Size tuning of Au nanoparticles formed by electron beam irradiation of Au₂₅ quantum clusters anchored within and outside of dipeptide nanotubes

Glutathione protected Au₂₅ quantum clusters, exhibiting characteristic fluorescence, have been uniformly coated inside and outside of β-Ala-L-Ile dipeptide nanotubes. These coated structures have been imaged using the inherent fluorescence of Au₂₅. Upon exposure to an electron beam, in a transmission electron microscope, the quantum clusters gradually transform to gold nanoparticles, of the metallic size regime. The nanoparticles grow to a size of 4.5 nm and thereafter the particle size is unaffected by electron beam exposure. The nanotubes are intact and this template is shown to control the uniformity of the size of the nanoparticles grown. The quantum clusters can be loaded selectively inside the tubes using capillarity of the nanotubes. The sizes of the nanoparticles grown are tuned using electron beam exposure.