Photoinduced Immobilization on Two-Dimensional Nano Borophene Spatially Orients Capture Antibody for Highly Sensitive Biological Interactions.

Two-dimensional (2D) nanomaterials are of great interest due to their unique properties and broad biological applications. Among these, borophene, a single-atom-thick boron sheet with a honeycomb structure, exhibits exceptional structural, electronic, and mechanical characteristics, making it a promising candidate for sensing, electronics, and biosensing. In this study, we report on a liquid-phase exfoliation method to synthesize stable borophene nanosheets and introduce a photoinduced immobilization technique to functionalize their surfaces with antibodies. By exploiting borophene's electron-deficient nature, we enable strong covalent bonding with electron-rich thiol groups in antibodies. UV irradiation cleaves antibody disulfide bonds, generating free thiols that form stable boron-sulfur bonds with borophene, resulting in spatially oriented antibodies that preserve antigen-binding activity. We demonstrate the application of these functionalized nanosheets in a lateral flow immunoassay (LFIA), a key tool in point-of-care diagnostics that is often limited by poor antibody orientation. The developed LFIA detects HMGB-1, a potential endometriosis biomarker, in menstrual effluent with results in 10 min and a limit of detection of 40 pg/mL. This performance surpasses that of conventional LFIAs, showing high sensitivity, specificity, and no cross-reactivity with common blood proteins. This study highlights a novel, reagent-free strategy for functionalizing borophene, enhancing its potential in biosensing applications.