Single-atom doping of MoS(2) with manganese enables ultrasensitive detection of dopamine: Experimental and computational approach

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 MoS(2) 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.