Optical Properties of Fluorescent Tags Based on Gold Nanoparticles at Physiological Salt Content: In Vitro and In Vivo Study

The study describes the optical properties of fluorescent tags based on gold nanoparticles coated with a polymer shell with incorporated cyanine 5.5 in water and medium with a physiological salt background. The radiant efficiency was assessed by fluorescence tomography for the tag suspensions placed in a black plate and after their local subcutaneous injection into ICR mice. Partial aggregation of tags is noted, which occurs at changing water on isotonic solution, which leads to the increase of dye fluorescent intensity. In vivo imaging was performed in a bimodal fluorescence and computed tomography regime with varying the dose of the tags. The fluorescence enhancement 30 min after the tags injection was revealed. Computed tomography images allow reliable identification of the area of gold tags localization when their content in the injected suspension is at least 23.7 mg/mL.