An “Enrichment-Detection” Electrochemiluminescence Biosensor Based on Bifunctional Nanozymes for Quantitative Detection of Exosomes with PD-L1

Exosomes with high programmed death ligand 1 expression (PD-L1⁺ exosomes) have proven instrumental in both screening non-small cell lung cancer (NSCLC) patients and forecasting responses to immune checkpoint inhibitors (ICIs). Nonetheless, effectively isolating from complex biological samples and achieving high sensitivity in analysis remain significant challenges in the detection of PD-L1⁺ exosomes. Herein, we innovatively constructed an "Enrichment-Detection" electrochemiluminescence (ECL) biosensor for quantitative detection of PD-L1⁺ exosomes based on an enzyme-mimicking magnetic mesoporous silica-palladium (MMS@Pd) bifunctional nanozymes (BFNs). Specifically, the MMS@Pd BFNs were synthesized through the interface coassembly reduction method, wherein Fe₃O₄ functioned as a magnetic harvester, and the mesoporous structure offered ample binding sites for Pd. Delightfully, the synthesized MMS@Pd BFNs demonstrated both magnetic and peroxidase-like activities. With rational design, an ECL biosensor developed by using MMS@Pd BFNs exhibited the capability to enrich and detect PD-L1⁺ exosomes. The analytical results reveal that the integrated dual-functional ECL biosensor exhibits a wide detection range of 1 × 10³ to 1 × 10⁹ particles/mL with a detection limit of 69.66 particles/mL. Overall, the ECL biosensor demonstrated excellent detection performance in the analysis of clinical samples, offering an innovative strategy for the diagnosis and treatment of NSCLC.