Colour tuneable anisotropic, water-dispersible gold nanoparticles stabilized by chitosan

Abstract

We present a novel one-pot synthesis of stable water dispersible multi-branched anisotropic gold nanoparticles using hydrazine as the principal reducing agent and chitosan as the secondary reducing agent, growth directing agent and stabilizer. They are colour tuneable in the purple to blue range due to the presence of both transverse and longitudinal overlapping localized surface plasmon resonance (LSPR) absorptions arising from the multi-branched nanoparticle morphology. The longitudinal LSPR absorbance tails into the near IR range. This provides a simple alternative approach to producing anisotropic gold nanoparticles.