In vivo detection of gold-imidazole self-assembly complexes: NIR-SERS signal reporters

Here we report in vitro and in vivo detection of self-assembled Au−imidazole by using near-infrared surface-enhanced Raman scattering (NIR-SERS). In vivo, the Au−imidazole structures were administered into tumor-bearing mice and detected noninvasively. The self-assembled Au−imidazole complexes were generated by the adsorption of imidazole molecules onto Au nanoparticles (NP) and were then characterized as aqueous suspensions by using NIR-SERS, angle-dependent light scattering with fractal dimension analysis, and visible extinction spectroscopy. The structure and optical activity was sensitive to imidazole concentration and Au NP size. Specifically, the Au−imidazole assemblies formed at lower imidazole concentrations had the lowest fractal dimension (Df = 1.2) and the largest Raman enhancement factors for the dominant NIR-SERS feature, a ring-breathing vibrational mode at 954 cm-1. Changes in elastic scattering intensity, fractal dimension, and surface plasmon absorption were observed with increasing imida...