An electrochemical immunosensor based on a 3D carbon system consisting of a suspended mesh and substrate-bound interdigitated array nanoelectrodes for sensitive cardiac biomarker detection.

We developed an electrochemical redox cycling-based immunosensor using a 3D carbon system consisting of a suspended mesh and substrate-bound interdigitated array (IDA) nanoelectrodes. The carbon structures were fabricated using a simple, cost-effective, and reproducible microfabrication technology known as carbon microelectromechanical systems (C-MEMS). We demonstrated that the 3D sub-micrometer-sized mesh architecture and selective modification of the suspended mesh facilitated the efficient production of large quantities of electrochemical redox species. The electrochemically active surfaces and small size of IDA nanoelectrodes with a 1:1 aspect ratio exhibited high signal amplification resulting from efficient redox cycling of electrochemical species (PAP/PQI) by a factor of ~25. The proposed selective surface modification scheme facilitated efficient redox cycling and exhibited a linear detection range of 0.001-100 ng/mL for cardiac myoglobin (cMyo). The specific detection of cMyo was also achieved in the presence of other interfering species. Moreover, the proposed 3D carbon system-based immunosensor successfully detected as low as ~0.4 pg/mL cMyo in phosphate-buffered saline and human serum.