Nat Methods. 2014 Nov;11(11):1177-81. doi:10.1038/nmeth.3105

Rees P, Wills JW, Brown MR, Tonkin J, Holton MD, Hondow N, Brown AP, Brydson R, Millar V, Carpenter AE, Summers HD.

Nanoparticle vesicle encoding for imaging and tracking cell populations.

More than 17,000 individual codes with 3 colors.