Label‐free Selective Detection of Protein Markers in the Picomolar Range via a Convenient Voltammetric Sensing Strategy

A convenient strategy for the preparation of label‐free selective protein biomarker sensors is presented. After formation of a ferrocene terminated monolayer on a gold electrode using thiol chemistry, grafting of an antifouling phenylalanine layer onto the preformed ferrocene monolayer is achieved by diazonium chemistry. This provides a platform for receptor (anti‐BSA or anti‐CRP) immobilization as well an antifouling interface. Specific target binding leads to attenuation of the voltammetric faradaic signal of the underlying ferrocene group. Thereby, label‐free, selective, voltammetric detection is achieved with highly competitive limits of detection in the low (≤4) picomolar range for both BSA and CRP.