Au@Ag-Au core@double shell SERS bioprobes for high-resolution tumor cells imaging

Surface-enhanced Raman spectroscopy (SERS) technique with high sensitivity and specificity, exhibits huge ap-plication potential in tumor cells imaging. In this work, Au@Ag-Au core@double shell bimetallic nanoparticles (Au@Ag-Au NPs) with excellent biocompatibility and good SERS activity were successfully designed and pre-pared, and Au@Ag-Au NPs showed uniform size and shape. The results of UV-vis spectra revealed that surface plasmon resonance (SPR) peak of Au@Ag-Au NPs generated bathochromic shift compared to that of Au@Ag NPs, inducing high SERS activity under 532 nm illumination. The limit of detection (LOD) for 4-mercaptobenzoic acid (4MBA) molecules adsorbed on Au@Ag-Au NPs was 5 x 10 -9 M, indicating this alloy nanostructure with good SERS detection sensitivity. Moreover, Au@Ag-Au NPs SERS substrate exhibited almost none toxicity from the methyl thiazolyl tetrazolium (MTT) assay results. Au@Ag-Au@4MBA SERS bioprobe was grafted with reduc-tive bovine serum albumin-folic acid (rBSA-FA), which improving SERS bioprobe stability, and providing specific recognition ability for tumor cells. Importantly, SERS imaging results of HepG2 cancer cells targeted with Au@Ag-Au@4MBA@rBSA-FA bioprobes demonstrated Au@Ag-Au NPs-based SERS bioprobe could effectively recognize tumor cells. This work indicated that high-resolution SERS imaging mode would play an important role in tumor imaging for cancer diagnosis.

Automated summary

In this work, Au@Ag-Au core@double shell bimetallic nanoparticles were successfully designed and prepared, showing uniform size and shape. The Au@Ag-Au NPs exhibited high SERS activity under 532 nm illumination due to the bathochromic shift of surface plasmon resonance peak. The SERS bioprobe based on Au@Ag-Au NPs effectively recognized tumor cells and could play an important role in cancer diagnosis.