Label‐Free Direct Electrical Detection of a Histidine‐Rich Protein with Sub‐Femtomolar Sensitivity using an Organic Field‐Effect Transistor

There is a growing interest in achieving sensor systems to enable on‐site testing of biomarkers. Herein, a new strategy for highly sensitive protein detection at sub‐femtomolar levels without any labelling has been demonstrated by using an organic field‐effect transistor (OFET). An artificial histidine‐rich protein receptor (Ni(II)‐nitrilotriacetic acid complex, Ni(II)‐nta) functionalizes a detection portion (i.e. an extended‐gate electrode) of the fabricated OFET device. The OFET responds electrically and selectively to a target analyte (bovine serum albumin), meaning that the binding processes at the Ni(II)‐nta on the extended‐gate electrode for the analyte affect the field‐effect properties of the device. Our results demonstrate that the combination of the OFET with the artificial receptor is an ideal approach for label‐free and immune‐free protein detection.