Gold peptide is an antigen used in immunoassay to reveal the presence of antibodies and other biospecific probes. The peptide is conjugated to an antibody or other biotinyl probe and bound to the surface of a membrane by a lectin, enzyme, or avidin, which facilitates a detection system such as a blot or dot assay. This allows for the direct detection of biologically active agents that can be used in the diagnosis and treatment of diseases. Such biospecific probes include antibodies, Fab- and scFv-antibody fragments, aptamers, and other ligands.
The gold peptide-gold nanoparticle (GNP) conjugation method is used in cancer diagnostics as well as other medical applications. It has been shown that conjugation of GNP with aptamers or antibodies increases the specific accumulation of nanoparticles in tumors compared to non-conjugated gold NPs. However, the mechanism of targeted cellular uptake remains to be fully understood.
In this study, we investigate the ability of GNP to bind P45 and P46 peptides at pHs above their pI through surface enhanced Raman scattering (SERS). The results show that conjugation of the peptides to gold NP does not destabilize them. Although the P44- and P45-modified gold particles exhibited some minor aggregation in solution, when the excess peptide was removed and the particles resuspended at pH 4 or 11, no significant aggregation was observed.
Furthermore, molecular dynamic simulations showed that the peptides adsorb and interact with the gold NP surface. This interaction is governed by the relative size of the peptides and their isoelectric points. Interestingly, the NC and NCL peptides are less flexible when conjugated to the NP than their free counterparts.