Mechanical modulation of photo-responsive DNA-PEG biosynthetic composites

Photo-responsive materials can change their physical or chemical properties in response to light, enabling a wide range of applications from 3D printing to wound healing. Bio-synthetic polymer composites are also promising platforms that leverage the multifunctionality and responsiveness of biopolymers with the commercial availability and established characterization of synthetic polymers. Here we design photo-responsive bio-synthetic composites that tunably alter their mechanical properties in response to light. Specifically, we use DNA as a mechanical scaffold which we responsively crosslink using 4-arm polyethylene glycol (PEG) functionalized with UV-responsive DNA intercalators. Using single-particle tracking microrheology, we measure time-varying particle transport and rheological properties during UV-illumination. We tune the mechanical trajectory of the composite during the gelation process by varying the DNA topology, PEG:DNA ratio and illumination intensity, thereby mapping the mechanics-formulation space of the composites. Our work sheds important new light on designing photo-responsive biocompatible materials such as bioinks for additive manufacturing.