Nano-Species Release System Activated by Enzyme-Based XOR Logic Gate

An enzyme-based XOR logic gate was realized at interface of an alginate-modified electrode. The biocatalytic production of H₂O₂ inside the alginate film was controlled by logically processed input signals. The in situ generated H₂O₂ was decomposed to yield free radicals in a Fenton-type reaction catalyzed by iron cations, which were present in the alginate film as cross-linkers stabilizing the hydrogel. The produced free radicals (*OH, *OOH) resulted in decomposition/dissolution of the alginate film removing it from the electrode surface and stimulating release process of magnetic nanoparticles (MNPs) functionalized with a fluorescent dye and entrapped in the alginate film. The release of the MNPs was analyzed by following fluorescence appearing in the solution. The release process followed the logic features of the XOR gate. The present system is the first realization of the enzyme-based XOR gate functionally integrated with the downstream actuation process in the form of the signal-stimulated release.