Gold-Nanoparticle-Decorated Hybrid Mesoflowers: An Efficient Surface-Enhanced Raman Scattering Substrate for Ultra-Trace Detection of Prostate Specific Antigen

We demonstrate a method for making highly sensitive hybrid gold mesoflower (MF) based surface-enhanced Raman scattering (SERS) substrate via programmed assembly of spherical gold nanoparticles (AuNPs) onto a highly anisotropic silica-coated MF. This imparts a new signal enhancing mechanism for the ultrasensitive detection of molecules from highly complex molecular environments. This substrate has been utilized as an ideal platform for the detection of Raman features corresponding to the prostate specific antigen (PSA) of a concentration as low as 2.5 ng/mL without the aid of any labels. We also demonstrated the possible conformational modifications of PSA on the hybrid MF surface and the influence of various parameters on obtaining reproducible SERS spectra of proteins. This is critical in SERS based label-free detection of biomarkers from a diagnostic perspective.