Label-free electrochemical detection of human α-thrombin in blood serum using ferrocene-coated gold nanoparticles

► We report a novel approach to label-free electrochemical detection of human α-thrombin in human blood serum that utilizes ferrocene coated gold nanoparticles (Fc-AuNPs). ► The fundamental electrostatic interaction between the positively charged Fc-AuNPs and the negatively charged phosphate backbone of the aptamer is the basis of our quantitative analysis of human α-thrombin. ► Human α-thrombin was specifically bound by the thiolated aptamers immobilized on the gold electrode. ► Positively charged Fc-AuNPs were electrostatically bound to the negatively charged aptamers.