An Alternating Current Electroosmotic Flow‐Based Ultrasensitive Electrochemiluminescence Microfluidic System for Ultrafast Monitoring, Detection of Proteins/miRNAs in Unprocessed Samples

Abstract Early diagnosis of acute diseases is restricted by the sensitivity and complex process of sample treatment. Here, an ultrasensitive, rapid, and portable electrochemiluminescence‐microfluidic (ECL‐M) system is described via sandwich‐type immunoassay and surface plasmonic resonance (SPR) assay. Using a sandwich immunoreaction approach, the ECL‐M system employs cardiac troponin‐I antigen (cTnI) as a detection model with a Ru@SiO 2 NPs labeled antibody as the signal probe. For miR‐499‐5p detection, gold nanoparticles generate SPR effects to enhance Ru(bpy) 3 2+ ECL signals. The system based on alternating current (AC) electroosmotic flow achieves an LOD of 2 fg mL −1 for cTnI in 5 min and 10 aM for miRNAs in 10 min at room temperature. The point‐of‐care testing (POCT) device demonstrated 100% sensitivity and 98% specificity for cTnI detection in 123 clinical serum samples. For miR‐499‐5p, it exhibited 100% sensitivity and 97% specificity in 55 clinical serum samples. Continuous monitoring of these biomarkers in rats' saliva, urine, and interstitial fluid samples for 48 hours revealed observations rarely documented in biotic fluids. The ECL‐M POCT device stands as a top‐performing system for ECL analysis, offering immense potential for ultrasensitive, rapid, highly accurate, and facile detection and monitoring of acute diseases in POC settings.