A novel immunosensor platform based on inorganic BST film for point-of-care application

In this investigation, we present a novel label-free immunosensor platform based on inorganic barium strontium titanate (BST) thin film and interdigitated microelectrodes for clinical point-of-care application. The immunosensor is based on non-faradaic process, using DI water as electrolyte. As proof of concept, anti-human IgG, a common biomarker found and associated with many diseases was immobilized on the chemically modified BST film surface as sensing probe for human IgG detection. The BST immunosensor was also used for real clinical sample with pre-inactivated dengue virus as sensing probe to detect dengue antibody in human serum. Good linear correlations were observed for the measured electrical signals, AC impedances or current changes, versus the dilution of the human IgG concentration or the dengue serum samples. The measured signal changes in impedance/current without/with the presence of antibody were attributed to the surface conductivity change upon biomolecules immobilization and the dipole-induced interfacial polarization potential at the BST film/biomolecules interface. Promising specificity was proven with the interference tests by mixing human IgG solution with BSA and rabbit IgG. The performance of BST immunosensors exhibited good long-term stability with very low fluctuation/degradation even after storing dry at 4°C for 60 days.