All-printed immunosensing microchip for fast and sensitive detection of urinary soluble Fms-like tyrosine kinase-1 in preeclampsia diagnosis.

We present an all-printed immunosensing microchip that integrates hydrophilic-hydrophobic patterning, covalent antibody immobilization, and photonic bandgap engineering into a single, scalable manufacturing platform for high-sensitivity protein detection. By precisely matching the microchip's photonic bandgap (centered at 680 nm) to the emission maximum of Cy5, the platform achieves an approximately 18.5-fold fluorescence enhancement, enabling a limit of detection of 3.61 pg mL-1 for the preeclampsia biomarker soluble Fms-like tyrosine kinase-1 (sFlt-1) using only 10 µL of urine, offering substantially enhanced sensitivity compared to conventional ELISA. The fully printed fabrication strategy eliminates the need for cleanroom facilities or manual assembly, allowing for cost-effective, substrate-independent production while maintaining rapid assay times (10 min) and high reproducibility. Clinical validation in 60 participants (30 preeclampsia patients and 30 healthy controls) confirmed the platform's diagnostic accuracy and strong correlation with blood pressure. This work establishes a generalizable, all-printed nanophotonic biochip that bridges the gap between high-performance optical biosensors and scalable, point-of-care deployable devices, offering a new materials framework for decentralized diagnostic applications.