Tape-assisted nanoplasmonic biosensors for facile protein-on-chip visualization and multiplexed point-of-care...

Visual point-of-care testing (POCT) technologies convert biomolecular events into naked-eye readable signals. These systems offer rapid assay times, user-friendly operation, and eliminate the need for specialized instruments, making them particularly valuable for clinical diagnosis, public health emergency response, and post-operative monitoring. Here, we report a tape-assisted plasmon-enabled (TAPE) sensor, which enables direct naked-eye visualization of protein-on-chip via a simple "physical" pasting step. Minimal thickness variations were transduced into visible signals through the plasmonic coupling effect. TAPE sensors enable highly sensitive, label-free protein quantification over a seven-order-of-magnitude dynamic range, as demonstrated by the accurate detection of hepatitis B surface antigen (HBsAg). The Limit of Confirmation (LoC) for detection of HBsAg is 2.80 ng mL^-1. This diagnostic capability extends to practical POCT applications, enabling the successful quantification of HBsAg in unprocessed whole blood (10 μL) within 30 min. Rigorous clinical validation, utilizing over 500 human serum samples, confirmed the reliability and robustness of this platform. Beyond single-analyte detection, the TAPE sensor exhibits remarkable versatility by enabling simultaneous high-throughput detection of six viral biomarkers (antigens and antibodies). Coupled with smartphone imaging and machine learning, this system offers a user-friendly diagnostic strategy. These features establish the TAPE sensor as a promising platform for advanced POCT diagnostics.