Pyrolyzed Walnut Shell‐Based Flexible Electrodes for Magnetically Triggered ON/OFF DNA Release

A magnetically gated, enzymatically driven DNA release platform based on sustainable pyrolyzed walnut shell‐derived carbon electrodes is reported. Upon glucose addition under aerobic conditions, biocatalytic oxygen reduction at the cathode induces a local pH increase, resulting in electrostatic repulsion of negatively charged 5(6)‐carboxyfluorescein‐labeled DNA (FAM‐labeled DNA). Electrochemical analysis reveals an oxygen reduction reaction (ORR) onset potential of +0.576 ± 0.003 V vs. Ag/AgCl and a maximum current of −8.2 ± 0.4 μA. Electrochemical impedance spectroscopy (EIS) confirms a post‐ORR increase in interfacial resistance from 6.2 ± 0.5 to 11.1 ± 0.9 kΩ. DNA release reaches 97% after 400 min, corresponding to a surface density of 22 ± 4 nmol cm −2 . A competing enzymatic gate, composed of co‐immobilized glucose oxidase and catalase (GOx–CAT) on magnetic nanoparticles (MNPs), enables remote suppression of electron flow and DNA release upon application of a 0.3 T magnetic field. Under “OFF” conditions, DNA release is reduced to 1%, and anodic current decreases by 60%. The system exhibits excellent reversibility over four ON–OFF cycles with minimal performance degradation. This bioelectronic platform represents a self‐powered, reversible strategy for stimuli‐responsive drug release.