Liquid-phase epitaxial grown UiO-66 as a bifunctional platform for electrochemical Aptasensing of cardiac troponin I

The construction of multifunctional nanointerface bearing rich active site for aptamer immobilization and effective signal transformation is critical for the development of high-performance electrochemical aptasensor. Herein, a layer of p-mercaptobenzoic acid (p-MBA) was self-assembled on the surface of bare gold electrode (AuE), acting as a scalfod for the consequent liquid-phase epitaxial growth of Universitetet i Oslo-66 (UiO-66) metal-organic framework via immersion in zirconium ions (Zr⁴⁺) and p-terephthalic acid (PTA) ligand. Then, the UiO-66 was utilized as a bifunctional platform for immobilization of aptamer probe for cardiac troponin I (cTnI) and the electrochemical signal transformation as an electrocatalyst. Electrochemical experiments showed that UiO-66 has catalase-like properties for electrocatalytic reduction of H₂O₂, while when the aptamer interacts with cTnI to form a complex, the catalytic acttivity is inhibited. The catalytic currents in chronoamperometric measurements showed a good linear relationship with the negative logarithm of the target concentration in the range of 100 fg mL^-1-100 ng mL^-1, and the detection limit was 13 fg mL^-1. The aptasensor has good selectivity for cTnI and can be used for the detection of cTnI in human serum samples.