Detection of Exosomal MicroRNA with Hybrid Plasmonic Nanoheater‐Driven PCR for Pulmonary Fibrosis Progression

Pulmonary fibrosis (PF) is a severe respiratory disease, but early diagnosis of PF is challenging. Here, a non-invasive approach is developed to rapidly detect bronchoalveolar lavage fluid (BALF)-derived exosomal microRNAs (miRNAs) for PF progression based on hybrid nanoheater-driven digital polymerase chain reaction (nanodPCR). The hybrid nanoheaters, composed of plasmonic nanostructures and attached black hole quenchers (BHQs), generate a synergistic photothermal effect from the plasmonic field amplification. Gelatin microcarriers doped with such nanoheaters enable ultra-rapid thermal cycling (9.5 °C s^-1 heating rate) under near-infrared laser irradiation, which is sufficient for ultrafast thermal cycling. This rapid thermal cycling capability, coupled with fluorescence detection, allows precise quantification of exosomal miRNAs through nanodPCR, thereby facilitating longitudinal monitoring of PF progression with an ultrashort turnover time (8.8 min), nearly seven-fold faster than conventional PCR protocols (≈60 min). Compared with normal mice, expression of miR-142-3p and miR-21-5p in PF mice at different stages significantly increases over time, while let-7d-5p expression decreases. Furthermore, clinical validation in 40 PF patients through this nanodPCR platform identifies disease-stage-specific miRNA profiles from healthy controls. Therefore, this work not only presents a robust photothermal-driven PCR platform but also demonstrates the potential of BALF-derived exosomal miRNA as non-invasive biomarkers for PF progression.