A one-step aptasensor for ultrasensitive detection of lung cancer marker homocysteine based on multifunctional carbon nanotubes by square-wave voltammetry

In this work, a one-step aptasensor for ultrasensitive detection of homocysteine (HCY) is developed based on multifunctional carbon nanotubes, which is magnetic multi-walled carbon nanotubes (Fe3O4@MWCNTs) com-bined with the aptamer (Apt) for HCY (Fe3O4@MWCNTs-Apt). Fe3O4@MWCNTs-Apt have multiple functions as follows. (1) Apt immobilized could selectively capture all target molecules HCY in the sample; (2) Magnetic Fe3O4 nanoparticles could separate all target molecules HCY captured by Apt from the sample substrate to eliminate the background interference and achieve one-step preparation of the aptasensor; And (3), MWCNTs with good electrical conductivity become a new electrode surface, construct a three-dimensional electrode surface network, make the electron transfer easier and thus then enhance the signal response. Results show that there is a good linear relationship between peak current of square-wave voltammetry (SWV) and HCY concen-tration in the range of 0.01 & mu;mol/L-1 & mu;mol/L, with a limit of detection (LOD) 0.002 & mu;mol/L. And, selectivity, reproducibility, precision and accuracy are all satisfactory. In addition, it could be applied to the detection of HCY in the plasma of lung cancer patients successfully, suggesting that this one-step aptasensor for HCY has a potential in practical clinical applications.