Integrated magneto-plasmonic nanostructures-based immunoassay for galectin-3 detection

Cardiovascular diseases remain a leading cause of global mortality, highlighting the need for accurate diagnostic tools and the detection of specific cardiac biomarkers. Surface-enhanced Raman scattering (SERS) spectroscopy has proved to be a promising alternative diagnostic tool to detect relevant biomarkers compared to traditional methods. To our knowledge, SERS methodology has never been used to detect galectin-3 (Gal-3), a crucial biomarker for cardiovascular conditions. Our study aimed to develop plasmonic and magneto-plasmonic nanoplatforms for the sensitive immunodetection of Gal-3 using SERS. Spherical gold nanoparticles (AuNPs) were synthesized and functionalized with 11-mercaptoundecanoic acid (MUDA) to enable antibody binding and 4-mercaptobenzoic acid (4MBA) that served as a Raman reporter due to its intense Raman signal. Following bioconjugation with Gal-3 antibody, the AuNPs were employed in the immunodetection of Gal-3 in phosphate-buffer saline (PBS) solution, offering a limit of detection (LOD) of 12.2 ng mL^-1 and a working range up to 120 ng mL^-1. Furthermore, our SERS-based immunosystem demonstrated selectivity for Gal-3 (40 ng mL^-1) in the presence of other biomolecules such as α-amylase, bovine serum albumin and human C-reactive protein. As a proof of concept, we developed magneto-plasmonic nanoparticles composed of silica-coated magnetite decorated with the bioconjugated AuNPs aimed at enhancing the uptake and detection of Gal-3 via SERS coupled with Raman imaging. Our findings underscore the potential of SERS-based techniques for the sensitive and specific detection of biomarkers, holding significant implications for improved diagnosis and surveillance of cardiovascular diseases. Future research will focus on further optimizing these nanoplatforms and their translation into clinical settings.