He ne 633 nm laser module

The D_h of nanoparticles was determined by DLS. Typically, an aqueous nanoparticle solution was measured with a Malvern Zetasizer NanoS instrument equipped with a 4 mW He-Ne 633 nm laser module at 25 °C. Measurements were carried out at a detector angle of 173° (back scattering). Data were analyzed by the Malvern DTS 6.20 software. D_h was calculated by fitting the apparent diffusion coefficient in the Stokes–Einstein equation D_h=kT/(3πηD_app), where k is the Boltzmann constant, T is the temperature and η is the viscosity of the solvent. D_h coincides with the hydrodynamic diameter when the sample is made of monodispersed spherical particles (D_app equals the translational diffusion D_t).

Dynamic light scattering (DLS) was measured on a Zetasizer ZS (Malvern Panalytical, Worcestershire, UK). Measurements were carried out using a 4 mW He-Ne 633 nm laser module operating at 25 °C at an angle of 173° (back scattering), and results were analyzed using Malvern DTS 7.03 software. All determinations were repeated in triplicate with at least three measurements recorded for each run.