Nanometric protein-patch arrays on glass and polydimethylsiloxane for cell adhesion studies

We present a simple cost-effective benchtop protocol to functionalize glass and polydimethylsiloxane (PDMS) with nanometric protein patches for cell adhesion studies. Evaporation masks, covering macroscopic areas on glass, were made using improved strategies for self-assembly of colloidal microbeads which then served as templates for creating the protein patch arrays via the intermediate steps of organo-aminosilane deposition and polyethylene-glycol grafting. The diameter of the patches could be varied down to about 80 nm. The glass substrates were used for advanced optical imaging of T-lymphocytes to explore adhesion by reflection interference contrast microscopy and the possible colocalization of T-cell receptor microclusters and the activating protein patches by total internal reflection fluorescence microscopy. The selectively functionalized glass could also serve as template for transferring the protein nanopatches to the surface of a soft elastomer. We demonstrated successful reverse contact printing onto the surface of thin layers of PDMS with stiffness ranging from 30 KPa to 3 MPa.