Geometry and surface characteristics of gold nanoparticles influence their biodistribution and uptake by macrophages

Abstract

Spherical and rod-shaped gold nanoparticles with surface poly(ethylene glycol) (PEG) chains were characterized for size, shape, charge, poly dispersity and surface plasmon resonance. The nanoparticles were injected intravenously to 6-8-week-old female nu/nu mice bearing orthotopic ovarian tumors, and their biodistribution in vital organs was compared. Gold nanorods were taken up to a lesser extent by the liver, had longer circulation time in the blood, and higher accumulation in the tumors, compared with their spherical counterparts. The cellular uptake of PEGylated gold nanoparticles by a murine macrophage-like cell line as a function of geometry was examined. Compared to nanospheres, PEGylated gold nanorods were taken up to a lesser extent by macrophages. These studies point to the importance of gold nanoparticle geometry and surface properties on transport across biological barriers.

Figure 1

Representative TEM images of PEGylated gold nanospheres (A) and rods (B). PEGylated gold nanospheres were uniform in size and shape whereas there was 6% shape discrepancy for nanorods (See Table 1 for physicochemical characteristics of the particles).

Figure 2

Bioditribution of gold nanoparticles in non metastatic orthotropic ovarian tumor bearing mice. A) nanorods, B) nanospheres. n=3 +/− SEM.

Figure 3

Comparison of plasma profile (A), distribution in liver (B) and tumor (C) of rod and spherical particles as a function of time. n=3+/− SEM.* = significant difference between rod and spherical particles p<0.05.

Figure 4

Uptake of gold nanoparticles by RAW 264.7 macrophages expressed as the amount of gold detected by ICP-MS normalized to mg of protein. n=3 +/− SD. * = significant difference between uptake of rod and spherical particles, p<0.01.

Figure 5

Interaction between gold nanoparticles with bovine serum albumin expressed as quenching efficiency (I°/I), where I° and I are fluorescence in the absence and presence of gold nanoparticles.

Figure 6

Comparison of uptake of gold nanoparticles by RAW 264.7 macrophages in the presence and absence of serum expressed as the amount of gold detected by ICP-MS normalized to mg of protein. R = rod; S= spherical; n=3 +/− SD, * = p < 0.01.