Gold nanoparticle quantitation via fluorescence in solution and cell culture.

This chapter provides a protocol for quantitative analysis of gold in solution as well as gold uptake by macrophages. A 96-well fluorescence assay was developed to be able to determine gold concentrations for a given gold nanoparticle as well as quantify the degree of gold nanoparticle uptake by macrophages. This assay detects a decrease in the fluorescence of a dye upon forming a complex with gold and a ligand. The decrease in fluorescence is proportional to the amount of gold. This protocol provides a preliminary and qualitative first-step alternative for the determination of gold nanoparticle concentration without requiring expensive, time-consuming methods such as inductively coupled plasma mass spectroscopy. This protocol can be used to support the uptake studies by the light microscopy method described in Chapter 23. This assay requires 200 μL of each test nanoparticle at a concentration of the users choosing. Up to 32 variations of test nanoparticles can be evaluated in duplicate in one assay run.