A label-free electrochemical aptasensor for the detection of cancer antigen 125 based on nickel hexacyanoferrate nanocubes/polydopamine functionalized graphene

A highly sensitive label-free electrochemical aptasensor has been proposed to detect ovarian cancer biomarker cancer antigen 125 (CA125) based on nickel hexacyanoferrate (NiHCF) nanocubes as the in-situ signal probe and polydopamine functionalized graphene ([email protected]) as substrate. NiHCF is a promising candidate in sensing analysis due to its highly reversible redox ability, good stability and easy synthesis. The [email protected] substrate can not only effectively enhance the conductivity and electrochemical activity of the NiHCF, but also covalently interact the aminoated CA125 aptamers with polydopamine by Michael addition reaction. Upon binding of CA125 to the electrode surface by the specifically recognition of aptamer, an insulating layer formed and the electron transfer rate reduced, resulting in the decrease of NiHCF signal. The decreased electrochemical signal can be used to detect CA125 quantitatively. As a result, the designed platform showed excellent sensitivity toward CA125 with a linear response range from 0.10 pg/mL to 1.0 μg/mL and a low detection limit of 0.076 pg/mL. More importantly, this sensing strategy can be extended to detect other biomolecules by simply substituting the aptamer in accordance with the demand.