Highly sensitive label-free electrochemical aptasensors based on photoresist derived carbon for cancer biomarker detection.

-Label-free electrochemical aptasensors for cancer biomarker detection can be a promising means for early detection of cancer due to their high sensitivity, selectivity, and stability, and low cost. In this study, a highly sensitive and selective label-free electrochemical aptasensor based on carbon microelectromechanical systems (C-MEMS) was developed for the detection of platelet-derived growth factor-BB (PDGF-BB). The active electrodes of the aptasensors were synthesized via carbonization of SU-8 derived electrodes at high temperatures in an oxygen-free furnace. An oxygen-plasma oxidation treatment was used to functionalize the C-MEMS electrodes, which provided efficient covalent immobilization of amino terminated affinity aptamers. The turn-off and turn-on detection strategies-based on capacitance and resistance measurement, respectively-were employed. The capacitance detection strategies exhibited a wide linear response range of 0.01-50 nM, with a high sensitivity of 3.33 mF cm-2 Logc-1 (unit of c, nM) and a low limit of detection of 7 pM (S/N = 3). The resistance detection strategies exhibited an even wider linear response range of 0.005-50 nM, and a lower limit of detection of 1.9 pM (S/N = 3), with a high sensitivity of 1.65 × 103 Ω Logc-1 (unit of c, nM). Both detection strategies provided high selectivity for PDGF-BB and high stability of 90.34% after 10 days. This research demonstrates that the developed label-free electrochemical C-MEMS based PDGF-BB aptasensor is highly sensitive, selective, and robust. This aptasensor is a promising prospect for the highly demanding task of early detection of cancer biomarkers.