Figure 1.

Schematic representation of the aptamer-based electrochemical sensor for the detection of HspX antigen in CSF.

Notes: The aptamer is thiol-labelled at the 3′ end that allows self-assembly of aptamer on a gold-coated electrode. The redox label (MB) is attached at the 5′ of the aptamer and it is in close proximity to the electrode surface, thereby allowing rapid electron transfer. The presence of HspX induces a structural change in the aptamer which increases the distance between MB and the electrode, and electron transfer is thus reduced. The differences in faradaic current before and after addition of HspX were quantified using DPV.

Abbreviations: MB, methylene blue; CSF, cerebrospinal fluid; DPV, differential pulse voltammetry.