Photomodulation of cellular gene expression in hydrogels

Biomaterials are designed to mimic aspects of various extracellular matrix environments, through chemical modifications to input biological or chemical signals. However, the dynamic nature and timing of gene expression during cellular events is much more difficult to mimic and control in these synthetic environments. Here, we utilized concepts of photochemistry combined with click chemistry for synthetic biology applications to modulate cellular gene expression in poly(ethylene glycol) (PEG) hydrogels. Specifically, a genetic inducer, isopropyl β-d-1-thiogalactopyranoside (IPTG), is covalently linked to PEG via a biocompatible and easy to synthesize 2-(2-azido-6-nitrophenyl) ethoxycarbonyl (ANPEOC) photocleavable moiety that, on a short exposure to UV light, effectively releases IPTG and activates gene expression of enhanced green fluorescence protein (EGFP). We anticipate that combining concepts of material chemistry with synthetic biology will further enable the construction of highly defined engineered niches that are capable of controlling both intrinsic and extrinsic cellular events.