Elucidation of Enhanced Lysine Sensing via Pt-Functionalized 2D WS₂ for Biosensing Applications

Amino acids (AAs) are vital biomolecules and important biomarkers for disease diagnosis, motivating the development of sensitive and selective detection methods. Among them, lysine (LYS) plays a crucial role in protein synthesis, and abnormal concentrations are linked to disorders such as anemia, neurological agitation, and cardiovascular disease. Therefore, the accurate detection of LYS is essential. Two-dimensional transition metal dichalcogenides (2D TMDCs) have emerged as promising receptor-free biosensing platforms due to their direct charge transfer capability upon biomolecular adsorption. However, pristine TMDCs often exhibit limited sensitivity and selectivity. Here, we functionalized monolayer WS₂ (1L-WS₂) with platinum nanoparticles (Pt NPs) using atomic layer deposition (ALD) to enhance biosensing performance. Pt NPs induced n-type doping of the WS₂ channel, thereby improving its sensitivity to LYS. The Pt NPs predominantly exhibited (111) facets, enabling stronger covalent or hydrogen bonding interactions with amino acids. The Pt-functionalized WS₂ (Pt-WS₂) biosensors showed markedly improved sensitivity and selectivity toward LYS compared with pristine WS₂. Density functional theory (DFT) calculations further revealed increased adsorption energy and charge transfer of LYS on Pt-WS₂, corroborating the experimental results. These findings highlight metal NP functionalization as an effective strategy to advance 2D TMDC-based biosensors for practical applications.