Cardiac troponin detection in one drop of saliva or urine for 10-minute assessment of acute myocardial infarction

Acute myocardial infarction (AMI) can be fatal with sudden death, heart failure, and cardiac rupture. However, it is a challenge to achieve point-of-care testing (POCT) for cardiac troponin T (CTnT), an acute myocardial infarction biomarker, using conventional ELISA because it requires professional expertise and involves time-consuming steps. Herein, we propose a printed immunosensing photonic crystal biochip (PCB), which enables the sensitive, convenient, and non-invasive detection of CTnT. The fluorescence enhancement property of the PCB enables detection of CTnT within 10 minutes, with a limit of detection of 0.25 pg mL^-1, compared to the conventional ELISA (2.5 h, 30 pg mL^-1). Owing to the hydrodynamic enrichment of the PCB, 10 μL of sample can be measured, minimizing interference from impurities in body fluids and human sampling errors. We used 100 clinical samples, including serum, saliva, and urine, to verify the reliability of the PCB assay; compared with ELISA, the PCB assay exhibited consistencies of 0.998, 0.999, and 0.999, respectively. Notably, monitoring the saliva of a patient with an AMI history using the PCB assay enables rapid therapeutic intervention within 30 minutes. The PCB was first used for non-invasive body fluid testing to provide reliable results for clinical diagnosis, with the potential to provide AMI health promotion.