4. Self-assembled Monolayers (SAM)
SAMs have been developed since 1980s.
SAM formation is induced by the strong chemical
adsorption with selected organic molecule.
SAMs give opportunity to control the thickness of
monolayer.
SAMs are composed with end group, alkyl group and
functional group.
5. Aminopropyltrimethoxysilane (APTS)
APTS is composed by amino group, alkyl
chain, and methoxy groups.
Surface and APTS (SAM) interaction is
occurred between –OH (from active surface)
and methoxy groups.
Amino groups provide to be bond the amino
acids easily such as histidine, leucine,
tryptophan, and serine.
6. Protein Adsorption
In the literature there are a lot of cell-surface interaction
studies.
However, proteins interact with the surface before cell-
surface interaction, if we think in nano scales.
Due to that reason we should consider that protein
adsorption studies should be prior then cell studies to
achieve better understanding.
In this study, immunoglobulin G (IgG), albumin and
fibrinogen will be used to investigate the protein adsorption.
7. Aim of the Study
To form self- assembled monolayers with newly synthesized
molecules
To investigate the surface modification of hydrophilic and
hydrophobic amino acids.
To evaluate biocompatibility of modified metallic and inorganic
surfaces
To evaluate usage of some amino acids such as histidine,
leucine, serine, tryptophan because of their benefits and duty
for human body.
To examine the protein adsorption onto SAM coated metallic
and inorganic surfaces
8. Sterilization and Activation of Surfaces
Wafers will be washed by deionized water and ethanol.
Then, they will be washed NH3, H2O, and deionized water
solution at 70°C for 20 min.
After that, surfaces will be washed with ethanol and will be
dried by nitrogen flow.
For surface activation, oxygen plasma method will be
performed.
9. Optimization of SAM
Wafers will be immersed in amino acid conjugated SAM
solution in:
o Different concentration (1-20mM)
Then after the determination of concentration, dipping time
will be evaluated:
o Different dipping time (30min-24h)
After that, determined concentration and dipping time will be
used in order to analyze protein adsorption by QCM
biosensor.
11. Surface Characterization
Contact Angle Measurement Device
To determine wettability of the surfaces
Atomic Force Microscope (AFM)
To determine roughness of surfaces
X-Ray Photoelectron Spectroscopy (XPS or ESCA)
To evaluate the chemical state of samples before and after modification
Ellipsometry
To measure the height and thickness of amino acid conjugated SAMs
12. Protein Adsorption Characterization
Quartz Crystal Microbalance (QCM) Biosensor
o To analyze protein adsorption of amino acid conjugated SAMs
by monitoring the change in resonance frequency of the quartz
plate (at 5Mhz).
o Crystals are;
Especially Au/SiO2 will be used
And/or Ti, Au/Ti, Ti/Al
o Proteins which will be analyzed:
Immunoglobulin G (IgG)
Albumin
Fibrinogen
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