Stable conjugates of peptides with gold nanorods for biomedical applications with reduced effects on cell viability.

Gold nanorods used in therapy and diagnosis must be nontoxic and stable in biological media and should be specific for the target. The complete combination of these three factors has hindered the use of gold nanorods as carriers in biological and biomedical applications. In this study, we produced a conjugate of gold nanorods with the peptide CLPFFD that recognizes toxic β-amyloid aggregates present in Alzheimer's disease, demonstrates colloidal stability, maintains plasmonic properties, and shows no effects on cell viability in the SH-SY5Y cell line. Furthermore, the irradiation of β-amyloid in the presence of the conjugate with near-infrared region irradiation energy reduces the amyloidogenic process reducing also its cytotoxicity. The nanorods were synthesized following the seed-mediated method in cetyltrimethylammonium bromide (CTAB) and were conjugated with the N-terminal cysteine peptide, CLPFFD. The conjugate was exhaustively characterized using different techniques (Absorption spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and zeta potential). The effects on cell viability and cell penetration by transmission electron microscopy of the conjugate were evaluated. The chemisorption of the peptide on the surface of gold nanorods increases their stability and reduces their effects on cell viability.