ENGINEERING ARTIFICIAL STEM CELL NICHES - Biologically-Responsive Hybrid Biomaterials - page 284

A

B C

D

Fig. 4. Microcontact printing to generate artificial niches via site-selective attachment of niche
proteins: A heterofunctional PEG linker is used to covalently attach ProteinA to PEG hydrogel
networks (a). Subsequently, ProteinA site-selectively anchors Fc-chimeric proteins on hydrogel
microwell arrays. Overview of multistep process to locally immobilize Fc-chimeric proteins to the
bottom of hydrogel microwells (b). Proof-of-principle experiments demonstrating the spatial
control of protein (here: FITC-labeled BSA) immobilization afforded by the hydrogel microcontact
printing process (c). Scale bar = 200 µm. Anchoring on the bottom of individual microwells (right
panel) rather than on the entire surface of the microwell array (left panel) can be achieved. 3D
confocal micrographs of projection of 84 stacks acquired at a constant slice thickness of 1.8 m.
Immobilization of Fc-chimeric proteins via selective binding to ProteinA. Alexa-conjugated Fc-
fragment and Fc-N-Cadherin were tethered and detected via fluorescence microscopy according to
the schemes (d, left & middle panels). Scale bar = 100 µm. As negative controls (right panels),
microwell arrays are shown that are not tethered with ProteinA or treated with isotype control
primary antibody. Reproduced with permission from 72 . Copyright 2008 Royal Society of
Chemistry.