Large-scale synthesis of phenylboronic acid-functionalized gold nanoparticles enables an oriented antibody interface for sensitive point-of-care diagnostics

One-pot scalable synthesis of phenylboronic acid-modified AuNPs at room temperature. • Rapid Fc-oriented antibody immobilization enabled by boronate-affinity interaction. • The oriented bio-interface enhances lateral flow immunoassay sensitivity by 16-fold. • The developed LFIA enables reliable assay of fecal occult blood in clinical samples. • This method offers a promising platform for colorectal cancer point-of-care testing. The analytical performance of lateral flow immunoassay (LFIA) is largely determined by the bio-interfacial orientation of antibodies immobilized on colloidal gold nanoparticles (AuNPs). Conventional citrate-capped AuNPs (Cit-AuNPs), however, mainly rely on random physical adsorption, which often produces unfavorable antibody orientations and poor accessibility of antigen-binding sites. In addition, Cit-AuNPs typically require harsh high-temperature reflux synthesis and specialized equipment for large-scale production, increasing industrialization costs. Here, we report a facile one-pot, room-temperature strategy for the large-scale synthesis of phenylboronic acid-modified AuNPs (PBA-AuNPs), achieving 5 L batch production within 10 min. The obtained PBA-AuNPs exhibit excellent monodisperse and a uniform size of 23.5 nm, and enable an oriented antibody immobilization via boronate-affinity interactions with the carbohydrate moieties of Fc fragments. When applied to fecal occult blood (FOB) detection, the PBA-AuNPs showed a remarkable 16-fold improvement in sensitivity compared with Cit-AuNP probes. Overall, this work provides a robust, scalable nanoplatform with strong clinical translational potential for high-sensitivity LFIA diagnostics.