In situ controllable heterojunction conversion strategy driven by oriented paper-based fluid transfer for human immunoglobulin G detection.

Mercury ions (Hg2+) mediating in situ heterojunction formation strategy based on spatially separated dual working areas was developed to achieve sensitive detection of human immunoglobulin G. To be specific, the complex of antibody, the silicon dioxide, and thymine-rich hairpin DNA were immobilized onto the antigen and antibody-modified electrodes, forming a special sandwich type where T-Hg2+-T structure could accommodate Hg2+. The zinc ions from zinc sulfide (ZnS) photoelectric materials were captured by Hg2+ to convert ZnS to zinc sulfide-mercuric sulfide nanocomposite. Such ion exchange approach with spatially separated working electrodes endowed the sensing platform with lower background interference and high selectivity, which also avoided damage of illumination on biomolecules. In addition, by regulating the ion recognition probe, the protocol could be extended to numerous other fields like clinical diagnosis, environmental monitoring, and public safety.