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.