Metallic Fe-Au Barcode Nanowires as a Simultaneous T Cell Capturing and Cytokine Sensing Platform for Immunoassay at the Single-Cell Level.

Barcode nanowires (BNWs) composed of multiple layered segments of different materials are attractive to bioengineering field due to their characteristics that allow the adjustment of physicochemical properties and conjugation with two or more types of biomolecules to facilitate multiple tasks. Here, we report a metallic Fe (iron)-Au (gold) BNW-based platform for capturing CD8 T cells and the interferon-γ (γ) they secrete, both of which play key roles in controlling infectious diseases such as tuberculosis, at the single-cell level. We also describe an efficient approach for conjugating distinct antibodies, which recognize different epitopes to appropriate materials. The platform achieved detection even with 4.45-35.6 μg mL-1 of BNWs. The T cell capture efficiency was close to 100% and the detection limit for interferon-γ was 460 pg mL-1. This work presents a potential guideline for the design of single-cell immunoassay platforms for eliminating diagnostic errors by unambiguously identifying disease-relevant immune mediators.