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aNanostructured surfaces for blood

proteins selective adsorption

Inês C Gonçalves1,2, Mª Cristina L Martins1, Mário A Barbosa1,2

11 INEB - Instituto de Engenharia Biomédica, Lab. Biomateriais, Porto, PortugalINEB - Instituto de Engenharia Biomédica, Lab. Biomateriais, Porto, Portugal22 Univ. Porto,Univ. Porto, Fac. Engenharia,Fac. Engenharia, Dep. Eng. Metalúrgica & Materiais, Univ. Porto, Porto, PortugalDep. Eng. Metalúrgica & Materiais, Univ. Porto, Porto, Portugal

icastro@ineb.up.pticastro@ineb.up.pt

1º Encontro Ciência em Portugal – Ciência 20071º Encontro Ciência em Portugal – Ciência 2007

Lisboa, 12 Abril 2007Lisboa, 12 Abril 2007

Blood-material interactions

Biomaterial

Protein Adsorption

Inflammation

Complement System

Activation

Leukocyte Adhesion and

Activation

Bacterial Adhesion

Infection

Thrombosis

Platelet Adhesion and

ActivationCoagulation

System Activation

Heart valves Catheters Stents

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

XX XXXX XX XX

S S S S S

XX- (CH2)n- SH

(X = OH; COOH; CH3; NH2; SO3H; etc...)gold

Research purpose

O=C=N-(CH2)17CH3

• selective for albumin

C18 ligand

C18 SAMs (0-10%)

• inhibit non-specific protein adsorption

EG4 SAMsgold

HS-(CH2)11-(O-CH2CH2)4-OH

Develop a model surface that binds albumin in a selective and reversible way in order to decrease the adhesion and activation of platelets.

EG4-C18 SAMs

EG4 10% C18 SAMs

Contact angle

Fourier transform infrared reflection absorption spectroscopy - IRAS

X-ray photoelectron spectroscopy - XPS

Atomic Force Microscopy - AFM

Ellipsometry

Selective & reversible adsorption of Albumin

0

20

40

60

80

100

EG4 2.5% C18 5% C18 10% C18

12

5I-

HS

A R

eten

tion

(%)

Washed with PBS Washed with HSA Washed with HFG

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

HSA 0.1mg/ml

0.0

0.4

0.8

1.2

1.6

2.0

EG4 2.5% C18 5% C18 10% C18

HSA

ads

orbe

d (m

g/m2 )

Albumin increases with the

amount of C18 ligands on

the surface

EG4 2.5% C18 5% C18 10% C18

PBS

HSA

Plasma

Platelet adhesion & activation

(original enlargement 630x)

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aFuture challenges…

Transpose the knowledge obtained with SAMs to polymers

Acknowledgements

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