ellipsometry

6. Selective & reversible adsorption of Albumin
Albumin increases with the amount of C18 ligands on the surface
The importance of the concentration of C18 ligands was stressed in the reversibility studies since EG4-2.5%C18 SAMs are the only surfaces to exchange almost all the pre-adsorbed HSA by HSA in solution, but not by HFG.
After seeing these results, we decided to investigate the effect of these proteins in a subsequent adhesion of platelets.
EG4-2.5%C18 SAMs are the only surfaces to exchange almost all the pre-adsorbed HSA by HSA in solution, but not by HFG

7. Platelet adhesion & activation
EG4
2.5% C18
5% C18
10% C18
PBS
HSA
Plasma
(original enlargement 630x)

8. Transpose the knowledge obtained with SAMs to polymers
Future challenges…
Transpose the knowledge obtained with SAMs to polymers

9. Acknowledgements INEB FCT for my PhD grant SFRH/BD/18337/2004
FCT for the project POCTI/CTM/55644/2004
Professor Ratner from University of Washington
Portuguese Blood Institute
INEB