Peptide-Functionalized Laser-Induced Graphene for Selective Detection of 2,4-Dinitrotoluene

Selective detection of nitroaromatic compounds remains a major challenge because graphene-based chemiresistive sensors are often governed by nonspecific adsorption and limited molecular discrimination. Here, we report a peptide-functionalized laser-induced graphene (LIG) platform for the selective detection of 2,4-dinitrotoluene (DNT) through biomolecular recognition. LIG was fabricated via single-step CO 2 laser carbonization of polyimide and was subsequently functionalized through EDC/NHS-mediated covalent immobilization of DNT-specific binding peptides. Structural and chemical characterization by XRD, Raman spectroscopy, FTIR, XPS, and SEM/EDS confirmed successful peptide immobilization while preserving the underlying sp 2 graphitic network of LIG. Electrical characterization using a Kelvin (pseudofour-point) configuration demonstrated stable ohmic behavior and a measurable increase in resistance after peptide functionalization. The peptide-functionalized LIG sensor exhibited a concentration-dependent chemiresistive response toward DNT over a wide dynamic range (10 –9 –10 –1 M) with an approximately linear semilogarithmic relationship ( R 2 = 0.93) and a limit of detection of 1.3 × 10 –8 M. Selectivity studies revealed substantially lower relative responses toward nitrotoluene (0.33), toluene (0.16), nitrobenzene (0.40), benzene (0.20), and ethanol (0.092) relative to DNT. These findings demonstrate a scalable biofunctionalized graphene platform for selective nitroaromatic sensing under controlled laboratory conditions.