Supramolecular DNA Photonic Hydrogels for On-Demand Control of Coloration with High Spatial and Temporal Resolution
Yixiao Dong, J. Dale Combs, Cong Cao, Eric R. Weeks, Alisina Bazrafshan, Sk Aysha Rashid, Khalid Salaita
Abstract
Hydrogels embedded with periodic arrays of nanoparticles display a striking photonic crystal coloration that may be useful for applications such as camouflage, anticounterfeiting, and chemical sensing. Dynamically generating color patterns requires control of nanoparticle organization within a polymer network on-demand, which is challenging. We solve this problem by creating a DNA hydrogel system that shows a 50 000-fold decrease in modulus upon heating by ∼10 °C. Magnetic nanoparticles entrapped within these DNA gels generate a structural color only when the gel is heated and a magnetic field is applied. A spatially controlled photonic crystal coloration was achieved by photopatterning with a near-infrared illumination. Color was "erased" by illuminating or heating the gel in the absence of an external magnetic field. The on-demand assembly technology demonstrated here may be beneficial for the development of a new generation of smart materials with potential applications in erasable lithography, encryption, and sensing.