Single-atom doping of MoS₂ with manganese enables ultrasensitive detection of dopamine: Experimental and...

Two-dimensional transition metal dichalcogenides (TMDs) emerged as a promising platform to construct sensitive biosensors. We report an ultrasensitive electrochemical dopamine sensor based on manganese-doped MoS₂ synthesized via a scalable two-step approach (with Mn ~2.15 atomic %). Selective dopamine detection is achieved with a detection limit of 50 pM in buffer solution, 5 nM in 10% serum, and 50 nM in artificial sweat. Density functional theory calculations and scanning transmission electron microscopy show that two types of Mn defects are dominant: Mn on top of a Mo atom (Mn_topMo) and Mn substituting a Mo atom (Mn_Mo). At low dopamine concentrations, physisorption on Mn_Mo dominates. At higher concentrations, dopamine chemisorbs on Mn_topMo, which is consistent with calculations of the dopamine binding energy (2.91 eV for Mn_topMo versus 0.65 eV for Mn_Mo). Our results demonstrate that metal-doped layered materials, such as TMDs, constitute an emergent platform to construct ultrasensitive and tunable biosensors.