Highly Electroactive Sb-Doped BaSrFeO_3-δ Semiconductor as a Label-Free Electrochemical Aptsensing Platform for Thrombin Detection

Thrombin plays a crucial role in regulating normal hemostatic function and various internal body processes but is rarely detected in vivo because anticoagulant substances in the blood can quickly neutralize it after early-stage coagulation. In this article, we designed a novel perovskite semiconductor Ba $_{{0}.{5}}$ Sr $_{{0}.{5}}$ FeO $_{{3}-\delta }$ by a one-step hydrothermal method as a sensing platform maintaining electroactive characteristics that can be used to conjugate the bio-recognition of aptamers and auto-probing of binding events for highly sensitive thrombin detection. In particular, the introduction of 10% Sb-dopant into Ba $_{{0}.{5}}$ Sr $_{{0}.{5}}$ FeO $_{{3}-\delta }$ semiconductor to tune the energy band structure for fast transport of charged species. Further, the synthesized Ba $_{{0}.{5}}$ Sr $_{{0}.{5}}$ SbxFe1.0-xO3-δ ( ${x}={0}$ –0.1) materials are physically characterized via XRD, FE-SEM, HR-TEM assisted by EDS, XPS, UV-Vis, and UPS. Moreover, aptamer plays a key role in amplifying the electrical signal, where the prepared BaSrSb $_{{0}.{1}}$ Fe $_{{0}.{9}} 0_{{3}-{\delta }}$ particles show dispersion and aggregation upon binding with aptamers and target analyte thrombin, respectively, thereby increasing the sensitivity of the aptasensor. The electrostatic forces are responsible for making it complex between aptamers and particles, while conformational changes in aptamers pursue biomolecular binding of aptamer with thrombin. Accordingly, the electrochemical aptasensor for thrombin detection shows an impressive low limit-of-detection (LOD) of 0.02 pM in a dynamic linear range (0.05 pM–0.3 nM). The proposed electrochemical aptasensor does not require special labeling of oligonucleotides or particle surface decoration.