Aptamer-modified magnetic SERS substrate for label-based determination of cardiac troponin I

A sensitive label-based SERS strategy composed of magnetic bimetallic nanoparticles Fe3O4@Ag@Au, specific aptamer, and Bradford method was developed for the quantitative determination of cardiac troponin I (cTnI) in human serum. The prepared substrate with high magnetic character, signal enhancement, and uniformity exhibited significant Raman response. After the substrate was bound to the aptamer, the target protein cTnI was specifically captured, and it showed the Raman signal when the signal reporter Coomassie Brilliant Blue G-250 (CBBG) was supplied. The Raman signal intensity at 1621 cm(-1) showed a wide linear relationship with the log value of the cTnI concentration in the range 0.01 to 100 ng.mL(-1), and the estimated limit of detection (LOD) was 5.50 pg.mL(-1). The recovery and relative standard deviation (RSD) of the spike experiment in human serum samples were 92-115% and 7.4-12.7%, respectively.

Automated summary

A sensitive label-based SERS strategy was developed for the quantitative determination of cTnI in human serum. The strategy utilized magnetic bimetallic nanoparticles as the substrate, specific aptamer for target protein capture, and the Bradford method for signal enhancement. The Raman signal intensity showed a linear relationship with cTnI concentration, and the LOD was estimated to be 5.50 pg.mL(-1).