A Locked Aptamer-Magnetic Nanoparticle Assay for Cardiac Troponin I Classification to Support Myocardial Infarction Diagnosis in Resource-Limited Environments

Clinical classification of cardiac troponin I (cTnI) levels is essential for accurately diagnosing acute myocardial infarction. This study introduces an innovative point-of-care test that combines an engineered locked aptamer, magnetic nanoparticle and isothermal, non-enzymatic hybridization chain reaction with surface-enhanced resonance Raman scattering for the sensitive and specific detection of cTnI at clinically significant concentrations. This high sensitivity cTnI assay enabled accurate quantification of cTnI in 25 μL of cTnl doped serum, with a detection limit of 0.403 ng/L and a quantification limit of 1.22 ng/L with a dynamic range spanning from 0.5 ng/L to 50,000 ng/L. Further, optimized to classify cTnI levels beyond the established clinical threshold of 40 ng/L, the assay demonstrates its efficacy by accurately distinguishing between healthy and unhealthy individual clinical samples, achieving over 83 % accuracy and 86 % precision. This approach represents a significant advancement in the point-of-care diagnosis of myocardial infarction, offering a rapid, reliable, and accessible diagnostic tool for cardiac troponin testing.