Highly sensitive surface-enhanced Raman spectroscopy (SERS) platform using core/double shell (Ag/polymer/Ag) nanohorn for proteolytic biosensor

Sensitive detection platforms have recently gathered more interest due to its ability to make an early diagnosis of several diseases, which increases the chances of successful treatment. Although several highly sensitive platforms have been developed, improvements are needed to reduce their reaction time and cost. In this study, we established a surface-enhanced Raman spectroscopy (SERS)-based ultrasensitive platform by using SERS-active hollow polypyrrole (hPPy) nanohorn and peptide-functionalized gold nanoparticles (AuNPs). To create a SERS-active platform, we deposited silver on the inside and outside of the hPPy nanohorn surface; this resulted in the formation of core/double-shells Ag/polymer/Ag nanostructures. In addition, peptide-functionalized AuNPs functionalized with Raman dye was pre-immobilized on the Ag/hPPy/Ag nanohorn to enhance the signals and skip additional steps for the biomolecular detection. Using this SERS-sensitive novel core/double-shell nanohorn platform, we enhanced the Raman signal and improved the sensitivity of caspase-3, which is associated with several diseases, and achieved a broad detection range from 10 pg/ml to 10 µg/ml. We suggest that the highly sensitive and simple detection of this nanohorn platform can be widely applied for sensitive detection of proteolytic biomarkers and early diagnosis of several diseases.