Controlling the Nucleation and Growth of Au on a-Se Nanospheres to Enhance Their Cellular Uptake and Cytotoxicity

We report a method to experimentally control the heterogeneous nucleation and growth of Au nanoparticles on the surface of amorphous Se (a-Se) nanospheres. When a AuIII precursor is added into a colloidal suspension of a-Se nanospheres, galvanic replacement occurs between them and the resultant Au0 atoms then heterogeneously nucleate and grow from the surface of the a-Se nanospheres. As a unique feature of this system, the Au0 atoms can only be produced on the surface of the a-Se nanospheres in the nucleation stage. Once Au nuclei are formed on the surface at the very beginning of a synthesis, they will serve as the preferential sites for further deposition of Au0 atoms, making it possible to control the number of Au nanoparticles on each nanosphere and the morphology of the final product. The dependence of the initial reduction rate on the pH can be used to obtain Se-Au hybrid nanoparticles containing one, two, three, and multiple Au nanoparticles on the surface of each a-Se nanosphere. The presence of Au patches on the hybrid nanoparticles offers an experimental handle to optimize the ligand distribution for the achievement of enhanced cellular uptake and cytotoxicity for the a-Se nanospheres.

Automated summary

We present a method for controlling the nucleation and growth of Au nanoparticles on the surface of a-Se nanospheres. The Au0 atoms are only produced on the surface of the a-Se nanospheres during the nucleation stage, allowing us to control the number and morphology of the Au nanoparticles. By adjusting the pH, Se-Au hybrid nanoparticles containing different numbers of Au nanoparticles on each a-Se nanosphere can be obtained. The presence of Au patches on the hybrid nanoparticles can enhance cellular uptake and cytotoxicity of the a-Se nanospheres.