Table 1.

Parameters of gold nanoparticles applied to 3D cell culture models.

c(Au stock dispersion)/g/L	0.30
V(medium) per well/µL	100
V(Au stock dispersion) per well/µL	5
m(Au) per well/µg	1.50
c(Au) in a well/g/L	0.014
Particle molar concentration (d = 2 nm) in each well/µmol/L	0.29
Particle number concentration (d = 2 nm) in each well/L	1.73 × 1017
Particle number (d = 2 nm) in each well	1.82 × 1013
Dye molecules in each well	1.64 × ·1014

For dissolved FAM-alkyne as control, the same molecular concentrations were used. The gold nanoparticles had a diameter of 1.57 ± 0.62 nm by DCS (lower than the core diameter due to the special characteristics of DCS with ultrasmall particles; see Ref.⁵⁴), of 2.28 ± 0.32 nm by TEM, and carried 9 FAM molecules per nanoparticle. Dynamic light scattering (DLS) was not possible due to the small particle size. Based on ¹H-DOSY results of similar nanoparticles, we estimate the hydrodynamic diameter to 3–4 nm (see Ref.³⁰ for a full characterization of the particles).