PLA-Coated Gold Nanoparticles for the Labeling of PLA Biocarriers

Poly-DL-lactide end-capped by a protected thiol was synthesized by bulk ring-opening polymerization (ROP) of DL-lactide initiated by the reaction product of aluminum isopropoxide [Al (iOPr) 3] with (alpha)(2,4-dinitrophenylsulfenyl) ethanol. After the thiol deprotection, PLA-SH was used to stabilize gold nanoparticles. Either these nanoparticles were prepared in the presence of PLA-SH, or PLA-SH was substituted for part of the undecanethiol (C11SH) that stabilized preformed gold nanoparticles. In contrast to C11SH-coated nanoparticles, those stabilized by PLA-SH were successfully entrapped into 100-nm PLA nanocarriers prepared by nanoprecipitation. This is an easy technique to label PLA biocarriers and therefore trace their fate in vivo.