Self-Assembly of Uniform Branched Gold Nanoparticles Induced by Using Thiol-Terminated Poly(ethylene glycol)

摘要

Branched gold nanoparticles with a sufficiently monodisperse distribution of size and shape were successfully synthesised using a tree-type multi-amine-head surfactant (C18N3) with a 100% yield using a seed-mediated method. C18N3 coated branched gold nanoparticles possess a positive zeta potential of similar to 40eV, which can keep branched gold nanoparticles stable in aqueous solution for several months without precipitation and transfiguration. However, C18N3 molecules were partially replaced by thiol-terminated poly(ethylene glycol) (mPEG-SH), due to the branched morphology of the as prepared gold nanoparticles, to make branched gold nanoparticles passivated by the adsorbing polymer with a positive zeta potential (17eV). The mPEG-SH passivated branched gold nanoparticles behaved as quasi-hard particles to overcome the restrictions of the rotational and positional degrees of freedom in neighbouring nanoparticles at high volume fractions, which favours the hydrophilic thiol-terminated poly(ethylene glycol) polymer passivated branched gold nanoparticles to self-arrange into close-packed 2D ensembles. Thus, the as prepared branched gold nanoparticles and their ensembles possess significant potential in bio-labelling, imaging, biosensing, therapeutic applications, and surface-enhanced Raman scattering.