(a) Biodistribution of DiR dye-labelled GNVs administrated subcutaneously (s.c.), intraperitoneally (i.p.), i.v. and intramuscularly (i.m.) to mice. (b) In vivo stability of DiR dye-labelled GNVs was determined by scanning (Odyssey scanner) each organ of mice that received an i.v. injection of DiR-labelled GNVs. (c) In vivo stability of circulating GNVs was determined by scanning (Kodak Image station) peripheral blood of mice injected i.v. with DiR dye-labelled GNVs. (d) Pregnant mice were injected i.v. with DiR dye-labelled GNVs 1 (1 × , left) or 5 times (5 × , right), the DiR signals (arrow indicated) in fetus and placenta (circled dotted line) were detected using a Kodak Image Station. (a–d) A representative image from each group of mice is shown, and followed by graphical figures presented as the mean net intensity (sum intensity/area, n=5). Data are representative of at least five independent experiments.