Portable miRNA profiling of sepsis-associated exosomes via a novel DNA molecular lock-mediated nanobiosensor

Sepsis represents a life-threatening systemic inflammatory condition characterized by organ dysfunction, where the identification of specific biomarkers and development of effective diagnostic modalities are critical for timely clinical intervention to mitigate disease progression. Emerging evidence positions exosomal microRNAs (exomiRs) as promising novel biomarkers with multi-dimensional clinical utility spanning early diagnosis, therapeutic efficacy assessment, and longitudinal prognostic monitoring in sepsis management. However, the direct rapid detection of exomiRs in clinical specimens undergoes severe critical challenges due to the absence of robust detection methodologies with these characteristics of operational simplicity, high sensitivity and analytical robustness. Here, we designed and constructed a hairpin/loop-constrained three-dimensional topological self-assembling nanostructure, which was denoted as DNA molecular lock (DML), and developed a spatially allosteric-mediated electrochemical nanobiosensor for ultrasensitive and specific analysis of exomiR-125b. This independent, rapid, and portable detection method, combined with Ti 3 C 2 T x MXene/AuAgNPs nanozymes, achieved excellent sensitivity with a linear range from 2 fM to 200 nM and a low detection limit of 0.15 fM. It provided required low-volume plasma samples (2 mL) for analysis while supported Bluetooth-enabled wireless communication and real-time data processing. Furthermore, integration of machine learning algorithms with this developed nanobiosensor improved differential diagnostic accuracy to 96.6 % in the training cohort ( n  = 83) and 89.2 % in the validation cohort ( n  = 57), effectively distinguishing sepsis patients (SPs), general inflammation patients (GIPs), and healthy donors (HDs). Our study establishes the sensor's efficacy in improving sepsis detection through biomarker-guided analysis. These findings highlight the potential application of this developed nanobiosensors for portable, personalized bedside monitoring of exomiRs as the point-of-care testing (POCT) platforms.