Zeta cell

NPs (0.1 mg) were dispersed
in 800 μL of deionized water in a folded capillary Zetacell
(Malvern Panalytical, Worcestershire, U.K.). Nanoparticle hydrodynamic
diameter and zeta potential were then measured with a Malvern Zetasizer
ZS90 (Malvern Panalytical) instrument at room temperature. Regarding
serum- and antibody-related experiments, a 20:1 volumetric ratio of
0.1 mg of NPs to mouse serum, or 2 mg/mL of IgG antibody, was used.
NPs were incubated with either serum alone, or serum and subsequently
antibody, for 15 min each. Incubations were done under gentle agitation
at room temperature. All diameter and zeta potential values are averages
of three replicates.

To determine the hydrodynamic diameter (HDD) of the liposome populations, dynamic light scattering (Zeta Sizer Nano, Malvern Panalytical Ltd, Malvern, United Kingdom) was used. Briefly, 1 mL of the liposome suspension was placed in a zeta cell (Malvern Pananalytical, Westborough, MA, USA). The cell was placed in the Zeta Sizer Nano (Malvern Pananalytical) and set to calculate size and zeta potential at a refractive index of 1.450, absorption of 0, and suspension in PBS solution.