Chemical organization in reaction-diffusion systems offers a strategy for the generation of materials with ordered morphologies and structural hierarchy. Periodic structures are formed by either molecules or nanoparticles. On the premise of new directing factors and materials, an emerging frontier is the design of systems in which the precipitation partners are nanoparticles and molecules. We show that solvent evaporation from a suspension of cellulose nanocrystals (CNCs) and l-(+)-tartaric acid [l-(+)-TA] causes phase separation and precipitation, which, being coupled with a reaction/diffusion, results in rhythmic alternation of CNC-rich and l-(+)-TA–rich rings. The CNC-rich regions have a cholesteric structure, while the l-(+)-TA–rich bands are formed by radially aligned elongated bundles. The moving edge of the pattern propagates with a finite constant velocity, which enables control of periodicity by varying film preparation conditions. This work expands knowledge about self-organizing reaction-diffusion systems and offers a strategy for the design of self-organizing materials.

Epilepsy is represented by a set of neurological disorders that result in recurring seizures and convulsions. Although several types of the condition have been characterized, the underlying cause for these remains largely unknown. A number of molecular biomarkers for epilepsy have been identified including glutamate, γ-aminobutyric acid, and miRNAs. In addition, a special role appears to be played by the potassium cation. Detection of these species is anticipated to assist in both diagnosis and fundamental understanding of the condition. This review details the application of a number of biosensor devices that have been designed specifically for the detection of both molecular biomarkers and the K+ cation in proximity to an animal cortex. These devices offer considerable potential not only for diagnostic goals, but also for study of the cause and spread of the epileptic seizure, especially if such biosensors can detect analytes in a multiplexed, real-time manner.