A novel Apt-SERS platform for the determination of cardiac troponin I based on coral-like silver-modified magnetic substrate and BCA method.

As a kind of acute cardiovascular disease, acute myocardial infarction (AMI) endangers human's life and fitness seriously. The detection of cardiac troponin I (cTnI), a biomarker of AMI, is the key to early medical prognosis and treatment. Surface-enhanced Raman spectroscopy is viewed to be an effective approach for detection of low-concentration substances, and aptamers are regarded to be effective fragments to recognize proteins specifically. In this work, a magnetic nanoparticle substrate coated with coral-like nano-silver was prepared, and the aptamer-modified substrate FeO@PEI/Ag NC-Apt was used as magnetic capture probe. Combined with BCA method and SERS detection technology, an Apt-SERS platform was successfully constructed and used for high sensitivity quantitative detection of protein. Taking cTnI as the target, the detection range of the proposed Apt-SERS platform was 0.001-100 ng mL, and the estimated detection of limit (LOD) was 0.23 pg mL. The recovery and relative standard deviations (RSD) of spiked experiment in human serum samples were 92-106% and 3.8-10.1%, respectively. The platform combining BCA method and SERS provides a high sensitivity and good reproducibility method for cTnI detection, which offers a new method for the specific detection and analysis of proteins.