Electrochemical aptasensor for determination of testosterone using an aptamer-nanogold-metal-organic framework-ionic liquid modified carbon paste electrode

The present study is based on the design and construction of a selective label-free electrochemical aptasensor for testosterone (TST) detection in real samples. A carbon paste electrode modified with gold nanoparticles and metal-organic framework-ionic liquid (AuNPs/Fe₃O₄–NH₂@Cu-ILCPE) was used to covalently immobilize the TST aptamer (TST-apt). The AuNPs/Fe₃O₄–NH₂@Cu-ILCPE represents a distinguished ability for enhancement of electrochemical peak current, which may emerge from the aptamer on the electrode surface. Initially, the dependency of signals to variables like the aptamer concentration, aptamer immobilization time, AuNPs electrodeposion time, and aptamer reaction time was investigated and optimized. Under the optimized conditions, the proposed aptasensor has two linear ranges over 1.0–50.0 nM and 50.1–1000.0 nM with a limit of detection of 0.31 nM, and a limit of quantification of 0.99 nM. The aptasensor was also applicable to detecting TST in urine samples with satisfactory recoveries of 97.2–103.8 %.