1. Angew. Chem. Int. Ed. 2009, 48, 4406 –4408
Using Azobenzene-Embedded Self-Assembled Monolayers To　Photochemically Control Cell Adhesion Reversibly
nano biomedicine

2. Cell attachment activity of fibronectin can be duplicated by small synthetic fragments of the molecule
Michael D. Pierschbacher & Erkki Ruoslahti
Horst Kessler and co-workers
Nature 309, ,1984
J. AM. CHEM. SOC. 2005, 127,
They used cyclo RGDfK [cyclo (Arg-Gly-Asp-d-Phe-Lys)] in PMMA disc.
Phototriggering of Cell Adhesion by Caged Cyclic RGD Peptides**
MC3T3 E1 mouse osteoblasts were seeded
on the BSA blocked substrate.
Attached cells were quantified by an ELISA.
Aranzazu del Campo*
Angew. Chem. 2008, 120, 3236 –3239

3. Introduction.. Many applications in biology.
Triggering with different external stimuli.
Problem: Existing technologies have mostly relied on irreversible control.
Solution: Azobenzene having isomerization property at different wavelength.
They used the idea that RGD in a background of PEG terminated SAMs allows
specific interaction between cells and surface and will prevent non specific adhesion.

4. Experimental..
They construct a mixed SAMs in two ways.
NHS (N- hydroxysuccinimide)

5. Rinsing with PBS : 3 times (pH 7.4)
Preparation of SAMs..
They used electron beam evaporation of gold (20nm) onto clean glass cover slips with a thin layer of chronium (8nm) to promote adhesion.
Selected way is
Total conc: SAMs-- 2 mmol L-1
0.01%
0.1% 1%
Time of dipping into ethanolic solution 4 hour
Rinsing with PBS : 3 times (pH 7.4)
: 5 times (pH 8.6)
: 3 times (pH 7.4)
: Milli-Q water 3 times
: Pure ethanol 3 times
: Dried with N2
GRGDS conc:-- 2 mgmL-1
Ratio of 3 and 2
Time of dipping in PBS solution of GRGDS --20 minute

6. Cell Adhesion..
Cell used : Murine NIH 3T3 fibroblasts.
Trans rich state : 5 hour visible light and stored in dark for 3 days.
Cis rich area : 10 hour UV irradiation.

7. Conclusion..
SAMs allow us to design and quickly obtain a surface that allows reversible control of cell adhesion on a molecularly well-defined surface.
Believe that by combining with the ability to spatially address surface chemistries, the technique presented herein can be used to control the mobility of parts of a single cell a single cell, or groups of cells directionally at will.
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