(315c) Aptasensors Based on Graphene Field-Effect Transistors for Arsenite Detection

All-electronic chemical sensors based on field-effect transistors (FETs) hold tremendous promise for rapidly and sensitively detecting arsenic in groundwater. Their sensitivity, however, is fundamentally limited by a chemical gating mechanism where target ion charges are directly measured. We have developed a highly sensitive aptasensor, based on graphene FET arrays using CVD-grown graphene and the scalable photolithography process. The resulting aptasensor relies on the conformational change of the negatively charged aptamer upon arsenite binding, offering a wide analytical range, from 0.05 to 1000 ppb with excellent specificity against nonspecific ions, and also with a 0.02 ppb detection limit. Circular dichroism spectroscopy studies confirmed the conformational change of the aptamer, and molecular dynamic studies further validated that arsenite had bound with the hairpin loop of the aptamer, with higher interaction energy compared with other positions, signifying the location of the binding cavities of the arsenite ions and the aptamer. This work provides a highly accurate chemical sensing platform for the rapid detection of arsenite in drinking water.