Ms x series 2

Dynamic light scattering (DLS) and zeta potential (Malvern Zetasizer Nano ZS, Malvern, UK) measurements were used to determine the nanoparticles hydrodynamic radius (Supplementary Materials Table S1). Additionally, Fourier transform infrared spectroscopy (FTIR) microscopy (Thermo-Nicolet Magna 550, Waltham, MA, USA) was performed to confirm the successful addition of ligand onto the surface of the particles via cycloaddition click-chemistry reaction. Inductively coupled plasma optical mass spectrometry (ICP-MS; Thermo-Scientific MS X Series II, Waltham, MA, USA) was performed to determine the concentration of iron [33 (link)].

ICP-MS (Thermo Fisher Scientific MS X Series II, Waltham, MA, USA) was run using only ⁵⁶Fe for analysis with ⁴⁵Sc as an internal standard. Cell samples were incinerated at 700 °C for 6 h to burn off all organic material. Samples were then digested with Aqua regia (a mixture of nitric acid and hydrochloric acid at an optimal molar ratio of 1:3) to remove any residual organic/char. The remaining inorganic was digested with 70% nitric acid. The nitric acid was boiled off and the resulting nitrate salts were dissolved in a known volume of 2% nitric acid solution. Unknown samples were run against a known set of standards between 0.01 and 100 ppm iron to calculate the concentration.