Dual signal amplified electrochemical aptasensor based on PEI-functionalized GO and ROP for highly sensitive detection of cTnI

Cardiac troponin I (cTnI) is considered as the gold standard for the diagnosis of acute myocardial infarction (AMI) because of its excellent specificity and sensitivity. Herein, a novel aptasensor based on the dual signal amplification strategy of Polyethyleneimine functionalized Graphene oxide (GO) and ring-opening polymerization (ROP) for the first time was successfully constructed to achieve high sensitivity detection of cTnI. Briefly, cTnI-aptamer 1 (Apt1) was immobilized on the surface of gold electrode by self-assembly of Au-S bonds to specifically capture cTnI. After specific recognition of cTnI, Apt2 coated PEI-functionalized GO composites acted as macroinitiators for the subsequent ROP reaction. Next, α-amino acid-N-carboxylic acid anhydride ferrocene derivatives (NCA-Fc), the monomer for ROP reaction, was added to the electrode surface. The combined application of PEI-functionalized GO and NCA-Fc better achieves the high sensitivity and signal amplification of the aptasensor. Under optimal conditions, the aptasensor exhibited a wide linear range of 10 fg mL−1 to 10 ng mL−1 and the limit of detection was 3.78 fg mL−1. Moreover, this method displayed the advantages of good selectivity, simple operation and excellent stability. Meanwhile, the aptasensor had good accuracy and applicability even in real serum samples analysis, demonstrating its considerable application potential in biomedical assays.