Fig. 4
From: Combinatorial hydrogels with biochemical gradients for screening 3D cellular microenvironments
Scheme for fabricating orthogonal biochemical gradients and characterization. a Norbornene-modified hyaluronic acid (NorHA) hydrogels were prepared on 5 × 5 × 0.5 mm3 molds via a thiol-norbornene UV light-mediated reaction between NorHA and di-thiol (DTT) crosslinker. b Hydrogels were then incubated in 5 mM mono-thiolated HAV peptide solution for 30 min and a gradient was generated with an opaque horizontal sliding mask to control the extent of light-mediated reaction between HAV peptides and norbornenes in the hydrogel. After washing, the hydrogel was then (c) incubated in 5 mM mono-thiolated RGD peptide solution for 30 min and an opaque sliding mask in the vertical direction was used to introduce a secondary orthogonal gradient. d Images of rhodamine-labeled RGD and fluorescein-labeled HAV orthogonal gradients, including quantified intensity profiles on each side. e Atomic force microscopy (AFM) indention moduli and f encapsulated mesenchymal stem cell (MSC) viability (after 7 days of culture) heat maps of hydrogels with orthogonal peptide gradients. Scale bar: 1 mm
