Ultrasensitive Electrochemiluminescence Biosensor Based on G‐quadruple Structure Targeted with Platinum(II) Complexes for Early Biomarker Detection of Disease

The determination of biomarkers is of key importance for the early diagnosis and treatment of diseases. However, it remains a tremendous challenge for rapid, accurate and real time detection of biomarkers at the early stage of diseases due to its extremely low content and serious interference. Herein, ultrasensitive electrochemiluminescence (ECL) biosensor is successfully constructed through specific binding between morpholinyl‐functionalized emissive Pt(II) (M‐Pt) nanocomplexes with aggregation‐induced emission and ECL properties and G‐quadruplex DNA via π–π stacking interactions. Combined with catalytic hairpin assembly, the ultrasensitive ECL biosensor is utilized to detect miRNA‐21 at early diseases. The biosensor can acquire ≈5‐fold ECL signal enhancement in the presence of miRNA‐21 compared with that in the absence of miRNA‐21 and has high sensitivity, wide linear range (1 f m –100 p m ), low limit of detection (≈0.33 f m ) and good stability and selectivity. The ultrasensitive ECL biosensor is successfully applied to determine miRNA‐21 in the urine samples of early‐stage kidney patients and has great prospects for universally screening any kind of biomarkers with corresponding specific targets.