(715f) Engineering Patterned Signalling Molecule Release Within Hydrogels Via Programmed Reaction and Diffusion Processes

A fundamental challenge in bioreactor design and tissue engineering is that when cells are grown outside of their normal environment, portions of the complex communications cells expect to receive during growth may be missing, leading to changes in function. While some aspects of cellular microenvironment can be synthetically emulated using tools such as microfluidics, the reconstruction of complex signalling gradients and gradients in 3 dimensions remain largely unaddressed.

We present a mechanism for the rational design of complex 2- or 3-dimensional spatial gradients for sustained release of nucleic acids within a hydrogel: the output molecule is released only within regions of the gel that are part of a programmed pattern. This pattern, which can have feature sizes on the scale of microns to centimeters, emerges from a designed network of interactions between interacting synthetic nucleic acid species embedded in the gel.  It requires as input to generate the pattern only a small number of "spots" of specific molecules that control pattern size. As a result, no specialized equipment is required to produce these patterns. We demonstrate the design of simple patterns such as points and lines and then how these structures can be modularly combined to produce more complex patterns.