Fluorescence Aptasensor for sST2 Detection Using In Vitro Selected Aptamers

Soluble suppression of tumorigenicity 2 (sST2) is a critical biomarker for heart failure (HF) diagnosis and prognosis, yet conventional antibody-based detection methods suffer from time-consuming protocols and high costs and involve complex detection procedures. To address these challenges, we first screened high-affinity aptamers under clinically relevant conditions and then coupled with the CRISPR/Cas12a system to develop a fluorescence aptasensor for rapid and sensitive sST2 detection. A serum matrix was introduced during aptamer selection to enhance specificity and anti-interference performance in real biological environments. Three sST2-specific aptamers (Apt-1, Apt-2, and Apt-3) were identified with dissociation constants (K_D) of 8.42, 46.08, and 25.02 nM, respectively. Among these, Apt-1 demonstrated superior performance, which was utilized to construct a fluorescence biosensor combining aptamer recognition with CRISPR/Cas12a trans-cleavage signal amplification. The sensor achieved a broad linear detection range (5-120 ng/mL) and an ultralow limit of detection (LOD, 0.816 ng/mL) when applied in detecting sST2 in both the buffer and human serum. Notably, the platform exhibited exceptional resistance to interference from HF-related proteins and maintained high accuracy in clinical serum samples, showing a strong correlation (R² = 0.9794) with enzyme-linked immunosorbent assay (ELISA) results. By integration of serum-matrix screening and CRISPR-based signal enhancement, this work establishes a robust, cost-effective, and rapid diagnostic tool for sST2 detection.