1. Paper Introduction
by Md. Jahirul Islam

2. Cell Adhesion Behavior Switching by Photo and Electro-Chemical Manner
Irreversible Control in Switching
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Mrksich M. et al. , J. Am. Chem. Soc.
2003 , 125 , 14994
Nakanishi J. et. al, Biomaterials 2012 , 33 , 2409

3. Cell Adhesion Behavior Switching by Thermoresponsive materials/ Bio-functionalized Azobenzene
Reversible Control in Switching but lack of high spatial and temporal resolution
completely reversible control of cell adhesion yet needed long time irradiation (more than 1h)
Jiang , X. et. al, Angew. Chem. Int. Ed , 48 ,
4406
Griesser H. J. et. al ,
Biomaterials 2009 , 30 , 1827

4. Rapid Reversible Photoswitching of Cell Adhesion (this work)
47% cis
A) Structure of the c(RGDfK)-azobenzene and covalent immobilization on glass. B) Mixed monolayer of polyethylene glycol (PEG) and c(RGDfK)-azobenzenes. UV illumination switches the azobenzene from the trans to the cis isomer and the c(RGDfK) headgroup (black circle) is immersed into the nonadhesive PEG background
UV–vis spectra verify reversible photoswitching of the mixed monolayer

5. Reversible Photoswitching of Cell Adhesion Study by Cell culture Assay
Fibroblasts (REF52wt) were seeded for 15 min onto either trans or cis Azobenzene surface
(A) Cells (REF52 wt) before irradiation. (B) Cells after 30 sec irradiation with 365 nm. (C) Cells after irradiating 30 sec with 365 nm and another 30 sec with 440 nm. No change in cell conformation can be observed.
Control Exp

6. Cantilever deflection is a measure of force acting on the cell
Reversible Photoswitching of Cell Adhesion Study by Single Cell Force Spectroscopy (SCFS)
Cell adhesion force measurement
Cantilever
Cantilever deflection is a measure of force acting on the cell
Control Exp.
Single-cell force spectroscopy control
experiment on blank glass after irradiation at 440 nm and 365 nm (cell-surface contact time:
1 sec, ≥ 80 force-distance curves for each situation).

7. Conclusion
Demonstration of efficient cell adhesion swithing at considerably shorter UV illumination
SCFS-based approach demonstrates the true reversibility of cell adhesion switching

8. Thank you for your kind attention