Salivary Glucose Detection with Laser Induced Graphene/AgNPs Non-Enzymatic Sensor

The tailoring of novel nanomaterials for sensitive glucose detection through a non-enzymatic mechanism is currently under intensive research. Here, we present a laser-induced graphene (LIG) electrode decorated with silver nanoparticles (AgNPs) as a catalytic element for the direct electrooxidation of glucose. The AgNPs were synthesized through cyclic voltammetry using LIG as a template, resulting in a porous tridimensional assembly with anchored nanostructures. The characterization corroborated the formation of LIG/AgNPs composite with distinctive peaks attributed to Ag2O and AgO interaction with glucose. The proposed non-enzymatic sensors were successfully applied for non-enzymatic amperometric detection, exhibiting a linear range from 1 to 10 mM in the first peak (+0.7 V) and a narrow range from 1 to 2 mM with higher sensitivity of 52.2 mA/mM and improved LOD of 45 μM in the second peak (+0.55 V). The applicability of the LIG/AgNPs sensor was evaluated with spiked artificial saliva in a PoC format using a smartphone potentiostat, showing an average recovery rate of 91%. The analysis was performed in a portable, mobile, and low-cost fashion using a simulated non-invasive sample, with promising results in clinical ranges.