Simple diagnosis of HbA1c using the dual-plasmonic platform integrated with LSPR and SERS

A plasmonic active chip was designed with a transparent polymer film self-assembled with gold nanoparticles (AuNPs). In this study, we demonstrated the feasibility and sensitivity of biosensors by employing a plasmonic resonance technique. AuNPs are widely used as biosensing probes because they facilitate stable immobilization of biomolecules. Transparent polymer film facilitated measurement of changes in absorbance via transmitted light and analysis of Raman scattering via scattered light. The cysteine rich protein G and anti-HbA1c were sequentially conjugated to self-assembled AuNPs on the transparent polymer film to detect a target protein. HbA1c, which is used as an indicator for diabetes diagnosis, was selected for target protein detection. We confirmed the linearly increased absorbance values with increasing HbA1c level (3.19-14.0%) by LSPR detection. We also verified the linear increase in SERS intensity as the concentration of anti-Hb increased from 10 ng mL−1 to 1 μg mL−1 by analyzing the SERS spectra of Cy3 labeled anti-Hb added substrates.