Nanostructured aptamer-based sensing platform for highly sensitive recognition of myoglobin

A composite was prepared from PtSn nanoparticles and carbon nanotubes (PtSnNP/CNTs) and applied to the electrochemical determination of myoglobin (Mb). An Mb-aptamer was immobilized on a glassy carbon electrode (GCE), and hexcyanoferrate was used as an electrochemical probe. The PtSnNP/CNTs were synthesized by a microwave-aided ethylene glycol reduction method. Detection is based on electron transfer inhibition that is caused by the folding and conformational change of the Mb-aptamer in the presence of Mb. The amperometric signal for hexacyanoferrate, best measured at 0.2 V vs. Ag/AgCl depends on the concentration of Mb that interacts with the aptamer on the GCE. This approach is selective and sensitive for Mb due to (a) the highly specific recognition ability of the aptamer for Mb, (b) the powerful electronic properties of carbon nanotubes, (c) the arranged decoration of CNTs with PtSnNPs, and (d), the superior electron transfer to hexacyanoferrate. The assay is highly selective, with linear relationships from 0.01-1 nM and 10 nM-200 nM, and a limit of detection as low as 2.2 +/- 0.1 pM. The modified GCE was applied to the quantitation of Mb in spiked human serum samples.