Laser-Scribed Graphene Electrodes Derived from Lignin for Biochemical Sensing

Laser scribing of porous graphene electrodes on flexible substrates is of great interest for developing disposable electrochemical biosensors. In this work, we present a new patterning process for highly conductive nitrogen-doped graphene derived from a lignin-based precursor. A CO2 laser scribing process was performed under ambient conditions to produce the porous graphene electrodes from lignin. The obtained nitrogen-doped laser-scribed graphene (N-LSG) is binder-free, hierarchical, and conductive. The interconnected carbon network displayed enhanced electrochemical activity with improved heterogeneous electron transfer rate. These features can be attributed to the high conductivity of porous N-LSG (down to 2.8 Ω per square) and its enriched active edge-plane sites. Furthermore, the N-LSG electrodes were decorated with MXene/Prussian blue (Ti3C2Tx/PB) composite via a simple spray-coating process, designed for sensitive detection of analytes. The Ti3C2Tx/PB-modified N-LSG electrodes were functionalized with catalytic enzymes for detecting glucose, lactate, and alcohol. The enzyme/Ti3C2Tx/PB/N-LSG electrodes exhibited remarkably enhanced electrochemical activity toward the detection of these biomarkers with a performance on par with previously reported on-chip carbon-based biosensors. Therefore, these materials have high potential for applications in personalized healthcare.