Fabricating Pt/Sn-In₂O₃ Nanoflower with Advanced Oxygen Reduction Reaction Performance for High-Sensitivity MicroRNA...

Herein, an efficient electrochemical tracer with advanced oxygen reduction reaction (ORR) performance was designed by controllably decorating platinum (Pt) (diameter, 1 nm) on the surface of compositionally tunable tin-doped indium oxide nanoparticle (Sn-In₂O₃) (diameter, 25 nm), and using the Pt/Sn-In₂O₃ as electrochemical tracer and interfacial term hairpin capture probe, a facile and ultrasensitive microRNA (miRNA) detection strategy was developed. The morphology and composition of the generated Pt/Sn-In₂O₃ NPs were comprehensively characterized by spectroscopic and microscopic measurements, indicating numerous Pt uniformly anchored on the surface of Sn-In₂O₃. The interaction between Pt and surface Sn as well as high Pt(111) exposure resulted in the excellent electrochemical catalytic ability and stability of the Pt/Sn-In₂O₃ ORR. As proof-of-principle, using streptavidin (SA) functionalized Pt/Sn-In₂O₃ (SA/Pt/Sn-In₂O₃) as electrochemical tracer to amplify the detectable signal and a interfacial term hairpin probe for target capture probe, a miRNA biosensor with a linear range from 5 pM to 0.5 fM and limit of detection (LOD) down to 1.92 fM was developed. Meanwhile, the inherent selectivity of the term hairpin capture probe endowed the biosensor with good base discrimination ability. The good feasibility for real sample detection was also demonstrated. The work paves a new avenue to fabricate and design high-effective electrocatalytic tracer, which have great promise in new bioanalytical applications.